These mini packets contain silicon dioxide, which dries out anything around it.
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Opals are essentially spheres of silicon dioxide with water combined into their chemistry.
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Ultimately that meant layering 90 nano-scale layers of tantalum oxide and silicon dioxide.
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It's a material that's mostly air by volume, trapped by a network of silicon dioxide.
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It may start in the Appalachian mountains, where deposits of silicon dioxide are of the highest quality.
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The products use silicon dioxide, which repels water and dirt, giving your car a longer-lasting clean.
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An intermediate type of magma, at about 55 to 65 percent silicon dioxide, ranges from 13,472 to 1,832 degrees Fahrenheit.
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This ultra‑elite deposit of silicon dioxide particles plays a key role in manufacturing the silicon used to make computer chips.
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Most of the world's sand grains are composed of quartz, which is a form of silicon dioxide, also known as silica.
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UPDATE on 3/20/2020: I've tried other silicon dioxide-based sprays after using 303 Touchless Sealant, and they haven't compared.
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They determined that the moon had a global ocean, and then a cosmic dust analyzer revealed silicon dioxide grains, indicating warm hydrothermal activity.
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Their material, though, consisted of seven alternating layers of hafnium dioxide and silicon dioxide of varying thicknesses, laid onto a wafer made of silicon.
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Also used are silicon dioxide and nitride, which are harmless, and a compostable polymer made of corn and potato starch holding it all together.
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This form of silicon dioxide was only discovered in 1976, and it exists as crystal-like structures within the cracks and fracture fillings of rocks.
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CementCCNMass %Calcium oxide, CaOC61–67%Silicon dioxide, SiO2S19–23%Aluminum oxide, Al2O103A 2.5–6%Ferric oxide, Fe2O3F 0–6%SulfateS̅1.5–4.5%CCN = Cement chemist's notation.
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The mafic or basaltic magma, which is only about 45 to 55 percent silicon dioxide, can be a very hot 1,832 to 2,192 degrees Fahrenheit.
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One type of magma, called felsic or rhyolitic, is about 21 percent to 2472 percent silicon dioxide; its temperature is roughly 1,112 to 1,472 degrees Fahrenheit.
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Indeed, lunar regolith—the Moon's loose surface rock—is packed with useful compounds like silicon dioxide and aluminum oxide that can be harvested as a propulsion resource.
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Lightning Ridge is famous for its opal gemstones, which form underground over long timescales from a solution of silicon dioxide and water (more about the process here).
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The spray uses a SiO2 (silicon dioxide) base to create a hydrophobic and UV barrier on paint, and it's also safe to use on windows and wheels.
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The winner, Peter Kilbride of University College, London, devised an ingenious vitrification method that uses tiny particles of silicon dioxide—sand, in essence—in lieu of the usual, potentially toxic cryoprotectants.
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High‑purity silicon dioxide particles are the essential raw materials from which we make computer chips, fiber‑optic cables, and other high‑tech hardware—the physical components on which the virtual world runs.
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Scientists know so little about opal — and the conditions that allow the formation of this rare, precious form of silicon dioxide, a substance that otherwise forms common materials like sand and glass — that "geologists are still scratching their heads about it," he said.
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It uses SiO2 (silicon dioxide) technology to create a hydrophobic and UV barrier on the surface of your car to repel water and dirt, and since it's safe to use on paint, glass, and wheels, you don't have to cover windows while spraying.
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The original solar-powered, semi-automated machine used low-tech laser cutting techniques to harness the sun's rays through a glass ball lens and cut out 2D objects.. Working with sun—an endless source of energy—and sand—an endless source of silica (silicon dioxide) in the form of quartz—Kayser was inspired to apply the process to 3D objects.
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Filamentous carbon can also form when acetylene decomposes on films of palladium and silicon dioxide. However, filamentous carbon does not form on the palladium and silicon dioxide films if they are preheated with hydrogen at temperatures of . This is because in those conditions, the palladium and silicon dioxide react to form palladium silicide. Iron and silicon dioxide together also act as a catalyst for formation of the structures.
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Being highly stable, silicon dioxide arises from many methods. Conceptually simple, but of little practical value, combustion of silane gives silicon dioxide. This reaction is analogous to the combustion of methane: :SiH4 + 2 O2 -> SiO2 + 2 H2O However the chemical vapor deposition of silicon dioxide onto crystal surface from silane had been used using nitrogen as a carrier gas at 200–500 °C.
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Examples of glidants include magnesium stearate, fumed silica (colloidal silicon dioxide), starch and talc.
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As perlite contains silicon dioxide, goggles and silica filtering masks are recommended when handling large quantities.
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The chemical name for simeticone is α-(trimethylsilyl)-ω-methylpoly[oxy(dimethylsilylene)], mixture with silicon dioxide.
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Growth of a group of V-NAND cells begins with an alternating stack of conducting (doped) polysilicon layers and insulating silicon dioxide layers. The next step is to form a cylindrical hole through these layers. In practice, a 128 Gibit V-NAND chip with 24 layers of memory cells requires about 2.9 billion such holes. Next, the hole's inner surface receives multiple coatings, first silicon dioxide, then silicon nitride, then a second layer of silicon dioxide.
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It is dark grey in colour, small-grained and intermediate rock containing about 28–40% silicon dioxide.
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Lithium metasilicate is prepared by the reaction of lithium carbonate and silicon dioxide at temperatures between 515-565°C.
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In rare occurrences, the silicon dioxide in silica is converted to silicon tetrachloride when the contaminated brine is electrolyzed.
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Smoky quartz is a brownish grey, translucent variety of quartz that ranges in clarity from almost complete transparency to an almost-opaque brownish-gray or black crystal. Like other quartz gems, it is a silicon dioxide crystal. The smoky colour results from free silicon formed from the silicon dioxide by natural irradiation.
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Silicon dioxide (SiO2) has been used as a gate oxide material for decades. As metal-oxide-semiconductor field- effect transistors (MOSFETs) have decreased in size, the thickness of the silicon dioxide gate dielectric has steadily decreased to increase the gate capacitance and thereby drive current, raising device performance. As the thickness scales below 2 nm, leakage currents due to tunneling increase drastically, leading to high power consumption and reduced device reliability. Replacing the silicon dioxide gate dielectric with a high-κ material allows increased gate capacitance without the associated leakage effects.
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Thermal oxidation may be applied to different materials, but most commonly involves the oxidation of silicon substrates to produce silicon dioxide.
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Fluorosilicate glass has a low-k dielectric and is used in between copper metal layers during silicon integrated circuit fabrication process. It is widely used by semiconductor foundries on geometries sub 0.25μ. Fluorosilicate glass is effectively a fluorine-containing silicon dioxide (k=3.5, while k of undoped silicon dioxide is 3.9). Fluorosilicate glass is used by IBM.
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The earliest gate dielectric used in a field-effect transistor was silicon dioxide (SiO2). The silicon and silicondioxide surface passivation process was developed by Egyptian engineer Mohamed M. Atalla at Bell Labs during the late 1950s, and then used in the first MOSFETs (metal-oxide-semiconductor field-effect transistors). Silicon dioxide remains the standard gate dielectric in MOSFET technology.
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Silica is converted to silicon by reduction with carbon. Fluorine reacts with silicon dioxide to form SiF4 and O2 whereas the other halogen gases (Cl2, Br2, I2) are essentially unreactive. Silicon dioxide is attacked by hydrofluoric acid (HF) to produce hexafluorosilicic acid: :SiO2 + 6 HF -> H2SiF6 + 2 H2O HF is used to remove or pattern silicon dioxide in the semiconductor industry. Under normal conditions, silicon does not react with most acids but is dissolved by hydrofluoric acid. :Si(s) + 6HF(aq) -> [SiF6]^{2-}(aq) + 2H+(aq) + 2H2(g) Silicon is attacked by bases such as aqueous sodium hydroxide to give silicates. :Si(s) + 4NaOH(aq) -> [SiO4]^{4-}(aq) + 4Na+(aq) + 2H2(g) Silicon dioxide acts as a Lux–Flood acid, being able to react with bases under certain conditions.
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Etch rates are typically in the 0.1–1 micrometer per minute range. Common masking materials for long etches in TMAH include silicon dioxide (LPCVD and thermal) and silicon nitride. Silicon nitride has a negligible etch rate in TMAH; the etch rate for silicon dioxide in TMAH varies with the quality of the film, but is generally on the order of 0.1 nm/minute.
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TTMS can be used for thin film coating with a nanostructured silicon dioxide prepared by plasma-enhanced chemical vapor deposition (PECVD) at atmospheric pressure.
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The process continues with vapor deposition of silicon dioxide to protect the exposed areas, and with all the remaining steps to complete the process.
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Ametrine is composed of silicon dioxide (SiO2) and it is a tectosilicate, which means it has a silicate framework linked together through shared oxygen atoms.
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Ion gels can also be made using non-copolymer polymers such as cellulose, oxides such as silicon dioxide or refractory materials such as boron nitride.
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Stishovite is an extremely hard, dense tetragonal form (polymorph) of silicon dioxide. It is very rare on the Earth's surface, however, it may be a predominant form of silicon dioxide in the Earth, especially in the lower mantle.Dmitry L. Lakshtanov et al. "The post-stishovite phase transition in hydrous alumina-bearing SiO2 in the lower mantle of the earth" PNAS 2007 104 (34) 13588-13590; .
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The vertical structures (only one shown) are cylinders that implement a channel that is wrapped in alternating dielectric and charge trapping layers (blue and yellow). To manufacture such a device layers of conducting polysilicon and silicon dioxide dielectric are deposited first on top of a silicon substrate that contains standard CMOS logic elements. A trench is then etched and its walls are deposited first with silicon dioxide (blue), then silicon nitride (yellow), then another silicon dioxide (blue) layer, forming the gate dielectric, the charge trap, and the tunnel dielectric in that order. Finally the hole is filled with conducting polysilicon (red) which forms the channel.
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Pure silica (silicon dioxide), when cooled as fused quartz into a glass with no true melting point, can be used as a glass fiber for fiberglass.
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This is an extended list of synonyms for silicon dioxide; all of these values are from a single source; values in the source were presented capitalized.
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Silicon dioxide has traditionally been used as the gate insulator. Silicon dioxide however has a modest dielectric constant. Increasing the dielectric constant of the gate dielectric allows a thicker layer while maintaining a high capacitance (capacitance is proportional to dielectric constant and inversely proportional to dielectric thickness). All else equal, a higher dielectric thickness reduces the quantum tunneling current through the dielectric between the gate and the channel.
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Like regular quartz, the chemical composition of phantom quartz is silicon dioxide (SiO2). The available forms of phantom quartz are crystal groups and single crystals used as jewelry pendants.
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Celery salt normally contains an anticaking agent such as silicon dioxide or calcium silicate. As a vegetable, celery seeds have potassium as the dominant ion over sodium (ninefold more).
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Various methods may be employed to create voids or pores in a silicon dioxide dielectric. Voids can have a relative dielectric constant of nearly 1, thus the dielectric constant of the porous material may be reduced by increasing the porosity of the film. Relative dielectric constants lower than 2.0 have been reported. Integration difficulties related to porous silicon dioxide implementation include low mechanical strength and difficult integration with etch and polish processes.
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Buffered oxide etch (BOE), also known as buffered HF or BHF, is a wet etchant used in microfabrication. Its primary use is in etching thin films of silicon dioxide (SiO2) or silicon nitride (Si3N4). It is a mixture of a buffering agent, such as ammonium fluoride (NH4F), and hydrofluoric acid (HF). Concentrated HF (typically 49% HF in water) etches silicon dioxide too quickly for good process control and also peels photoresist used in lithographic patterning.
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Vapor etching overcomes stiction because no liquids are used during the etch process. Commonly, hydrogen fluoride and xenon difluorides are used to etch silicon dioxide and silicon sacrificial layers respectively.
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DA.50 (IUPAC: silicon dioxide) #Seinäjokite (löllingite: IMA1976-001) 2.EB.15b (IUPAC: iron diantimonide) #Sejkoraite-(Y) (zippeite: IMA2009-008) 7.EC.15 [no] [no] #Sekaninaite (beryl: IMA1967-047) 9.
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The chemical composition: dominant are silicon dioxide, aluminium oxide and iron oxide, with other oxides, microelements and a significant amount of total sulfur. The lake was declared a Nature park "Rusanda".
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Silicon sulfide is the inorganic compound with the formula SiS2. Like silicon dioxide, this material is polymeric, but it adopts a 1-dimensional structure quite different from the usual forms of SiO2.
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In many parts of the world, silica is the major constituent of sand. The various forms of silicon dioxide can be converted from one form to another by heating and changes in pressure.
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1,1-DCE is mainly used as a comonomer in the polymerization of vinyl chloride, acrylonitrile, and acrylates. It is also used in semiconductor device fabrication for growing high purity silicon dioxide (SiO) films.
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Silica granulomas are a skin condition which may be caused by automobile and other types of accidents which produces tattooing of dirt (silicon dioxide) into the skin that then induces the granuloma formation.
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Electret materials are quite common in nature. Quartz and other forms of silicon dioxide, for example, are naturally occurring electrets. Today, most electrets are made from synthetic polymers, e.g. fluoropolymers, polypropylene, polyethyleneterephthalate (PET), etc.
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The geothermally heated mineral water emerges from the ground at per minute at a temperature of . The mineral content includes: sodium, potassium, calcium, magnesium, iron, aluminum, silicon dioxide, boron, lithium, bicarbonate, sulfate, chlorine, fluorine.
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Silicalite is an inorganic compound with the formula SiO2. It is one of several forms (polymorphs) of silicon dioxide. It is a white solid. It consists of tetrahedral silicon centers and two-coordinate oxides.
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Orthosilicic acid is a chemical compound with formula . It has been synthesized using non-aqueous solutions. It is assumed to be present when silicon dioxide (silica) dissolves in water at a millimolar concentration level.
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In 1890, the German chemist Clemens Winkler (the discoverer of germanium) was the first to attempt to synthesize SiO by heating silicon dioxide with silicon in a combustion furnace.C. Winkler Ber. 23, (1890) p. 2652.
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20 and is also a component of borosilicate glass, widely used for laboratory glassware and domestic ovenware for its low thermal expansion.Kreith & Goswami 2005, p. 12–109 Most ordinary glassware is made from silicon dioxide.
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One implementation uses a silicon dioxide chip. The circuits require only two terminals instead of three, as in most memory chips. The approach resists heat and radiation. The design uses a crossbar (a rectangular grid) architecture.
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Common materials are magnesium fluoride , silicon dioxide , tantalum pentoxide , zinc sulfide , and titanium dioxide . Polymeric dielectric mirrors are fabricated industrially via co-hextrusion of melt polymers, and by spin-coating or dip-coating on smaller scale.
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Calculations suggest that the two rocks contain mostly the minerals orthopyroxene (magnesium-iron silicate), feldspars (aluminum silicates of potassium, sodium, and calcium), and quartz (silicon dioxide), with smaller amounts of magnetite, ilmenite, iron sulfide, and calcium phosphate.
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Like most marine diatoms, C. pseudocurvisetus is characterized by its frustule, or cell wall, which is composed of silicon dioxide and other organic matter. The frustule forms as different sized valves, which overlap and are called thecae.
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The term high-κ dielectric refers to a material with a high dielectric constant (κ, kappa), as compared to silicon dioxide. High-κ dielectrics are used in semiconductor manufacturing processes where they are usually used to replace a silicon dioxide gate dielectric or another dielectric layer of a device. The implementation of high-κ gate dielectrics is one of several strategies developed to allow further miniaturization of microelectronic components, colloquially referred to as extending Moore's Law. Sometimes, these materials are called "high-k" (spoken high kay), instead of "high-κ" (high kappa).
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In 2017, the Nobel prize for chemistry was awarded for the development of this technology, which can be used to image objects such as proteins or virus particles. Ordinary soda-lime glass, used in windows and drinking containers, is created by the addition of sodium carbonate and lime (calcium oxide) to silicon dioxide. Without these additives, silicon dioxide will require very high temperature to obtain a melt, and subsequently (with slow cooling) a glass. Vitrification is used in disposal and long-term storage of nuclear waste or other hazardous wastes in a method called geomelting.
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Silicon dioxide, also known as silica and quartz, is very abundant in the universe and has a large temperature range where it is liquid. However, its melting point is , so it would be impossible to make organic compounds in that temperature, because all of them would decompose. Silicates are similar to silicon dioxide and some have lower melting points than silica. Gerald Feinberg and Robert Shapiro have suggested that molten silicate rock could serve as a liquid medium for organisms with a chemistry based on silicon, oxygen, and other elements such as aluminium.
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Silicon dioxide is mostly obtained by mining, including sand mining and purification of quartz. Quartz is suitable for many purposes, while chemical processing is required to make a purer or otherwise more suitable (e.g. more reactive or fine-grained) product.
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Tiger's eye is composed chiefly of silicon dioxide (SiO2) and is coloured mainly by iron oxide. The specific gravity ranges from 2.64 to 2.71.Listing of SG of gems and gem simulants , Berkeley.edu It is formed by the alteration of crocidolite.
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Thin films of silicon oxynitride can be grown on silicon using a variety of plasma deposition techniques and used in microelectronics as a dielectric layer alternative to silicon dioxide and silicon nitride with the advantages of low leakage currents and high thermal stability. These films have an amorphous structure and therefore their chemical composition can widely deviate from Si2N2O. By changing the nitrogen/oxygen ratio in these films, their refractive index can be continuously tuned between the value of ~1.45 for silicon dioxide and ~2.0 for silicon nitride. This property is useful for gradient-index optics components such as graded-index fibers.
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Replacing the silicon dioxide gate dielectric with another material adds complexity to the manufacturing process. Silicon dioxide can be formed by oxidizing the underlying silicon, ensuring a uniform, conformal oxide and high interface quality. As a consequence, development efforts have focused on finding a material with a requisitely high dielectric constant that can be easily integrated into a manufacturing process. Other key considerations include band alignment to silicon (which may alter leakage current), film morphology, thermal stability, maintenance of a high mobility of charge carriers in the channel and minimization of electrical defects in the film/interface.
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The volcano does not show evidence of producing lahars. Eruptive activity began at an eruptive vent by Diamond Peak's northern summit, and shortly after, eruptions commenced at a second, slightly higher vent closer to the southern summit. Though Diamond Peak's eruptions always produced olivine-rich basaltic andesite, they likely grew more rich in silicon dioxide over time, ranging from 55 to 58 percent silicon dioxide. Lava flows from the volcano vary from in thickness, rich in porphyritic rocks like olivine, plagioclase, and clinopyroxene; there is no silicic rock (rich in silica) in the Diamond Peak vicinity.
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The process consists of heating a mixture of silicon dioxide (SiO2), in the form of silica or quartz sand, and carbon, in its elemental form as powdered coke, in an iron bowl. In the furnace, the silicon dioxide, which sometimes also contains other additives, is melted surrounding a graphite rod, which serves as a core. An electric current is passed through the graphite, which heats the mixture to 1700–2500 °C. The result of the carbothermic reaction is a layer of silicon carbide (especially in its alpha and beta phases) forming around the rod and emission of carbon monoxide (CO).
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The wafer is initially heated to a temperature sufficient to drive off any moisture that may be present on the wafer surface; 150 °C for ten minutes is sufficient. Wafers that have been in storage must be chemically cleaned to remove contamination. A liquid or gaseous "adhesion promoter", such as Bis(trimethylsilyl)amine ("hexamethyldisilazane", HMDS), is applied to promote adhesion of the photoresist to the wafer. The surface layer of silicon dioxide on the wafer reacts with HMDS to form tri-methylated silicon-dioxide, a highly water repellent layer not unlike the layer of wax on a car's paint.
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Insulators that have a larger dielectric constant than silicon dioxide (referred to as high-κ dielectrics), such as group IVb metal silicates e.g. hafnium and zirconium silicates and oxides are being used to reduce the gate leakage from the 45 nanometer technology node onwards. On the other hand, the barrier height of the new gate insulator is an important consideration; the difference in conduction band energy between the semiconductor and the dielectric (and the corresponding difference in valence band energy) also affects leakage current level. For the traditional gate oxide, silicon dioxide, the former barrier is approximately 8 eV.
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Microfabrication processes widely use CVD to deposit materials in various forms, including: monocrystalline, polycrystalline, amorphous, and epitaxial. These materials include: silicon (dioxide, carbide, nitride, oxynitride), carbon (fiber, nanofibers, nanotubes, diamond and graphene), fluorocarbons, filaments, tungsten, titanium nitride and various high-k dielectrics.
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Sketch of the cross-section of a rectangular waveguide (450 nm x 220 nm). The waveguide consists of a silicon core (dark gray) on top of a silicon-dioxide layer (light-gray). Marcatili's method is sketched. The four outer quadrants are neglected.
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These crystals can be synthesized by dissolving nitrogen gas with indium-scandium melts, magnetron sputtering, MBE, HVPE and other deposition methods.. Scandium Nitride Scandium nitride is also an effective gate for semiconductors on a silicon dioxide (SiO2) or hafnium dioxide (HfO2) substrate.
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Fairburn formation takes place in sedimentary limestone, where calcite inside the limestone is replaced by silicon-dioxide or silicic acid over time in a high pressure, micropourous environment. In this theory, bands of agate formed from the inside of the agate outwards.
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Replacing the silicon dioxide with a low-κ dielectric of the same thickness reduces parasitic capacitance, enabling faster switching speeds and lower heat dissipation. In conversation such materials may be referred to as "low-k" (spoken "low kay") rather than "low-κ" (low-kappa).
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The peristaltic CCD has an additional implant that keeps the charge away from the silicon/silicon dioxide interface and generates a large lateral electric field from one gate to the next. This provides an additional driving force to aid in transfer of the charge packets.
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In the park, there is the most typical and complete geomorphic system of rhyolitic mountainous land. In terms of volcanic geology and petrology, the region is of great scientific value. The volcanic rock is acidic in the park. Its silicon dioxide content is over 66%.
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Oxidised silicon is quartz, i.e. silicon dioxide, the primary component of glass. In high voltage systems containing transformers and capacitors, liquid insulator oil is the typical method used for preventing arcs. The oil replaces air in spaces that must support significant voltage without electrical breakdown.
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The gate oxide is the dielectric layer that separates the gate terminal of a MOSFET (metal-oxide-semiconductor field-effect transistor) from the underlying source and drain terminals as well as the conductive channel that connects source and drain when the transistor is turned on. Gate oxide is formed by thermal oxidation of the silicon of the channel to form a thin (5 - 200 nm) insulating layer of silicon dioxide. The insulating silicon dioxide layer is formed through a process of self-limiting oxidation, which is described by the Deal-Grove model. A conductive gate material is subsequently deposited over the gate oxide to form the transistor.
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Molecular SiO2 with a linear structure is produced when molecular silicon monoxide, SiO, is condensed in an argon matrix cooled with helium along with oxygen atoms generated by microwave discharge. Dimeric silicon dioxide, (SiO2)2 has been prepared by reacting O2 with matrix isolated dimeric silicon monoxide, (Si2O2). In dimeric silicon dioxide there are two oxygen atoms bridging between the silicon atoms with an Si-O-Si angle of 94° and bond length of 164.6 pm and the terminal Si-O bond length is 150.2 pm. The Si-O bond length is 148.3 pm, which compares with the length of 161 pm in α-quartz.
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The hole's polysilicon surface acts as the gate electrode. The outermost silicon dioxide cylinder acts as the gate dielectric, enclosing a silicon nitride cylinder that stores charge, in turn enclosing a silicon dioxide cylinder as the tunnel dielectric that surrounds a central rod of conducting polysilicon which acts as the conducting channel. Memory cells in different vertical layers do not interfere with each other, as the charges cannot move vertically through the silicon nitride storage medium, and the electric fields associated with the gates are closely confined within each layer. The vertical collection is electrically identical to the serial-linked groups in which conventional NAND flash memory is configured.
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Copper silicate mineral chrysocolla. Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of the Earth's crust. In mineralogy, silica (silicon dioxide) SiO2 is usually considered a silicate mineral.
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Supports are porous materials with a high surface area, most commonly alumina, zeolites or various kinds of activated carbon. Specialized supports include silicon dioxide, titanium dioxide, calcium carbonate, and barium sulfate. In slurry reactions, heterogeneous catalysts can be lost by dissolving. Many heterogeneous catalysts are in fact nanomaterials.
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It is sometimes classified as a mineraloid. Though obsidian is usually dark in color, similar to mafic rocks such as basalt, obsidian's composition is extremely felsic. Obsidian consists mainly of SiO2 (silicon dioxide), usually 70% by weight or more. Crystalline rocks with a similar composition include granite and rhyolite.
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Tetrafluoromethane is sometimes used as a low temperature refrigerant (R-14). It is used in electronics microfabrication alone or in combination with oxygen as a plasma etchant for silicon, silicon dioxide, and silicon nitride.K. Williams, K. Gupta, M. Wasilik. Etch Rates for Micromachining Processing – Part II J. Microelectromech. Syst.
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Supercritical carbon dioxide is used in the production of silica, carbon and metal based aerogels. For example, silicon dioxide gel is formed and then exposed to s. When the goes supercritical, all surface tension is removed, allowing the liquid to leave the aerogel and produce nanometer sized pores.
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In integrated circuits, and CMOS devices, silicon dioxide can readily be formed on surfaces of Si through thermal oxidation, and can further be deposited on the surfaces of conductors using chemical vapor deposition or various other thin film fabrication methods. Due to the wide range of methods that can be used to cheaply form silicon dioxide layers, this material is used conventionally as the baseline to which other low permittivity dielectrics are compared. The relative dielectric constant of SiO2, the insulating material still used in silicon chips, is 3.9. This number is the ratio of the permittivity of SiO2 divided by permittivity of vacuum, εSiO2/ε0,where ε0 = 8.854×10−6 pF/μm.
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In semiconductor manufacturing, silicon on insulator (SOI) technology is fabrication of silicon semiconductor devices in a layered silicon–insulator–silicon substrate, to reduce parasitic capacitance within the device, thereby improving performance. SOI-based devices differ from conventional silicon-built devices in that the silicon junction is above an electrical insulator, typically silicon dioxide or sapphire (these types of devices are called silicon on sapphire, or SOS). The choice of insulator depends largely on intended application, with sapphire being used for high- performance radio frequency (RF) and radiation-sensitive applications, and silicon dioxide for diminished short-channel effects in other microelectronics devices. The insulating layer and topmost silicon layer also vary widely with application.
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In the area of microelectronics and photovoltaics surface passivation is usually implemented by oxidation to a coating of silicon dioxide. The effect of passivation on the efficiency of solar cells ranges from 3-7%. Passivation is effected by thermal oxidation at 1000 °C. The surface resistivity is high, >100 Ωcm.
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However, it will form a polycrystalline film unless tightly controlled, and it allows oxidizing species that leak into the reactor to contaminate the epitaxial layer with unwanted compounds such as silicon dioxide. VPE is sometimes classified by the chemistry of the source gases, such as hydride VPE and metalorganic VPE.
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Sand provides structure, strength, and bulk to earthen plasters. Sand consists of tiny mineral granules of rock, its parent material. Predominately composed of silicon dioxide (quartz), sand is a non-reactive substance. Because sand occurs naturally in many subsoils, all of the sand necessary may be already found in the soil.
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Anatase to Rutile Transition ART, in J. Mat. Sci. They also exhibit different melting points, solubilities, and X-ray diffraction patterns. One good example of this is the quartz form of silicon dioxide, or SiO2. In the vast majority of silicates, the Si atom shows tetrahedral coordination by 4 oxygens.
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It has also been proven that inorganic particles like titanium dioxide, silicon dioxide and asbestos can trigger activation of the inflammasome. One study even indicates that NLRP3 inflammasome activation is involved in sleep regulation. Recent studies show that NLRP3 inflammasome-mediated neuroinflammation is involved in secondary brain injury after intracerebral hemorrhage.
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Jasper Seamount formed years ago. Base volcanics are very similar to those found at Hawaii. The flanks formed about years ago, and its summit years ago. The maintenance of a near-constant silicon dioxide ratio in all of the rocks collected is a sign of increasingly lower degrees of mantle melting.
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There has been renewed interest in silver- doped germanium selenide devices due to their high, high resistance state. Copper-doped silicon dioxide glass PMC would be compatible with the CMOS fabrication process. In 1996, Axon Technologies was founded to commercialize the PMC technology. Micron Technology announced work with PMC in 2002.
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Precipitated silica is an amorphous form of silica (silicon dioxide, SiO2); it is a white, powdery material. Precipitated silica is produced by precipitation from a solution containing silicate salts. The three main classes of amorphous silica are pyrogenic silica, precipitated silica and silica gel. Among them, precipitated silica has the greatest commercial significance.
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The bulk chemical composition of the ash has been found to be approximately 65% silicon dioxide, 18% aluminium oxide, 5% ferric oxide, 4% each calcium oxide and sodium oxide and 2% magnesium oxide. Trace chemicals were also detected, their concentrations varying as shown: 0.05–0.09% chlorine, 0.02–0.03% fluorine, and 0.09–0.3% sulfur.
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Aluminium silicate (or aluminum silicate) is a name commonly applied to chemical compounds which are derived from aluminium oxide, Al2O3 and silicon dioxide, SiO2 which may be anhydrous or hydrated, naturally occurring as minerals or synthetic. Their chemical formulae are often expressed as xAl2O3·ySiO2·zH2O. It is known as E number E559.
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Aluminium silicate is a type of fibrous material made of aluminium oxide and silicon dioxide, (such materials are also called aluminosilicate fibres). These are glassy solid solutions rather than chemical compounds. The compositions are often described in terms of % weight of alumina, Al2O3 and silica, SiO2. Temperature resistance increases as the % alumina increases.
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Recent research has also demonstrated that under the high temperature and high pressure conditions in the mantle, silicon dioxide, the most abundant mineral in the mantle (on Earth and probably also on Venus) can form carbonates that are stable under these conditions. This opens up the possibility of carbon dioxide sequestration in the mantle.
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The reaction is exothermic but slow. To recover the heat produced by the reaction to produce electricity, a large volume of olivine must be thermally well-isolated. The end-products of the reaction are silicon dioxide, magnesium carbonate, and small amounts of iron oxide. Olivine is used as a substitute for dolomite in steel works.
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TFT electrical performance is dramatically degraded if a zinc–tin–oxide TFT is covered with a dielectric layer and does not undergo both types of annealing. In addition to silicon dioxide, successful passivation of zinc–tin–oxide TFTs is accomplished using thermally evaporated calcium fluoride, germanium oxide, strontium fluoride, or antimony oxide as passivation.
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To make NCA more resistant, in particular for batteries that need to operate at temperatures above 50 °C, the NCA active material is usually coated. The coatings demonstrated in research may comprise fluorides such as aluminium fluoride AlF3, crystalline oxides (e.g. CoO2, TiO2, NMC) or glassy oxides (silicon dioxide SiO2) or phosphates such as FePO4.
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Medium particle size is 2-6.5 mm and fine particle size is 1-2 mm. Components include silicon dioxide SiO2 42.7%, calcium oxide CaO 0.98%, magnesium oxide MgO 2.5%, manganese oxide MnO 0.15%, iron oxide Fe2O3 8.4% and aluminium oxide Al2O3 25.1%. A pH of 6.9 and conductivity of 0.052 ms/cm are used.
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Hydrophobic silica is a form of silicon dioxide (commonly known as silica) that has hydrophobic groups chemically bonded to the surface. The hydrophobic groups are normally alkyl or polydimethylsiloxane chains. Hydrophobic silica can be processed in different ways; such as fumed silica, precipitated silica, and aerosol assisted self assembly, all existing in the form of nanoparticles.
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The post radiation signal is permanently stored and is dose rate independent. Gate oxide of MOSFET which is conventionally silicon dioxide is an active sensing material in MOSFET dosimeters. Radiation creates defects (acts like electron-hole pairs) in oxide, which in turn affects the threshold voltage of the MOSFET. This change in threshold voltage is proportional to radiation dose.
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The equilibrium can theoretically be driven either way, but it's impractically slow if the forward and reverse reaction rates are minuscule. At low temperatures the reaction energetics dominate everything else, and in this sense too silicon outperforms carbon, because silicon dioxide has a much larger heat of formation than the carbon oxides, as best seen in Ellingham diagrams.
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For example, the chemical formula of the mineral olivine can be written either as (Mg,Fe)2SiO4 or as (MgO,FeO)2SiO2. This mineral is said to be ultramafic, meaning that it has a very high nominal content of the bases magnesium oxide and iron oxide and hence, a low content of the acid silicon dioxide.
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Coesite is a form (polymorph) of silicon dioxide SiO2 that is formed when very high pressure (2–3 gigapascals), and moderately high temperature (), are applied to quartz. Coesite was first synthesized by Loring Coes Jr., a chemist at the Norton Company, in 1953.The word "coesite" is pronounced as "Coze-ite" after chemist Loring Coes Jr.
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Top and side views of graphene (left) and HBS structures (right). Red atoms are oxygens. TEM images of defects in HBS (middle) and graphene (bottom row): Stone-Wales (a), flower (b), divacancy (c) and a more complex, interstitial defect (d). TEM images of amorphous HBS Two-dimensional silica (2D silica) is a layered polymorph of silicon dioxide.
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Verpoorte's research explores simulating in vivo organismic biology onto microscopic external devices. This is achieved through fabrication and control of chemical detectors and separations modules onto silicon dioxide chips. This dramatically decreases the amount of analyte, solution, or cells required to perform a given analysis. Her specific interests involve electrokinetic control over movement of various substances on these chips.
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Silicon-based life's feasibility is commonly discussed. However, it is less able than carbon to form elaborate rings and chains. Silicon in the form of silicon dioxide is used by diatoms and sea sponges to form their cell walls and skeletons. Silicon is essential for bone growth in chickens and rats and may also be essential in humans.
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An empirical formula makes no mention of the arrangement or number of atoms. It is standard for many ionic compounds, like calcium chloride (CaCl2), and for macromolecules, such as silicon dioxide (SiO2). The molecular formula, on the other hand, shows the number of each type of atom in a molecule. The structural formula shows the arrangement of the molecule.
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The siliceous sponges form a major group of the phylum Porifera, consisting of classes Demospongiae and Hexactinellida. They are characterized by spicules made out of silicon dioxide, unlike calcareous sponges. Individual siliachoates (silica skeleton scaffolding) can be arranged tightly within the sponginocyte or crosshatched and fused together. Siliceous spicules come in two sizes called megascleres and microscleres.
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The post radiation signal is permanently stored and is dose rate independent. Gate oxide of MOSFET which is conventionally silicon dioxide is an active sensing material in MOSFET dosimeters. Radiation creates defects (acts like electron-hole pairs) in oxide, which in turn affects the threshold voltage of the MOSFET. This change in threshold voltage is proportional to radiation dose.
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The patterning of the Mn12 molecules on a silicon surface is achieved by first derivatizing this surface with a self-assembled monolayer of APTES, which leaves it terminated by amino groups (-NH2). Such termination electrostatically repels the Mn12 molecules. Subsequently, a pattern of silicon dioxide is defined by LON. The SMM molecules are predominantly deposited on the oxide motives because of electrostatic attraction.
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In chemistry and materials science, thiosilicate refers to materials containing anions of the formula SiS(2+n)]2n-. Derivatives where some sulfide is replaced by oxide are also called thiosilicates, examples being materials derived from the oxohexathiodisilicate [Si2OS6]6-. Silicon is tetrahedral in all thiosilicates. Formally such materials are derived from silicon disulfide in analogy to the relationship between silicon dioxide and silicates.
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Phytoliths may also provide plants with protection. These rigid silica structures help to make plants more difficult to consume and digest, lending the plant's tissues a grainy or prickly texture. Phytoliths also appear to provide physiologic benefits. Experimental studies have shown that the silicon dioxide in phytoliths may help to alleviate the damaging effects of toxic heavy metals, such as aluminum.
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Some materials that are known to form glass in binary combination with aluminum oxide are: rare earth oxides, alkaline earth oxides (CaO, SrO, BaO) lead oxide, and silicon dioxide. Also, the Al2O3 (aluminate) system has been discovered to form sapphire-like glass ceramics. Often, this ability is based upon compositions in which interplay between glass forming ability and glass stability is approximately balanced.
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Hydrated silica is a form of silicon dioxide, which has a variable amount of water in the formula. When dissolved in water it is usually known as silicic acid. It is found in nature, as opal (which has been mined as a gemstone for centuries), and in the cell walls of diatoms. It is also manufactured for use in toothpaste.
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Chalcedony () is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. These are both silica minerals, but they differ in that quartz has a trigonal crystal structure, while moganite is monoclinic. Chalcedony's standard chemical structure (based on the chemical structure of quartz) is SiO2 (silicon dioxide). Chalcedony has a waxy luster, and may be semitransparent or translucent.
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Keilhauite (also known as yttrotitanite) is a variety of the mineral titanite of a brownish black color, related to titanite in form. It consists chiefly of silicon dioxide, titanium dioxide, calcium oxide, and yttrium oxide. The variety was described in 1841 and named for Baltazar Mathias Keilhau (1797-1858) a Norwegian geologist. Keilhauite has a chemical formula of (CaTi,Al2,Fe23+,Y23+)SiO5.
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The bedrock of Vinga is mostly made up of porphyrite (porfyrit), a volcanic rock with less Silicon dioxide, SiO2, than porphyry. The rock has a fine-grained structure, dark with lighter grains of feldspar and other minerals. The mineralogical composition of the Vinga porphyry classifies it as a monzogranite or quartz diorite. The northern part of the island contains orthopyroxene.
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Many common fire extinguishing agents, including water, either are ineffective or make a potassium fire worse. Nitrogen, argon, sodium chloride (table salt), sodium carbonate (soda ash), and silicon dioxide (sand) are effective if they are dry. Some Class D dry powder extinguishers designed for metal fires are also effective. These agents deprive the fire of oxygen and cool the potassium metal.
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Carbon fibers are used in numerous applications, such as satellite struts, because the fibers are highly strong yet elastic. Silicon dioxide has a wide variety of applications, including toothpaste, construction fillers, and silica is a major component of glass. 50% of pure silicon is devoted to the manufacture of metal alloys. 45% of silicon is devoted to the manufacture of silicones.
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Elemental carbon is not generally toxic, but many of its compounds are, such as carbon monoxide and hydrogen cyanide. However, carbon dust can be dangerous because it lodges in the lungs in a manner similar to asbestos. Silicon minerals are not typically poisonous. However, silicon dioxide dust, such as that emitted by volcanoes can cause adverse health effects if it enters the lungs.
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This method involved heating silicon and oxygen by running silicon tetrachloride gas through an oxygen flame. The result was a fine, glassy powder of silicon dioxide, which could be pressed into various shapes. Hyde’s method proved to be a breakthrough in glass production. Fused silica was initially used in mirrors, telescopes, radar, and later in spacecraft windows and fiber optics.
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LAAS technological facility in Toulouse, France. In microfabrication, thermal oxidation is a way to produce a thin layer of oxide (usually silicon dioxide) on the surface of a wafer. The technique forces an oxidizing agent to diffuse into the wafer at high temperature and react with it. The rate of oxide growth is often predicted by the Deal–Grove model.
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The Reflector series telescopes are reflectors with optics aluminized and overcoated with silicon dioxide, available in 76 mm to 254 mm sizes (2.99" – 10.00"). All but the smallest size are presented in equatorial mounting; the smallest one in Alt-azimuth. They are available in short, medium, and long focal ratios and chiefly parabolic mirrors. They are made with Black Diamond aluminum tubes.
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Such anisotropy is maximized in deep reactive ion etching. The use of the term anisotropy for plasma etching should not be conflated with the use of the same term when referring to orientation-dependent etching. The source gas for the plasma usually contains small molecules rich in chlorine or fluorine. For instance, carbon tetrachloride () etches silicon and aluminium, and trifluoromethane etches silicon dioxide and silicon nitride.
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The CGD capacitance can be seen as the connection in series of two elementary capacitances. The first one is the oxide capacitance (CoxD), constituted by the gate electrode, the silicon dioxide and the top of the N epitaxial layer. It has a constant value. The second capacitance (CGDj) is caused by the extension of the space-charge zone when the MOSFET is in off-state.
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Chemically, quartz is a specific form of a compound called silicon dioxide. Many materials can be formed into plates that will resonate. However, quartz is also a piezoelectric material: that is, when a quartz crystal is subject to mechanical stress, such as bending, it accumulates electrical charge across some planes. In a reverse effect, if charges are placed across the crystal plane, quartz crystals will bend.
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Surface of a concrete pillar with crack pattern of alkali–silica reaction Alkali–aggregate reaction is a term mainly referring to a reaction which occurs over time in concrete between the highly alkaline cement paste and non- crystalline silicon dioxide, which is found in many common aggregates. This reaction can cause expansion of the altered aggregate, leading to spalling and loss of strength of the concrete.
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AES wool consists of amorphous glass fibres that are produced by melting a combination of calcium oxide (CaO−), magnesium oxide (MgO−), and silicon dioxide (SiO2). Products made from AES wool are generally used in equipment that continuously operates and in domestic appliances. AES wool has the advantage of being bio- soluble—it dissolves in bodily fluids within a few weeks and is quickly cleared from the lungs.
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When it was discovered in 1888, it was thought that the early Cambrian Volborthella was a cephalopod. However discoveries of more detailed fossils showed that Volborthella’s small, conical shell was not secreted but built from grains of the mineral silicon dioxide (silica); neither was it septate. This illusion was a result of the laminated texture of the organisms' tests. Therefore, Volborthella’s classification is now uncertain.
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CRC Handbook of Chemistry and Physics, Edition 85 (CRC Press, Boca Raton, FL) (2004) and Thermographic cameras. GeO2 is preferred over other IR transparent glasses because it is mechanically strong and therefore preferred for rugged military usage."Germanium" Mineral Commodity Profile, U.S. Geological Survey, 2005. A mixture of silicon dioxide and germanium dioxide ("silica-germania") is used as an optical material for optical fibers and optical waveguides.
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CTAB formed micelles in the solution and these micelles further formed a two dimensional hexagonal mesostructure. The silicon precursor began to hydrolyze between the micelles and finally filled the gap with silicon dioxide. The template could be further removed by calcination and left a pore structure behind. These pores mimicked exactly the structure of mesoscale soft template and led to highly ordered mesoporous silica materials.
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Retrieved 7 July 2011. Other anticaking agents sometimes used include tricalcium phosphate, calcium or magnesium carbonates, fatty acid salts (acid salts), magnesium oxide, silicon dioxide, calcium silicate, sodium aluminosilicate and calcium aluminosilicate. Both the European Union and the United States Food and Drug Administration permitted the use of aluminium in the latter two compounds. In "doubly fortified salt", both iodide and iron salts are added.
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Hexafluoroethane is used as a versatile etchant in semiconductor manufacturing. It can be used for selective etching of metal silicides and oxides versus their metal substrates and also for etching of silicon dioxide over silicon. The primary aluminium and the semiconductor manufacturing industries are the major emitters of hexafluoroethane using the Hall-Héroult process. Together with trifluoromethane it is used in refrigerants R508A (61%) and R508B (54%).
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Moganite is an oxide mineral with the chemical formula SiO2 (silicon dioxide) that was discovered in 1984. It crystallises in the monoclinic crystal system. Moganite is considered a polymorph of quartz: it has the same chemical composition as quartz, but a different crystal structure. In 1994, the International Mineralogical Association (IMA) had disapproved it as being a separate mineral because it was not clearly distinguishable from quartz.
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G. Tellez et al., INFRARED CHARACTERIZATION OF SiN FILMS ON Si FOR HIGH SPEED ELECTRONICS APPLICATIONS. MASTER OF SCIENCE IN APPLIED PHYSICS, Naval Postgraduate School, Monterey, California, USA (2004) This is often used as a surface and bulk passivating layer for commercial multicrystalline silicon photovoltaic cells. Silicon dioxide can also be deposited from a tetraethoxysilane (TEOS) silicon precursor in an oxygen or oxygen-argon plasma.
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Next, Kean describes silicon. In general, he states that they are cousins because silicon mimics carbon in the sense that it also seeks to attach to four more atoms to fill its energy levels. The big issue that silicon encounters is that silicon does not have the life-sustaining abilities like carbon to attach to oxygen. Silicon dioxide can be fatal and carbon dioxide is not.
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A patch of 90% pure opaline silicon dioxide was unearthed by Spirit in the vicinity of Home Plate. The patch is believed to be formed in acidic hydrothermal conditions, which supports the theory that Home Plate is of an explosive volcanic origin. Water is also present as mineral hydrates. Since 2008, scientists believe that this formation is an example of an eroded, ancient, and extinct fumarole.
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Hughes went on to produce this new EEPROM devices. But this patent cited NEC's EEPROM® invention. In May 1977, some important research result was disclosed by Fairchild and Siemens. They used SONOS (polysilicon-oxynitride-nitride- oxide-silicon) structure with thickness of silicon dioxide less than 30 Å, and SIMOS (stacked-gate injection MOS) structure, respectively, for using Fowler- Nordheim tunnelling hot-carrier injection.
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The hydraulic fluid is injected at high pressure into the fracture. The proppant keeps the fracture open to allow more oil and gas to be extracted out. Silicon dioxide (SiO2) is the chemical compound of silica, which is a prevalent component of rock, soil and sand. The most common form of silica is quartz, and it can break apart into dust microparticles that become respirable crystalline silica.
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The synthesis of triacetin from acetic anhydride and glycerol is simple and inexpensive. : 3 \+ 2 → 2 \+ 3 This synthesis has been conducted with catalytic sodium hydroxide and microwave irradiation to give a 99% yield of triacetin. It has also been conducted with a cobalt(II) Salen complex catalyst supported by silicon dioxide and heated to 50 °C for 55 minutes to give a 99% yield of triacetin.
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To obtain DNA sequence, the DNA nanoballs are attached to a patterned array flow cell. The flow cell is a silicon wafer coated with silicon dioxide, titanium, hexamethyldisilazane (HMDS), and a photoresist material. The DNA nanoballs are added to the flow cell and selectively bind to the positively-charged aminosilane in a highly ordered pattern, allowing a very high density of DNA nanoballs to be sequenced.
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H. Antoniadis, A. J. Bard. (Hewlett-Packard Company & The Board of Regents of The University of Palo Alto, CA, 1997) Organic field effect transistors of DIP have been studied.M. Münch, Ph.D. thesis, Universität Stuttgart (2001) The charge carrier mobility achieved was up to 0.1 cm2/(V·s) for thin film transistors with silicon dioxide as gate dielectric, making DIP a good candidate for further optimisation.
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Doping carbon nanotubes with oxidized metal is another way to adjust conductivity. It creates a very interesting high temperature superconducting state as the Fermi level is significantly reduced. A good application would be the introduction of silicon dioxide to carbon nanotubes. It constructs memory effect as some research group has invented ways to create memory devices based on carbon peapods grown on Si/SiO2 surfaces.
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In 1955, Carl Frosch and Lincoln Derick at Bell Telephone Laboratories (BTL) accidentally discovered that silicon dioxide could be grown on silicon. Later in 1958, they proposed that silicon oxide layers could protect silicon surfaces during diffusion processes, and could be used for diffusion masking. Surface passivation, the process by which a semiconductor surface is rendered inert, and does not change semiconductor properties as a result of interaction with air or other materials in contact with the surface or edge of the crystal, was first developed by Egyptian engineer Mohamed M. Atalla at BTL in the late 1950s. He discovered that the formation of a thermally grown silicon dioxide (SiO2) layer greatly reduced the concentration of electronic states at the silicon surface, and discovered the important quality of SiO2 films to preserve the electrical characteristics of p–n junctions and prevent these electrical characteristics from deteriorating by the gaseous ambient environment.
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The major raw material for the clinker-making is usually limestone mixed with a second material containing clay as a source of alumino-silicate. Normally, an impure limestone which contains clay or silicon dioxide (SiO2) is used. The calcium carbonate (CaCO3) content of these limestones can be as low as 80%. Second raw materials (materials in the rawmix other than limestone) depend on the purity of the limestone.
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It is used in structural materials, microelectronics (as an electrical insulator), and as components in the food and pharmaceutical industries. Inhaling finely divided crystalline silica is toxic and can lead to severe inflammation of the lung tissue, silicosis, bronchitis, lung cancer, and systemic autoimmune diseases, such as lupus and rheumatoid arthritis. Inhalation of amorphous silicon dioxide, in high doses, leads to non-permanent short-term inflammation, where all effects heal.
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The only stable form under normal conditions is alpha quartz, in which crystalline silicon dioxide is usually encountered. In nature, impurities in crystalline α-quartz can give rise to colors (see list). The high-temperature minerals, cristobalite and tridymite, have both lower densities and indices of refraction than quartz. Since the composition is identical, the reason for the discrepancies must be in the increased spacing in the high-temperature minerals.
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Many routes to silicon dioxide start with an organosilicon compound, e.g., HMDSO, TEOS. Synthesis of silica is illustrated below using tetraethyl orthosilicate (TEOS). Simply heating TEOS at 680–730 °C results in the oxide: :Si(OC2H5)4 -> SiO2 + 2 O(C2H5)2 Similarly TEOS combusts around 400 °C: :Si(OC2H5)4 + 12 O2 -> SiO2 + 10 H2O + 8 CO2 TEOS undergoes hydrolysis via the so-called sol-gel process.
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Lower temperature deposition of silicon dioxide and doped glasses from TEOS using ozone rather than oxygen has also been explored (350 to 500 °C). Ozone glasses have excellent conformality but tend to be hygroscopic – that is, they absorb water from the air due to the incorporation of silanol (Si-OH) in the glass. Infrared spectroscopy and mechanical strain as a function of temperature are valuable diagnostic tools for diagnosing such problems.
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Generally, polysilicon is used as one of the substrate layers while silicon dioxide is used as a sacrificial layer. The sacrificial layer is removed or etched out to create any necessary void in the thickness direction. Added layers tend to vary in size from 2-5 micrometres. The main advantage of this machining process is the ability to build electronic and mechanical components (functions) on the same substrate.
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In 1959, developing an idea he had noted as early as 1957, Jean Hoerni submitted two patent applications describing his "Planar process". He presented a novel adaptation of silicon manufacturing processes that had originated at Bell Labs. The planar process created a flat surface structure protected with an insulating silicon dioxide layer. Robert Noyce showed how Hoerni’s planar process could be exploited to electrically interconnect the components of an integrated circuit.
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Ultrafine TiO2 is believed to be one of the three most produced nanomaterials, along with silicon dioxide nanoparticles and zinc oxide nanoparticles. It is the second most advertised nanomaterial in consumer products, behind silver nanoparticles. Due to its long use as a commodity chemical, TiO2 can be considered a "legacy nanomaterial." Ultrafine TiO2 is used in sunscreens due to its ability to block UV radiation while remaining transparent on the skin.
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Reacting NHSis with oxygen strips the diimine backbone, and produces solid silicon dioxide, likely through a two NHSi dioxo- bridged intermediate. Reactions with 1 equivalent of S8 yields a dithio- bridged two NHSi complex. The formation of the dithio dimer occurs through an intermediate attributed to a thiosilylone, with a Si-S double bond. Excess sulfur yields a repeating NHSi(S2)(SiS2)nNHSi oligomer with complimentary diimine loss.
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Around 1976 to 1978, Intel's team, including George Perlegos, made some inventions to improve this tunneling E2PROM technology. In 1978, they developed a 16K (2K word × 8) bit Intel 2816 device with a thin silicon dioxide layer, which was less than 200 Å. In 1980. this structure was publicly introduced as FLOTOX; floating gate tunnel oxide. The FLOTOX structure improved reliability of erase/write cycles per byte up to 10,000 times.
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The transistor can therefore be very small, very fast and consume less power. Another important element is the development of a new material that replaces silicon dioxide on the wafer. All transistors have a "gate-dielectric," a material that separates a transistor's "gate" from its active region (the gate controls the on-off state of the transistor). According to Intel, the new design could use only 0.6 volts.
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Diatoms are a form of algae that, when they die, often form layers at the bottoms of lakes, bays, or oceans. Their cell walls are made up of hydrated silicon dioxide which gives them structural coloration and therefore the appearance of tiny opals when viewed under a microscope. These cell walls or "tests" form the “grains” for the diatomaceous earth. This sedimentary rock is white, opaque, and chalky in texture.
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For example, aluminium is slowly eroded by atomic oxygen, while gold and platinum are highly corrosion-resistant. Gold-coated foils and thin layers of gold on exposed surfaces are therefore used to protect the spacecraft from the harsh environment. Thin layers of silicon dioxide deposited on the surfaces can also protect metals from the effects of atomic oxygen; e.g., the Starshine 3 satellite aluminium front mirrors were protected that way.
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Sodium oxide is a significant component of most glass, although it is added in the form of "soda" (sodium carbonate). Typically, manufactured glass contains around 15% sodium oxide, 70% silica (silicon dioxide) and 9% lime (calcium oxide). The sodium carbonate "soda" serves as a flux to lower the temperature at which the silica mixture melts. Soda glass has a much lower melting temperature than pure silica, and has slightly higher elasticity.
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In the 1980s initial attempts were performed to improve the adhesion of metal-plastic composites in dental ceramics using flame- pyrolytically deposited silicon dioxide (SiO2). The silicoater process derived from these studies provided a starting point in the development of CCVD processes. This process was constantly developed and new applications for flame-pyrolytically deposited SiO2 layers where found. At this time, the name "Pyrosil" was coined for these layers.
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Emerald, colored green with trace amounts of chromium, is a variety of the mineral beryl which is beryllium aluminium silicate. Most beryllium is extracted from beryllium hydroxide. One production method is sintering, done by mixing beryl, sodium fluorosilicate, and soda at high temperatures to form sodium fluoroberyllate, aluminium oxide, and silicon dioxide. A solution of sodium fluoroberyllate and sodium hydroxide in water is then used to form beryllium hydroxide by precipitation.
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Clarkdale, Arizona showing the striations from the rusting corrugated sheets retaining it. The Manufacture of Iron - Carting Away the Scoriæ (slag), an 1873 wood engraving Molten slag is carried outside and poured to a dump Slag is the glass-like by-product left over after a desired metal has been separated (i.e., smelted) from its raw ore. Slag is usually a mixture of metal oxides and silicon dioxide.
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ZnO is a wide-bandgap semiconductor with an energy gap of 3.37 eV at room temperature. ZnO nanoparticles are believed to be one of the three most produced nanomaterials, along with titanium dioxide nanoparticles and silicon dioxide nanoparticles. The most common use of ZnO nanoparticles is in sunscreen. They are used because they effectively absorb ultraviolet light, but possess a large enough bandgap to be completely transparent to visible light.
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Scanning probe microscopy, and advanced electronic materials, especially in the transport properties and device physics of carbon-based optoelectronic thin film materials, the preparation and characterization of oxide-based low- dimensional nanostructures, the interface properties of silicon-compound-based ultrathin gate insulating layers, novel scanning probe techniques, plasmonic nanophotonics, nano-characteristics of ferroelectric materials, nanoscale thermal conduction, and atomic force microscopy of crystallographic morphology. Major attainments include the insightful understanding of the interaction of graphene with silicon dioxide substrate, especially carrier transport properties and scattering mechanisms; achieving the highest carrier mobility of graphene on silicon dioxide at room temperature; growth of graphene and other 2D layered materials both experimentally and theoretically; and the development of high-quality graphene growth; the advances in high- performance graphene-based broadband photodetectors; the transport properties of organic semiconductor thin films and monocrystalline crystals, the interface properties of oxide-based semiconductor thin films; the development of high-k dielectric layers for the fabrication of low-cost and low-voltage organic transistors.
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A simple way to carve or create patterns on the surface of nanodiamonds without damaging them could lead to a new photonic devices. Diamond patterning is a method of forming diamond MEMS. It is achieved by the lithographic application of diamond films to a substrate such as silicon. The patterns can be formed by selective deposition through a silicon dioxide mask, or by deposition followed by micromachining or focused ion beam milling.
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Quartz is a common crystalline mineral made of silica, or silicon dioxide () The rest of the Earth's crust is formed also of oxygen compounds, most importantly calcium carbonate (in limestone) and silicates (in feldspars). Water-soluble silicates in the form of , , and are used as detergents and adhesives. Peroxides retain some of oxygen's original molecular structure ((−O-O−). White or light yellow sodium peroxide () is formed when metallic sodium is burned in oxygen.
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Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as synthetic product. Notable examples include fused quartz, fumed silica, silica gel, and aerogels.
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Silica is the primary ingredient in the production of most glass. As other minerals are melted with silica, the principle of Freezing Point Depression lowers the melting point of the mixture and increases fluidity. The glass transition temperature of pure SiO2 is about 1475 K. When molten silicon dioxide SiO2 is rapidly cooled, it does not crystallize, but solidifies as a glass. Because of this, most ceramic glazes have silica as the main ingredient.
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The Advanced Space Vision System images objects with cooperative targets and uses the known positions of the targets to triangulate their exact relative positions in real time. The targets are composed of thin films of silicon dioxide layered with inconel to form an inconel interference stack. A stack like this has nearly no reflectivity in the Electromagnetic spectrum. The result is a black color that appears even blacker than the flattest black paint.
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Petrified wood is often heavily silicified (the organic material replaced by silicon dioxide), and the impregnated tissue is often preserved in fine detail. Such specimens may be cut and polished using lapidary equipment. Fossil forests of petrified wood have been found in all continents. Fossils of seed ferns such as Glossopteris are widely distributed throughout several continents of the Southern Hemisphere, a fact that gave support to Alfred Wegener's early ideas regarding Continental drift theory.
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SEGR was observed in power MOSFETs when a heavy ion hits the gate region while a high voltage is applied to the gate. A local breakdown then happens in the insulating layer of silicon dioxide, causing local overheat and destruction (looking like a microscopic explosion) of the gate region. It can occur even in EEPROM cells during write or erase, when the cells are subjected to a comparatively high voltage. Hard error, irreversible.
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It is marketed by GlaxoSmithKline under the trade names Valtrex and Zelitrex. Valaciclovir has been available as a generic drug in the U.S. since November 25, 2009. Valtrex is offered in 500 mg and 1 gram tablets, with the active ingredient valacyclovir hydrochloride. The inactive ingredients include carnauba wax, colloidal silicon dioxide, crospovidone, FD&C; Blue No. 2 Lake, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polysorbate 80, povidone, and titanium dioxide.
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Shocked quartz is usually associated in nature with two high-pressure polymorphs of silicon dioxide: coesite and stishovite. These polymorphs have a crystal structure different from standard quartz. This structure can be formed only by intense pressure (more than 2 gigapascals), but at moderate temperatures. Coesite and stishovite are usually viewed as indicative of impact events, eclogite facies metamorphism, (or thermonuclear explosion), but are also found in sediments prone to lightning strikes and in fulgurites.
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Retrieved 31 October 2009. While normally carbon dioxide forms molecular crystals, where individual molecules are bound by Van der Waals forces, in amorphous carbonia a covalently bound three-dimensional network of atoms is formed, in a structure analogous to silicon dioxide or germanium dioxide glass. Mixtures of a-carbonia and a-silica may be a prospective very hard and stiff glass material stable at room temperature. Such glass may serve as protective coatings, e.g.
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It is made of tiny spheres of Silicon Dioxide which stack onto each other in a pyramid grid shape. This grid is what allows the cat’s eye effect to be displayed when the stone is cut into a high domed cabochon. Natural opalite is referred to as "common opal" to prevent confusing it with glass opalite. When opalite glass is placed against a dark background, it appears to have a blue color.
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Salicide process The salicide process begins with deposition of a thin transition metal layer over fully formed and patterned semiconductor devices (e.g. transistors). The wafer is heated, allowing the transition metal to react with exposed silicon in the active regions of the semiconductor device (e.g., source, drain, gate) forming a low-resistance transition metal silicide. The transition metal does not react with the silicon dioxide nor the silicon nitride insulators present on the wafer.
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In step 1, silicon dioxide layers are formed initially through thermal oxidation Note: Gate, source and drain contacts are not normally in the same plane in real devices, and the diagram is not to scale. This example shows a NAND logic device drawn as a physical representation as it would be manufactured. The physical layout perspective is a "bird's eye view" of a stack of layers. The circuit is constructed on a P-type substrate.
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Prasiolite (also known as green quartz, green amethyst or vermarine) is a green variety of quartz, a silicate mineral chemically silicon dioxide. Since 1950, almost all natural prasiolite has come from a small Brazilian mine, but it has also been mined in Lower Silesia in Poland. Naturally occurring prasiolite has also been found in the Thunder Bay area of Canada. , the only mine producing prasiolite is in Brazil but even that is almost mined out.
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Photoelectrowetting can be used to circulate aqueous solution-based sessile droplets on a silicon wafer covered with silicon dioxide and Teflon – the latter providing a hydrophobic surface. Droplet transport is achieved by focusing a laser at the leading edge of the droplet. Droplet speeds of more than 10 mm/s can be achieved without the necessity of underlying patterned electrodes.C. Palma and R.D. Deegan "Droplet Translation Actuated by Photoelectrowetting" Langmuir 34, 3177 (2018). .
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The landscape and its customs are at a point of transition between mountain country to the east and the gently rolling landscape Lorriane Plain to the west. The soil type reflects a mixture of underlying limestone and clay, with very little Silicon dioxide. The result is a soil known locally as white earth (terres blanches) and ashen earth (terres rousses): the latter are particularly suitable for growing cereals in general and especially for wheat.
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In 1990, the safety of synthetic magnesium silicate was reviewed by the Scientific Committee on Food (SCF) together with that of silica and the other metal alkali silicates. The SCF noted that “the available data, including a number of short-term studies in two species, appear to substantiate the biological inertness of those compounds”. The SCF established a group Acceptable Daily Intake (ADI) not specified for silicon dioxide and the alkali metal silicates.
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It is sometimes used as a reducing agent for high-temperature soldering and brazing, to remove oxidation of the joint without the use of flux. It also finds application in microchip production, where a high-temperature anneal in forming gas assists in silicon- silicon dioxide interface passivation. Quite often forming gas is used in furnaces during annealing or sintering for the thermal treatment of metals, because it reduces oxides on the metal surface.
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Almost all commercial electrodes respond to single- charged ions, like H+, Na+, Ag+. The most common glass electrode is the pH- electrode. Only a few chalcogenide glass electrodes are sensitive to double- charged ions, like Pb2+, Cd2+ and some others. There are two main glass- forming systems: silicate matrix based on molecular network of silicon dioxide (SiO2) with additions of other metal oxides, such as Na, K, Li, Al, B, Ca, etc.
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The metal layer can be made from titanium, nickel or chromium, or from an alloy like Nichrome or Inconel, and has thickness ranging from 0.5 to 9 nanometers. The dielectric layer comprises a suitable oxide, e.g. chromium oxide, silicon dioxide, or titanium dioxide; its thickness determines the reflective properties of the resulting dielectric mirror. The manufacturing process is similar to making anti-reflective coating, and mirror and antireflective coatings can be deposited in the same sequence of operations.
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Physical weathering includes temperature effects, freeze and thaw of water in cracks, rain, wind, impact and other mechanisms. Chemical weathering includes dissolution of matter composing a rock and precipitation in the form of another mineral. Clay minerals, for example can be formed by weathering of feldspar, which is the most common mineral present in igneous rock. The most common mineral constituent of silt and sand is quartz, also called silica, which has the chemical name silicon dioxide.
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Phytoliths are composed mainly of noncrystalline silicon dioxide, and about 4% to 9% of their mass is water. Carbon, nitrogen, and other major nutrient elements comprise less than 5%, and commonly less than 1%, of phytolith material by mass. These elements are present in the living cells in which the silica concretions form, so traces are retained in the phytoliths. Such immobilised elements, in particular carbon, are valuable in that they permit radiometric dating in reconstructing past vegetation patterns.
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The bedrock is quartzite, which is almost entirely silicon dioxide with little more than trace amounts of nutrient-bearing minerals; consequently, the soils are infertile. They are also so stony as to be non-arable. The dominant soil, a Gleyed Humo-Ferric Podzol under the Canadian system of soil classification, is mapped as the Danesville Series. Somewhat stunted but well-exploited forests of black spruce, white spruce, tamarack and balsam fir alternate with treeless barrens and peat bogs.
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About 95% of the commercial use of silicon dioxide (sand) occurs in the construction industry, e.g. for the production of concrete (Portland cement concrete). Certain deposits of silica sand, with desirable particle size and shape and desirable clay and other mineral content, were important for sand casting of metallic products. The high melting point of silica enables it to be used in such applications such as iron casting; modern sand casting sometimes uses other minerals for other reasons.
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One of the first patents pertaining to the production of graphene was filed in October 2002 and granted in 2006. It detailed one of the first large scale graphene production processes. Two years later, in 2004 Geim and Novoselov extracted single-atom-thick crystallites from bulk graphite. They pulled graphene layers from graphite and transferred them onto thin silicon dioxide () on a silicon wafer in a process called either micromechanical cleavage or the Scotch tape technique.
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Dental composite resin. As with other composite materials, a dental composite typically consists of a resin-based oligomer matrix, such as a bisphenol A-glycidyl methacrylate (BISGMA), urethane dimethacrylate (UDMA) or semi-crystalline polyceram (PEX), and an inorganic filler such as silicon dioxide (silica). Without a filler the resin wears easily, exhibits high shrinkage and is exothermic. Compositions vary widely, with proprietary mixes of resins forming the matrix, as well as engineered filler glasses and glass ceramics.
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Another use of zirconium silicate is as beads for milling and grinding. Thin films of zirconium silicate and hafnium silicate produced by chemical vapor deposition, most often MOCVD, can be used as a high-k dielectric as a replacement for silicon dioxide in semiconductors. Zirconium silicates have also been studied for potential use in medical applications. For example, ZS-9 is a zirconium silicate that was designed specifically to trap potassium ions over other ions throughout the gastrointestinal tract.
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Blue Lake Crater has a mafic composition (rich in magnesium and iron). Blue Lake Crater's major rock composition components are basalt and picrite basalt (picrobasalt). Analysis of components from Blue Lake Crater eruptive deposits for calc-alkaline melt inclusion showed compositional similarities with the Yapoah and Collier cones, indicating that Blue Lake Crater is also made up of basaltic andesite. By weight percentage, Blue Lake Crater deposits consist of about 54% Silicon dioxide (silica) and about 5% magnesium oxide.
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Silicon tetrachloride is prepared by the chlorination of various silicon compounds such as ferrosilicon, silicon carbide, or mixtures of silicon dioxide and carbon. The ferrosilicon route is most common. In the laboratory, SiCl4 can be prepared by treating silicon with chlorine: :Si + 2 Cl2 → SiCl4 It was first prepared by Jöns Jakob Berzelius in 1823. Brine can be contaminated with silica when the production of chlorine is a byproduct of a metal refining process from metal chloride ore.
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The number of nanoparticles involved in self-assembly can be controlled by manipulating the concentration of the electrolyte, which can be in the aqueous or the organic phase. Higher electrolyte concentrations correspond to decreased spacing between the nanoparticles. Pickering and Ramsden worked with oil/water (O/W) interfaces to portray this idea. Pickering and Ramsden explained the idea of pickering emulsions when experimenting with paraffin-water emulsions with solid particles like iron oxide and silicon dioxide.
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The bilateral trade between Indonesia and Venezuela saw a remarkable increase, tripled in five years between 2003 and 2008. In 2003 the trade stood at just US$24.93 million, rose to $82.55 million in 2007, and US$92.27 million in 2008. In 2009 bilateral trade rose to US$96 million. From Indonesia, Venezuela imported textiles, cotton, natural rubber, fiber, wood products, electrical equipment, footwear and sports equipment, while exporting plastic, cyclic amides, silicon dioxide and aluminum alloys to Indonesia.
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Sodium carbonate serves as a flux for silica, lowering the melting point of the mixture to something achievable without special materials. This "soda glass" is mildly water-soluble, so some calcium carbonate is added to the melt mixture to make the glass insoluble. Bottle and window glass (soda-lime glass) is made by melting such mixtures of sodium carbonate, calcium carbonate, and silica sand (silicon dioxide (SiO2)). When these materials are heated, the carbonates release carbon dioxide.
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The outgassing of volatile silicones on low Earth orbit devices leads to presence of a cloud of contaminants around the spacecraft. Together with atomic oxygen bombardment, this may lead to gradual deposition of thin layers of carbon-containing silicon dioxide. Their poor transparency is a concern in case of optical systems and solar panels. Deposits of up to several micrometers were observed after 10 years of service on the solar panels of the Mir space station.
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The Negriales rocks are the richest in silicon dioxide, and their trace element composition sharply diverges as well. The Negriales rocks may originate from parental magmas that are different from the main Lastarria magmas. The petrogenesis of Lastarria rocks, like those of other volcanoes in the Central Volcanic Zone, involves the prolonged interaction with crustal rocks in magma chambers as well as the fractionation of certain minerals. Enriched lower crust and upper mantle might also contribute.
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Unfortunately, many semiconductors with better electrical properties than silicon, such as gallium arsenide, do not form good semiconductor-to- insulator interfaces, and thus are not suitable for MOSFETs. Research continues on creating insulators with acceptable electrical characteristics on other semiconductor materials. To overcome the increase in power consumption due to gate current leakage, a high-κ dielectric is used instead of silicon dioxide for the gate insulator, while polysilicon is replaced by metal gates (e.g. Intel, 2009).
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Hydrofluoric acid is commonly used as an aqueous etchant for silicon dioxide (, also known as BOX for SOI), usually in 49% concentrated form, 5:1, 10:1 or 20:1 BOE (buffered oxide etchant) or BHF (Buffered HF). They were first used in medieval times for glass etching. It was used in IC fabrication for patterning the gate oxide until the process step was replaced by RIE. Hydrofluoric acid is considered one of the more dangerous acids in the cleanroom.
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The local oxidation of a surface by means of a scanning probe technique was first observed by Dagata and co-workers in 1990 who locally modified a hydrogen- terminated silicon surface into silicon dioxide by applying a bias voltage between the tip of a scanning tunneling microscope and the surface itself. In 1993 Day and Allee demonstrated the possibility of performing local oxidation experiments with an atomic force microscope, which opened the way to applying the technique to a large variety of materials.
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The chemistry of these reactions is not completely clear and is still the object of research.Cement's basic molecular structure finally decoded (MIT, 2009) First, the limestone (calcium carbonate) is burned to remove its carbon, producing lime (calcium oxide) in what is known as a calcination reaction. This single chemical reaction is a major emitter of global carbon dioxide emissions. :CaCO3 → CaO + CO2 The lime reacts with silicon dioxide to produce dicalcium silicate and tricalcium silicate. :2CaO + SiO2 → 2CaO.SiO2 :3CaO + SiO2 → 3CaO.
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The crystal structure of coesite is similar to that of feldspar and consists of four silicon dioxide tetrahedra arranged in Si4O8 and Si8O16 rings. The rings are further arranged into chains. This structure is metastable within the stability field of quartz: coesite will eventually decay back into quartz with a consequent volume increase, although the metamorphic reaction is very slow at the low temperatures of the Earth's surface. The crystal symmetry is monoclinic C2/c, No.15, Pearson symbol mS48.
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Some of them are radially symmetrical, but most are asymmetrical. The shapes of their bodies are adapted for maximal efficiency of water flow through the central cavity, where the water deposits nutrients and then leaves through a hole called the osculum. Many sponges have internal skeletons of spongin and/or spicules (skeletal-like fragments) of calcium carbonate or silicon dioxide. All sponges are sessile aquatic animals, meaning that they attach to an underwater surface and remain fixed in place (i.e.
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Schwarzites are negatively curved carbon surfaces originally proposed by decorating triply periodic minimal surfaces with carbon atoms. The geometric topology of the structure is determined by the presence of ring defects, such as heptagons and octagons, to graphene's hexagonal lattice. (Negative curvature bends surfaces outwards like a saddle rather than bending inwards like a sphere.) Recent work has proposed Zeolite-templated carbons (ZTCs) may be Schwarzites. The name, ZTC, derives from their origin inside the pores of zeolites, crystalline silicon dioxide minerals.
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Gangjingun Kiln Sites is a tentative World Heritage site listed by the South Korean government at UNESCO. It is a complex of 188 kilns which produced Goryeo ware. The kiln sites are located in Gangjin-gun, Jeollanam-do, South Korea near the sea. Mountains in the north provided the necessary raw materials such as firewood, kaolinite, and silicon dioxide for the master potters while a well established system of distribution transported pottery throughout Korea and facilitated export to China and Japan.
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The latter were found to be much more numerous and to have much longer relaxation times. At the time Philo Farnsworth and others came up with various methods of producing atomically clean semiconductor surfaces. In 1955, Carl Frosch and Lincoln Derrick accidentally covered the surface of silicon wafer with a layer of silicon dioxide. They showed that oxide layer prevented certain dopants into the silicon wafer, while allowing for others, thus discovering the passivating effect of oxidation on the semiconductor surface.
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Commonly used for holding silicon wafers during lithography processes, an electrostatic chuck comprises a metal base- plate and a thin dielectric layer; the metal base-plate is maintained at a high-voltage relative to the wafer, and so an electrostatic force clamps the wafer to it. Electrostatic chucks may have pins, or mesas, the height of which is included in the reported dielectric thickness; a design by Sandia National Laboratory uses a patterned silicon-dioxide dielectric to form the pins.
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A cold mirror is made by using a transparent substrate and choosing a coating material that is more reflective to visible light and more transmissive to infrared light. A hot mirror is the opposite, the coating preferentially reflects infrared. Mirror surfaces are sometimes given thin film overcoatings both to retard degradation of the surface and to increase their reflectivity in parts of the spectrum where they will be used. For instance, aluminum mirrors are commonly coated with silicon dioxide or magnesium fluoride.
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Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum. In the last case, the material is properly called silica xerogel. Silica xerogel with an average pore size of 2.4 nanometers has a strong affinity for water molecules and is widely used as a desiccant.
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In the 1930s, long-term occupational exposure among workers in the cristobalite D.E. industry who were exposed to high levels of airborne crystalline silica over decades were found to have an increased risk of silicosis. Today, workers are required to use respiratory-protection measures when concentrations of silica exceed allowable levels. Diatomite produced for pool filters is treated with high heat (calcination) and a fluxing agent (soda ash), causing the formerly harmless amorphous silicon dioxide to assume its crystalline form.
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Out of that meeting came the idea of using a heavily doped polycrystalline silicon layer as the gate of an FET. The gate was to be supported on dual layers of a silicon nitride and silicon dioxide serving as the gate insulator. Using the FET as a model for integrated circuits, they fabricated and characterized hundreds of FET devices at high yield that exhibited close electrical tolerances. Klein and his group published numerous papers on this new technology and also patented the process.
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The silica cycle is the biogeochemical cycle in which silica is transported between the Earth's systems. Opal silica (SiO2) is a chemical compound of silicon, and is also called silicon dioxide. Silicon is considered a bioessential element and is one of the most abundant elements on Earth. The silica cycle has significant overlap with the carbon cycle (see Carbonate- Silicate cycle) and plays an important role in the sequestration of carbon through continental weathering, biogenic export and burial as oozes on geologic timescales.
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Chemical deposition techniques include chemical vapor deposition (CVD), in which a stream of source gas reacts on the substrate to grow the material desired. This can be further divided into categories depending on the details of the technique, for example LPCVD (low-pressure chemical vapor deposition) and PECVD (plasma-enhanced chemical vapor deposition). Oxide films can also be grown by the technique of thermal oxidation, in which the (typically silicon) wafer is exposed to oxygen and/or steam, to grow a thin surface layer of silicon dioxide.
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Along with additional gaps in the fiber network, these allow for silicon to expand without damaging the cell. Three other factors reduce expansion: a 1 nm shell of silicon dioxide; a second carbon coating that creates a buffer layer; and the 8-25 nm fiber size, which is below the size at which silicon tends to fracture. Conventional lithium-ion cells use binders to hold together the active material and keep it in contact with the current collectors. These inactive materials make the battery bigger and heavier.
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Xenotime is a rare-earth phosphate mineral, the major component of which is yttrium orthophosphate (YPO4). It forms a solid solution series with chernovite-(Y) (YAsO4) and therefore may contain trace impurities of arsenic, as well as silicon dioxide and calcium. The rare-earth elements dysprosium, erbium, terbium and ytterbium, as well as metal elements such as thorium and uranium (all replacing yttrium) are the expressive secondary components of xenotime. Due to uranium and thorium impurities, some xenotime specimens may be weakly to strongly radioactive.
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The finer regolith, the lunar soil of silicon dioxide glass, has a texture resembling snow and a scent resembling spent gunpowder. The regolith of older surfaces is generally thicker than for younger surfaces: it varies in thickness from in the highlands and in the maria. Beneath the finely comminuted regolith layer is the megaregolith, a layer of highly fractured bedrock many kilometers thick. Comparison of high-resolution images obtained by the Lunar Reconnaissance Orbiter has shown a contemporary crater- production rate significantly higher than previously estimated.
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It is also used as part of the water-based hydraulic fluid used to control subsea oil and gas production equipment. Ethylene glycol is used as a protecting group in organic synthesis to protect carbonyl compounds such as ketones and aldehydes. Silicon dioxide reacts in heated reflux under dinitrogen with ethylene glycol and an alkali metal base to produce highly reactive, pentacoordinate silicates which provide access to a wide variety of new silicon compounds. The silicates are essentially insoluble in all polar solvent except methanol.
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Tanaka breaks into convulsions and displays a high fever, but refuses any help from Mulder or Scully. When he is put on a stretcher for a medivac pickup, Mulder notices a throbbing bulge in his neck. Tanaka flees into the woods and dies when a tentacle-like ascocarp bursts out of his throat. An autopsy by Scully finds sand (silicon dioxide) in his lungs, indicating the existence of a silicon-based lifeform; she theorizes that the organism infects the nearest hosts or otherwise dies.
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He found that silicon oxide layers could be used to electrically stabilize silicon surfaces. He developed the surface passivation process, a new method of semiconductor device fabrication that involves coating a silicon wafer with an insulating layer of silicon oxide so that electricity could reliably penetrate to the conducting silicon below. By growing a layer of silicon dioxide on top of a silicon wafer, Atalla was able to overcome the surface states that prevented electricity from reaching the semiconducting layer. Atalla first published his findings in 1957.
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Reactive ion etching is an important extension that uses chemical reactivity to enhance the physical sputtering effect. In a typical use in semiconductor manufacturing, a mask can selectively expose a layer of photoresist on a substrate made of a semiconductor material such as a silicon dioxide or gallium arsenide wafer. The wafer is developed, and for a positive photoresist, the exposed portions are removed in a chemical process. The result is a pattern left on the surface areas of the wafer that had been masked from exposure.
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Since nickel is not Raman active, direct Raman spectroscopy of graphene layers on top of the nickel is achievable. Another approach covered a sheet of silicon dioxide glass (the substrate) on one side with a nickel film. Graphene deposited via chemical vapor deposition formed into layers on both sides of the film, one on the exposed top side, and one on the underside, sandwiched between nickel and glass. Peeling the nickel and the top layer of graphene left an intervening layer of graphene on the glass.
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OFET schematic Thermally oxidized silicon is a traditional substrate for OFETs where the silicon dioxide serves as the gate insulator. The active FET layer is usually deposited onto this substrate using either (i) thermal evaporation, (ii) coating from organic solution, or (iii) electrostatic lamination. The first two techniques result in polycrystalline active layers; they are much easier to produce, but result in relatively poor transistor performance. Numerous variations of the solution coating technique (ii) are known, including dip-coating, spin-coating, inkjet printing and screen printing.
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Aerogels are composed of 99.8% air, or empty space. This solid matter is usually made by removing the liquid from Silica Gels, leaving behind just the molecular structure of Silicon Dioxide (SiO2). Hurwitz has, instead, researched producing aerogels with a different chemical composition so the properties of aerogels, like the temperature limits, would increase and allow space travel to be safer. She has helped create an Aluminosilicate aerogel, which caused the lower thermal conductivities of the aerogels to be able to withstand temperatures higher than 900.
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Early immunosignature tests used glass microscope slides, with spots of 10,000 random peptides. Newer immunosignature work is run on wafers made of silicon dioxide, with each wafer cut into standard slide size and spotted with 330,034 peptides; however, further description will focus on the glass slide experiments. These random- sequence peptides, 20 amino acids long, are chemically attached to the slides. Of the 20 amino acid length, 3 amino acids (at the C-terminus side of the peptide) are common to each peptide spot.
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A CNT QD is formed when electrons are confined to a small region within a carbon nanotube. This is normally accomplished by application of a voltage to a gate electrode, dragging the valence band of the CNT down in energy, thereby causing electrons to pool in a region in the vicinity of the electrode. Experimentally this is accomplished by laying a CNT on a silicon dioxide surface, sitting on a doped silicon wafer. This can be done by chemical vapor deposition using carbon monoxide.
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Di-positronium, or dipositronium, is an exotic molecule consisting of two atoms of positronium. It was predicted to exist in 1946 by John Archibald Wheeler, and subsequently studied theoretically, but was not observed until 2007 in an experiment performed by David Cassidy and Allen Mills at the University of California, Riverside. The researchers made the positronium molecules by firing intense bursts of positrons into a thin film of porous silicon dioxide. Upon slowing down in the silica, the positrons captured ordinary electrons to form positronium atoms.
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Slot cutting is employed to create expansion joints in dams afflicted with compression stresses due to concrete swelling. Alkali Aggregate Reaction, or AAR, is a chemical reaction in concrete created where the aggregate has a high silicon dioxide content. The southeast USA is one such region, and dams in that area require periodic slot cuts to avoid cracking, leakage, and interference with mechanical components such as gates and turbines. The time intervals depend on the AAR specifics of each structure, but 10 years is an average.
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Charging mechanism of today's NOR-type FLASH memory cell Discharging mechanism of today's NOR-type FLASH memory cell As is described in former section, old EEPROMs are based on Avalanche breakdown-based hot-carrier injection with high reverse breakdown voltage. But FLOTOX's theoretical basis is Fowler–Nordheim tunneling hot-carrier injection through a thin silicon dioxide layer between the floating-gate and the wafer. In other words, it uses a tunnel junction. Theoretical basis of the physical phenomenon itself is the same as today's flash memory.
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Zeolite Y is a catalyst that enhances the amount of gasoline fractioned from petroleum, making refining petroleum safer and more productive. In addition to her work on molecular sieves, Flanigen also co-invented a synthetic emerald, which Union Carbide produced and sold for many years. The emeralds were used mainly in masers (predecessors to lasers) and were even used in jewelry for a time, in a line marketed as the "Quintessa Collection." Structure of silicalite, a form of silicon dioxide discovered by Flanigan et al.
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Chao worked on a variety of topics over the course of his USGS career, including engineering geology, economic geology, and coal petrology. However, he was best known for his work on impact geology and tektites. Shortly after he began work on tektites in 1960, Chao was given a sample of sandstone from the vicinity of Meteor Crater, Arizona. From this material, he was able to isolate an unusual mineral with high refractive index, which he showed to be a high-pressure polymorph of silicon dioxide.
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The metal coating of glass mirrors is usually protected from abrasion and corrosion by a layer of paint applied over it. Mirrors for optical instruments often have the metal layer on the front face, so that the light does not have to cross the glass twice. In these mirrors, the metal may be protected by a thin transparent coating of anon-metallic (dielectric) material. The first metallic mirror to be enhanced with a dielectric coating of silicon dioxide was created by Hass in 1937.
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The liquid fills up numerous voids making the material more structurally homogeneous. Light scattering in an ideal defect-free crystalline (non-metallic) solid which provides no scattering centers for incoming light will be due primarily to any effects of anharmonicity within the ordered lattice. Light transmission will be highly directional due to the typical anisotropy of crystalline substances, which includes their symmetry group and Bravais lattice. For example, the seven different crystalline forms of quartz silica (silicon dioxide, SiO2) are all clear, transparent materials.
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The groundmass contains plagioclase, pyroxene, silicon dioxide and oxides of iron and titanium. The composition of Ciomadul's rocks has been fairly constant throughout its evolution albeit with two shifts 1 million and 650,000 years before present, and this diversity of its components indicate that the genesis of Ciomadul magmas involved mixing between felsic and mafic magma. A large proportion of crystals in the rocks consists of antecrysts and xenocrysts, making radiometric dating of the rocks difficult. These include the amphibole, biotite, feldspar and zircon.
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Animal Ingredients A to Z, p 73, E.G. Smith Collective, AK Press, 2004, Finings are used to clear the beer of yeast - there are a variety of agents used as finings, including silicon dioxide, gelatin, polyclar, and isinglass. Isinglass is the most common fining used to clear cask ale. Isinglass is produced from the swim bladders of fish, usually sturgeon, though also those in the polynemidae, sciaenidae and siluridae families;scientificsocieties.org as it is an animal product, cask ale cleared with isinglass is not considered vegetarian.
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At a 1958 Electrochemical Society meeting, Atalla presented a paper about the surface passivation of PN junctions by oxide (based on his 1957 BTL memos), and demonstrated silicon dioxide's passivating effect on a silicon surface. Jean Hoerni attended the same meeting, and was intrigued by Atalla's presentation. Hoerni came up with a "planar idea" one morning while thinking about Atalla's device. Taking advantage of silicon dioxide's passivating effect on the silicon surface, Hoerni proposed to make transistors that were protected by a layer of silicon dioxide.
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Toshiba in 2007 and Samsung in 2009 announced the development of 3D V-NAND, a means of building a standard NAND flash bit string vertically rather than horizontally to increase the number of bits in a given area of silicon. Figure 6. Vertical NAND Structure A rough idea of the cross section of this is shown in Figure 6. In this drawing the red portions represent conductive polysilicon, the blue is silicon dioxide insulating layers, and the yellow is the nitride charge trapping layer.
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The gate is separated from the channel by a thin insulating layer, traditionally of silicon dioxide and later of silicon oxynitride. Some companies have started to introduce a high-κ dielectric and metal gate combination in the 45 nanometer node. When a voltage is applied between the gate and body terminals, the electric field generated penetrates through the oxide and creates an inversion layer or channel at the semiconductor-insulator interface. The inversion layer provides a channel through which current can pass between source and drain terminals.
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Soluble silica, also called monosilicic acid with a chemical formula of (Si(OH)4), is taken up from the soil when plant roots absorb groundwater. From there, it is carried to other plant organs by the xylem. By an unknown mechanism, which appears to be linked to genetics and metabolism, some of the silica is then laid down in the plant as silicon dioxide. This biological mechanism does not appear to be limited to specific plant structures, as some plants have been found with silica in their reproductive and sub-surface organs.
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The laser fluence must be carefully controlled in order to induce crystallization without causing widespread melting. Crystallization of the film occurs as a very small portion of the silicon film is melted and allowed to cool. Ideally, the laser should melt the silicon film through its entire thickness, but not damage the substrate. Toward this end, a layer of silicon dioxide is sometimes added to act as a thermal barrier.. This allows the use of substrates that cannot be exposed to the high temperatures of standard annealing, polymers for instance.
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In semiconductor manufacturing, a low-κ is a material with a small relative dielectric constant (κ, kappa) relative to silicon dioxide. Low-κ dielectric material implementation is one of several strategies used to allow continued scaling of microelectronic devices, colloquially referred to as extending Moore's law. In digital circuits, insulating dielectrics separate the conducting parts (wire interconnects and transistors) from one another. As components have scaled and transistors have gotten closer together, the insulating dielectrics have thinned to the point where charge build up and crosstalk adversely affect the performance of the device.
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A glass building facade Glass is a non-crystalline, often transparent amorphous solid, that has widespread practical, technological, and decorative use in, for example, window panes, tableware, and optics. Glass is most often formed by rapid cooling (quenching) of the molten form; some glasses such as volcanic glass are naturally occurring. The most familiar, and historically the oldest, types of manufactured glass are "silicate glasses" based on the chemical compound silica (silicon dioxide, or quartz), the primary constituent of sand. Soda-lime glass, containing around 70% silica, accounts for around 90% of manufactured glass.
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Hafnium silicate is the hafnium(IV) salt of silicic acid with the chemical formula of HfSiO4. Thin films of hafnium silicate and zirconium silicate grown by atomic layer deposition, chemical vapor deposition or MOCVD, can be used as a high-k dielectric as a replacement for silicon dioxide in modern semiconductor devices. The addition of silicon to hafnium oxide increases the band gap, while decreasing the dielectric constant. Furthermore, it increases the crystallization temperature of amorphous films and further increases the material's thermal stability with Si at high temperatures.
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The solubility of silicon dioxide in water strongly depends on its crystalline form and is three-four times higher for silica than quartz; as a function of temperature, it peaks around 340 °C. This property is used to grow single crystals of quartz in a hydrothermal process where natural quartz is dissolved in superheated water in a pressure vessel that is cooler at the top. Crystals of 0.5–1 kg can be grown over a period of 1–2 months. These crystals are a source of very pure quartz for use in electronic applications.
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In 1914 Hahn and Meitner had developed a new technique for separating the tantalum group from pitchblende, which they hoped would speed the isolation of the new isotope. But when Meitner resumed work in 1917, not only Hahn but most of the students, laboratory assistants and technicians had been called up, so Meitner had to do everything herself. In February, Meitner extracted 2 grams of silicon dioxide () from 21 grams of pitchblende. She set 1.5 grams aside and added a tantalum pentafluoride () carrier to the other 0.5 grams, which she dissolved in hydrogen fluoride ().
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When silicone is burned in air or oxygen, it forms solid silica (silicon dioxide, SiO2) as a white powder, char, and various gases. The readily dispersed powder is sometimes called silica fume. The pyrolysis of certain polysiloxanes under an inert atmosphere is a valuable pathway towards the production of amorphous silicon oxycarbide ceramics, also known as polymer derived ceramics. Polysiloxanes terminated with functional ligands such as vinyl, mercapto or acrylate groups have been cross linked to yield preceramic polymers, which can be photopolymerised for the additive manufacturing of polymer derived ceramics by stereolithography techniques.
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Dentistry is one field in which free radical photopolymers have found wide usage as adhesives, sealant composites, and protective coatings. These dental composites are based on a camphorquinone photoinitiator and a matrix containing methacrylate oligomers with inorganic fillers such as silicon dioxide. Resin cements are utilized in luting cast ceramic, full porcelain, and veneer restorations that are thin or translucent to permit visible light penetration and thus polymerize the cement. Light-activated cements may be radiolucent and are usually provided in various shades since they are utilized in esthetically demanding situations.
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Alumino silicate wool, also known as refractory ceramic fibre (RCF), consists of amorphous fibres produced by melting a combination of aluminum oxide (Al2O3) and silicon dioxide (SiO2), usually in a weight ratio 50:50 (see also VDI 3469 Parts 1 and 5,VDI Guideline: VDI 3469 Part 1 - Overview Part 5 – High-Temperature Insulation Wool as well as TRGS 521). Products made of alumino silicate wool are generally used at application temperatures of greater than 900 °C for equipment that operates intermittently and in critical application conditions (see Technical Rules TRGS 619).
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Volborthella is an animal of uncertain classification, whose fossils pre-date . It has been considered for a period a cephalopod. However discoveries of more detailed fossils showed that Volborthella’s small, conical shell was not secreted but built from grains of the mineral silicon dioxide (silica), and that it was not divided into a series of compartments by septa as those of fossil shelled cephalopods and the living Nautilus are. This illusion was a result of the laminated texture of the organisms' tests. Therefore, Volborthella’s classification is now uncertain.
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Calcium silicate, also known as slag, is produced when molten iron is made from iron ore, silicon dioxide and calcium carbonate in a blast furnace. When this material is processed into a highly refined, re-purposed calcium silicate aggregate, it is used in the remediation of acid mine drainage (AMD) on active and passive mine sites. Calcium silicate neutralizes active acidity in AMD systems by removing free hydrogen ions from the bulk solution, thereby increasing pH. As its silicate anion captures H+ ions (raising the pH), it forms monosilicic acid (H4SiO4), a neutral solute.
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Typically thick film circuit substrates are Al2O3/alumina, beryllium oxide (BeO), aluminum nitride (AlN), stainless steel, sometimes even some polymers and in rare cases even silicon (Si) coated with silicon dioxide (SiO2)., Most used substrates for a thick-film process are either 94 or 96% alumina. Alumina is very hard and therefore lasering of the material is the most efficient way to machine it. The thick-film process is also a process of miniaturization where one substrates normally contain many units (final circuits), with the lasering it is possible to scribe, profile and drill holes.
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Multi-threshold CMOS (MTCMOS), now available from foundries, is one approach to managing leakage power. With MTCMOS, high Vth transistors are used when switching speed is not critical, while low Vth transistors are used in speed sensitive paths. Further technology advances that use even thinner gate dielectrics have an additional leakage component because of current tunnelling through the extremely thin gate dielectric. Using high-κ dielectrics instead of silicon dioxide that is the conventional gate dielectric allows similar device performance, but with a thicker gate insulator, thus avoiding this current.
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Silica fume particles viewed in a transmission electron microscope Silica fume, also known as microsilica, (CAS number 69012-64-2, EINECS number 273-761-1) is an amorphous (non-crystalline) polymorph of silicon dioxide, silica. It is an ultrafine powder collected as a by-product of the silicon and ferrosilicon alloy production and consists of spherical particles with an average particle diameter of 150 nm. The main field of application is as pozzolanic material for high performance concrete. It is sometimes confused with fumed silica (also known as pyrogenic silica, CAS number 112945-52-5).
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He envisioned it as a form of memory, years before the floating gate MOSFET. In February 1957, John Wallmark filed a patent for FET in which germanium monoxide was used as a gate dielectric, but he didn't pursue the idea. In his other patent filed the same year he described a double gate FET. In March 1957, in his laboratory notebook, Ernesto Labate, a research scientist at Bell Labs, conceived of a device similar to the later proposed MOSFET, although Labate's device didn't explicitly use silicon dioxide as an insulator.
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The hydroxides themselves are the most basic hydroxides known, reacting with acids to give salts and with alcohols to give oligomeric alkoxides. They easily react with carbon dioxide to form carbonates or bicarbonates, or with hydrogen sulfide to form sulfides or bisulfides, and may be used to separate thiols from petroleum. They react with amphoteric oxides: for example, the oxides of aluminium, zinc, tin, and lead react with the alkali metal hydroxides to give aluminates, zincates, stannates, and plumbates. Silicon dioxide is acidic, and thus the alkali metal hydroxides can also attack silicate glass.
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These films can be contaminated with significant carbon and hydrogen as silanol, and can be unstable in air. Pressures of a few torr and small electrode spacings, and/or dual frequency deposition, are helpful to achieve high deposition rates with good film stability. High-density plasma deposition of silicon dioxide from silane and oxygen/argon has been widely used to create a nearly hydrogen-free film with good conformality over complex surfaces, the latter resulting from intense ion bombardment and consequent sputtering of the deposited molecules from vertical onto horizontal surfaces.
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Burned residential areas may contain silica dust, asbestos, metals, or polyaromatic hydrocarbons. Additional health hazards of fire debris cleanup work may include carbon monoxide and hazardous liquids Silica, or silicon dioxide, can occur in a crystalline or noncrystalline (amorphous) form. In fire debris, silica can be found in concrete, roofing tiles, or it may be a naturally occurring element in the rocks and soil of the burnt out areas. Occupational exposures to silica dust can cause silicosis, lung cancer, pulmonary tuberculosis, airway diseases, and some additional non-respiratory diseases.
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Molybdenum disilicide (MoSi2, or molybdenum silicide), an intermetallic compound, a silicide of molybdenum, is a refractory ceramic with primary use in heating elements. It has moderate density, melting point 2030 °C, and is electrically conductive. At high temperatures it forms a passivation layer of silicon dioxide, protecting it from further oxidation. The thermal stability of MoSi2 alongside its high emissivity make this material, alongside WSi2 attractive for applications as a high emissivity coatings in heat shields for atmospheric entryHigh emissivity coatings on fibrous ceramics for reusable space systems Corrosion Science 2019 .
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Silvered polymer films with solar reflectances of 0.97 and thermal emittance of 0.96, which remain 11 °C cooler than commercial white paints under the mid-summer sun, were reported in 2015. Researchers explored designs with dielectric silicon dioxide or silicon carbide particles embedded in polymers that are translucent in the solar wavelengths and emissive in the infrared. In 2017, an example of this design with resonant polar silica microspheres randomly embedded in a polymeric matrix, was reported. The material is translucent to sunlight and has infrared emissivity of 0.93 in the infrared atmospheric transmission window.
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Semiconductor devices (as of 2005) are built by depositing and patterning many thin layers. The patterning steps, or lithography, define the function of the device and the density of its components. For example, in the interconnect layers of a modern microprocessor, a conductive material (copper or aluminum) is inlaid in an electrically insulating matrix (typically fluorinated silicon dioxide or another low-k dielectric). The metal patterns define multiple electrical circuits that are used to connect the microchip's transistors to one another and ultimately to external devices via the chip's pins.
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Intel TeraHertz was Intel's new design for transistors. It uses new materials such as zirconium dioxide which is a superior insulator reducing current leakages. Using zirconium dioxide instead of silicon dioxide, this transistor can reduce the current leakage, and thus reduces power consumption while still working at higher speed and using lower voltages. One element of this structure is a "depleted substrate transistor," which is a type of CMOS device where the transistor is built in an ultra-thin layer of silicon on top of an embedded layer of insulation.
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The term “hot carrier injection” usually refers to the effect in MOSFETs, where a carrier is injected from the conducting channel in the silicon substrate to the gate dielectric, which usually is made of silicon dioxide (SiO2). To become “hot” and enter the conduction band of SiO2, an electron must gain a kinetic energy of ~3.2 eV. For holes, the valence band offset in this case dictates they must have a kinetic energy of 4.6 eV. The term "hot electron" comes from the effective temperature term used when modelling carrier density (i.e.
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Isotropic etching is a method commonly used in semiconductors to remove material from a substrate via a chemical process using an etchant substance. The etchant may be in liquid-, gas- or plasma-phase, although liquid etchants such as buffered hydrofluoric acid (BHF) for silicon dioxide etching are more often used. Unlike anisotropic etching, isotropic etching does not etch in a single direction, but rather etches in multiple directions within the substrate. Any horizontal component of the etch direction may therefore result in undercutting of patterned areas, and significant changes to device characteristics.
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Edziza's rounded, steep-sided lava domes were built by eruptions of very thick light-coloured magma, including trachyte. Such magmas are typically too thick to move far from the vent it extrudes from, causing it to solidify quickly and build on previous volcanic extrusions, creating a characteristic dome-like shape. The thickness of the magma is attributed to high levels of silica, a naturally occurring silicon dioxide found in various crystalline and amorphous forms. Edziza's domes reach heights of several hundred metres, and grew slowly and steadily for months to years.
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Dacitic magma at the Lassen center formed from mafic (rich in magnesium and iron) magma meeting silicic (high in silicon dioxide) magma chambers with felsic (rich in feldspar and quartz) phenocrysts. Some dacitic crystals were partially reabsorbed as a result of mixing of hot mafic magma with cool dacitic magma, and this along with undercooling of mixed magma led to phenocryst variation within certain domes exceeding variation between the domes. All three sequences — Bumpass, Eagle Peak, and Twin Lakes — formed from lava subjected to magma-mixing processes, accounting for their heterogeneous appearance and composition.
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Pozzolanic mortar is a lime based mortar, but is made with an additive of volcanic ash that allows it to be hardened underwater; thus it is known as hydraulic cement. The Greeks obtained the volcanic ash from the Greek islands Thira and Nisiros, or from the then Greek colony of Dicaearchia (Pozzuoli) near Naples, Italy. The Romans later improved the use and methods of making what became known as pozzolanic mortar and cement. Even later, the Romans used a mortar without pozzolana using crushed terra cotta, introducing aluminum oxide and silicon dioxide into the mix.
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The Utah valvata snail persists in a variety of aquatic habitats, including cold-water springs, spring creeks and tributaries, the mainstem Snake River and associated tributary stream habitats, and reservoirs. It was thought that the snail is specialized on well-oxygenated areas of limestone, mud, or mud-sand substrate, among stream beds with submergent aquatic vegetation. It was thought to be absent from pure gravel-boulder substrate. Chara, a rooted aquatic plant that concentrates both calcium carbonate (CaCO3) and silicon dioxide (SiO2), is a common associate of Valvata utahensis.
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The reaction of powdered sand with magnesium powder. It can be produced by heating silicon dioxide, SiO2, found in sand, with excess magnesium. The process first forms silicon metal and magnesium oxide, and, if an excess of SiO2 is used, then elemental silicon is formed: :2 Mg + SiO2 → 2 MgO + Si If an excess of Mg is present, Mg2Si is formed from the reaction of the remaining magnesium with the silicon: :2 Mg + Si → Mg2Si These reactions proceed exothermically,Ehrlich, P. (1963) "Alkaline Earth Metals", p. 920 in Handbook of Preparative Inorganic Chemistry, 2nd ed.
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The volcano also possess a small volcanic plug (created when magma hardens within a vent on an active volcano), situated under the summit. Jefferson's main cone ranges from 58 to 64 percent silicon dioxide, and is mostly made up of andesite and dacite. The upper of Jefferson's cone formed within the past 100,000 years, and consists mostly of dacite lava flows and lava domes. While it is possible that glaciers shed material from the burgeoning lava domes, any evidence of these domes generating pyroclastic flows or lahars has not been preserved in the geological record.
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The main materials were indium tin oxide transparent electrical conductor, silicon dioxide diffusion barrier, and chromium and copper conductors. AFC progressed from supplying coated glass to supplying the thin film coating equipment to produce these electrodes. AFC merged with the large area display coating divisions of Donnelly Mirrors of Holland, Michigan (now Magna International of Ontario, Canada) in 1992, and with Balzers and Leybold (Unaxis Corporation) of Alzenau, Germany in 2000. In 2004 AFC acquired the equipment division of Helix Corporation in Tainan, Taiwan, and it 2005 acquired VACT, Inc.
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Depending on the type of coal that was burned, the chemical composition found in coal ash can vary. Coal ash obtained from the combustion of bituminous coal is constituted principally of aluminum oxide (Al2O3), calcium oxide (CaO) and silicon dioxide (SiO2). In the composition of coal, there are many potentially hazardous substances that, if found at elevated concentration in inhaled particles, can cause major health problems in humans. Such constituents that are found at various concentrations in coal ash are arsenic, cadmium, chromium, cobalt, copper, lead, lithium, mercury, molybdenum, selenium, thallium and uranium.
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Ferrous and non-ferrous smelting processes produce different slags. The smelting of copper, lead and bauxite in non-ferrous smelting, for instance, is designed to remove the iron and silica that often occurs with those ores, and separates them as iron- silicate-based slags. Slag from steel mills in ferrous smelting, on the other hand, is designed to minimize iron loss and so mainly contains oxides of calcium, silicon, magnesium, and aluminium. Any sandy component or quartz component of the original ore automatically carries through the smelting process as silicon dioxide.
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Quartz sand (silica) is the main raw material in commercial glass production Silicon dioxide (SiO2) is a common fundamental constituent of glass. Fused quartz is a glass made from chemically-pure silica. It has very low thermal expansion and excellent resistance to thermal shock, being able to survive immersion in water while red hot, resists high temperatures (1000–1500 °C) and chemical weathering, and is very hard. It is also transparent to a wider spectral range than ordinary glass, extending from the visible further into both the UV and IR ranges, and is sometimes used where transparency to these wavelengths is necessary.
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In addition, silicon dioxide alloyed with phosphorus pentoxide ("P-glass") can be used to smooth out uneven surfaces. P-glass softens and reflows at temperatures above 1000 °C. This process requires a phosphorus concentration of at least 6%, but concentrations above 8% can corrode aluminium. Phosphorus is deposited from phosphine gas and oxygen: :4 PH3 \+ 5 O2 → 2 P2O5 \+ 6 H2 Glasses containing both boron and phosphorus (borophosphosilicate glass, BPSG) undergo viscous flow at lower temperatures; around 850 °C is achievable with glasses containing around 5 weight % of both constituents, but stability in air can be difficult to achieve.
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A colloidal crystal is a highly ordered array of particles which can be formed over a long range (to about a centimeter). Arrays such as this appear to be analogous to their atomic or molecular counterparts with proper scaling considerations. A good natural example of this phenomenon can be found in precious opal, where brilliant regions of pure spectral color result from close-packed domains of colloidal spheres of amorphous silicon dioxide, SiO2 (see above illustration). The spherical particles precipitate in highly siliceous pools and form highly ordered arrays after years of sedimentation and compression under hydrostatic and gravitational forces.
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It is also a fairly good thermal conductor, thus enabling very dense packing of transistors that need to get rid of their heat of operation, all very desirable for design and manufacturing of very large ICs. Such good mechanical characteristics also make it a suitable material for the rapidly developing field of nanoelectronics. Naturally, a GaAs surface cannot withstand the high temperatures needed for diffusion; however a viable and actively pursued alternative as of the 1980s was ion implantation. The second major advantage of Si is the existence of a native oxide (silicon dioxide, SiO2), which is used as an insulator.
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Silicon dioxide can be incorporated onto silicon circuits easily, and such layers are adherent to the underlying silicon. SiO2 is not only a good insulator (with a band gap of 8.9 eV), but the Si-SiO2 interface can be easily engineered to have excellent electrical properties, most importantly low density of interface states. GaAs does not have a native oxide, does not easily support a stable adherent insulating layer, and does not possess the dielectric strength or surface passivating qualities of the Si-SiO2. Aluminum oxide (Al2O3) has been extensively studied as a possible gate oxide for GaAs (as well as InGaAs).
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Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. The second most common type of sand is calcium carbonate, for example, aragonite, which has mostly been created, over the past half billion years, by various forms of life, like coral and shellfish.
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Much of its central volcanic cone formed within the last 200,000 years, including lava flows on the sides of the mountain that are between 30,000 and 20,000 years old. The volcano has a volume of , and its lava is predominantly basaltic andesite with silicon dioxide content between 53 and 57 percent, though it also has andesite. During the last ice age, a large ice cap buried most of the High Cascades, reaching thicknesses in the thousands of feet. Pleistocene glaciers carved out McLoughlin's major volcanic cone, excavating two solidified lava tubes that reached the summit crater.
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At a 1958 Electrochemical Society meeting, Mohamed Atalla presented a paper about the surface passivation of PN junctions by thermal oxidation, based on his 1957 BTL memos, and demonstrated silicon dioxide's passivating effect on a silicon surface. This was the first demonstration to show that high-quality silicon dioxide insulator films could be grown thermally on the silicon surface to protect the underlying silicon p-n junction diodes and transistors. Swiss engineer Jean Hoerni attended the same 1958 meeting, and was intrigued by Atalla's presentation. Hoerni came up with the "planar idea" one morning while thinking about Atalla's device.
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Diatoms have two distinct shapes: a few (centric diatoms) are radially symmetric, while most (pennate diatoms) are broadly bilaterally symmetric. A unique feature of diatom anatomy is that they are surrounded by a cell wall made of silica (hydrated silicon dioxide), called a frustule. These frustules have structural coloration due to their photonic nanostructure, prompting them to be described as "jewels of the sea" and "living opals". Movement in diatoms primarily occurs passively as a result of both water currents and wind-induced water turbulence; however, male gametes of centric diatoms have flagella, permitting active movement for seeking female gametes.
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The survival of the art in adverse climatic conditions is due to their protection by a naturally forming thin layer of silicon dioxide on the rock surface. Värikallio, Finland. The Comb Ceramic Culture who lived in what is now Finland between 5000 BC and 2000 BC is credited with their production. The paints used included a mix of iron oxide, blood, and animal fat or egg, although traces of the organic materials are no longer detectable. Characteristic to the art are sacrificial parts (arrow points, bones, signs of fire, etc.) and the location on steep cliffs at water’s edge.
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Exposure time for sunlight of one week or three years for room fluorescent lighting may cause erasure. The recommended erasure procedure is exposure to UV light at 253.7 nm of at least 15 Ws/cm2, usually achieved in 20 to 30 minutes with the lamp at a distance of about 2.5 cm. Erasure can also be accomplished with X-rays: EPROMs have a limited but large number of erase cycles; the silicon dioxide around the gates accumulates damage from each cycle, making the chip unreliable after several thousand cycles. EPROM programming is slow compared to other forms of memory.
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However, research has shown thin insulating layers between metal and semiconductors improve solar cell performance, generating interest in metal- insulator-semiconductor Schottky junction solar cells. A thin insulating layer, such as silicon dioxide, can reduce rates of electron-hole pair recombination and dark current by allowing the possibility of minority carriers to tunnel through this layer. The Schottky-junction is an attempt to increase the efficiency of solar cells by introducing an impurity energy level in the band gap. This impurity can absorb more lower energy photons, which improves the power conversion efficiency of the cell.
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Erupting magma that ranged from high-alumina olivine tholeiite to magnesian basaltic andesite, these volcanoes show increased contents of subduction-produced or melted fluids that mixed with another magma chamber in the mantle. These magmas vary from 47.6 percent to 73.2 percent silicon dioxide. Mazama and Crater Lake form part of the Mazama reach of the Oregon Cascades, which stretches for from Timber Crater to the Big Bunchgrass shield volcano. This includes 175 Quaternary volcanic vents within a belt that ranges from in width, which has a high vent density with many shields and monogenetic volcanic centers.
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Shield volcanoes near Mazama feature lava flows made of agglutinated mafic andesite, which form sheets about thick, as well as more deposits from more viscous andesite and dacite magma that reach thicknesses up to . Many of these deposits (both dacitic and andesitic) contain undercooled, crystal-poor segments of andesite, including at Mount Scott and Phantom Cone. Lava and ice interactions are suggested by exposures of glassy breccia in Mazama's caldera, and lava flows cover glaciated lava deposits. About 70,000 years ago, several silicic (rich in silicon dioxide), explosive eruptions occurred, including a significant event at Pumice Castle on the eastern wall of Mazama.
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Silicon is the eighth most common element in the universe by mass, but very rarely occurs as the pure free element in nature. It is most widely distributed in dusts, sands, planetoids, and planets as various forms of silicon dioxide (silica) or silicates. Over 90% of the Earth's crust is composed of silicate minerals, making silicon the second most abundant element in the Earth's crust (about 28% by mass) after oxygen.Nave, R. Abundances of the Elements in the Earth's Crust, Georgia State University Most silicon is used commercially without being separated, and indeed often with little processing of compounds from nature.
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Microoptoelectromechanical systems (MOEMS), also written as micro-opto- electro-mechanical systems or micro-optoelectromechanical systems, also known as optical microelectromechanical systems or optical MEMS, are not a special class of microelectromechanical systems (MEMS) but rather the combination of MEMS merged with micro-optics; this involves sensing or manipulating optical signals on a very small size scale using integrated mechanical, optical, and electrical systems. MOEMS includes a wide variety of devices, for example optical switch, optical cross-connect, tunable VCSEL, microbolometers. These devices are usually fabricated using micro-optics and standard micromachining technologies using materials like silicon, silicon dioxide, silicon nitride and gallium arsenide.
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Synthetic pyroxferroite crystals can be produced by compressing synthetic clinopyroxene (composition Ca0.15Fe0.85SiO3) to a pressure in the range of 10–17.5 kbar and heating it to 1130–1250 °C. It is metastable at low temperatures and pressures: at pressures below 10 kbar pyroxferroite converts to a mixture of olivine, pyroxene and a silicon dioxide phase, whereas at low temperatures, it transforms to a clinopyroxene. The presence of cristobalite, vesicular texture and some other petrographic observations indicate that the lunar pyroxferroite was produced upon rapid cooling from low-pressure and high-temperature (volcanic) conditions, i.e. that the mineral is metastable.
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Pelagosite is a form of pisolitic aragonite (CaCO3) whose type locality is the Croatian island group of Palagruža (Italian Pelagosa, whence the name) in the middle of the Adriatic. It was identified by R. Moser in Mineralogische und petrographische Mitteilungen, new series (Vienna) 1 (1878), 174. It has a higher content of magnesium carbonate, strontium carbonate, calcium sulfate (gypsum) and silicon dioxide(silica) than is found in typical limy sediments elsewhere. It occurs as a superficial calcareous crust no more than a few millimetres thick, which is generally white, grey, or brownish with a pearly lustre.
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The term silicic acid has traditionally been used as a synonym for silica, SiO2. Strictly speaking, silica is the anhydride of orthosilicic acid, Si(OH)4. :Si(OH)4 SiO2↓ + 2H2O The solubility of silicon dioxide in water strongly depends on its crystal structure. The solubility of amorphous silica at the vapor pressure of solutions from 0 to 250 °C is given by the equation :log C = − + 4.52 where C is the silica concentration in mg/kg and T is absolute temperature in kelvins. This equates to a maximum solubility of about 2 mmol/L at ambient temperatures.
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Balances can only compare the mass of a silicon sphere to that of a reference mass. Given the latest understanding of the lack of long-term mass stability with the IPK and its replicas, there is no known, perfectly stable mass artefact to compare against. Single-pan scales, which measure weight relative to an invariant of nature, are not precise to the necessary long-term uncertainty of 10–20 parts per billion. Another issue to be overcome is that silicon oxidises and forms a thin layer (equivalent to silicon atoms deep) of silicon dioxide (quartz) and silicon monoxide.
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Spectrographic evidence of large amounts of silicon dioxide gas indicates the smaller of the two, which had been at least the size of Earth's moon, was destroyed, and the larger, which was at least the size of Mercury, was severely damaged. Evidence of the collision was detected by NASA's Spitzer Space Telescope. In the south of the constellation, Epsilon Pavonis is a 3.95-magnitude white main sequence star of spectral type A0Va located around 105 light years distant from Earth. It appears to be surrounded by a narrow ring of dust at a distance of 107 AU.
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Atalla's surface passivation process became the solution to this problem. He discovered that when a thin layer of silicon dioxide was grown on the surface of silicon where a p–n junction intercepts the surface, the leakage current of the junction was reduced by a factor from 10 to 100. This showed that the oxide reduces and stabilizes many of the interface and oxide traps. Oxide-passivation of silicon surfaces allowed diodes and transistors to be fabricated with significantly improved device characteristics, while the leakage path along the surface of the silicon was also effectively shut off.
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This crystallises trisodium phosphate decahydrate when cooled below 60 °C; uranium impurities in this product increase with the amount of silicon dioxide in the reaction mixture, necessitating recrystallisation before commercial use. The hydroxides are dissolved at 80 °C in 37% hydrochloric acid. Filtration of the remaining precipitates followed by addition of 47% sodium hydroxide results in the precipitation of thorium and uranium at about pH 5.8. Complete drying of the precipitate must be avoided, as air may oxidise cerium from the +3 to the +4 oxidation state, and the cerium(IV) formed can liberate free chlorine from the hydrochloric acid.
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This thick block, the best preserved specimen of Sangay's early construction, consists of sequentially layered breccias, pyroclastic flows, and lahar deposits. Acidic andesites with just under 60% silicon dioxide dominate these flows, but more basic andesites can be found as well. Sangay's second edifice began to form anew after the massive sector collapse that damaged the first, being constructed between 100,000 and 50,000 years ago. Remnants of its second structure lie within the southern and eastern parts of the debris from its first collapse; some remnants of the volcano lie to the west and north as well.
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This exemplifies a fundamental difference between germanium and the other Group 14 elements carbon and silicon (carbon dioxide and silicon dioxide do not exhibit the same catalytic properties). 2Ge2H6 \+ 7O2 → 4GeO2 \+ 6H2O In liquid ammonia, digermane undergoes disproportionation. Ammonia acts as a weakly basic catalyst. Products of the reaction are hydrogen, germane, and a solid polymeric germanium hydride. Pyrolysis of digermane is proposed to follow multiple steps: :Ge2H6 → 2GeH3 :GeH3 \+ Ge2H6 → GeH4 \+ Ge2H5 :Ge2H5 → GeH2 \+ GeH3 :GeH2 → Ge + H2 :2GeH2 → GeH4 \+ Ge :nGeH2 → (GeH2)n This pyrolysis has been found to be more endothermic than the pyrolysis of disilane.
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In semiconductor technology, aluminum interconnects (Al interconnects) are interconnects made of aluminum or aluminum-based alloys. Since the invention of monolithic integrated circuit (IC) by Robert Noyce at Fairchild Semiconductor in 1959, Al interconnects were widely used in silicon (Si) ICs until its replacement by copper interconnects during the late 1990s and early 2000s in advanced process technologies. Al was an ideal material for interconnects due to its ease of deposition and good adherence to silicon and silicon dioxide. Initially, pure aluminum was used, but due to junction spiking, Si was added to form an alloy.
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In 2013 the United States the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) released a hazard alert based on data collected by NIOSH that "workers may be exposed to dust with high levels of respirable crystalline silica (silicon dioxide) during hydraulic fracturing." Crystalline silica is the basic component of many minerals including sand, soil, and granite, but the most common form is quartz. Inhaling respirable crystalline silica can cause silicosis, lung cancer, autoimmune disorders, kidney disease, and can increase the risk of tuberculosis. It is also classified as a known human carcinogen.
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FETs were theorized as potential alternatives to junction transistors, but researchers were unable to build practical FETs, largely due to the troublesome surface state barrier that prevented the external electric field from penetrating into the material. In the 1950s, researchers had largely given up on the FET concept, and instead focused on BJT technology. In 1955, Carl Frosch and Lincoln Derrick accidentally covered the surface of silicon wafer with a layer of silicon dioxide. They showed that oxide layer prevented certain dopants into the silicon wafer, while allowing for others, thus discovering the passivating effect of oxidation on the semiconductor surface.
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Initial measurements show very good agreement between experimental values and calculations based on quantum theory. The research project using this production method relocated to TRIUMF in 2012, where over 106 francium atoms have been held at a time, including large amounts of 209Fr in addition to 207Fr and 221Fr. Other synthesis methods include bombarding radium with neutrons, and bombarding thorium with protons, deuterons, or helium ions. 223Fr can also be isolated from samples of its parent 227Ac, the francium being milked via elution with NH4Cl–CrO3 from an actinium-containing cation exchanger and purified by passing the solution through a silicon dioxide compound loaded with barium sulfate.
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The rest are polygenetic shield volcanoes. About 80 percent of the lava erupted by Indian Heaven volcanoes consists of basalt; it represents the most voluminous Quaternary basalt produced by a volcanic field in the Cascade Arc north of Newberry Volcano in Oregon, with an eruptive output volume between . Basalt composition varies from low-potassium high-alumina olivine tholeiite to calc- alkaline, shoshonite, and alkaline intraplate compositions, though olivine- bearing basalt with different amounts of porphyritic plagioclase dominates. Volcanoes within the field have produced smaller amounts of basaltic andesite and andesite with silicon dioxide compositions up to 59 percent, though dacite is not very common among Indian Heaven eruptive products.
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Melting is effected at approximately 1650 °C (3000 °F) using either an electrically heated furnace (electrically fused) or a gas/oxygen-fuelled furnace (flame-fused). Fused silica can be made from almost any silicon-rich chemical precursor, usually using a continuous process which involves flame oxidation of volatile silicon compounds to silicon dioxide, and thermal fusion of the resulting dust (although alternative processes are used). This results in a transparent glass with an ultra-high purity and improved optical transmission in the deep ultraviolet. One common method involves adding silicon tetrachloride to a hydrogen–oxygen flame, but this precursor results in environmentally unfriendly byproducts including chlorine and hydrochloric acid.
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He found that silicon oxide layers could be used to electrically stabilize silicon surfaces. J.R. Ligenza and W.G. Spitzer, who studied the mechanism of thermally grown oxides, managed to fabricate a high quality Si/SiO2 stack, with Atalla and Kahng making use of their findings. Atalla developed the surface passivation process, a new method of semiconductor device fabrication that involves coating a silicon wafer with an insulating layer of silicon oxide so that electricity could reliably penetrate to the conducting silicon below. By growing a layer of silicon dioxide on top of a silicon wafer, Atalla was able to overcome the surface states that prevented electricity from reaching the semiconducting layer.
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For the surface passivation process, he developed the method of thermal oxidation, which was a breakthrough in silicon semiconductor technology. Before the development of integrated circuit chips, discrete diodes and transistors exhibited relatively high reverse-bias junction leakages and low breakdown voltage, caused by the large density of traps at the surface of single crystal silicon. Atalla's surface passivation process became the solution to this problem. He discovered that when a thin layer of silicon dioxide was grown on the surface of silicon where a p–n junction intercepts the surface, the leakage current of the junction was reduced by a factor from 10 to 100.
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The inclusions are small particles of insoluble substances suspended in the cytosol. A huge range of inclusions exist in different cell types, and range from crystals of calcium oxalate or silicon dioxide in plants, to granules of energy-storage materials such as starch, glycogen, or polyhydroxybutyrate. A particularly widespread example are lipid droplets, which are spherical droplets composed of lipids and proteins that are used in both prokaryotes and eukaryotes as a way of storing lipids such as fatty acids and sterols. Lipid droplets make up much of the volume of adipocytes, which are specialized lipid-storage cells, but they are also found in a range of other cell types.
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Carl JohnThe Canadian Patent Office Record and Register of Copyrights and Trade Marks, Volume 77, Issues 36-43 Frosch (September 6, 1908 - May 18, 1984)Carl J Frosch (1908-1984), Find A Grave was a Bell Labs researcher who discovered that silicon could be protectively coated with silicon dioxide by the right exposure to oxygen when hot. Such protective coating overcame a problem of surface states found in active silicon circuit elements. The discovery also revealed the potential for the process of silicon etching. This discovery process was akin to that of penicillin in that an accidental event led to the discovery of the solution to a major problem.
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The key concept is to view a circuit in its two-dimensional projection (a plane), thus allowing the use of photographic processing concepts such as film negatives to mask the projection of light exposed chemicals. This allows the use of a series of exposures on a substrate (silicon) to create silicon oxide (insulators) or doped regions (conductors). Together with the use of metallization, and the concepts of p–n junction isolation and surface passivation, it is possible to create circuits on a single silicon crystal slice (a wafer) from a monocrystalline silicon boule. The process involves the basic procedures of silicon dioxide (SiO2) oxidation, SiO2 etching and heat diffusion.
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The solution of silica is mixed with a catalyst and allowed to gel during a hydrolysis reaction which forms particles of silicon dioxide. The oxide suspension begins to undergo condensation reactions which result in the creation of metal oxide bridges (either M–O–M, "oxo" bridges, or M–OH–M, "ol" bridges) linking the dispersed colloidal particles. These reactions generally have moderately slow reaction rates, and as a result either acidic or basic catalysts are used to improve the processing speed. Basic catalysts tend to produce more transparent aerogels and minimize the shrinkage during the drying process and also strengthen it to prevent pore collapse during drying.
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Silicon-on-insulator (SOI) films with silicon thicknesses of 0.05 µm to 10 µm above a buried silicon dioxide layer are increasingly popular for semiconductor devices due to the increased dielectric isolation associated with SOI/ SOI wafers contain a thin-layer of silicon on an oxide layer and a thin-film of single-crystal silicon, which reduces the effective thermal conductivity of the material by up to 50% as compared to bulk silicon, due to phonon-interface scattering and defects and dislocations in the crystalline structure. Previous studies by Asheghi et al., show a similar trend. Other studies of thin-films show similar thermal effects .
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The crust of the Ogasawara Islands was formed by volcanic activity when subduction began 45–50 million years ago, and is composed mostly of an andesitic volcanic rock called boninite, which is rich in magnesium oxide, chromium, and silicon dioxide. The Ogasawara Islands may represent the exposed parts of an ophiolite that has not yet been emplaced on oceanic crust. The rocks of the Volcano Islands are much younger; Iwo Jima is a dormant volcano characterized by rapid uplift and several hot springs. Most of the islands have steep shorelines, often with sea cliffs ranging from in height, but the islands are also fringed with coral reefs and have many beaches.
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Cyanogen is typically generated from cyanide compounds. One laboratory method entails thermal decomposition of mercuric cyanide: :2 Hg(CN)2 → (CN)2 \+ Hg2(CN)2 Alternatively, one can combine solutions of copper(II) salts (such as copper(II) sulfate) with cyanides; an unstable copper(II) cyanide is formed which rapidly decomposes into copper(I) cyanide and cyanogen. :2 CuSO4 \+ 4 KCN → (CN)2 \+ 2 CuCN + 2 K2SO4 Industrially, it is created by the oxidation of hydrogen cyanide, usually using chlorine over an activated silicon dioxide catalyst or nitrogen dioxide over a copper salt. It is also formed when nitrogen and acetylene are reacted by an electrical spark or discharge.
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The versatility of dielectric coatings leads to their use in many scientific optical instruments (such as lasers, optical microscopes, refracting telescopes, and interferometers) as well as consumer devices such as binoculars, spectacles, and photographic lenses. Dielectric layers are sometimes applied over top of metal films, either to provide a protective layer (as in silicon dioxide over aluminium), or to enhance the reflectivity of the metal film. Metal and dielectric combinations are also used to make advanced coatings that cannot be made any other way. One example is the so- called "perfect mirror", which exhibits high (but not perfect) reflection, with unusually low sensitivity to wavelength, angle, and polarization.
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He found that silicon oxide layers could be used to electrically stabilize silicon surfaces. He developed the surface passivation process, a new method of semiconductor device fabrication that involves coating a silicon wafer with an insulating layer of silicon oxide so that electricity could reliably penetrate to the conducting silicon below. By growing a layer of silicon dioxide on top of a silicon wafer, Atalla was able to overcome the surface states that prevented electricity from reaching the semiconducting layer. His surface passivation method was a critical step that made possible the ubiquity of silicon integrated circuits, and later became critical to the semiconductor industry.
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Alprazolam regular release and orally disintegrating tablets are available as 0.25 mg, 0.5 mg, 1 mg, and 2 mg tablets, while extended release tablets are available as 0.5 mg, 1 mg, 2 mg, and 3 mg. Liquid alprazolam is available in a 1 mg/mL oral concentrate. Inactive ingredients in alprazolam tablets and solutions include microcrystalline cellulose, corn starch, docusate sodium, povidone, sodium starch glycollate, lactose monohydrate, magnesium stearate, colloidal silicon dioxide, and sodium benzoate. In addition, the 0.25 mg tablet contains D&C; Yellow No. 10 and the 0.5 mg tablet contains FD&C; Yellow No. 6 and D&C; Yellow No. 10.
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Wide use of the term nanotechnology in recent years has created the impression that regulatory frameworks are suddenly having to contend with entirely new challenges that they are unequipped to deal with. Many regulatory systems around the world already assess new substances or products for safety on a case by case basis, before they are permitted on the market. These regulatory systems have been assessing the safety of nanometre scale molecular arrangements for many years and many substances comprising nanometre scale particles have been in use for decades e.g. Carbon black, Titanium dioxide, Zinc oxide, Bentonite, Aluminum silicate, Iron oxides, Silicon dioxide, Diatomaceous earth, Kaolin, Talc, Montmorillonite, Magnesium oxide, Copper sulphate.
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If it were produced without any additives, the surface of the film would be so smooth that layers would adhere strongly to one another when the film is wound up, similar to the sticking of clean glass plates when stacked. To make handling possible, microscopic inert inorganic particles are usually embedded in the PET to roughen the surface of the film such as silicon dioxide. Biaxially oriented PET film can be metallized by vapor deposition of a thin film of evaporated aluminium, gold, or other metal onto it. The result is much less permeable to gases (important in food packaging) and reflects up to 99% of light, including much of the infrared spectrum.
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According to David H. Levy, Gene "saw the craters on the Moon as logical impact sites that were formed not gradually, in eons, but explosively, in seconds." For his Ph.D. degree at Princeton (1960), under the guidance of Harry Hammond Hess, Shoemaker studied the impact dynamics of Barringer Meteor Crater. Shoemaker noted Meteor Crater had the same form and structure as two explosion craters created from atomic bomb tests at the Nevada Test Site, notably Jangle U in 1951 and Teapot Ess in 1955. In 1960, Edward C. T. Chao and Shoemaker identified coesite (a form of silicon dioxide) at Meteor Crater, proving the crater was formed from an impact generating extremely high temperatures and pressures.
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Thin films of silica grow spontaneously on silicon wafers via thermal oxidation, producing a very shallow layer of about 1 nm or 10 Å of so-called native oxide. Higher temperatures and alternative environments are used to grow well-controlled layers of silicon dioxide on silicon, for example at temperatures between 600 and 1200 °C, using so-called dry oxidation with O2 :Si + O2 -> SiO2 or wet oxidation with H2O. :Si + 2 H2O -> SiO2 + 2 H2 The native oxide layer is beneficial in microelectronics, where it acts as electric insulator with high chemical stability. It can protect the silicon, store charge, block current, and even act as a controlled pathway to limit current flow.
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Before the invention of the integrated circuit, discrete diodes and transistors exhibited relatively high reverse-bias junction leakages and low breakdown voltage, caused by the large density of traps at the surface of single crystal silicon. The solution to this problem was the surface passivation process developed by Egyptian engineer Mohamed Atalla at Bell Telephone Laboratories (BTL). He discovered that when a thin layer of silicon dioxide was grown on the surface of silicon where a p–n junction intercepts the surface, the leakage current of the junction was reduced by a factor from 10 to 100. This showed that the oxide reduces and stabilizes many of the interface and oxide traps.
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Taking advantage of silicon dioxide's passivating effect on the silicon surface, Hoerni proposed to make transistors that were protected by a layer of silicon dioxide. This led to the first successful product implementation of the Atalla silicon transistor passivation technique by thermal oxide. The planar process was developed by Jean Hoerni, one of the "traitorous eight", while working at Fairchild Semiconductor, with a first patent issued 1959. Together with the use of metallization (to join together the integrated circuits), and the concept of p–n junction isolation (from Kurt Lehovec), the researchers at Fairchild were able to create circuits on a single silicon crystal slice (a wafer) from a monocrystalline silicon boule.
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The deposition process occurs at temperatures between 300 and 800 °C and results in formation of hydrofluoric acid vapors: :WF6 \+ 3 H2 → W + 6 HF The crystallinity of the produced tungsten layers can be controlled by altering the WF6/H2 ratio and the substrate temperature: low ratios and temperatures result in (100) oriented tungsten crystallites whereas higher values favor the (111) orientation. Formation of HF is a drawback, as the HF vapor is very aggressive and etches away most materials. Also, the deposited tungsten shows poor adhesion to the silicon dioxide which is the main passivation material in semiconductor electronics. Therefore, SiO2 has to be covered with an extra buffer layer prior to the tungsten deposition.
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But Shockley's strange behavior compelled the so- called "traitorous eight": Hoerni, Julius Blank, Victor Grinich, Eugene Kleiner, Jay Last, Gordon Moore, Robert Noyce and Sheldon Roberts, to leave his laboratory and create the Fairchild Semiconductor corporation. In 1958, Hoerni attended an Electrochemical Society meeting, where Bell Labs engineer Mohamed Atalla presented a paper about the passivation of p-n junctions by oxide, and demonstrated silicon dioxide's passivating effect on a silicon surface. Hoerni was intrigued, and came up with the concept of planar technology one morning while thinking about Atalla's device. Taking advantage of silicon dioxide's passivating effect on the silicon surface, Hoerni proposed to make transistors that were protected by a layer of silicon dioxide.
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This allows this material to better insulate space shuttles and materials in space and in re-entry of the space objects, causing less damage to the shuttle itself and the people inside it. In the same research project, she experimented with aerogels by adding in Titanium to the Aluminosilicate gels, which allowed for bigger average pore sizes and higher pore volumes. She concluded that by adding Titanium to Aluminosilicate gels, the lower thermal conductivities can now go up to temperatures of 1,200 instead of the 900 limit of regular Silicon Dioxide gels. In addition, Hurwitz has conducted research that has shown a way to image aerogels with very small pores through the use of scanning electron microscopes.
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Cutting en cabochon (French: "in the manner of a cabochon") is usually applied to opaque gems, while faceting is usually applied to transparent stones. Hardness is also taken into account as softer gemstones with a hardness lower than 7 on the Mohs hardness scale are easily scratched, mainly by silicon dioxide in dust and grit. This would quickly make translucent gems unattractive—instead they are polished as cabochons, making the scratches less evident. In the case of asteriated stones such as star sapphires and chatoyant stones such as cat's eye chrysoberyl, a domed cabochon cut is used to show the star or eye, which would not be visible in a faceted cut.
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It was initially thought that methane is chemically unstable in an oxidizing atmosphere with UV radiation and so its lifetime in the Martian atmosphere should be about 400 years, but in 2014, it was concluded that the strong methane sinks are not subject to atmospheric oxidation, suggesting an efficient physical-chemical process at the surface that "consumes" methane, generically called a "sink". A hypothesis postulates that the methane is not consumed at all, but rather condenses and evaporates seasonally from clathrates. Another hypothesis is that methane reacts with tumbling surface sand quartz (silicon dioxide ) and olivine to form covalent Si – bonds. The researchers showed that these solids can be oxidized and gases are ionized during the erosion processes.
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IPDs on a silicon substrate are generally fabricated using standard wafer fabrication technologies such as thin film and photolithography processing. IPDs can be designed as flip chip mountable or wire bondable components. However to differentiate technically from IC technologies IPD technologies may utilise thicker metal (for higher Q value of inductors) or different resistive (like SiCr) layers, thinner or different higher K (higher dielectric constant) dielectric layers (like PZT instead of silicon dioxide or silicon nitride) for higher capacitance density than with typical IC technologies. IPDs on silicon can be grinded - if needed - below 100µm in thickness and with many packaging options (micro-bumping, wire bonding, copper pads) and delivery mode options (as wafers, tape & reel).
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He made a breakthrough with his development of the surface passivation process. This is the process by which a semiconductor surface is rendered inert, and does not change semiconductor properties as a result of interaction with air or other materials in contact with the surface or edge of the crystal. The surface passivation process was first developed by Atalla in the late 1950s. He discovered that the formation of a thermally grown silicon dioxide (SiO2) layer greatly reduced the concentration of electronic states at the silicon surface, and discovered the important quality of SiO2 films to preserve the electrical characteristics of p–n junctions and prevent these electrical characteristics from deteriorating by the gaseous ambient environment.
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Silica "crystal" litter Silica gel litter, often referred to as "crystal litter", is a porous granular form of silicon dioxide, has the highest absorbency of any litter, and has excellent moisture control and complete odor elimination for an extended period of time compared to other litters. Some owners praise its absorbency because can absorb liquid and odor for up to 30 days for one healthy normal weight cat. It is important to lightly stir the crystals daily while scooping the solid waste, otherwise urine can pool in the box. When crystal litter is saturated, at the end of 30 days or so, it begins to smell and is visibly saturated (the white crystals have turned slightly yellow).
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The product is a 98% pure baryte (by mass); the purity should be no less than 95%, with a minimal content of iron and silicon dioxide. It is then reduced by carbon to barium sulfide: :BaSO4 \+ 2 C → BaS + 2 CO2↑ The water-soluble barium sulfide is the starting point for other compounds: reacting BaS with oxygen produces the sulfate, with nitric acid the nitrate, with carbon dioxide the carbonate, and so on. The nitrate can be thermally decomposed to yield the oxide. Barium metal is produced by reduction with aluminium at . The intermetallic compound BaAl4 is produced first: :3 BaO + 14 Al → 3 BaAl4 \+ Al2O3 BaAl4 is an intermediate reacted with barium oxide to produce the metal.
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The metal–oxide–semiconductor field-effect transistor (MOSFET) was invented by Atalla and Kahng at Bell Labs. They fabricated the device in November 1959, and presented it as the "silicon-silicon dioxide field induced surface device" in early 1960. With its high scalability, and much lower power consumption and higher density than bipolar junction transistors, the MOSFET made it possible to build high-density integrated circuits (ICs), allowing the integration of more than 10,000 transistors in a single IC. The first gallium- arsenide Schottky-gate field-effect transistor (MESFET) was made by Carver Mead and reported in 1966. The first report of a floating-gate MOSFET (FGMOS) was made by Dawon Kahng and Simon Sze in 1967.
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4-Formylphenylboronsäure mit n-Butyllithium Disadvantages of both routes are the high price of the educts used (such as 4-bromobenzaldehyde, boronic esters of higher alcohols and butyllithium) as well as in the Nöth route the difficult workup after the hydrolysis by n-butanol. More recently, an improved process has been patented using less expensive starting materials such as 4-chlorobenzaldehyde, metallic lithium and trimethyl borate. Synthese von 4-Formylphenylboronsäure aus 4-Chlorbenzaldehy und Lithiummetall 4-Formylphenylboronic acid can also be prepared by hydrolysis of potassium 4-formylphenyl-trifluoroborate by means of acidic alumina or silicon dioxide. As a rule, phenylboronic acids serve as starting compounds for the corresponding potassium aryl trifluoroborates.
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A stochastic particle method is used to calculate evaporating liquid sprays, including the effects of droplet collisions, agglomeration, and aerodynamic breakups. Although specifically designed for simulating internal combustion engines, the modularity of the code facilitates easy modifications for solving a variety of hydrodynamics problems involving chemical reactions. The versatility and range of features have made KIVA programs attractive to a variety of non-engine applications as well; these range from convection towers to modeling silicon dioxide condensation in high pressure oxidation chambers. Other applications have included the analysis of flows in automotive catalytic converters, power plant smokestack cleaning, pyrolytic treatment of biomass, design of fire suppression systems, Pulsed Detonation Engines (PDEs), stationary burners, aerosol dispersion, and design of heating, ventilation, and air conditioning systems.
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Silicon dioxide (usually called simply "oxide" in the semiconductor industry) may be deposited by several different processes. Common source gases include silane and oxygen, dichlorosilane (SiCl2H2) and nitrous oxideProceedings of the Third World Congress of Chemical Engineering, Tokyo, p. 290 (1986) (N2O), or tetraethylorthosilicate (TEOS; Si(OC2H5)4). The reactions are as follows: :SiH4 \+ O2 → SiO2 \+ 2 H2 :SiCl2H2 \+ 2 N2O → SiO2 \+ 2 N2 \+ 2 HCl :Si(OC2H5)4 → SiO2 \+ byproducts The choice of source gas depends on the thermal stability of the substrate; for instance, aluminium is sensitive to high temperature. Silane deposits between 300 and 500 °C, dichlorosilane at around 900 °C, and TEOS between 650 and 750 °C, resulting in a layer of low- temperature oxide (LTO).
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The deposition of silica by diatoms may also prove to be of utility to nanotechnology. Diatom cells repeatedly and reliably manufacture valves of various shapes and sizes, potentially allowing diatoms to manufacture micro- or nano-scale structures which may be of use in a range of devices, including: optical systems; semiconductor nanolithography; and even vehicles for drug delivery. With an appropriate artificial selection procedure, diatoms that produce valves of particular shapes and sizes might be evolved for cultivation in chemostat cultures to mass-produce nanoscale components. It has also been proposed that diatoms could be used as a component of solar cells by substituting photosensitive titanium dioxide for the silicon dioxide that diatoms normally use to create their cell walls.
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Single lava units at the field have uniform compositions, which is distinct from other young lava deposits within the surrounding region; major distinguishing elements include silicon dioxide (silica), titanium dioxide, magnesium oxide, and calcium oxide. The Sand group has high compositional variation, ranging from basalt to basaltic andesite, while the Lost Lake group is mostly basalt, and the Nash group is completely composed of basaltic andesite. The Nash group shows distinctively high silica content and a unique ratio of iron(II) oxide to magnesium oxide, and the Lost Lake Group is distinguished by its lower iron(II) oxide to magnesium oxide ratio and high magnesium oxide content. According to Wood and Kienle (1993), the field has a lava composition of subalkaline basalt and basaltic andesite.
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Like Hogg Rock and other andesite lava domes in the area, it has lower incompatible element abundances than surrounding andesitic rock deposits. A 1992 element abundance analysis of Hayrick Butte andesite samples from the margin of the volcano shows a silicon dioxide (silica) level of 60.1 percent, aluminum oxide level of 18.4 percent, calcium oxide level of 6.24 percent, iron(II) oxide level of 5.55 percent, and sodium oxide level of 4.42 percent. Magnesium oxide made up 3.3 percent of the samples, with potassium oxide levels at 1.08 percent and manganese(II) oxide, phosphorus pentoxide, and titanium dioxide all below 1 percent. Additional studies from 1980 and 1983 exhibit similar levels of silica in samples from Hogg Rock and Hayrick Butte at about 59 to 60 percent.
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Precious opal consists of spheres of silicon dioxide molecules arranged in regular, closely packed planes. (Idealized diagram) Multicolor rough crystal opal from Coober Pedy, South Australia, expressing nearly every color of the visible spectrum Precious opal replacing ichthyosaur backbone; display specimen, South Australian Museum Precious opal shows a variable interplay of internal colors, and though it is a mineraloid, it has an internal structure. At microscopic scales, precious opal is composed of silica spheres some 150 to 300 nm in diameter in a hexagonal or cubic close-packed lattice. It was shown by J. V. Sanders in the mid-1960s that these ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of the opal.
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Life on Earth is based on carbon and water. Carbon provides stable frameworks for complex chemicals and can be easily extracted from the environment, especially from carbon dioxide. There is no other chemical element whose properties are similar enough to carbon's to be called an analogue; silicon, the element directly below carbon on the periodic table, does not form very many complex stable molecules, and because most of its compounds are water-insoluble and because silicon dioxide is a hard and abrasive solid in contrast to carbon dioxide at temperatures associated with living things, it would be more difficult for organisms to extract. The elements boron and phosphorus have more complex chemistries, but suffer from other limitations relative to carbon.
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On this scale, for sand the value of Φ varies from −1 to +4, with the divisions between sub- categories at whole numbers. Close up of black volcanic sand from Perissa, Santorini, Greece The most common constituent of sand, in inland continental settings and non-tropical coastal settings, is silica (silicon dioxide, or SiO2), usually in the form of quartz, which, because of its chemical inertness and considerable hardness, is the most common mineral resistant to weathering. The composition of mineral sand is highly variable, depending on the local rock sources and conditions. The bright white sands found in tropical and subtropical coastal settings are eroded limestone and may contain coral and shell fragments in addition to other organic or organically derived fragmental material, suggesting that sand formation depends on living organisms, too.
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The surface passivation process, also known as the Atalla passivation technique, was developed by Mohamed M. Atalla at Bell Telephone Laboratories (BTL) in the late 1950s. In 1955, Carl Frosch and Lincoln Derick at Bell Telephone Laboratories (BTL) accidentally discovered that silicon dioxide (SiO2) could be grown on silicon. They showed that oxide layer prevented certain dopants into the silicon wafer, while allowing for others, thus discovering the passivating effect of oxidation on the semiconductor surface. In the late 1950s, Atalla further discovered that the formation of a thermally grown SiO2 layer greatly reduced the concentration of electronic states at the silicon surface, and discovered the important quality of SiO2 films to preserve the electrical characteristics of p–n junctions and prevent these electrical characteristics from deteriorating by the gaseous ambient environment.
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The signal delay of a wire or other circuit, measured as group delay or phase delay or the effective propagation delay of a digital transition, may be dominated by resistive-capacitive effects, depending on the distance and other parameters, or may alternatively be dominated by inductive, wave, and speed of light effects in other realms. Resistive-capacitive delay, or RC delay, hinders the further increasing of speed in microelectronic integrated circuits. When the feature size becomes smaller and smaller to increase the clock speed, the RC delay plays an increasingly important role. This delay can be reduced by replacing the aluminum conducting wire by copper, thus reducing the resistance; it can also be reduced by changing the interlayer dielectric (typically silicon dioxide) to low-dielectric-constant materials, thus reducing the capacitance.
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Plasma deposition is often used in semiconductor manufacturing to deposit films conformally (covering sidewalls) and onto wafers containing metal layers or other temperature-sensitive structures. PECVD also yields some of the fastest deposition rates while maintaining film quality (such as roughness, defects/voids), as compared with sputter deposition and thermal/electron-beam evaporation, often at the expense of uniformity. Silicon dioxide can be deposited using a combination of silicon precursor gasses like dichlorosilane or silane and oxygen precursors, such as oxygen and nitrous oxide, typically at pressures from a few millitorr to a few torr. Plasma-deposited silicon nitride, formed from silane and ammonia or nitrogen, is also widely used, although it is important to note that it is not possible to deposit a pure nitride in this fashion.
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Associated with these pipe-like features are objects that were described as "rusty scraps" and "strangely shaped stones". Analysis of the former by Liu Shaolin at a local smeltery reportedly found that they consist of 30 percent ferric oxide (oxidized iron) and large amounts of silicon dioxide and calcium oxide. Because any metallurgical analysis reports the composition of a material analyzed not in terms of the actual minerals comprising it, but only in terms of percentages of the oxides of the specific elements present, the calcium present in the analyzed material could have been in the form of calcite, a mineral that naturally forms concretions. According to news stories, the pipes were first discovered by a group of scientists from the United States who were seeking dinosaur fossils.
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In 1955, Carl Frosch and Lincoln Derick at Bell Telephone Laboratories (BTL) accidentally discovered that silicon dioxide could be grown on silicon. The thermal oxidation process was then developed in the late 1950s by Egyptian engineer Mohamed Atalla, who initially used it for the surface passivation of silicon semiconductors, before he later used the process to fabricate the first MOSFETs (metal-oxide-semiconductor field-effect transistors) with Dawon Kahng at Bell Labs. The process was adopted by Fairchild Semiconductor for technologies which enable the fabrication of silicon integrated circuits (such as the planar process and CMOS). A Scientist’s Perspective on the Early Days of MOS Technology by Bruce Deal By the mid-1960s, Atalla's process for oxidized silicon surfaces was used to fabricate virtually all integrated circuits and silicon devices.
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Chemical-state analysis is widely used for carbon. It reveals the presence or absence of the chemical states of carbon, in approximate order of increasing binding energy, as: carbide (-C2−), silane (-Si-CH3), methylene/methyl/hydrocarbon (-CH2-CH2-, CH3-CH2-, and -CH=CH-), amine (-CH2-NH2), alcohol (-C-OH), ketone (-C=O), organic ester (-COOR), carbonate (-CO32−), monofluoro-hydrocarbon (-CFH-CH2-), difluoro-hydrocarbon (-CF2-CH2-), and trifluorocarbon (-CH2-CF3), to name but a few. Chemical state analysis of the surface of a silicon wafer reveals chemical shifts due to different formal oxidation states, such as: n-doped silicon and p-doped silicon (metallic silicon), silicon suboxide (Si2O), silicon monoxide (SiO), Si2O3, and silicon dioxide (SiO2). An example of this is seen in the figure "High-resolution spectrum of an oxidized silicon wafer in the energy range of the Si 2p signal".
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However, other scientists are not convinced these Early Cambrian fossils show clear signs of the torsion that identifies modern gastropods twists the internal organs so the anus lies above the head. Volborthella, some fossils of which predate , was long thought to be a cephalopod, but discoveries of more detailed fossils showed its shell was not secreted, but built from grains of the mineral silicon dioxide (silica), and it was not divided into a series of compartments by septa as those of fossil shelled cephalopods and the living Nautilus are. Volborthella's classification is uncertain. The Late Cambrian fossil Plectronoceras is now thought to be the earliest clearly cephalopod fossil, as its shell had septa and a siphuncle, a strand of tissue that Nautilus uses to remove water from compartments it has vacated as it grows, and which is also visible in fossil ammonite shells.
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Wanlass later filed US patent 3,356,858 for CMOS circuitry in June 1963, and it was granted in 1967. In both the research paper and the patent, the fabrication of CMOS devices was outlined, on the basis of thermal oxidation of a silicon substrate to yield a layer of silicon dioxide located between the drain contact and the source contact.Low stand-by power complementary field effect circuitry CMOS was commercialised by RCA in the late 1960s. RCA adopted CMOS for the design of integrated circuits (ICs), developing CMOS circuits for an Air Force computer in 1965 and then a 288-bit CMOS SRAM memory chip in 1968. RCA also used CMOS for its 4000-series integrated circuits in 1968, starting with a 20μm semiconductor manufacturing process before gradually scaling to a 10 μm process over the next several years.
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For the surface passivation process, he developed the method of thermal oxidation, which was a breakthrough in silicon semiconductor technology. The surface passivation process was a breakthrough in silicon semiconductor research, as it enabled silicon to surpass the conductivity and performance of germanium, and was the breakthrough that led to silicon replacing germanium as the dominant semiconductor material. The process also laid the foundations for the monolithic integrated circuit chip, as it was the first time that high-quality silicon dioxide insulator films could be grown thermally on the silicon surface to protect the underlying silicon p-n junction diodes and transistors. Before the development of integrated circuit chips, discrete diodes and transistors exhibited relatively high reverse-bias junction leakages and low breakdown voltage, caused by the large density of traps at the surface of single crystal silicon.
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Because it retains its strength at high temperatures and has a high melting point, elemental tungsten is used in many high-temperature applications, such as Incandescent light bulb, cathode-ray tube, and vacuum tube filaments, heating elements, and rocket engine nozzles. Its high melting point also makes tungsten suitable for aerospace and high-temperature uses such as electrical, heating, and welding applications, notably in the gas tungsten arc welding process (also called tungsten inert gas (TIG) welding). Tungsten electrode used in a gas tungsten arc welding torch Because of its conductive properties and relative chemical inertness, tungsten is also used in electrodes, and in the emitter tips in electron-beam instruments that use field emission guns, such as electron microscopes. In electronics, tungsten is used as an interconnect material in integrated circuits, between the silicon dioxide dielectric material and the transistors.
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In 1955, Carl Frosch and Lincoln Derick at Bell Telephone Laboratories (BTL) accidentally discovered that silicon dioxide (SiO2) could be grown on silicon. They showed that oxide layer prevented certain dopants into the silicon wafer, while allowing for others, thus discovering the passivating effect of oxidation on the semiconductor surface. In the 1950s, Mohamed Atalla, picked up Frosch's work on oxidation, investigated the surface properties of silicon semiconductors at Bell Labs, where he proposed a new method of semiconductor device fabrication, coating a silicon wafer with an insulating layer of silicon oxide so that electricity could reliably penetrate to the conducting silicon below, overcoming the surface states that prevented electricity from reaching the semiconducting layer. This is known as surface passivation, a method that became critical to the semiconductor industry as it later made possible the mass-production of silicon integrated circuits.
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In invertebrates, these parts are composed of silica (silicon dioxide), calcite or aragonite (both forms of calcium carbonate), chitin (a protein often infused with tricalcium phosphate), or keratin (an even-more complex protein), rather than the vertebrate bone (hydroxyapatite) or cartilage of fishes and land-dwelling tetrapods. The chitinous jaws of annelids (such as the marine scolecodonts) are sometimes preserved as fossils; while many arthropods and inarticulate brachiopods have easily fossilized hard parts of calcite, chitin, or keratin. The most common and often-found macrofossils are the very hard calcareous shells of articulate brachiopods (that is, the everyday "lampshells") and of mollusks (such as the omnipresent clams, snails, mussels and oysters). On the other hand, shell-less slugs and non-tubiferous worms (for instance, earthworms) lack hard parts and therefore such organisms are poorly represented in the fossil record.
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A colloidal crystal is a highly ordered array of particles that can be formed over a very long range (typically on the order of a few millimeters to one centimeter) and that appear analogous to their atomic or molecular counterparts. One of the finest natural examples of this ordering phenomenon can be found in precious opal, in which brilliant regions of pure spectral color result from close-packed domains of amorphous colloidal spheres of silicon dioxide (or silica, SiO2). These spherical particles precipitate in highly siliceous pools in Australia and elsewhere, and form these highly ordered arrays after years of sedimentation and compression under hydrostatic and gravitational forces. The periodic arrays of submicrometre spherical particles provide similar arrays of interstitial voids, which act as a natural diffraction grating for visible light waves, particularly when the interstitial spacing is of the same order of magnitude as the incident lightwave.
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An alternative method of focusing X-rays is to use a tiny Fresnel zone plate of concentric gold or nickel rings on a silicon dioxide substrate. Sir Lawrence Bragg produced some of the first usable X-ray images with his apparatus in the late 1940s. Indirect drive laser inertial confinement fusion uses a "hohlraum" which is irradiated with laser beam cones from either side on its inner surface to bathe a fusion microcapsule inside with smooth high intensity X-rays. The highest energy X-rays which penetrate the hohlraum can be visualized using an X-ray microscope such as here, where X-radiation is represented in orange/red. In the 1950s Sterling Newberry produced a shadow X-ray microscope which placed the specimen between the source and a target plate, this became the basis for the first commercial X-ray microscopes from the General Electric Company.
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In 2013 the United States the Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) released a hazard alert based on data collected by NIOSH that "workers may be exposed to dust with high levels of respirable crystalline silica (silicon dioxide) during hydraulic fracturing." NIOSH notified company representatives of these findings and provided reports with recommendations to control exposure to crystalline silica and recommend that all hydraulic fracturing sites evaluate their operations to determine the potential for worker exposure to crystalline silica and implement controls as necessary to protect workers. The EPA states in their Hydraulic Fracturing Study Plan (2011) that the exposure to hydraulic fracturing chemicals in an occupational setting needs to be examined to determine the acute and chronic effects on health. The exposure risks such as “transport, mixing, delivery, and potential accidents” have not been properly assessed (p. 57).
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Structural motif found in α-quartz, but also found in almost all forms of silicon dioxide Relationship between refractive index and density for some SiO2 forms In the majority of silicates, the silicon atom shows tetrahedral coordination, with four oxygen atoms surrounding a central Si atom. The most common example is seen in the quartz polymorphs. It is a 3 dimensional network solid in which each silicon atom is covalently bonded in a tetrahedral manner to 4 oxygen atoms. For example, in the unit cell of α-quartz, the central tetrahedron shares all four of its corner O atoms, the two face-centered tetrahedra share two of their corner O atoms, and the four edge-centered tetrahedra share just one of their O atoms with other SiO4 tetrahedra. This leaves a net average of 12 out of 24 total vertices for that portion of the seven SiO4 tetrahedra that are considered to be a part of the unit cell for silica (see 3-D Unit Cell).
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Unlike electronic integration where silicon is the dominant material, system photonic integrated circuits have been fabricated from a variety of material systems, including electro-optic crystals such as lithium niobate, silica on silicon, Silicon on insulator, various polymers and semiconductor materials which are used to make semiconductor lasers such as GaAs and InP. The different material systems are used because they each provide different advantages and limitations depending on the function to be integrated. For instance, silica (silicon dioxide) based PICs have very desirable properties for passive photonic circuits such as AWGs (see below) due to their comparatively low losses and low thermal sensitivity, GaAs or InP based PICs allow the direct integration of light sources and Silicon PICs enable co-integration of the photonics with transistor based electronics. The fabrication techniques are similar to those used in electronic integrated circuits in which photolithography is used to pattern wafers for etching and material deposition.
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As an oceanic plate descends into the upper mantle, its minerals tend to lose water. How much water is lost and when depends on the pressure, temperature and mineralogy. Water is carried by a variety of minerals that combine various proportions of magnesium oxide (MgO), silicon dioxide (SiO2), and water. At low pressures (below 5 GPa), these include antigorite, a form of serpentine, and clinochlore (both carrying 13 wt% water); talc (4.8 wt%) and some other minerals with a lower capacity. At moderate pressure (5–7 GPa) the minerals include phlogopite (4.8 wt%), the 10Å phase (a high pressure product of talc and water, 10–13 wt%) and lawsonite (11.5 wt%). At pressures above 7 GPa, there is topaz-OH (Al2SiO4(OH)2, 10 wt%), phase Egg (AlSiO3(OH), 11–18 wt%) and a collection of dense hydrous magnesium silicate (DHMS) or "alphabet" phases such as phase A (12 wt%), D (10 wt%) and E (11 wt%).
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In the figure, a two-layer structure is shown, consisting of an insulator as left-hand layer and a semiconductor as right-hand layer. An example of such a structure is the MOS capacitor, a two-terminal structure made up of a metal gate contact, a semiconductor body (such as silicon) with a body contact, and an intervening insulating layer (such as silicon dioxide, hence the designation O). The left panels show the lowest energy level of the conduction band and the highest energy level of the valence band. These levels are "bent" by the application of a positive voltage V. By convention, the energy of electrons is shown, so a positive voltage penetrating the surface lowers the conduction edge. A dashed line depicts the occupancy situation: below this Fermi level the states are more likely to be occupied, the conduction band moves closer to the Fermi level, indicating more electrons are in the conducting band near the insulator.
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The usual metallurgic use of carbon as the reducing agent instead of silicon cannot be used, because the silicon dioxide is a solid, while carbon dioxide and monoxide are both gaseous, and would follow the magnesium into the condensing zone, reverting the reaction as follows. : C(s) + MgO(s) → CO(g) + Mg(g) (high temperature, distillation boiling zone) : CO(g) + Mg(g) → C(s) + MgO(s) (low temperature, distillation condensing zone) In this case, the carbothermic reaction would produce no yield when the vapors moved into the cooler condensing zones inside the reactor, even though temporarily there would be intermediate carbon monoxide and actual magnesium vapors. There is still a feasible process with carbon, that uses shock-freezing of the vapors, to disallow any time for the reverse reaction - though such shock cooling is a far stretch from being an economical industrial process. At temperatures where the magnesium is still liquid or solid (say 600-700 °C), but carbon oxides are gaseous, the immense thermodynamic counter drive makes the reactions impractical, even if the carbon monoxide was purged away by argon, for example.
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A woman wears sunglasses featuring a highly reflective optical coating High-reflection (HR) coatings work the opposite way to antireflection coatings. The general idea is usually based on the periodic layer system composed from two materials, one with a high index, such as zinc sulfide (n=2.32) or titanium dioxide (n=2.4), and one with a low index, such as magnesium fluoride (n=1.38) or silicon dioxide (n=1.49). This periodic system significantly enhances the reflectivity of the surface in the certain wavelength range called band-stop, whose width is determined by the ratio of the two used indices only (for quarter-wave systems), while the maximum reflectivity increases up to almost 100% with a number of layers in the stack. The thicknesses of the layers are generally quarter-wave (then they yield to the broadest high reflection band in comparison to the non-quarter-wave systems composed from the same materials), this time designed such that reflected beams constructively interfere with one another to maximize reflection and minimize transmission.
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Owens-Corning is still the major glass-fiber producer in the market today. The most common types of glass fiber used in fiberglass is E-glass, which is alumino- borosilicate glass with less than 1% w/w alkali oxides, mainly used for glass- reinforced plastics. Other types of glass used are A-glass (Alkali-lime glass with little or no boron oxide), E-CR-glass (Electrical/Chemical Resistance; alumino-lime silicate with less than 1% w/w alkali oxides, with high acid resistance), C-glass (alkali-lime glass with high boron oxide content, used for glass staple fibers and insulation), D-glass (borosilicate glass, named for its low Dielectric constant), R-glass (alumino silicate glass without MgO and CaO with high mechanical requirements as reinforcement), and S-glass (alumino silicate glass without CaO but with high MgO content with high tensile strength). Pure silica (silicon dioxide), when cooled as fused quartz into a glass with no true melting point, can be used as a glass fiber for fiberglass, but has the drawback that it must be worked at very high temperatures.
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Composition: the most common types of glass fiber used in fiberglass is E-glass, which is alumino-borosilicate glass with less than 1% w/w alkali oxides, mainly used for glass-reinforced plastics. Other types of glass used are A-glass (Alkali-lime glass with little or no boron oxide), E-CR-glass (Electrical/Chemical Resistance; alumino-lime silicate with less than 1% w/w alkali oxides, with high acid resistance), C-glass (alkali-lime glass with high boron oxide content, used for glass staple fibers and insulation), D-glass (borosilicate glass, named for its low Dielectric constant), R-glass (alumino silicate glass without MgO and CaO with high mechanical requirements as Reinforcement), and S-glass (alumino silicate glass without CaO but with high MgO content with high tensile strength). Naming and use: pure silica (silicon dioxide), when cooled as fused quartz into a glass with no true melting point, can be used as a glass fiber for fiberglass but has the drawback that it must be worked at very high temperatures. In order to lower the necessary work temperature, other materials are introduced as "fluxing agents" (i.e.
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One of their research studies includes MONOS (metal-oxide-nitride-oxide-semiconductor) technology, which used Renesas Electronics' flash memory integrated in single-chip microcontrollers. In 1972, a type of electrically re-programmable non-volatile memory was invented by Fujio Masuoka at Toshiba, who is also known as the inventor of flash memory. Most of the major semiconductor manufactures, such as Toshiba, Sanyo (later, ON Semiconductor), IBM, Intel, NEC (later, Renesas Electronics), Philips (later, NXP Semiconductors), Siemens (later, Infineon Technologies), Honeywell (later, Atmel), Texas Instruments, studied, invented, and manufactured some electrically re-programmable non-volatile devices until 1977. The theoretical basis of these devices is Avalanche hot-carrier injection. But in general, programmable memories, including EPROM, of early 1970s had reliability and endurance problems such as the data retention periods and the number of erase/write cycles. In 1975, NEC's semiconductor operations unit, later NEC Electronics, currently Renesas Electronics, applied the trademark name EEPROM® to Japan Patent Office. In 1978, this trademark right is granted and registered as No.1,342,184 in Japan, and still survives as of March 2018. In February 1977, Eliyahou Harari at Hughes Aircraft Company invented a new EEPROM technology using Fowler-Nordheim tunnelling through a thin silicon dioxide layer between the floating-gate and the wafer.
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