The gathering maintains the aesthetics of liberation but runs with an operational slickness that is both impressive and unnerving: While waiting in line for Indian food, I saw a small surveillance camera in the folds of a dangling tetragonal lantern.
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By the time the pressure raised to about a gigapascal, roughly 10 times that at the bottom of the Marianas Trench, the water had transformed into a tetragonal crystal called ice VI. By about 2 gigapascals, it had switched into ice VII, a denser, cubic form transparent to the naked eye that scientists recently discovered also exists in tiny pockets inside natural diamonds.
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WB2 has the same hexagonal structure as most diborides (AlB2, MgB2, etc.). WB has several forms, α(tetragonal), β (orthorhombic) and δ (tetragonal).
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A tetragonal disphenoid viewed orthogonally to the two green edges. This property also applies for tetragonal disphenoids when applied to the two special edge pairs.
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The ZrO2 band gap is dependent on the phase (cubic, tetragonal, monoclinic, or amorphous) and preparation methods, with typical estimates from 5–7 eV. A special case of zirconia is that of tetragonal zirconia polycrystal, or TZP, which is indicative of polycrystalline zirconia composed of only the metastable tetragonal phase.
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A number of other structure types can also be adopted, with varying electrical properties: cubic, tetragonal I and hexagonal phases are metallic, whereas orthorhombic and tetragonal II structures are semiconducting.
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An example of the tetragonal crystals, wulfenite In crystallography, the tetragonal crystal system is one of the 7 crystal systems. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a square base (a by a) and height (c, which is different from a).
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Yttria blends of approximately 3% are called either tetragonal polycrystalline zirconia or tetragonal zirconia polycrystal (forming the initialisms TZP or TPZ) and have the finest grain size. These grades exhibit the highest toughness at room temperature, because they are nearly 100% tetragonal, but this degrades severely between 200 and 500 °C as these irreversible crystal transformations also cause dimensional change.
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Pure α-tetragonal can only be synthesized as thin layers deposited on an underlying substrate of isotropic boron carbide (B50C2) or nitride (B50N2). Most examples of α-tetragonal boron are in fact boron-rich carbide or nitrides.
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KIO4 forms tetragonal crystals of the Scheelite type (space group I41/a).
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It has tetragonal crystal symmetry, P42/mnm, No. 136, Pearson symbol tP6.
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In terms of electronic structure, Mn(acac)3 is high spin. Its distorted octahedral structure reflects geometric distortions due to the Jahn–Teller effect. The two most common structures for this complex include one with tetragonal elongation and one with tetragonal compression. For the elongation, two Mn–O bonds are 2.12 Å while the other four are 1.93 Å. For the compression, two Mn–O bonds are 1.95 Å and the other four are 2.00 Å. The effects of the tetragonal elongation are noticeably more significant than the effects of the tetragonal compression.
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There is only one tetragonal Bravais lattice in two dimensions: the square lattice.
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Ordoñezite or ordóñezite is a rare tetragonal zinc antimonate mineral with chemical formula: ZnSb2O6.
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For orthorhombic, tetragonal and cubic lattices with as well, then :V = a b c .
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It consists of tin dioxide, or stannic oxide, and crystallizes in the tetragonal system.
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CH4, Xe, Kr) are cubic and the symmetry lowers to tetragonal for non-spherical guests like tetrahydrofuran or tetrahydrothiophene. Since many molecules form unstable guests, the symmetry of melanophlogite can change between cubic and tetragonal upon mild heating (<100 °C). Even the cubic melanophlogite often shows anisotropic optical properties. They were attributed not to tetragonal fragments but to the organic film in the mineral which could be removed by low-temperature annealing (~400 °C).
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Bearing balls Zirconium dioxide is one of the most studied ceramic materials. ZrO2 adopts a monoclinic crystal structure at room temperature and transitions to tetragonal and cubic at higher temperatures. The change of volume caused by the structure transitions from tetragonal to monoclinic to cubic induces large stresses, causing it to crack upon cooling from high temperatures. When the zirconia is blended with some other oxides, the tetragonal and/or cubic phases are stabilized.
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The larvae feed on Celastraceae species, including Cassine tetragonal, Maytenus acuminate, Maytenus heterophylla and Rawsonia lucida.
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Superconductivity disappears at x ≈ 0.6, where the structural transformation of YBCO occurs from orthorhombic to tetragonal.
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The two predominant polymorphs of GeO2 are hexagonal and tetragonal. Hexagonal GeO2 has the same structure as β-quartz, with germanium having coordination number 4. Tetragonal GeO2 (the mineral argutite) has the rutile-like structure seen in stishovite. In this motif, germanium has the coordination number 6.
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As determined by X-ray crystallography, both polymorphs, tetragonal and orthorhombic feature a pyramidal four-coordinate lead center. In the tetragonal form the four lead–oxygen bonds have the same length, but in the orthorhombic two are shorter and two longer. The pyramidal nature indicates the presence of a stereochemically active lone pair of electrons. When PbO occurs in tetragonal lattice structure it is called litharge; and when the PbO has orthorhombic lattice structure it is called massicot.
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Massicot is lead (II) oxide mineral with an orthorhombic lattice structure. Lead(II) oxide (formula: PbO) can occur in one of two lattice formats, orthorhombic and tetragonal. The tetragonal form is called litharge. PbO can be changed from massicot to litharge (or vice versa) by controlled heating and cooling.
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A tetragonal form is also known as the very rare mineral called polhemusite, with the formula (Zn,Hg)S.
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Its dual, the elongated tetragonal disphenoid, can be found as cells of the duals of the p-q duoantiprisms.
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The tetragonal hosohedron is topologically equivalent to the bicylinder Steinmetz solid, the intersection of two cylinders at right-angles.
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The tetragonal trapezohedron is first in a series of dual snub polyhedra and tilings with face configuration V3.3.4.3.n.
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It has a hardness of 3 and a specific gravity of 4.45. Enargite is dimorph of the tetragonal luzonite.
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When decompressed to 66 GPa it decomposes to solid FeH3. The unit cell is tetragonal with symmetry I4/mmm.
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In some cases, the tetragonal phase can be metastable. If sufficient quantities of the metastable tetragonal phase is present, then an applied stress, magnified by the stress concentration at a crack tip, can cause the tetragonal phase to convert to monoclinic, with the associated volume expansion. This phase transformation can then put the crack into compression, retarding its growth, and enhancing the fracture toughness. This mechanism is known as transformation toughening, and significantly extends the reliability and lifetime of products made with stabilized zirconia.
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The pollen of F. longifolia is shed as loose, permanent, tetragonal or tetrahedral tetrads that are 115 micrometers in diameter.
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Behind the wing the fuselage tapered further to a cantilever T-tail. The broad vertical tail was essentially tetragonal in profile, with a generous rudder. The horizontal tail was also tetragonal but much smaller in area. The KAI-19 landed on an electrically operated, fully retractable monowheel with an oleo strut and a disc brake.
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On cooling from high temperature, KNbO3 undergoes a series of structural phase transitions. At 435 °C, the crystal symmetry changes from cubic centrosymmetric (Pmm) to tetragonal non-centrosymmetric (P4mm). On further cooling, at 225 °C the crystal symmetry changes from tetragonal (P4mm) to orthorhombic (Amm2) and at −50 °C from orthorhombic (Amm2) to rhombohedral (R3m).
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Tetragonal ZrF4 Three crystalline phases of ZrF4 have been reported, α (monoclinic), β (tetragonal, Pearson symbol tP40, space group P42/m, No 84) and γ (unknown structure). β and γ phases are unstable and irreversibly transform into the α phase at 400 °C. Zirconium fluoride is used as a zirconium source in oxygen-sensitive applications, e.g. metal production.
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A regular tetrahedron or tetragonal disphenoid can be dissected into two halves with a central square. Each half is a topological triangular prism.
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Also, it was demonstrated by Tsuei, Kirtley et al. that there was a pure dx2-y2 order parameter symmetry in the tetragonal Tl2Ba2CuO6.
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The silicon atoms are 8-fold coordinated by hydrogen (i.e. each silicon atom is bonded to 8 hydrogen atoms) forming a tetragonal structure.
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There is evidence of a tetragonal phase, observed in X-ray powder tests and later under a microscope. When tested two meteorites gave d-values that could "be indexed on the basis of a tetragonal unit cell, but not on the basis of a cubic or hexagonal unit cell". It has been speculated to be e-iron, a hexagonal polymorph of iron.
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Inflorescence is a terminal tetragonal spike. The flowers are blue-violet or purple-white, 2.5–3 cm long. They bloom from June to August.
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Amorphous powder boron Boron (likely mixed allotropes) Boron can be prepared in several crystalline and amorphous forms. Well known crystalline forms are α-rhombohedral, β-rhombohedral, and β-tetragonal. In special circumstances, boron can also be synthesized in the form of its α-tetragonal and γ-orthorhombic allotropes. Two amorphous forms, one a finely divided powder and the other a glassy solid, are also known.
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Zn3P2 has a room-temperature tetragonal form that converts to a cubic form at around 845 °C.Evgeniĭ I︠U︡rʹevich Tonkov, 1992, High Pressure Phase Transformations: A Handbook, Vol 2, Gordon and Breach Science Publishers, In the room-temperature form there are discrete P atoms, zinc atoms are tetrahedrally coordinated and phosphorus six coordinate, with zinc atoms at 6 of the vertices of a distorted cube.Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ZnP2 also has two forms, a lower-temperature red tetragonal form and a black monoclinic form. In both of these there are chains of P atoms, helical in the tetragonal, semi-spiral in the monoclinic.
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Rosenbergite is a mineral with the chemical formula AlF3·3H2O. It is a trihydrate of aluminium fluoride. It is colorless. Its crystals are tetragonal to dipyramidal.
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The gyrobifastigium topology exists in a tetragonal disphenoid with its lateral faces divided on the plane of symmetry which with specific proportions can tessellate 3-space.
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Due to this, this copper site is instead a centered tetragonal pyramid with the oxygen atom of water molecule at a distant fifth apex CuO4(H2O).
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This difference is attributed to the effects of hydrogen bonding, which is absent in the gaseous state. Crystals of are tetragonal with the space group D'P4121.
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When freshly prepared, polonium dioxide is always in the tetragonal form, and changes to the cubic form after being left to stand or after being cooled strongly.
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Six tetragonal disphenoids attached end-to-end in a ring construct a kaleidocycle, a paper toy that can rotate on 4 sets of faces in a hexagon.
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The composition of the active material is approximately Sn0.3Co0.4C0.3. Recent research showed that only some crystalline facets of tetragonal (beta) Sn are responsible for undesirable electrochemical activity.
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Boleite has cubes over half an inch on each side, which consist of pseudo-octahedral tetragonal dipyramids.Weber, Julius (1974). The Formation of Minerals. Van Nostrand Reinhold Company.
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The amount of the tetragonal and untwined hexagonal crystal forms of PB-1 decreased by irradiation but the overall crystallinity in the irradiated samples is nearly unchanged.
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The PbO can be changed from massicot to litharge or vice versa by controlled heating and cooling.A simple example is given in A more complex example is in The tetragonal form is usually red or orange color, while the orthorhombic is usually yellow or orange, but the color is not a very reliable indicator of the structure. The tetragonal and orthorhombic forms of PbO occur naturally as rare minerals.
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In this process, the normal face- centered cubic structure is transformed to a face-centered tetragonal configuration, offering a higher density product useful for many storage media applications.
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Its crystal system is tetragonal and its crystal class is 4/m, which is also called the tetragonal-dipyramidal class because it only has a vertical four-fold rotation axis that is perpendicular to the symmetry plane.Roberts, W., Campbell, T., and Rapp, G. (1990) Encyclopedia of Minerals (Second Edition), 558 p. Van Nordstrand Reinhold, New York.Klein, C., and Dutrow, B. (2007) The 23rd Edition of the Manual of Mineral Science (23rd edition), 194 p.
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439 p. Oxford University Press, Great Clarendon Street, Oxford. Tetragonal minerals have three axes of different lengths and angles of 90 degrees. Fluorapophyllite is an anisotropic mineral and has low relief.
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Females have on their head a tetragonal cap like patch varying in color from pale pink to grey, iris colour reddish to golden brown (see the image: a = male;b = female).
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Capa rose is considered a small evergreen tree or shrub. It can grow up to tall. When twigs are young, they are whitish color. The branches are tetragonal, meaning four- sided.
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At ambient conditions calcium disilicide exists in two polymorphs, hR9 and hR18; in the hR18 structure the hR9 unit cell is stacked twice along the c axis. Upon heating to 1000 °C at a pressure of ca. 40 kBar, calcium disilicide converts to a (semi-stable) tetragonal phase. The tetragonal phase is a superconductor with a transition temperature of 1.37 K to 1.58 K. Although there is no observable superconducting transition temperature for the trigonal/rhombohedral (i.e.
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Schematic of transformation toughening in partially stabilized zirconia The TRIP effect is found in partially stabilized zirconia. Partially stabilized zirconia is composed of tetragonal phase at high temperature and monoclinic phase and cubic phase at lower temperature in equilibrium. In some components, the onset temperature of tetragonal monoclinic martensite transformation is lower than room temperature. The stress field near the crack tip triggers the martensitic transformation at velocities hypothesized to approach that of sound in the material.
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The tetragonal particle size should be controlled properly. It is due to that too large particle size leads to spontaneous transformation and too small particle size leads to a very small toughening effect.
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Gold(I) bromide can be formed by synthesis from the elements or partial decomposition of gold(III) bromide by careful control of temperatures and pressures. It occurs in two modifications. One (I-AuBr) is isostructural with gold(I) chloride and has a body centered tetragonal unit cell with a=6.734A and c=8.674A and space group I41/amd. The other is isostructural with gold(I) iodide and has a primitive tetragonal cell a=4.296A and c=12.146A and space group P42/ncm.
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This occurrence in neptunium compounds is somewhat surprising because they often exhibit strong magnetism, which usually destroys superconductivity. The alloy has a tetragonal structure with a superconductivity transition temperature of −268.3 °C (4.9 K).
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Grains of cubic zirconia and cubic strontium titanate were significantly refined by TSS compared to CRH. However, the grain size changes in other ceramic materials, like tetragonal zirconia and hexagonal alumina, were not statistically significant.
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KN3, RbN3, CsN3, and TlN3 adopt the same structures. They crystallize in a tetragonal habit. The azide is bound to eight cations in an eclipsed orientation. The cations are bound to eight terminal N centers.
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The mechanical robustness compared to alumina is attributed to the displacive phase transformation of the metastable tetragonal zirconia grains when the material is stressed. The stress concentration at a crack tip can cause a transformation from a tetragonal crystal structure to a monoclinic one, which has an associated volume expansion of zirconia. This volume expansion effectively pushes back the propagation of the crack and results in higher toughness and strength.Zirconia Toughened Alumina A common specimen of Zirconia Toughened Alumina will have 10-20% zirconium oxides.
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The two resulting electrons reduce both copper centers to their Cu(I)-Cu(I) state. Dioxygen then binds one copper center, displacing the coordinated water molecule, and another molecule of catechol binds to the other copper center, displacing another histidine residue. This forms a complex in which one copper center has a tetragonal planar coordination with His240, His244 and the dioxygen molecule. The other copper center retains its initial tetragonal pyramidal geometry with dioxygen, His88 and His118 in the equatorial positions, and His109 in an axial position.
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Cr11Ge19 crystals Cr11Ge19 lattice structure In inorganic chemistry, a Nowotny chimney ladder phase (NCL phase) is a particular intermetallic crystal structure found with certain binary compounds. NLC phases are generally tetragonal and are composed of two separate sublattices. The first is a tetragonal array of transition metal atoms, generally from group 4 through group 9 of the periodic table. Contained within this array of transition metal atoms is a second network of main group atoms, typically from group 13 (boron group) or group 14 (carbon group).
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The particulate phase of greatest interest is tetragonal zirconia because of the toughening that can be achieved from the phase transformation from the metastable tetragonal to the monoclinic crystalline phase, aka transformation toughening. There is also substantial interest in dispersion of hard, non-oxide phases such as SiC, TiB, TiC, boron, carbon and especially oxide matrices like alumina and mullite. There is also interest too incorporating other ceramic particulates, especially those of highly anisotropic thermal expansion. Examples include Al2O3, TiO2, graphite, and boron nitride.
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Yttrium oxyfluoride forms colorless crystals of tetragonal crystal system; its cell parameters are: a = 0.3910 nm, c = 0.5431 nm. According to hexagonal crystal family, the cell parameters are: a = 0.38727 nm, c = 1.897 nm, Z = 6.
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1980, pp. 166–71 The existence of such allotropes can complicate the classification of the elements involved.Fine & Beall 1990, p. 578 Tin, for example, has two allotropes: tetragonal "white" β-tin and cubic "grey" α-tin.
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Abswurmbachite is a copper manganese silicate mineral ((Cu,Mn2+)Mn3+6O8SiO4). It was first described in 1991 and named after Irmgard Abs-Wurmbach (born 1938), a German mineralogist. It crystallizes in the tetragonal system. Its Moh.
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At room temperature, polonium dioxide has a face-centered cubic (fluorite) crystal structure; upon heating to high temperatures, it crystallises in the tetragonal crystal system. The cubic form is pale yellow, while the tetragonal form is red. Polonium dioxide darkens upon heating, and is chocolate brown at its sublimation point, 885 °C. The ionic radius of the ion is 1.02 or 1.04 Å; thus, the ratio of the ionic radii / is about 0.73, the lower limit of stability for the cubic crystal system, allowing polonium dioxide to have two modifications.
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This ceramic layer creates the largest thermal gradient of the TBC and keeps the lower layers at a lower temperature than the surface. However, above 1200 °C, YSZ suffers from unfavorable phase transformations, going from t'-tetragonal to tetragonal to cubic to monoclinic. Such phase transformations lead to crack formation within the top coating. Recent advancements in finding an alternative for YSZ ceramic topcoat identified many novel ceramics (rare earth zirconates) having superior performance at temperatures above 1200 °C, however with inferior fracture toughness compared to that of YSZ.
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Another example is tin, which transitions from a cubic crystal below 13.2 °C to a tetragonal crystal above that temperature. In the case of ferroelectric or ferromagnetic crystals, a transition temperature may be known as the Curie temperature.
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So, by tuning their technique further, they found that there was an admixture of s symmetry in YBCO within about 3%. Also, they found that there was a pure dx2-y2 order parameter symmetry in the tetragonal Tl2Ba2CuO6.
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Asisite (Pb7SiO8Cl2) is a yellow tetragonal mineral. It is found at Kombat Mine, Kombat, Grootfontein District, Otjozondjupa Region, Namibia. It was named for a farm, Asis, which covers the mine where it was found. It was discovered in 1988.
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The term can also refer to octahedral influenced by the Jahn–Teller effect, which is a common phenomenon encountered in coordination chemistry. This reduces the symmetry of the molecule from Oh to D4h and is known as a tetragonal distortion.
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Monoammonium phosphate is a widely used crystal in the field of optics due to its birefringence properties. As a result of its tetragonal crystal structure, this material has negative uniaxial optical symmetry with typical refractive indices and at optical wavelengths.
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Iron disilicide (FeSi2) is an intermetallic compound, a silicide of iron that occurs in nature as the rare mineral linzhiite. At room temperature it forms orthorhombic crystals (β phase), which convert into a tetragonal α phase upon heating to 970 °C.
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There is a stretched hexagon in the bottom for writing the awarding date. The medal is bordered with a salient ledge. All inscriptions and pictures are salient. With the help of eye ring the medal is attached to a tetragonal block.
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Sheffield Steel, . The characteristic body-centered tetragonal martensite microstructure was first observed by German microscopist Adolf Martens around 1890. In 1912, Elwood Haynes applied for a U.S. patent on a martensitic stainless steel alloy. This patent was not granted until 1919.
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Cologne's bursary officer, Roland von Odendorp, was responsible for its construction. The Gothic building with its two tetragonal upper stories and two more octagonal top stories has some similarities to Dutch belfries of the time and rises to 61 m.
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Marialite has tetragonal crystallography and a 4/m crystal class. It has a 4 fold rotation with 90° mirror planes. Crystals are usually prismatic with prominent forms of prisms and dipyramids.Johnsen, O. (2000) Photographic Guide to Minerals of the World.
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Wulfenite crystallizes in the tetragonal system and possesses nearly equal axial ratios; as a result, it is considered to be crystallographically similar to scheelite(CaWO4). Wulfenite is classed by a pyramidal-hemihedral (tetragonal dipyramidal) (C4h) crystal symmetry. Therefore, the unit cell is formed by placing points at the vertices and centers of the faces of rhomboids with square bases and the crystallographic axes coincide in directions with the edges of the rhomboids. Two of these lattices interpenetrate such that a point on the first is diagonal to the second and one quarter the distance between the two seconds.
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In the solid state, MgO2 has a cubic pyrite-type crystal structure with 6-coordinate Mg2+ ions and O22− peroxide-groups, according to experimental data and evolutionary crystal structure prediction, the latter predicting a phase transition at the pressure of 53 GPa to a tetragonal structure with 8-coordinate Mg2+ ions. While at normal conditions MgO2 is a metastable compound (less stable than MgO +1/2O2), at pressures above 116 GPa it is predicted to become thermodynamically stable in the tetragonal phase. This theoretical prediction has been experimentally confirmed via synthesis in a laser-heated diamond anvil cell.
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ScB12 was originally reported as having a cubic structure, later studies showed it to have tetragonal structure (unit cell with a=522pm, c=735pm). More recently it has been shown that there is indeed a cubic form but that it requires stabilization.
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Tantalite is also very close to tapiolite. Those minerals have same chemical composition, but different crystal symmetry orthorhombic for tantalite and tetragonal for tapiolite. Tantalite is black to brown in both color and streak. Manganese- rich tantalites can be brown and translucent.
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It is carinate at the periphery and slightly deflected anteriorly. The base of the shell is nearly flat with numerous (15 to 20) close finely beaded concentric lirulae. The tetragonal aperture is very oblique. The upper lip is straightened and wrinkled within.
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The structure of these materials depends on the oxygen content. This non- stoichiometry is denoted by the x in the chemical formula YBa2Cu3O7−x. When x = 1, the O(1) sites in the Cu(1) layer are vacant and the structure is tetragonal.
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The periphery is roundly carinate. The convex base contains nine fine granulose cinguli with axially lirate interstices. The obliqua aperture is tetragonal. The outer lip is thick, with two rows of denticles, the outer corresponding to the cinguli, the inner about six in number.
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When the phosphate anion is replaced by the larger vanadate anion, the tetragonal crystal system preferentially accommodates the larger light rare- earth elements.Miyawaki R., and I. Nakai. (1996). "Crystal Chemical Aspects of Rare Earth Minerals". Ed. Andrian P. Jones, Frances Wall, and C. Terry Williams.
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The band gap of thoria is about 6 eV. A tetragonal form of thoria is also known. Thorium dioxide is more stable than thorium monoxide (ThO). Only with careful control of reaction conditions can oxidation of thorium metal give the monoxide rather than the dioxide.
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The elements studied to date as solid samples have eight kinds of crystal structures: cubic, body-centered cubic, face-centered cubic, hexagonal, monoclinic, orthorhombic, rhombohedral, and tetragonal. For some of the synthetically produced transuranic elements, available samples have been too small to determine crystal structures.
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X-ray diffraction shows that the complex is tetrameric, in contrast to the trimeric palladium analog. The four platinum atoms form a square cluster, with eight bridging acetate ligands surrounding them. The compound has slight distortions from idealized D2d symmetry. The crystal structure is tetragonal.
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Three phases are known: monoclinic below 1170 °C, tetragonal between 1170 °C and 2370 °C, and cubic above 2370 °C.R. Stevens, 1986. Introduction to Zirconia. Magnesium Elektron Publication No 113 The trend is for higher symmetry at higher temperatures, as is usually the case.
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Parakhinite crystallizes in the tetragonal system. Khinite and parakhinite are also called khinite-4O and khinite-3T, respectively. Khinite and parakhinite are identical in colour and many other properties, like reactivity. They do differ in optical properties: Khinite is biaxial (+), while parakhinite is uniaxial (-).
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Berzelianite is a rare copper selenide mineral with the formula Cu2Se. It occurs as thin dendritic crusts or as fine-grained inclusions. It crystallizes in the isometric system, unlike its dimorph, bellidoite, which crystallizes in the tetragonal system. The crystals are opaque and slightly malleable.
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The 122s form in the I4/mmm tetragonal structure. For example, the tetragonal unit cell of SrFe2As2, at room temperature, has lattice parameters a = b = 3.9243 Å and c = 12.3644 Å. The planar geometry is reminiscent of the cuprate high-Tc superconductors in which the Cu-O layers are believed to support superconductivity. These materials undergo a first- order structural phase transition into the Fmmm orthorhombic structure below some characteristic temperature T0 that is compound specific. NMR experiments on the CaFe2As2 show that there is a first-order antiferromagnetic magnetic phase transition at the same temperature; in contrast, the antiferromagnetic transition occurs at a lower temperature in the 1111s.
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For example, three boron atoms make up a triangle where they share two electrons to complete the so-called three-center bonding. Boron polyhedra, such as B6 octahedron, B12 cuboctahedron and B12 icosahedron, lack two valence electrons per polyhedron to complete the polyhedron-based framework structure. Metal atoms need to donate two electrons per boron polyhedron to form boron-rich metal borides. Thus, boron compounds are often regarded as electron-deficient solids. Icosahedral B12 compounds include α-rhombohedral boron (B13C2), β-rhombohedral boron (MeBx, 23≤x), α-tetragonal boron (B48B2C2), β-tetragonal boron (β-AlB12), AlB10 or AlC4B24, YB25, YB50, YB66, NaB15 or MgAlB14, γ-AlB12, BeB3 and SiB6. Fig. 2.
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Minium is the naturally occurring form of lead tetroxide, Pb2+2Pb4+O4 also known as red lead. Minium is a light-to-vivid red and may have brown-to-yellow tints. It typically occurs in scaly-to-earthy masses. It crystallizes in the tetragonal crystal system.
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Nickel(II) fluoride is the chemical compound with the formula NiF2. Its is an ionic compound of nickel and fluorine and forms yellowish to green tetragonal crystals. Unlike many fluorides, NiF2 is stable in air. NiF2 comprises the passivating surface that forms on nickel alloys (e.g.
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They have a brown, entirely corneous, circular, multispiral operculum which fits the aperture snugly. The operculum is formed of numerous gradually increasing whorls with a central nucleus. The aperture may be entire, tetragonal or rounded and has no reflected lip. The peristome is generally not continuous.
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Sideritis cypria, Cyprus ironwort. Erect perennial herb with a woody base, 60 cm high, with densely hairy tetragonal shoots. Leaves, opposite, simple, obscurely serrate, densely hairy, thick, oblanceolate, 3-12 x 1–5 cm. Flowers in verticillasters subtended by the cup-like bracts, zygomorphic, corolla bright yellow.
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Chalcopyrite ( ) is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical formula CuFeS2. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.
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Compounds of nickel with other metals can be called alloys. The substances with fixed composition include nickel aluminide (NiAl) melting at 1638° with hexagonal structure. NiY, NiY3, Ni3Y, Ni4Y, NiGd3, BaNi2Ge2 changes structure from orthorhombic to tetragonal around 480 °C. This is a ternary intermetallic compound.
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Edingtonite is a white, gray, brown, colorless, pink or yellow zeolite mineral. Its chemical formula is BaAl2Si3O10·4H2O. It has varieties with tetragonal, orthorhombic or triclinic crystals.Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason, and Abraham Rosenzweig: "Dana's new mineralogy", pp. 1683-1684.
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Trigonal, tetragonal and hexagonal crystals have a single optic axis, parallel to the c crystal axis. They are said to be uniaxial. Triclinic, monoclinic and orthorhombic crystals have two optic axes, and are said to be biaxial. The angle between the two axes is denoted by 2V.
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The structure may called a tetragonal layer structure. MgUO4 structure.Magnesium uranate, MgUO4, has a quite different structure. Distorted UO6 octahedra are linked into infinite chains; the "uranyl" U-O bond length is 192 pm, not much shorter than the other U-O bond length of 218 pm.
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In contrast, abundant tracheids are arranged in radial files. The tracheid files vary in tangential dimension. The tetragonal tracheids of the secondary xylem are 17–(30)−45 µm in diameter, usually with the smaller ones situated beside the periphery of the metaxylem strand (Fig. 44, arrows).
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Silver chlorate (AgClO3) forms white, tetragonal crystals. Like all chlorates, it is water-soluble and an oxidizing agent. As a simple metal salt, it is a common chemical in basic inorganic chemistry experiments. It is light- sensitive, so it must be stored in tightly closed dark-coloured containers.
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It has gone through several repairs in the past 800 years. The Fahua Pagoda located in central Jiading is a tetragonal brick-wooden pagoda with seven floors and a height of . The Bamboo Carving Museum, covering bamboo carving over the past 400 years since the mid-Ming Dynasty.
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The aperture is nearly horizontal, tetragonal. The superior lip is straightened, bearing a very large subbifid squarish tubercle in the middle. The place of the periphery is marked inside by an entering lamellar fold. The basal margin is curved, slightly expanded, bearing two or three fold-like denticles inside.
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Structure of YB4 YB4 has tetragonal crystal structure with space group P4/mbm (No. 127), Pearson symbol tP20, a = 0.711 nm, c = 0.4019 nm, calculated density 4.32 g/cm3. High-quality YB4 crystals of few centimeters in size can be grown by the multiple-pass floating zone technique.
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The dioxide may be prepared by, for example, halogenization of lead(II) salts. The alpha allotrope is rhombohedral, and the beta allotrope is tetragonal. Both allotropes are black-brown in color and always contain some water, which cannot be removed, as heating also causes decomposition (to PbO and Pb3O4).
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The (red) side edges of tetragonal disphenoid represent a regular zig-zag skew quadrilateral. In geometry, a skew polygon is a polygon whose vertices are not all coplanar. Skew polygons must have at least 4 vertices. The interior surface (or area) of such a polygon is not uniquely defined.
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The body whorl scarcely descends anteriorly, above with 6 to 8 spiral closely granose cinguli, beneath with 7 to 9 similar concentric cinguli. The interstices both above and below are closely, sharply, obliquely, microscopically striate. The base of the shell is slightly convex. The oblique aperture is tetragonal.
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The base of the shell is a trifle convex, the middle portion concave toward the umbilicus. The tetragonal aperture is very oblique and almost horizontal. The upper lip is straight, bearing a strong tubercular tooth midway. The outer and basal lips are well rounded, thickened and plicate- denticulate within.
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For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural colour of zircon varies between colourless, yellow-golden, red, brown, blue and green. The name derives from the Persian zargun, meaning "gold-hued".
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The crystal structure of β- (akaganeite) is that of hollandite or . The unit cell is tetragonal with a=1.048 and c=0.3023 nm, and contains eight formula units of FeOOH. Its dimensions are about 500 × 50 × 50 nm. Twinning often produces particles with the shape of hexagonal stars.
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A ceramic knife made from blackened zirconia, super heated under pressure. Zirconium oxide is used due to its polymorphism. It exists in three phases: monoclinic, tetragonal and cubic. Cooling to the monoclinic phase after sintering causes a large volume change, which often causes stress fractures in pure zirconia.
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Cyrilovite is a vitreous translucent mineral that can appear in colors ranging from a bright yellow, honey-yellow, orange to brownish yellow, or brown and it has a hardness of 4. It has a yellow streak. The mineral is classified under the space group P41212 and is tetragonal.
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Khatyrkite viewed close to the tetragonal axis. Red balls are copper atoms. In the initial studies of khatyrkite, a negative correlation was observed between copper and zinc, i.e. the higher the copper the lower the zinc content and vice versa, which is why the formula was specified as (Cu,Zn)Al2.
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Sellaite is a magnesium fluoride mineral with the formula MgF2. It crystallizes in the tetragonal crystal system typically as clear to white vitreous prisms. It may be fibrous and occur as radiating aggregates. It has a Mohs hardness of 5 to 6 and a specific gravity of 2.97 to 3.15.
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Cahnite (Cahnit in German, Cahnita in Spanish, Канит in RussianMindat data sheet for Cahnite.) is a brittle white or colorless mineral that has perfect cleavage and is usually transparent. It usually forms tetragonal-shaped crystals and it has a hardness of 3 mohs.Mineral Data sheet for Cahnite.Database entry from Mineral Collecting.
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Piypite is a rare potassium, copper sulfate mineral with formula: K2Cu2O(SO4)2. It crystallizes in the tetragonal system and occurs as needlelike crystals and masses. Individual crystals are square in cross- section and often hollow. It is emerald green to black in color with a vitreous to greasy luster.
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Structure of cubic BaTiO3. The red spheres are oxide centres, blue are Ti4+ cations, and the green spheres are Ba2+. The solid exists in one of four polymorphs depending on temperature. From high to low temperature, these crystal symmetries of the four polymorphs are cubic, tetragonal, orthorhombic and rhombohedral crystal structure.
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Khinite is a rare tellurate mineral with the formula Pb2+Cu2+3TeO6(OH)2 It crystallizes in the orthorhombic system and has a bottle-green colour. It is often found as dipyramidal, curved or corroded crystals no more than 0.15 mm in size. The tetragonal dimorph of khinite is called parakhinite.
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Eskebornite is a selenide mineral with the formula CuFeSe2. It crystallizes in the tetragonal system and it has a brassy colour. Eskebornite is sometimes found as thick tabular crystals, but is more often found intergrown with other selenides. It is part of the chalcopyrite group and forms a series with chalcopyrite.
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It contains tetrahedral borate anion instead of planar BO3 group, which is more common among minerals. Schiavinatoite is one of the most simple niobium minerals. It forms a solid solution with its tantalum-analogue, béhierite. Both minerals possess zircon-type structure (tetragonal, space group I41/amd) and occur in pegmatites.
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It contains simple tetrahedral borate anions, instead of more common among minerals, planar BO3 groups. It forms a solid solution with its niobium-analogue, schiavinatoite. Both have zircon-type structure (tetragonal, space group I41/amd) and are found in pegmatites. Béhierite and holtite are minerals with essential tantalum and boron.
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The team cooled fermionic lithium-6 to less than (150 billionths of one kelvin) using infrared laser cooling. This demonstration is the first time that ferromagnetism has been demonstrated in a gas. In 2018, a team of University of Minnesota physicists demonstrated that body-centered tetragonal ruthenium exhibits ferromagnetism at room temperature.
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Coffinite is isostructural with the orthosilicates zircon (ZrSiO4) and thorite (ThSiO4). Stieff et al. analyzed coffinite using the x-ray powder diffraction technique and determined that it has a tetragonal structure. Occurring naturally with U4+ cations, the UO8 triangular dodecahedra coordinate with edge-sharing, alternating SiO4 tetrahedra in chains along the c-axis.
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International Ghetto was a historical tetragonal region in Pest (Budapest) bounded by Pozsonyi út, Szent István park, Újpesti rakpart, Sziget út for diplomatically protected Jews during World War II. It was established by the government of Ferenc Szálasi, Leader of the Hungarian Nation, after his rise to power on 15 October 1944.
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In addition to the typical semiconducting hexagonal structure, WSe2 exists in another polymorph, a metallic octahedral coordination phase 1T-WSe2 based on a tetragonal symmetry with one WSe2 layer per repeating unit. The 1T-WSe2 phase is less stable and transitions to the 2H-WSe2 phase. WSe2 can form a fullerene-like structure.
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The hexamers are interlinked into an infinite network. Indium atoms are five coordinate the equatorial In-C distances average 216.7pm almost identical to the average for the tetragonal form, and the axial bonds are 302.8pm joining the InMe3 units into hexamers and 313.4 pm linking the hexamers to form the infinite network.
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The MPaF6 formula can be represented as a combination of MF and PaF5. These compounds can be obtained by evaporating a hydrofluoric acid solution containing these both complexes. For the small alkali cations like Na, the crystal structure is tetragonal, whereas it lowers to orthorphombic for larger cations K+, Rb+, Cs+ or NH4+.
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The oblique aperture is tetragonal. The outer and basal lips are thickened and plicate within. The oblique columella is inserted nearly in the bottom of the broad umbilical excavation, its edge reflexed and bearing about 10 denticles, twisted near the insertion, terminating below in a simple tooth. The parietal tract is wrinkled.
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Mooihoekite crystallizes in the tetragonal crystal system. It has a short optical c-axis that is perpendicular to two longer a-axes of equal length. For Mooihoekite, the c-axis is a 4-fold rotoinversion axis. Mooihoekite is an opaque mineral which shows weak anisotropism in polished section under reflected light microscopy.
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Various solid solutions with tetragonal ferroelectric perovskites including BaTiO3, Bi0.5K0.5TiO3Sasaki, A.; Chiba, T.; Mamiya, Y.; Otsuki, E. Dielectric and piezoelectric properties of (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3 systems. Jpn. J. Appl. Phys. Part 1 1999, 38, 5564–5567. have been developed to obtain morphotropic phase boundaries to enhance the piezoelectric properties of Na0.5Bi0.5TiO3.
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A promising candidate for high-density storage is the face-centered tetragonal phase FePt alloy. Grain sizes can be as small as 3 nanometers. If it's possible to modify the MNPs at this small scale, the information density that can be achieved with this media could easily surpass 1 Terabyte per square inch.
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Due to the different size and chemical nature of Te2− and O2− the ions occupy different positions in the crystal structure. Some of these structures are layered. Many of the crystal systems are tetragonal. One unusual structure has stacked tubes made from tellurium, with nested tubes of antimony oxide, which contain alkali metal.
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Under atmospheric pressure mercuric oxide has two crystalline forms: one is called montroydite (orthorhombic, 2/m 2/m 2/m, Pnma), and the second is analogous to the sulfide mineral cinnabar (hexagonal, hP6, P3221); both are characterized by Hg-O chains. At pressures above 10 GPa both structures convert to a tetragonal form.
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Unlike the tetragonal disphenoid, the rhombic disphenoid has no reflection symmetry, so it is chiral. Both tetragonal disphenoids and rhombic disphenoids are isohedra: as well as being congruent to each other, all of their faces are symmetric to each other. It is not possible to construct a disphenoid with right triangle or obtuse triangle faces. When right triangles are glued together in the pattern of a disphenoid, they form a flat figure (a doubly-covered rectangle) that does not enclose any volume.. When obtuse triangles are glued in this way, the resulting surface can be folded to form a disphenoid (by Alexandrov's uniqueness theorem) but one with acute triangle faces and with edges that in general do not lie along the edges of the given obtuse triangles.
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Powellite is a calcium molybdate mineral with formula CaMoO4. Powellite crystallizes with tetragonal - dipyramidal crystal structure as transparent adamantine blue, greenish brown, yellow to grey typically anhedral forms. It exhibits distinct cleavage and has a brittle to conchoidal fracture. It has a Mohs hardness of 3.5 to 4 and a specific gravity of 4.25.
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Its melting and boiling points are respectively 770 °C and 921 °C. It undergoes a phase transition at 405 °C, with a low-temperature α phase and high-temperature β phase. Nevertheless, the β phase usually persists below the transition temperature. Both phases crystallise in the tetragonal crystal system and the structural differences are small.
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Aluminium may sit on either the T or the B site. Minerals with the melilite structure may show a cleavage parallel to the (001) crystallographic directions and may show weaker cleavage perpendicular to this, in the {110} directions. Melilite is tetragonal. The important endmembers of common melilite are åkermanite Ca2Mg(Si2O7) and gehlenite Ca2Al[AlSiO7].
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The structure of PdO is tetragonal (P42/mmc) a = 3.044, c = 5.328 Å. The Pd atoms are square planar as expected for a d8 metal ion and the oxygen atoms are approximately tetrahedral. The closest Pd–Pd distance is 3.044 Å and is almost within the range which can be considered a bonding distance.
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Phosgenite is a rare mineral consisting of lead chlorocarbonate, (PbCl)2CO3. The tetragonal crystals are prismatic or tabular in habit: they are usually colorless and transparent, and have a brilliant adamantine lustre. Sometimes the crystals have a curious helical twist about the tetrad or principal axis. The hardness is 3 and the specific gravity 6.3.
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The anhydrous form has 3 polymorphs, α-, β-, and a metastable γ. The high temperature form α- is monoclinic, with 8 coordinate calcium, the lower temperature form β- is tetragonal, with calcium in four different coordination environments, 2 that are 7 coordinate, one eight and one 9. In both the pyrophosphates are essentially eclipsed.
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Carletonite is a rare silicate mineral with formula KNa4Ca4(CO3)4Si8O18(F,OH)·(H2O). It is a phyllosilicate and a member of the apophyllite group. Its tetragonal crystals are a translucent blue, white, colorless or pink with a vitreous to dull lustre. It has a density of 2.45 and a hardness of 4-4.5.
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Magnesium fluoride is prepared from magnesium oxide with sources of hydrogen fluoride such as ammonium bifluoride: :MgO + (NH4)HF2 → MgF2 \+ NH3 \+ H2O Related metathesis reactions are also feasible. The compound crystallizes as tetragonal birefringent crystals. The structure of the compound is similar to that in rutile, featuring octahedral Mg2+ centers and 3-coordinate fluoride centres.
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Tetraxenonogold(II), gold tetraxenide(II) or AuXe is a cationic complex with a square planar configuration of atoms. It is found in the compound AuXe(SbF), which exists in triclinic and tetragonal crystal modifications. The AuXe ion is stabilised by interactions with the fluoride atoms of the counterion. The Au−Xe bond length is .
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Pure synthetic magnesium majorite (MgSiO3) is polymorphous with enstatite, and akimotoite. Majorite is a member of the garnet group. It has Mg in eight- coordination with oxygen; it also has both Mg and Si in octahedral (6) coordination; and Si in tetrahedral (4) coordination with oxygen. Unlike most garnets, which are cubic, pure MgSiO3 majorite is tetragonal.
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Wakefieldite forms crystals of tetragonal structure. In terms of crystal structure, it is the vanadate analog of the rare-earth phosphate mineral xenotime. Unlike xenotime, it is more favorable for wakefieldite to contain the lighter rare-earth elements over the heavier ones. Due to the lanthanide contraction, the heavier rare earths have smaller ionic radii than the lighter ones.
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Yttrium oxide is used as the stabilizer. This material is predominantly tetragonal in structure. Y-TZP has the highest flexural strength of all the zirconia based materials. The fine grain size of Y-TZP lends itself to be used in cutting tools where a very sharp edge can be achieved and maintained due to its high wear resistance.
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Barium tungstate can be obtained from the precipitation reaction between barium nitrate and ammonium paratungstate or sodium tungstate. :Ba(NO3)2 \+ Na2WO4 → BaWO4↓ + 2 NaNO3 It is a white solid, which at normal conditions forms tetragonal crystals similar to scheelite, CaWO4. Under pressures above 7 GPa, the compound undergoes transformation to a monoclinic structure similar to fergusonite, YNbO4.
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There are differences between the species in both the floral and vegetative parts. In the flower receptacle, where the base is elliptic in N. leibergii, the base has angular protrusions and appears tetragonal in N. tetragona. N. leibergii also has fewer petals and stamens, and a yellowish-brown stigma, where the stigma is purple in N. tetragona.
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Schreibersite is generally a rare iron nickel phosphide mineral, , though common in iron-nickel meteorites. The only known occurrence of the mineral on Earth is located on Disko Island in Greenland."Power behind primordial soup discovered", Eurekalert, April 4, 2013 Another name used for the mineral is rhabdite. It forms tetragonal crystals with perfect 001 cleavage.
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The about 6 whorls are slightly convex, and spirally lirate. The body whorl is encircled by about 14 granose separated lirae, of which about 6 are on the upper surface, their interstices bearing spiral stripe. The body whorl is obtusely angular at the periphery, slightly convex beneath, a little descending anteriorly. The aperture is rounded-tetragonal.
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Phytologia 68(4): 316 distribution map on page 316 Grindelia sublanuginosa is a branching herb up to tall. Leaves are olive-green, up to long, with small teeth along the edges. Flower heads contain 8-21 yellow or yellow-orange ray flowers surrounding numerous small disc flowers. The achenes are distinctive in the genus in being tetragonal.
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The convex hull of two cantellated 24-cells in opposite positions is a nonuniform polychoron composed of 864 cells: 48 cuboctahedra, 144 square antiprisms, 384 octahedra (as triangular antipodiums), 288 tetrahedra (as tetragonal disphenoids), and 576 vertices. Its vertex figure is a shape topologically equivalent to a cube with a triangular prism attached to one of its square faces.
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The apical ones, when not eroded, are spirally striate, the following granose-lirate, the last bearing on its upper surface five coarse beaded lirae, the fifth forming the periphery. The base of the shell is slightly convex, bearing six beaded lirae. The interstices between the lirae are finely obliquely striate. The aperture is rounded-tetragonal, pearly within.
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Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula PbO. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer components. It is an amphoteric oxide.
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The mineral was named in 1863 after the forest god Tapio of Finnish mythology, and the original tapiolite material came from Sukula, Tammela, Tavastia Proper, Finland.webmineral Tapiolite Tapiolite is very close to columbite and tantalite. Those minerals have the same chemical composition, but different crystal symmetry orthorhombic for tantalite or columbite and tetragonal for tapiolite.P. Cerny et al.
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Its crystals are in the tetragonal crystal system, appearing as dipyramidal pseudo-octahedra. Colors include golden yellow, brownish green to dark brown, pinkish to reddish gray, orange and colorless. Transparency ranges from translucent to transparent and crystal faces are highly lustrous (vitreous to adamantine). Scheelite possesses distinct cleavage and its fracture may be subconchoidal to uneven.
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Vesuvianite, also known as idocrase, is a green, brown, yellow, or blue silicate mineral. Vesuvianite occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism. It was first discovered within included blocks or adjacent to lavas on Mount Vesuvius, hence its name. Attractive-looking crystals are sometimes cut as gemstones.
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Nickel may substitute for iron, yielding the more general formula "Mineral 314-687: Akaganeite". Mindat.org database, accessed on 2019-02-12. Akaganeite has a metallic luster and a brownish yellow streak. Its crystal structure is monoclinic and similar to that of hollandite , characterised by the presence of tunnels parallel to the c-axis of the tetragonal lattice.
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The normal room temperature form has a similar structure to which has a distorted rock salt structure with essentially five coordinate thallium, the sixth fluoride ion is at 370 pm. At 62 °C it transforms to a tetragonal structure. This structure is unchanged up to pressure of 40 GPa.U.Haussermann, P.Berastegui, S.Carlson, J.Haines, and J.Leger Angewandte Chemie, 31, pp.
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Seitz, Frederick and Turnbull, David (1964) Solid state physics: advances in research and applications, Academic Press, pp. 289–291, . Protactinium is a metal with silvery-gray luster that is preserved for some time in air. Protactinium easily reacts with oxygen, water vapor and acids, but not with alkalis. At room temperature, protactinium crystallizes in the body-centered tetragonal structure which can be regarded as distorted body-centered cubic lattice; this structure does not change upon compression up to 53 GPa. The structure changes to face-centered cubic (fcc) upon cooling from high temperature, at about 1200 °C.Young, David A. (1991) Phase diagrams of the elements, University of California Press, p. 222, . The thermal expansion coefficient of the tetragonal phase between room temperature and 700 °C is 9.9/°C.
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The tetrahedral molecule features C-I distances of 2.12 ± 0.02 Å. The molecule is slightly crowded with short contacts between iodine atoms of 3.459 ± 0.03 Å, and possibly for this reason, it is thermally and photochemically unstable. Carbon tetraiodide crystallizes in tetragonal crystal structure (a 6.409, c 9.558 (.10−1 nm)). It has zero dipole moment due to its symmetrically substituted tetrahedral molecule.
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Apophyllite-(KF) or fluorapophyllite is a mineral of the apophyllite group, with the chemical formula of KCa4Si8O20(F,OH)·8(H2O). It gets the first half of its name, "fluor", from containing more fluorine than hydroxide compared to the other minerals in the apophyllite group. Fluorapophyllite crystallizes in the tetragonal crystal system.Johnsen, O. (2002) Photographic Guide to Minerals of the World.
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DG.10 in the Nickel–Strunz system. The mineral has tetragonal crystal symmetry and the same structure as scheelite (calcium tungstate, CaWO4), but can be metamict (amorphous) due to radiation damage from its small content of thorium. It is found as needle-like or prismatic crystals in pegmatite. It was named after British politician and mineral collector Robert Ferguson of Raith (1767–1840).
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In fact a lower tetragonal symmetry is usually found experimentally. The origin of this JTE distortion it revealed by examining the electronic configuration of the undistorted complex. For an octahedral geometry, the five 3d orbitals partition into t2g and eg orbitals (see diagram). These orbitals are occupied by nine electrons corresponding to the d^9 electronic configuration of Cu(II).
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This phase transition is of the first order; it is accompanied by an anomaly in the heat capacity, elastic, and other properties. In particular, whereas adamantane molecules freely rotate in the cubic phase, they are frozen in the tetragonal one; the density increases stepwise from 1.08 to 1.18 g/cm3 and the entropy changes by a significant amount of 1594 J/(mol·K).
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It is also sometimes called a trisoctahedron, or, more fully, trigonal trisoctahedron. Both names reflect the fact that it has three triangular faces for every face of an octahedron. The tetragonal trisoctahedron is another name for the deltoidal icositetrahedron, a different polyhedron with three quadrilateral faces for every face of an octahedron. This convex polyhedron is topologically similar to the concave stellated octahedron.
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Common salt has a 1:1 molar ratio of sodium and chlorine. In 2013, compounds of sodium and chloride of different stoichiometries have been discovered; five new compounds were predicted (e.g., Na3Cl, Na2Cl, Na3Cl2, NaCl3, and NaCl7). The existence of some of them has been experimentally confirmed at high pressures: cubic and orthorhombic NaCl3 and two-dimensional metallic tetragonal Na3Cl.
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The base of the shell is convex. The aperture is tetragonal. The outer lip bears within a strong tubercle above, and a few plicae on the outer and lower part. The short columella is oblique, with a very slight fold above, very deeply entering the profound, extremely narrow axial pit, and at the base terminating in a large squarish trifid tooth.
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A door below the right-hand seat gave access to the engine hatch via the cabin. The cockpit was normally accessed through a low, tetragonal, port-side door. Behind them was a baggage hold. The A.23's straight-edged tailplane, mounted on the upper fuselage and strut-braced from below, was adjustable in flight and carried separate rounded, balanced elevators.
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Wulfenite is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes called "yellow lead ore". It crystallizes in the tetragonal system, often occurring as stubby, pyramidal or tabular crystals.
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Wardite is a hydrous sodium aluminium phosphate hydroxide mineral with formula: NaAl3(PO4)2(OH)4·2(H2O). Wardite is of interest for its rare crystallography. It crystallizes in the tetragonal trapezohedral class and is one of only a few minerals in that class. Wardite forms vitreous green to bluish green to white to colorless crystals, masses, and fibrous encrustations.
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Raspite is a mineral, a lead tungstate; with the formula PbWO4. It forms yellow to yellowish brown monoclinic crystals.Handbook of Mineralogy It is the low temperature monoclinic dimorph of the tetragonal stolzite.Mindat entry It was discovered in 1897 at Broken Hill, New South Wales, Australia, it was named for Charles Rasp (1846–1907), German-Australian prospector, discoverer of the Broken Hill ore deposit.
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Hexagonal layered polymeric nitrogen (HLP-N) is the third form of polymeric nitrogen found stable under pressure and was experimentally synthesized at 244 GPa and 3300 K. It adopts a tetragonal unit cell (P42bc) in which the single-bonded nitrogen atoms form two layers of interconnected N6 hexagons. It was found to be metastable down to at least 66 GPa.
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Tin at room temperature has a tetragonal crystal structure. Lead has a face-centered cubic crystal structure. The densities of the carbon group elements tend to increase with increasing atomic number. Carbon has a density of 2.26 grams per cubic centimeter, silicon has a density of 2.33 grams per cubic centimeter, germanium has a density of 5.32 grams per cubic centimeter.
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Chalcopyrite is a member of the tetragonal crystal system. Crystallographically the structure of chalcopyrite is closely related to that of zinc blende ZnS (sphalerite). The unit cell is twice as large, reflecting an alternation of Cu+ and Fe3+ ions replacing Zn2+ ions in adjacent cells. In contrast to the pyrite structure chalcopyrite has single S2− sulfide anions rather than disulfide pairs.
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The compound crystallizes in a tetragonal body-centered unit cell of space group symmetry I41md. In the solid-state diethylzinc shows nearly linear Zn centres. The Zn-C bonds measure 194.8(5) pm, while the C-Zn-C angle is slightly bent with 176.2(4)°. The structure of the gas-phase shows a very similar Zn-C distance (195.0(2) pm).
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Nepeta troodi, commonly known as Troodos cat-mint is a suberect, aromatic, perennial herb, 20–50 cm high, with a woody base and hairy tetragonal shoots. Leaves opposite, simple, serrate, cordate at base, deltoid, apex obtuse, 1-4 x 0.6–2 cm, petiolate, densely hairy. Flowers in many flowered verticillasters, zygomorphic, corolla white with the lower lip dotted purple. Flowers June to October.
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In the solid state the compound exists in two modifications. The tetragonal high-temperature phase shows a two-dimensional disorder, while the low-temperature phase which is monoclinic is ordered. The molecules are linear with Zn-C bond lengths measuring 192.7(6) pm. The structure of the gas-phase shows a very similar Zn-C distance of 193.0(2) pm.
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Cobalt(II) fluoride is a chemical compound with the formula (CoF2). It is a pink crystalline solid compound which is antiferromagnetic at low temperatures (TN=37.7 K)Ashcroft/Mermin: Solid State Physics (Tab. 33.2) The formula is given for both the red tetragonal crystal, (CoF2), and the tetrahydrate red orthogonal crystal, (CoF2·4H2O). CoF2 is used in oxygen-sensitive fields, namely metal production.
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The coordination geometry thus changes from tetragonal to tetrahedral, forming a cubic crystal structure, analogous to the structure of Cd(CN)2. Due to the ambidentate nature of the CN ligands, this tetrahedral structure is distorted, but the distortion lessens with increasing pressure until the structure becomes nearly perfectly tetrahedral at >40 kbar.Wong, P.T.T. J. Chem. Phys. 1984, 80(12), 5937-41.
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The crystal structure of tungsten trioxide is temperature dependent. It is tetragonal at temperatures above 740 °C, orthorhombic from 330 to 740 °C, monoclinic from 17 to 330 °C, triclinic from -50 to 17 °C, and monoclinic again at temperatures below -50 °C.H. A. Wriedt: The O-W (oxygen- tungsten) system. In: Bulletin of Alloy Phase Diagrams. 10, 1989, S. 368, .
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Larger crystals most commonly have the form of a square prism terminated by a low pyramid, the prism angle being nearly a right angle. The crystals are tetragonal in appearance, though actually orthorhombic. There are perfect cleavages parallel to the faces of the prism. The mineral also often occurs in compact fibrous aggregates, the fibers having a divergent or radial arrangement.
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Ferroelasticity is a phenomenon in which a material may exhibit a spontaneous strain. In ferroics, ferroelasticity is the mechanical equivalent of ferroelectricity and ferromagnetism. When stress is applied to a ferroelastic material, a phase change will occur in the material from one phase to an equally stable phase, either of different crystal structure (e.g. cubic to tetragonal), or of different orientation (a 'twin' phase).
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Transition α → α′ occurs slowly and therefore is most likely an intermediate phase. Transition α′ → α″ occurs much faster than α → α′ and has very small thermal hysteresis. This transition results in a change in the fourfold axis of the tetragonal cell, causing crystal twinning. The width of the loop is independent of the rate of heating although it becomes narrower after several temperature cycles.
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The unit cell of Cd3As2 is tetragonal. The arsenic ions are cubic close packed and the cadmium ions are tetrahedrally coordinated. The vacant tetrahedral sites provoked research by von Stackelberg and Paulus (1935), who determined the primary structure. Each arsenic ion was surrounded by cadmium ions at six of the eight corners of a distorted cube and the two vacant sites were at the diagonals.
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Segnitite exhibits weak pleochroism from a pale yellow to a more moderate yellow under different angles of plane polarized light, although the effects can be much more dramatic under polarized light. Dichroism and trichroism are both types of pleochroism. The term dichroism is used to describe optical properties of minerals that are uniaxial, including segnitite. Minerals that exhibit dichroism are generally trigonal, hexagonal and tetragonal.
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Previously glass-infiltrated aluminium oxide ceramic frameworks have been used. More recently, yttrium tetragonal zirconia polycrystal-based materials such as Lava (3M ESPE) and Cercon (Degudent) have come into use. These frameworks can be designed by wax-ups or using CAD-CAM. The main advantage of this type of bridge is the aesthetics as well as good biocompatibility and lower levels of plaque accumulation.
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Wiluite is a dark green, brownish, or black blocky silicate mineral with formula: Ca19(Al,Mg,Fe,Ti)13(B,Al,[ ])5Si18O68(O,OH)10. It has a Mohs hardness of 6 and a specific gravity of 3.36. It has a vitreous lustre, poor cleavage and an irregular brittle fracture. It crystallizes in the tetragonal system and occurs as well-formed crystals with good external form.
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Braggite is a sulfide mineral of platinum, palladium and nickel with chemical formula: (Pt, Pd, Ni)S. It is a dense (specific gravity of 10), steel grey, opaque mineral which crystallizes in the tetragonal crystal system. It is the central member in the platinum group end-members cooperite and vysotskite. It was first described in 1932 for an occurrence in the Bushveld Igneous Complex of South Africa.
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Aft, the fuselage tapered from below to a 90° butterfly tail with tetragonal fixed and control surfaces. There were tanks for of water ballast. It landed on a central, semi-retractable monowheel aided by forward and tail skids. Testing over 1961-2 showed that the flight characteristics were poor, with directional instabilities and a need for large pitch inputs, and that its spin behaviour was unusual.
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Huttonite is a thorium nesosilicate mineral with the chemical formula 4 and which crystallizes in the monoclinic system. It is dimorphous with tetragonal thorite, and isostructual with monazite. An uncommon mineral, huttonite forms transparent or translucent cream-colored crystals. It was first identified in samples of beach sands from the West Coast region of New Zealand by the mineralogist Colin Osborne Hutton (1910–1971).
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The tailplane pedestal was raised and the tailplane plan changed from elliptical to tetragonal with rounded tips. The rudder was also redesigned, with an aerodynamic balance and an increase in chord. Overall, the Szittya III's fuselage was longer than that of the Szittya II. These changes improved the minimum sinking speed to at . The single Szittya III was destroyed in a hangar fire in 1940.
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TaAs is the first discovered Weyl semimetal (conductor). Large-size (~1 cm), high-quality TaAs single crystals can be obtained by chemical vapor transport method using iodine as the transport agent. TaAs crystallizes in a body-centered tetragonal unit cell with lattice constants a = 3.44 Å and c = 11.64 Å and space group I41md (No. 109). Ta and As atoms are six coordinated to each other.
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MoSi2 is a gray metallic-looking material with tetragonal crystal structure (alpha-modification); its beta- modification is hexagonal and unstable. It is insoluble in most acids but soluble in nitric acid and hydrofluoric acid. While MoSi2 has excellent resistance to oxidation and high Young's modulus at temperatures above 1000 °C, it is brittle in lower temperatures. Also, at above 1200 °C it loses creep resistance.
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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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Tetrataenite has a highly ordered crystal structure, appearing creamy in color and displaying optical anisotropy. Its appearance is distinguishable from taenite, which is dark gray with low reflectivity. FeNi easily forms into a cubic crystal structure, but does not have magnetic anisotropy in this form. Three variants of the L10 tetragonal crystal structure have been found, as chemical ordering can occur along any of the three axes.
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Tugtupite is tenebrescent, sharing much of its crystal structure with sodalite, and the two minerals are occasionally found together in the same sample. Tugtupite occurs as vitreous, transparent to translucent masses of tetragonal crystals and is commonly found in white, pink, to crimson, and even blue and green. It has a Mohs hardness of 4 and a specific gravity of 2.36. It fluoresces crimson under ultraviolet radiation.
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Pure thulium metal has a bright, silvery luster, which tarnishes on exposure to air. The metal can be cut with a knife, as it has a Mohs hardness of 2 to 3; it is malleable and ductile. Thulium is ferromagnetic below 32K, antiferromagnetic between 32 and 56K, and paramagnetic above 56K. Thulium has two major allotropes: the tetragonal α-Tm and the more stable hexagonal β-Tm.
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Unlike related phases such as Pseudomalachite, the copper atoms are all five- fold coordinated by oxygen. There are three unique copper sites that are all quite distorted from ideal symmetry. Two are in approximate tetragonal pyramids and the third is essentially a trigonal bipyramidal coordination. Edge sharing polyhedra lead to copper-copper dimer formation, and the overall structure is a three-dimensional network of copper-oxygen polyhedra.
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A narrow, roughly rectangular tailplane was mounted on the upper longeron and strut braced to the lower one. It carried an elevator with two tetragonal, fabric-covered surfaces mounted on a common axle, allowing rudder movement between them. Despite the W.J.6's low cost, build-simplicity, low weight, which allowed easy ground transport, and decent handling in flight trials only one was built.
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Silver molybdate (Ag2MoO4), a chemical compound, is a yellow, cubic crystalline substance often used in glass. Its crystals present two types of electronic structure, depending on the pressure conditions to which the crystal is subjected. At room temperature, Ag2MoO4 exhibits a spinel-type cubic structure, known as β-Ag2MoO4, which is more stable in nature. However, when exposed to high hydrostatic pressure, the tetragonal α-Ag2MoO4 forms as a metastable phase.
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Baotite Ba4Ti4(Ti, Nb, Fe)4(Si4O12)O16Cl is a rare mineral recognized as having a unique four-fold silicate ring.Chakhmouradian, A.R. and Mitchell, R.H. (2002) The mineralogy of Ba- and Zr-rich alkaline pegmatites from Gordon Butte, Crazy Mountains (Montana, USA): comparisons between potassic and sodic agpaitic pegmatites. Contributions to Mineralogy and Petrography, 143, 93-114. Crystals are tetragonal, though commonly deformed to the extent of appearing monoclinic.
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Phase diagram of water, showing the region where ice III is stable. Ice III is a form of solid matter which consists of tetragonal crystalline ice, formed by cooling water down to at . It is the least dense of the high-pressure water phases, with a density of (at 350 MPa). The proton-ordered form of is ice IX. Ordinary water ice is known as , (in the Bridgman nomenclature).
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The primitive cell contains two formula units of aluminium oxide. Aluminium oxide also exists in other, metastable, phases, including the cubic γ and η phases, the monoclinic θ phase, the hexagonal χ phase, the orthorhombic κ phase and the δ phase that can be tetragonal or orthorhombic. Each has a unique crystal structure and properties. Cubic γ-Al2O3 has important technical applications. The so-called β-Al2O3 proved to be NaAl11O17.
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If the faces of a disphenoid are equilateral triangles, it is a regular tetrahedron with Td tetrahedral symmetry, although this is not normally called a disphenoid. When the faces of a disphenoid are isosceles triangles, it is called a tetragonal disphenoid. In this case it has D2d dihedral symmetry. A sphenoid with scalene triangles as its faces is called a rhombic disphenoid and it has D2 dihedral symmetry.
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The tetragonal form of YBCO is insulating and does not superconduct. Increasing the oxygen content slightly causes more of the O(1) sites to become occupied. For x < 0.65, Cu-O chains along the b axis of the crystal are formed. Elongation of the b axis changes the structure to orthorhombic, with lattice parameters of a = 3.82, b = 3.89, and c = 11.68 Å. Optimum superconducting properties occur when x ~ 0.07, i.e.
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The magnetic shape memory effect occurs in the low temperature martensite phase of the alloy, where the elementary cells composing the alloy have tetragonal geometry. If the temperature is increased beyond the martensite–austenite transformation temperature, the alloy goes to the austenite phase where the elementary cells have cubic geometry. With such geometry the magnetic shape memory effect is lost. The transition from martensite to austenite produces force and deformation.
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Banksia because of its straight styles. He made it the type species of B. ser. Tetragonae, the members of which are defined by their pendulous inflorescences and tetragonal limbs. He considered it closely related to B. aculeata and B. caleyi, which are smaller, more compact, shrubs with red- or pink-tinged inflorescences. In 1996, Kevin Thiele and Pauline Ladiges published the results of a cladistic analysis of morphological characters of Banksia.
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The uptake and loss of oxygen are reversible in YBa2Cu3O7−x. A fully oxygenated orthorhombic YBa2Cu3O7−x sample can be transformed into tetragonal YBa2Cu3O6 by heating in a vacuum at temperature above 700 °C. The preparation of Bi-, Tl- and Hg-based high-Tc superconductors is more difficult than the YBCO preparation. Problems in these superconductors arise because of the existence of three or more phases having a similar layered structure.
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Ice IX is a form of solid water stable at temperatures below 140 K and pressures between 200 and 400 MPa. It has a tetragonal crystal lattice and a density of 1.16 g/cm³, 26% higher than ordinary ice. It is formed by cooling ice III from 208 K to 165 K (rapidly--to avoid forming ice II). Its structure is identical to ice III other than being hydrogen-ordered.
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Paramelaconite crystallizes in the tetragonal crystal system. Its space group was correctly identified by Frondel as I41/amd. In 1978, O'Keeffe and Bovin determined the formula to be Cu4O3, specifically Cu21+Cu22+O3. There has been misunderstanding and misreporting of the mineral's crystal structure, due in part to a typographical error in O'Keeffe and Bovin's paper and the commonality of choosing an incorrect origin for the I41/amd space group.
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Pleochroism is the phenomenon of crystals appearing to change color as they are rotated in plane polarized light.Klein and Hurlbut (1993) Manual of Mineralogy, 21st edition, Wiley This is due to differential absorption of light vibrating in different directions. Isometric crystals cannot be pleochroic. Uniaxial crystals (trigonal, tetragonal or hexagonal) may show two, but not three, different colors as they are rotated, then they are said to be dichroic (two colors).
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There are four different nitrogen clathrate phases depending on pressure. At higher pressures the CS-II phase changes to a hexagonal structure termed SH. The SH unit cell contains 34 water molecules, 20 small cavities (512), 20 medium cavities (435663) and 36 large cavities (51268). At still higher pressures a tetragonal form (termed ST) (425864) exists. At even higher pressures a phase called a filled ice structure (FIS) is formed.
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The decavanadate ion consists of 10 fused VO6 octahedra and has D2h symmetry. The structure of Na6[V10O28]·18H2O has been confirmed with X-ray crystallography. Figure 1: structure of decavanadate ion with equivalent V and O atoms indicated The decavanadate anions contains three sets of equivalent V atoms (see fig. 1). These include two central VO6 octahedra (Vc) and four each peripheral tetragonal-pyramidal VO5 groups (Va and Vb).
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The gallium atoms carry a positive charge and the ruthenium atoms have a formal charge of −2 (filled 4d shell). In Ru2Sn3 the ruthenium atoms spiral around the tin inner helix. In two dimension the Ru atoms form a tetragonal lattice with the tin atoms appearing as triangular units in the Ru channels. The occurrence of a LCP phase can be predicted by the so-called 14 electron rule.
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Sturmanite is a rare sulfate mineral with the chemical formula Ca6Fe3+2(SO4)2.5(B(OH)4)(OH)12 · 25 H2O. It crystallises in the tetragonal system and it has a Moh's hardness of 2.5. Sturmanite has a bright yellow to amber colour and falls in the ettringite group. It was named after Bozidar Darko Sturman (born 1937), Croatian-Canadian mineralogist and Curator Emeritus of Mineralogy, Royal Ontario Museum.
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The various properties of iron-platinum nanoparticles allow them to function in multiple ways. In standard conditions, FePt NPs exist in the face-centered cubic phase with a 3 to 10 nanometer diameter. However, once heat is added the structure becomes a face-centered tetragonal and superparamagnetic. The nanoparticles become superparamagnetic because the addition of heat makes the particle smaller and iron rich, since it removes any impurities in the particles.
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Ball-and-stick model of Δ-Mn(acac)3, with Jahn–Teller tetragonal elongation It has been prepared by the comproportionation of the manganese(II) compound Mn(acac)2 with potassium permanganate in the presence of additional acetylacetone. Alternatively the direct reaction of acetylacetone with potassium permanganate.Girolami, G.; Rauchfuss, T.; Angelici, R. Synthesis and Technique in Inorganic Chemistry, 3rd ed.; University Science Books: Sausalito, CA, 1999; pp. 85-92.
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Silver chromate is produced by the salt metathesis reaction of potassium chromate and silver nitrate in purified water - the silver chromate will precipitate out of the aqueous reaction mixture. The solubility of silver chromate is very low (Ksp = 1.1×10−12 or 6.5×10−5 mol/L). It crystallzes in the orthorhombic space group Pnma, with two distinct coordination environments for the silver ions, one tetragonal bipyramidal and the other distorted tetrahedral.
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The symmetry of defects in crystals is described by the point groups. They differ from the space groups describing the symmetry of crystals by absence of translations, and thus are much fewer in number. In diamond, only defects of the following symmetries have been observed thus far: tetrahedral (Td), tetragonal (D2d), trigonal (D3d, C3v), rhombic (C2v), monoclinic (C2h, C1h, C2) and triclinic (C1 or CS). The defect symmetry allows predicting many optical properties.
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975-977 It was also reported from brine in Bristol Dry Lake, California, and stratified brine within blue holes on North Andros Island in the Bahamas. It has also been noted within fluid inclusions within quartz in pegmatite bodies in the Bushveld complex of South Africa. It occurs in association with halite, gypsum and celestine in the California dry lake. A similar mineral, sinjarite, the dihydrate of calcium chloride, crystallizes in the tetragonal system.
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This involves the austenite/martensite phase transformation between a face-centered crystal lattice (FCC) and a body-centered tetragonal crystal structure (BCT). Superelastic alloys belong to the larger family of shape-memory alloys. When mechanically loaded, a superelastic alloy deforms reversibly to very high strains (up to 10%) by the creation of a stress-induced phase. When the load is removed, the new phase becomes unstable and the material regains its original shape.
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Anatase is a metastable mineral form of titanium dioxide (TiO2). The mineral in natural forms is mostly encountered as a black solid, although the pure material is colorless or white. Two other naturally occurring mineral forms of TiO2 are known, brookite and rutile. Anatase is always found as small, isolated and sharply developed crystals, and like the thermodynamically stable rutile (the more commonly occurring polymorph of titanium dioxide), it crystallizes in the tetragonal system.
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Hungarians, mostly minority in the region, are nevertheless in high number, and majority in some villages. The dominant religion in this ethnic group is Calvinism, with the exception of the village Leghia () which is Catholic, and Huedin () also has a smaller Catholic church. The churches are typically of white color, surrounded by wall, they have a tetragonal bell tower with a wooden pointed dome. The worship is attended segregated by gender and age.
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Stolzite is a mineral, a lead tungstate; with the formula PbWO4. It is similar to, and often associated with, wulfenite which is the same chemical formula except that the tungsten is replaced by molybdenum. Stolzite crystallizes in the tetragonal crystal system and is dimorphous with the monoclinic form raspite.Mindat.org Lead tungstate crystals have the optical transparency of glass combined with much higher density (8.28 g/cm3 vs ~2.2 g/cm3 for fused silica).
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Zinc hydroxide Zn(OH)2 is an inorganic chemical compound. It also occurs naturally as 3 rare minerals: wülfingite (orthorhombic), ashoverite and sweetite (both tetragonal). Like the hydroxides of other metals, such as lead, aluminium, beryllium, tin and chromium, Zinc hydroxide (and Zinc oxide), is amphoteric. Thus it will dissolve readily in a dilute solution of a strong acid, such as HCl, and also in a solution of an alkali such as sodium hydroxide.
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Columnar liquid crystals are grouped by their structural order and the ways of packing of the columns. Nematic columnar liquid crystals have no long-range order and are less organized than other columnar liquid crystals. Other columnar phases with long-range order are classified by their two-dimensional lattices: hexagonal, tetragonal, rectangular, and oblique phases. The discotic nematic phase includes nematic liquid crystals composed of flat-shaped discotic molecules without long-range order.
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Thorite crystallizes in a higher symmetry and lower density tetragonal form in which the thorium atoms coordinate to one less oxygen atom in an octahedral arrangement. Thorite is stable at lower temperatures than huttonite; at 1 atmosphere, the thorite–huttonite phase transition occurs between 1210 and 1225 °C. With increasing pressure the transition temperature increases. This relatively high transition temperature is thought to explain the relative rarity of huttonite on the Earth's crust.
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Bismuth(III) oxide is perhaps the most industrially important compound of bismuth. It is also a common starting point for bismuth chemistry. It is found naturally as the mineral bismite (monoclinic) and sphaerobismoite (tetragonal, much more rare), but it is usually obtained as a by-product of the smelting of copper and lead ores. Dibismuth trioxide is commonly used to produce the "Dragon's eggs" effect in fireworks, as a replacement of red lead.
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J. Alloys Compd., 743 (2018), pp. 203-220, 10.1016/j.jallcom.2018.01.224 γ’ precipitates are coherent with the parent γ phase, and are resistant to shearing due to the development of an anti-phase boundary when the precipitate is sheared. The γ” phase is a tetragonal Ni3Nb or Ni3V structure. The γ” phase, however, is unstable above 650 °C, so γ” is less commonly used as a strengthening phase in high temperature applications.
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At ambient temperature and ambient pressure, Hg(CN)2 takes the form of tetragonal crystals. These crystals are composed of nearly linear Hg(CN)2 molecules with a C-Hg-C bond angle of 175.0° and an Hg-C-N bond angle of 177.0° (AylettAylett, B.J. "Mercury (II) Pseudohalides: Cyanide, Thiocyanate, Selenocyanate, Azide, Fulminate." Comprehensive Inorganic Chemistry 3:304-306. J.C. Bailar, Harry Julius Emeléus, Sir Ronald Nyholm, and A.F. Trotman-Dickenson, ed.
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Indium(III) sulfide (Indium sesquisulfide, Indium sulfide (2:3), Indium (3+) sulfide) is the inorganic compound with the formula In2S3. It has a "rotten egg" odor characteristic of sulfur compounds, and produces hydrogen sulfide gas when reacted with mineral acids.Indium Sulfide. indium.com Three different structures ("polymorphs") are known: yellow, α-In2S3 has a defect cubic structure, red β-In2S3 has a defect spinel, tetragonal, structure, and γ-In2S3 has a layered structure.
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The KhAI-4 was the Kharkov Institute's first tailless design, making its first flight two years before the Kharkov KhAI-3. It was an all-wood machine. It was rather similar in layout to the powered version of the Lippisch Delta 1, first flown three years earlier in 1931, and had similar dimensions but a much more powerful engine. Its low-mounted wing was tetragonal in plan, with sweep (15°) only on the leading edges.
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At the rear tetragonal plan, mid-mounted tailplanes with marked dihedral carried vertical endplate fins which, with their rudders, were roughly oval in profile. The trailing edges of broad chord elevators were slightly curved, with inboard trim tabs. A retractable tailwheel was positioned just ahead of the tailplane leading edge. The first prototype, the VM-16, was crewed by just a pilot and navigator/gunner/bomb-aimer, seated alongside but facing rearwards.
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Changbaiite (PbNb2O6) is a member of the oxide mineral class in which the mineral contains oxygen which is grouped along with one or two metal ion. Changbaiite is classified as a multiple Oxide XY2O6 and it generally has an ionic bond. Furthermore, it is also orthorhombic at a temperature of 25 °C and it changes to orthorhombic-tetragonal at 570 °C.Subbarao, E. C., and Shirane, G. (1960) "Nonstoichiometry and Ferroelectric Properties of PbNb2O6-Type Compounds".
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Bukovite is a rare selenide mineral with formula Tl2Cu3FeSe4. It is a brown to black metallic mineral which crystallizes in the tetragonal system. It was first described in 1971 for an occurrence in the Bukov uranium mine, Rožná deposit, Vysočina Region, Moravia, Czech Republic. It has also been reported in Skrikerum, near Tryserum, Kalmar, Sweden; near Vernet-la-Varenne, Puy-de- Dôme, France; and Tuminico, Sierra de Cacho, La Rioja Province, Argentina.
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Cluster of scolecite needles Scolecite commonly occurs as sprays of thin, prismatic needles, frequently flattened on one side, with slanted terminations and striated parallel to the length of the needles. The crystals appear to be pseudo-orthorhombic or pseudo-tetragonal, and may be square in cross section. It also occurs as radiating groups and fibrous masses. Epitaxial intergrowths (intergrowths of two different crystalline substances in a non-random way) with mesolite, Na2Ca2Al6Si9O30·8H2O, are common.
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The crystal structure of the dihydrate was partially determined in 1927 by Hendricks and Dickinson and refined in 1934 by Chrobak. The structure is tetragonal P42/mnm (136), Z=2, isostructural with ammonium tetrachoridocuprate(II) ()2·2 and rubidium tetrachoridocuprate(II) ·2. Each copper atom is immediately surrounded by two oxygen atoms and four chlorine atoms forming a hydrated tetrachloridocuprate(II) anion. Two of the chlorine atoms are about 0.75 angstroms further away than the other two.
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The low temperature stable phases are the tetragonal PbO-structure (P4/nmm) β-Fe1−xSe and α-Fe7Se8. The high temperature phase is the hexagonal, NiAs structure (P63/mmc) δ-Fe1−xSe. Iron(II) selenide occurs naturally as the NiAs-structure mineral achavalite. More selenium rich iron selenide phases are the γ phases (γ and γˈ), assigned the Fe3Se4 stoichiometry, and FeSe2, which occurs as the marcasite-structure natural mineral ferroselite, or the rare pyrite-structure mineral dzharkenite.
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Single crystals of both modifications have been grown by chemical vapor transport. Small amounts of aluminum, gallium, or iron were used as catalysts for the transport process to obtain the I-AuBr modification. The two structures both consist of -Br-Au-Br-Au-Br- polymeric zigzag chains, but they are stacked in a different arrangement. In the primitive tetragonal phase the chains form layers (see figure) in contrast to the body centered one, where they are more interwoven.
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The light passing through the mineral will therefore have different colors when it is viewed from different angles, making the stone seem to be of different colors. Tetragonal, trigonal, and hexagonal minerals can only show two colors and are called dichroic. Orthorhombic, monoclinic, and triclinic crystals can show three and are trichroic. For example, hypersthene, which has two optical axes, can have a red, yellow, or blue appearance when oriented in three different ways in three-dimensional space.
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As such, substitutional solute atoms do not interact with the shear stress fields characteristic of screw dislocations. Conversely, in interstitial solid solutions, solute atoms cause a tetragonal distortion, generating a shear field that can interact with edge, screw, and mixed dislocations. The attraction or repulsion of the dislocation to the solute atom depends on whether the atom sits above or below the slip plane. For example, consider an edge dislocation encountering a smaller solute atom above its slip plane.
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The Twin Pagodas () was first built in 1096 under the Song dynasty and underwent two renovations, respectively in 1989 and 2014. In 1956, the Twin Pagodas were inscribed as provincial key cultural units by the Anhui Provincial Government. In January 1988, the Twin Pagodas was listed among the third batch of "Major National Historical and Cultural Sites in Anhui" by the State Council of China. The seven story, tall, tetragonal-based Twin Pagodas is made of brick and stone.
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At 1200 °C with 70–85% boron, mixtures of PuB4 and PuB6 are formed, with more of the latter as the temperature increases; PuB4 has the tetragonal structure (same as UB4), and PuB6 has cubic structure, same as all hexaborides (CaB6, LaB6 etc.). The most remarkable plutonium boride is arguably PuB100. Its existence demonstrates the importance of contamination in boride research because as little as 1% of an impurity is capable of changing its crystal structure.
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Calcium oxalate is a common crystalline compound found in many fungi, including the earthstars. The presence of calcium oxalate crystals—apparent as a whitish powder on the surface of the spore sac—has been verified for G. pectinatum using scanning electron microscopy. The calcium oxalate crystals occur in the tetragonal form, known as weddellite. A study on the related species Geastrum saccatum has shown that these crystals are responsible for the characteristic opening (dehiscence) of the outer peridial layers.
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In powdered tetragonal litharge form, it can be mixed with linseed oil and then boiled to create a weather-resistant sizing used in gilding. The litharge would give the sizing a dark red color that made the gold leaf appear warm and lustrous, while the linseed oil would impart adhesion and a flat durable binding surface. PbO is used in certain condensation reactions in organic synthesis. PbO is the input photoconductor in a video camera tube called the Plumbicon.
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Americium monosilicide (AmSi) and "disilicide" (nominally AmSix with: 1.87 < x < 2.0) were obtained by reduction of americium(III) fluoride with elementary silicon in vacuum at 1050 °C (AmSi) and 1150−1200 °C (AmSix). AmSi is a black solid isomorphic with LaSi, it has an orthorhombic crystal symmetry. AmSix has a bright silvery lustre and a tetragonal crystal lattice (space group I41/amd), it is isomorphic with PuSi2 and ThSi2. Borides of americium include AmB4 and AmB6.
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Black, α-SnO adopts the tetragonal PbO layer structure containing four coordinate square pyramidal tin atoms.Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications This form is found in nature as the rare mineral romarchite. The asymmetry is usually simply ascribed to a sterically active lone pair; however, electron density calculations show that the asymmetry is caused by an antibonding interaction of the Sn(5s) and the O(2p) orbitals. Non-stoichiometry has been observed in SnO.
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Mint green Annabergite, a nickel arsenite Important nickel oxo acid salts include nickel(II) sulfate can crystallise with six water molecules yielding Retgersite or with seven making Morenosite which is isomorphic to Epsom salts. These contain the hexaquanickel(II) ion. There is also an anhydrous form, a dihydrate and a tetrahydrate, the last two crystallised from sulfuric acid. The hexahydrate has two forms, a blue tetragonal form, and a green monoclinic form, with a transition temperature around 53 °C.
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In some cases however lines will split or coalesce, e.g. if the material undergoes a continuous, second order phase transition. In such cases the symmetry may change because the existing structure is distorted rather than replaced by a completely different one. For example, the diffraction peaks for the lattice planes (100) and (001) can be found at two different values of q for a tetragonal phase, but if the symmetry becomes cubic the two peaks will come to coincide.
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The lead atoms are six- coordinate. The symmetry of the beta form is tetragonal, space group P42/mnm (No. 136), Pearson symbol tP6, lattice constants a = 0.491 nm, c = 0.3385 nm, Z = 2 and related to the rutile structure and can be envisaged as containing columns of octahedra sharing opposite edges and joined to other chains by corners. This contrasts with the alpha form where the octahedra are linked by adjacent edges to give zigzag chains.
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Tensile bond strength to zirconia of ethanol solutions that contains MDP were measured. MDP showed high bond strengths to zirconia.M. Takei, S. Yamaguchi, "Effect of Functional Monomers on Tensile Bond Strength to Zirconia", 87th General Session & Exhibition of the IADR, April, #519 (2009)., M. Arai, T. Takagaki, A. Takahashi, J. Tagami, "The role of functional phosphoric acid ester monomers in the surface treatment of yttria-stabilized tetragonal zirconia polycrystals", Dental Materials Journal 36(2):190-194 (2017).
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The wing was tetragonal in plan, with more sweep on the trailing edge than on the leading edge, though the tips were semi-elliptical. It had an all-wood structure with a single box spar which incorporated an upper flange of gumbo-limbo, a Central and South American wood of particularly high bulk modulus, together with spruce and plywood ribs. The ply skin was finished with a fabric overlay. Its ailerons were carried on auxiliary spars.
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There is also an anhydrous form, a dihydrate and a tetrahydrate, the last two crystallised from sulfuric acid. The hexahydrate has two forms, a blue tetragonal form, and a green monoclinic form, with a transition temperature around 53 °C.Mellor pp462-465 The heptahydrate crystallises from water below 31.5 above this blue hexhydrate forms, and above 53.3 the green form.Mellor p 466-467 Heating nickel sulfate dehydrates it, and then 700° it loses sulfur trioxide, sulfur dioxide and oxygen.
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Models of Kepler-277b's internal structure suggest that it has a very large iron core with an estimated radius of 2.435 . The core predominantly consists of an allotrope of iron with a face-centered cubic (FCC) crystalline structure. At the innermost region of Kepler-277b's core where pressures reach as high as 37.52 terapascals, iron exists in a body-centered-tetragonal (BCT) and body-centered cubic (BCC) crystalline structure. Kepler-277b has a relatively thin silicate mantle in comparison to its core.
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Braggite is a tetragonal mineral with lattice spacing a=6.38, c=6.57 Å, Z=8 and angles between axes α=β=γ=90° with space group symmetry P41/m. Ionic bonds form between X and Z sites, but braggite also tends to exhibit metallic bonding characteristics. The general sulfide structure is XmZn, where X represents the metallic elements and Z the nonmetallic element. In the braggite structure, the Z site is always filled by sulfur with a charge of 2−.
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However, the intrinsic symmetry of these complexes is already tetragonal and no degenerate eg orbital exists, having split into a1g (mainly 3z^2-r^2) and b1g (mainly x^2-y^2) orbitals due to the different electronic interactions with axial X ligands and equatorial Y ligands. In this and other similar cases some remaining vibronic effects related to the JTE are still present but are quenched with respect to the case with degeneracy due to the splitting of the orbitals.
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The mouth is bow-shaped with a row of six papillae (nipple-like structures) across the floor. The seven upper and 12–14 lower tooth rows at the center are functional, though the total number of tooth rows is much greater. The teeth are arranged with a quincunx pattern into flattened surfaces; each has a tetragonal base with a blunt crown in juveniles and females, and a pointed cusp in adult males. The pelvic fins have nearly straight margins and angular tips.
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Pinnoite is a magnesium borate mineral with formula: MgB2O(OH)6 or MgB2O4·3(H2O). It crystallizes in the tetragonal crystal system and occurs as colorless to yellow or light green radial fibrous clusters and rarely as short prismatic crystals. Pinnoite was first described in 1884 for an occurrence in the Stassfurt potash deposit, Saxony-Anhalt, Germany and named for the mine counselor Oberbergrat Pinno of Halle, Germany. It occurs in marine evaporite deposits and as efflorescence associated with mineral springs.
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The 2-3 duoantiprism is an alternation of the 4-6 duoprism, represented by , but is not uniform. It has a highest symmetry construction of order 24, with 22 cells composed of 4 octahedra (as triangular antiprisms) and 18 tetrahedra (6 tetragonal disphenoids and 12 digonal disphenoids). There exists a construction with regular octahedra with an edge length ratio of 1 : 1.155. The vertex figure is an augmented triangular prism, which has a regular-faced variant that is not isogonal.
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Silicene, a two-dimensional allotrope of silicon, with a hexagonal honeycomb structure similar to that of graphene, was observed in 2010. The synthesis of an orthorhombic allotrope Si24, was subsequently reported in 2014. At pressure of ~10–11 GPa, germanium transforms to a metallic phase with the same tetragonal structure as tin; when decompressed—and depending on the speed of pressure release—metallic germanium forms a series of allotropes that are metastable at ambient condition. Germanium also forms a graphene analogue, germanene.
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Under compression, it has high plasticity that allows almost unlimited deformation (2.14 MPa of compression resistance) and under tensile it has low elongation (4 MPa of tensile resistance). Indium is used in dental alloys, semiconductor components, nuclear reactor panels, sodium lamps, strengthening factor in lead-based welds and low melting temperature welds. The metal has a body centered tetragonal structure, atomic radius of 1.63 Å, electronegativity of 1.81 and valence of +3 or +5, being the trivalent the more common.
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In ferroelastic crystals, in going from the nonferroic (or prototypic phase) to the ferroic phase, a spontaneous strain is induced. An example of a ferroelastic phase transition is when the crystal structure spontaneously changes from a tetragonal structure (a square prism shape) to a monoclinic structure (a general parallelepiped). Here the shapes of the unit cell before and after the phase transition are different, and hence a strain is induced within the bulk. In recent years a new class of ferroic materials has been attracting increased interest.
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The minerals that accompany them are calcite, epidote, vesuvianite, garnet, wollastonite, diopside and amphibole. The scapolites are colorless, flesh-colored, grey or greenish; occasionally they are nearly black from the presence of very small enclosures of graphitic material. They are not in very perfect crystals, though sometimes incomplete octagonal sections are visible; the tetragonal cleavage, strong double refraction and uniaxial interference figure distinguish them readily from other minerals. Commonly they weather to micaceous aggregate, but sometimes an isotropic substance of unknown nature is seen replacing them.
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In the northeast, the citadel contains the first settlement inside Diyarbakir, and those walls stretch 598 meters long. The bailey houses a tower and the city walls, surrounding the much more urban walled city region of Diyarbakir. Most of these walls are constructed with traditional masonry and construction styles; the towers consist of 2-4 floors and are 4.4 meters thick on the ground floor and get thinner on higher floors. The castle plans reveal the dominance of two different building forms, circular and tetragonal.
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Homaloceras is the most primitive, with a laterally compressed, cyrtoconic to gyroconic shell with a narrow, concave venter, broadly convex flanks, and rounded dorsum, The suture is only slightly sinuous, the siphuncle tubular and near the venter. Centroceras, the type genus, is evolute with only a few, rapidly expanding whorls and wide, perforate umbilicus. The cross section may be faintly hexagonal from the effect of a median ridge on either flank, otherwise is tetragonal. Flanks converge from a broad dorsum to a narrow, barely convex venter.
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The energy density for a tetragonal crystal is :\displaystyle E/V = K_1 \sin^2\theta + K_2 \sin^4\theta + K_3\sin^4\theta \sin 2\phi . Note that the term, the one that determines the basal plane anisotropy, is fourth order (same as the term). The definition of may vary by a constant multiple between publications. The energy density for a rhombohedral crystal is :\displaystyle E/V = K_1 \sin^2\theta + K_2 \sin^4\theta + K_3\cos\theta\sin^3\theta \cos 3\phi .
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It contrasts with black tin, which is unrefined tin ore (cassiterite) as extracted from the ground. The term "white tin" was historically associated with tin mining in Devon and Cornwall where it was smelted from black tin in blowing houses. White tin may also refer specifically to β-tin, the metallic allotrope of the pure element, as opposed to the nonmetallic allotrope α-tin (also known as gray tin) which occurs at temperatures below , a transformation known as tin pest). White tin has tetragonal unit cell.
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The hermaphrodite shrub, having both the male and female reproductive organs in the same individual, is 3–5 m tall with a 5 cm diameter at breast height. Twigs are free from hair and somewhat tetragonal, while the angle ridges are prominent. The leaves are elliptic to narrowly elliptic-ovate while being wedge-shaped or round at the base. The leaves are 5–12 cm long, 2–5 cm wide having the sub-3-veined from the base with the outer 2 nerves forming submarginal veins.
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Compressing boron above 160 GPa produces a boron phase with an as yet unknown structure. Contrary to other phases, which are semiconductors, this phase is a metal and becomes a superconductor with a critical temperature increasing from 4 K at 160 GPa to 11 K at 250 GPa. This structural transformation occurs at pressures at which theory predicts the icosahedra will dissociate. Speculation as to the structure of this phase has included face-centred cubic (analogous to Al); α-Ga, and body-centred tetragonal (analogous to In).
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Babefphite is tetragonal, which means crystallographically, it contains two horizontal and interchangeable equal axes (a1 and 2) and a longitudinal axis (c). It belongs to the 4/m 2/m 2/m point group; meaning it has four horizontal axes of twofold symmetry, two of which coincide with the crystallographic axes (a1) and (a2) and the remaining two at 45° to the (a1) and (a2).Klein, C., and Dutrow, B. (2007) The 23rd edition of the Manual of Mineral Science,675p. John Wiley and Sons, Inc.
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They are white, comparatively thin, usually short and hardly branched. The rhizome is covered by dried imbricating steaths which get increasingly larger at the base of pseudobulb becoming articulated foliar steaths that partially cover them. The pseudobulbs and leaves vary in color from yellowish bright light green to olive green depending on the species and to the amount of sunlight they are exposed to. They may be more oval and laterally highly flattened to slightly tetragonal and elongated and almost always bear two apical leaves.
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Mackinawite is an iron nickel sulfide mineral with formula (Fe,Ni)1 + xS (where x = 0 to 0.11). The mineral crystallizes in the tetragonal crystal system and has been described as a distorted, close packed, cubic array of S atoms with some of the gaps filled with Fe. Mackinawite occurs as opaque bronze to grey-white tabular crystals and anhedral masses. It has a Mohs hardness of 2.5 and a specific gravity of 4.17. It was first described in 1962 for an occurrence in the Mackinaw mine, Snohomish County, Washington for which it was named.
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Cinnamomum iners is an evergreen tree growing up to 20 m in height; the branches have opposite twigs, robust and angular, sometimes tetragonal, glabrescent. Leaves are subopposed, ovate to elliptic, measuring 120–350 mm long and 60–85 mm broad. They are glabrous and the base of the leaf is wedge-shaped with a blunt apex (see illustrations); petioles are more or less pubescent, have a reddish brown colour and 10–30 mm in length. Flowers small and bisexual, pubescent, grouped in axillary or terminal panicles; these inflorescences are 60–260 mm in length.
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The cubic honeycomb has a lower symmetry as a runcinated cubic honeycomb, with two sizes of cubes. A double symmetry construction can be constructed by placing a small cube into each large cube, resulting in a nonuniform honeycomb with cubes, square prisms, and rectangular trapezoprisms (a cube with D2d symmetry). Its vertex figure is a triangular pyramid with its lateral faces augmented by tetrahedra. 120px Dual cell The resulting honeycomb can be alternated to produce another nonuniform honeycomb with regular tetrahedra, two kinds of tetragonal disphenoids, triangular pyramids, and sphenoids.
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Pure ice XII can be created from ice Ih at by rapid compression (0.81-1.00 GPa/min) or by warming high density amorphous ice at pressures between . The proton-ordered form of ice XII is ice XIV. While it is similar in density (1.29 g/cm3 at ) to ice IV (also found in the ice V space) it exists as a tetragonal crystal. Topologically it is a mix of seven- and eight- membered rings, a 4-connected net (4-coordinate sphere packing)—the densest possible arrangement without hydrogen bond interpenetration.
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Fluorescence of an intermediate member of the group Marialite, a component of scapolite, from Tanzania at the National Museum of Natural History The group is an isomorphous mixture of the meionite and marialite endmembers. The tetragonal crystals are hemihedral with parallel faces (like scheelite), and at times of considerable size. They are distinct and usually have the form of square columns, some cleavages parallel to the prism-faces. Crystals are usually white or greyish- white and opaque, though meionite is found as colorless glassy crystals in the ejected limestone blocks of Monte Somma, Vesuvius.
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Lemanskiite is a member of the lavendulan group, and has a crystal structure that is based on heteropolyhedral layers parallel to (100). The heteropolyherdal layer are represented as Cu2+-centered polyhedra and AsO4 tetrahedra. This new structural type being formed, shows clusters of four-edge shared copper fivefold polyhedra forming distorted tetragonal pyramids, with a chlorine being the shared apex. However, even though lemanskiite is a member of the lavendulan group, it differs in that the fourth vertex in each of the AsO4 is linked a copper-centered without a copper fivefold polyhedra cluster.
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Ice VI has a density of 1.31 g/cm³ and a tetragonal crystal system with the space group P42/nmc; its unit cell contains 10 water molecules and has the dimensions a=6.27 Å and c=5.79 Å.Reports: Structure of Ice VI science.sciencemag.org, B. Kamb, 8 October 1965. The triple point of ice VI with ice VII and liquid water is at about 82°C and 2.22 GPa and its triple point with ice V and liquid water is at 0.16°C and 0.6324 GPa = 6324 bar.Water Phase Diagram www1.lsbu.ac.
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The most common electrolyte, again similar to solid-oxide fuel cells, is a dense ionic conductor consisting of ZrO2 doped with 8 mol % Y2O3 (also known as YSZ). Zirconia dioxide is used because of its high strength, high melting temperature (approximately 2700 °C) and excellent corrosion resistance. Y2O3 is added to mitigate the phase transition from the tetragonal to the monoclinic phase on rapid cooling, which can lead to cracks and decrease the conductive properties of the electrolyte by causing scattering.Bocanegra-Bernal, M. H., & De la Torre, S. D. (2002).
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Thorite, (Th,U)SiO4, is a rare nesosilicate of thorium that crystallizes in the tetragonal system and is isomorphous with zircon and hafnon. It is the most common mineral of thorium and is nearly always strongly radioactive. It was named in 1829 to reflect its thorium content. Thorite was discovered in 1828 on the island of Løvøya, Norway, by the vicar and mineralogist, Hans Morten Thrane Esmark, who sent the first specimens of this black mineral to his father, Jens Esmark, who was a professor of mineralogy and geology.
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Porphyrin readily binds to transition metals, which are capable of octahedral or square planar geometries. Boron, without available d-orbitals, typically adopts a trigonal planar or tetrahedral local bonding environment. Diboryl porphyrins, on the other hand, find boron in a pseudo-tetrahedral local environment and introduce a tetragonal distortion to the porphyrin, as can be seen in the DFT image above.423x423pxCorroles are distinct from porphyrins in that they contain one less methine to bridge between pyrrole units, creating a lower-symmetry compound and a smaller N4 pocket.
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Its shoulder mounted wing was largely based on that of the DFS Olympia though reduced in span by to by clipping the Olympia's tips to produce a tetragonal, equal-tapered plan. It is built around a single spar and an inboard, internal, diagonal drag strut rearwards to the fuselage on each side. The leading edge is plywood-covered back to the spar and struts. Apart from some ply reinforcement around the Schempp-Hirth type spoiler mounted on the rear of the spar at around mid-span, the rest of the wing surface is fabric-covered.
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At room temperature, strontium bromide adopts a crystal structure with a tetragonal unit cell and space group P4/n. This structure is referred to as α-SrBr2 and is isostructural with EuBr2 and USe2. Around 920 K (650 °C), α-SrBr2 undergoes a first-order solid-solid phase transition to a much less ordered phase, β-SrBr2, which adopts the cubic fluorite structure. The beta phase of strontium bromide has a much higher ionic conductivity of about 1 S cm−1, comparable to that of molten SrBr2, due to extensive disorder in the bromide sublattice.
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This fish is of roughly tetragonal shape, light grey in coloring, with a black patch, surrounded by iridescent silver edging, posterior of the gills on each side. The male's fins are black, as is the female's dorsal fin; the female's pelvic, anal, and adipose fins are reddish in color. A long-finned variety, apparently developed by captive breeders, is sometimes sold in the aquarium trade (the male has elongated dorsal and anal fins even in the wild form). The black phantom tetra reaches a maximum standard length of .
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The 2-4 duoantiprism is an alternation of the 4-8 duoprism, but is not uniform. It has a highest symmetry construction of order 64, with 28 cells composed of 4 square antiprisms and 24 tetrahedra (8 tetragonal disphenoids and 16 digonal disphenoids). There exists a construction with uniform square antiprisms with an edge length ratio of 1 : 1.189. 120px Vertex figure for the 2-4 duoantiprism Also related is the bialternatosnub 2-4 duoprism, constructed by removing alternating long rectangles from the octagons, but is also not uniform.
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Crystal structure of 122-type AEFe2Pn2 superconductors, AE = alkaline earth metal (Ca, Se, etc.), Pn = pnictide (As, P, etc.) The 122 iron arsenide unconventional superconductors are part of a new class of iron-based superconductors. They form in the tetragonal I4/mmm, ThCr2Si2 type, crystal structure. The shorthand name "122" comes from their stoichiometry; the 122s have the chemical formula AEFe2Pn2, where AE stands for alkaline earth metal (Ca, Ba, Sr or Eu) and Pn is pnictide (As, P, etc.). These materials become superconducting under pressure and also upon doping.
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ScB19+xSiy has a tetragonal crystal structure with space group P41212 (No. 92) or P43212 and lattice constants of a, b = 1.03081(2) and c = 1.42589(3) nm; it is isotypic to the α-AlB12 structure type. There are 28 atomic sites in the unit cell, which are assigned to 3 scandium atoms, 24 boron atoms and one silicon atom. Atomic coordinates, site occupancies and isotropic displacement factors are listed in table VI. The boron framework of ScB19+xSiy is based on one B12 icosahedron and one B22 unit.
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This unit can be observed in β-tetragonal boron and is a modification of the B20 unit of α-AlB12 (or B19 unit in early reports). The B20 unit is a twinned icosahedron made from B13 to B22 sites with two vacant sites and one B atom (B23) bridging both sides of the unit. The twinned icosahedron is shown in figure 18a. B23 was treated as an isolated atom in the early reports; it is bonded to each twinned icosahedra through B18 and to another icosahedron through B5 site.
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Boron chunks Boron (B) is the chemical element with atomic number 5, occurring as 10B and 11B. At standard temperature and pressure, boron is a trivalent metalloid that has several different allotropes. Amorphous boron is a brown powder formed as a product of many chemical reactions. Crystalline boron is a very hard, black material with a high melting point and exists in many polymorphs: Two rhombohedral forms, α-boron and β-boron containing 12 and 106.7 atoms in the rhombohedral unit cell respectively, and 50-atom tetragonal boron are the most common.
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The exact room-temperature crystal structure of sodium bismuth titanate has been a matter of debate for several years. Early studies in the 1960s using X-ray diffraction suggested Na0.5Bi0.5TiO3 to adopt either a pseudo-cubic or a rhombohedral crystal structure. In 2010, based on the high-resolution single- crystal X-ray diffraction data, a monoclinic structure (space group Cc) was proposed. On heating, Na0.5Bi0.5TiO3 transforms at 533 ± 5 K to a tetragonal structure (space group P4bm) and above 793 ± 5 K to cubic structure (space group Pmm).
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Smith, pp. 386–387 ; Quenching: Carbon steel with at least 0.4 wt% C is heated to normalizing temperatures and then rapidly cooled (quenched) in water, brine, or oil to the critical temperature. The critical temperature is dependent on the carbon content, but as a general rule is lower as the carbon content increases. This results in a martensitic structure; a form of steel that possesses a super-saturated carbon content in a deformed body-centered cubic (BCC) crystalline structure, properly termed body-centered tetragonal (BCT), with much internal stress.
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Uranium ruthenium silicide (URu2Si2) is a heavy fermion alloy composed of uranium, ruthenium, and silicon. URu2Si2 has the same '122' tetragonal crystal structure as many other compounds of present condensed matter research. URu2Si2 is a superconductor with a "hidden order" (HO) phase below a temperature of 17.5 K. Below this temperature, it is magnetic, and below about 1.5 K it superconducts. However, the nature of the ordered phase below 17.5K is still under debate despite a wide variety of scenarios that have been proposed to explain this phase.
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Crystals with an inversion center cannot display certain properties, such as the piezoelectric effect. The following space groups have inversion symmetry: the triclinic space group 2, the monoclinic 10-15, the orthorhombic 47-74, the tetragonal 83-88 and 123-142, the trigonal 147, 148 and 162-167, the hexagonal 175, 176 and 191-194, the cubic 200-206 and 221-230. Point groups lacking an inversion center (non-centrosymmetric) can be polar, chiral, both, or neither. A polar point group is one whose symmetry operations leave more than one common point unmoved.
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Tetrataenite forms naturally in iron meteorites that contain taenite that are slow-cooled at a rate of a few degrees per million years, which allows for ordering of the Fe and Ni atoms. It is found most abundantly in slow-cooled chondrite meteorites, as well as in mesosiderites. At high (as much as 52%) Ni content and temperatures below 320 °C (the order-disorder transition temperature), tetrataenite is broken down from taenite and distorts its face centered cubic crystal structure to form the tetragonal L10 structure."Taenite." Britannica Academic, Encyclopædia Britannica, 6 Nov. 2009.
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Additives such as magnesia, calcia and yttria are used in manufacturing the knife material to stabilize the high-temperature phases and minimize this volume change. The highest strength and toughness is produced by the addition of 3 mol% yttrium oxide yielding partially stabilized zirconia. This material consists of a mixture of tetragonal and cubic phases with a bending strength of nearly 1,200 MPa. Small cracks allow phase transformations to occur, which essentially close the cracks and prevent catastrophic failure, resulting in a relatively tough ceramic material, sometimes known as TTZ (transformation-toughened zirconia).
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Hafnia typically adopts the same structure as zirconia (ZrO2). Unlike TiO2, which features six-coordinate Ti in all phases, zirconia and hafnia consist of seven-coordinate metal centres. A variety of other crystalline phases have been experimentally observed, including cubic fluorite (Fmm), tetragonal (P42/nmc), monoclinic (P21/c) and orthorhombic (Pbca and Pnma).Table III, It is also known that hafnia may adopt two other orthorhombic metastable phases (space group Pca21 and Pmn21) over a wide range of pressures and temperatures, presumably being the sources of the ferroelectricity observed in thin films of hafnia.
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Phase I is noted as the superprotonic phase (strong conducting phase), which triggers an extreme growth in proton conductivity by four orders of magnitude, reaching 10 mS/cm. This makes the conductivity of CsHSO4 ten-fold stronger than the conductivity of a sodium chloride aqueous solution. In the superprotonic phase, the movement of an SO4 tetrahedron generates a disruption of the hydrogen bond network, which accelerates proton transfer. The tetragonal anions available in the structure are accountable for the arrangement of the hydrogen bonds with the moving protons.
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The room temperature form of NbO2 has a tetragonal, rutile-like structure with short Nb-Nb distances, indicating Nb-Nb bonding.Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications The high temperature form also has a rutile-like structure with short Nb-Nb distances. Two high-pressure phases have been reported one with a rutile-like structure, again with short Nb-Nb distances, and a higher pressure with baddeleyite-related structure. NbO2 is insoluble in water and is a powerful reducing agent, reducing carbon dioxide to carbon and sulfur dioxide to sulfur.
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Miami 200 Maid in early tests The Miami Maid was an all-wood flying boat with a cantilever parasol wing. It made use of existing components: the wing was a Fokker design and the hull that of a Curtiss F flying boat. In plan the wing was tetragonal out to rounded tips and swept only on the trailing edge. It was built from mahogany and spruce, with box spars and fabric-covering, and was held over the fuselage by pairs of inverted-V cabane struts between the upper fuselage longerons and the forward and aft wing spars, the latter outward-leaning.
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Among the anhydrous rare-earth phosphates, it is the tetragonal mineral xenotime that incorporates yttrium and the HREE, whereas the monoclinic monazite phase incorporates cerium and the LREE preferentially. The smaller size of the HREE allows greater solid solubility in the rock-forming minerals that make up Earth's mantle, and thus yttrium and the HREE show less enrichment in Earth's crust relative to chondritic abundance than does cerium and the LREE. This has economic consequences: large ore bodies of LREE are known around the world and are being exploited. Ore bodies for HREE are more rare, smaller, and less concentrated.
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Most ferromagnetic materials are metals, since the conducting electrons are often responsible for mediating the ferromagnetic interactions. It is therefore a challenge to develop ferromagnetic insulators, especially multiferroic materials, which are both ferromagnetic and ferroelectric. A number of actinide compounds are ferromagnets at room temperature or exhibit ferromagnetism upon cooling. PuP is a paramagnet with cubic symmetry at room temperature, but which undergoes a structural transition into a tetragonal state with ferromagnetic order when cooled below its TC = 125 K. In its ferromagnetic state, PuP's easy axis is in the <100> direction. In NpFe2 the easy axis is <111>.
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Gehlenite is one of five, isostructural tetragonal crystal system minerals in the melilite group. The tetrahedral linkage within the structure is similar to that of an aluminosilicate framework structureLouisnathan S (1969), Refinement of the crystal structure of gehlenite, Canadian Mineralogist, 10, 822-837 and was once considered a feldspathoid-like mineralBest MG (2003), Igneous and Metamorphic Petrology (2nd Ed), 398, 693, 702-703 due to silica undersaturation. Gehlenite has a Mohs hardness of 5-6, a vitreous to greasy lustre, distinct to good cleavage and is yellow brown, greenish grey or colourless. Its streak is white or grey- white.
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Scanning electron micrograph of the surface of a kidney stone showing tetragonal crystals of weddellite (calcium oxalate dihydrate) emerging from the amorphous central part of the stone; the horizontal length of the picture represents 0.5 mm of the figured original. In the body, oxalic acid combines with divalent metallic cations such as calcium (Ca2+) and iron(II) (Fe2+) to form crystals of the corresponding oxalates which are then excreted in urine as minute crystals. These oxalates can form larger kidney stones that can obstruct the kidney tubules. An estimated 80% of kidney stones are formed from calcium oxalate.
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Monoammonium phosphate is soluble in water and crystallizes from it as the anhydrous salt in the tetragonal system, as elongated prisms or needles. It is practically insoluble in ethanol.Dejun Xu, Xing Xiong, Lin Yang, Zhiye Zhang, and Xinlong Wang (2016): "Determination of the Solubility of Ammonium Dihydrogen Phosphate in Water-Ethanol System at Different Temperatures from 283.2 to 343.2 K". Journal of Chemincal Engineering Data, volume 61, issue 1, pages 78–82. Solid monoammonium phosphate can be considered stable in practice for temperatures up to 200 °C, when it decomposes into gaseous ammonia and molten phosphoric acid .
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The electric and magnetic properties of high quality epitaxial thin films of bismuth ferrite reported in 2003 revived the scientific interest for bismuth ferrite. Epitaxial thin films have the great advantage that they can be integrated in electronic circuitry. Epitaxial strain induced by singly crystalline substrates with different lattice parameters than bismuth ferrite can be used to modify the crystal structure to monoclinic or tetragonal symmetry and change the ferroelectric, piezoelectric or magnetic properties. Pulsed laser deposition (PLD) is a very common route to epitaxial BiFeO3 films, and SrTiO3 substrates with SrRuO3 electrodes are typically used.
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Sodium metaperiodate (NaIO4) forms tetragonal crystals (space group I41/a) consisting of slightly distorted ions with average I–O bond distances of 1.775 Å; the Na+ ions are surrounded by 8 oxygen atoms at distances of 2.54 and 2.60 Å. Sodium hydrogen periodate (Na2H3IO6) forms orthorhombic crystals (space group Pnnm). Iodine and sodium atoms are both surrounded by an octahedral arrangement of 6 oxygen atoms; however the NaO6 octahedron is strongly distorted. IO6 and NaO6 groups are linked via common vertices and edges. Powder diffraction indicates that Na5IO6 crystallises in the monoclinic system (space group C2/m).
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Some gold-copper–aluminium alloys form a fine surface texture at heat treatment, yielding an interesting spangling effect. At cooling, they undergo a quasi-martensitic transformation from body- centered cubic to body-centered tetragonal phase; the transformation does not depend on the cooling rate. A polished object is heated in hot oil to 150–200 °C for 10 minutes then cooled below 20 °C, forming a sparkly surface covered with tiny facets. The alloy of 76% gold, 19% copper, and 5% aluminium yields a yellow color; the alloy of 76% gold, 18% copper and 6% aluminium is pink.
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These features indicate that the formation of magnetosomes is under precise biological control and is mediated biomineralization. Magnetotactic bacteria usually mineralize either iron oxide magnetosomes, which contain crystals of magnetite (), or iron sulfide magnetosomes, which contain crystals of greigite (). Several other iron sulfide minerals have also been identified in iron sulfide magnetosomes—including mackinawite (tetragonal ) and a cubic —which are thought to be precursors of . One type of magnetotactic bacterium present at the oxic-anoxic transition zone (OATZ) of the southern basin of the Pettaquamscutt River Estuary, Narragansett, Rhode Island, United States is known to produce both iron oxide and iron sulfide magnetosomes.
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The other superconducting cuprates have another structure: they have a tetragonal cell. Each perovskite cell contains a Y or Ba atom at the center: Ba in the bottom unit cell, Y in the middle one, and Ba in the top unit cell. Thus, Y and Ba are stacked in the sequence [Ba–Y–Ba] along the c-axis. All corner sites of the unit cell are occupied by Cu, which has two different coordinations, Cu(1) and Cu(2), with respect to oxygen. There are four possible crystallographic sites for oxygen: O(1), O(2), O(3) and O(4).
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The longnose stingray has a diamond-shaped pectoral fin disc slightly wider than long, with outer corners forming approximately right angles and gently concave anterior margins converging to an obtuse, moderately projecting snout. The mouth is curved with a median projection in the upper jaw that fits into an indentation in the lower jaw. A row of three papillae are found across the floor of the mouth. There are 34-46 tooth rows in the upper jaw; the teeth have tetragonal bases and blunt crowns in females and juveniles and sharp, pointed cusps in mature males.
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The (red) side edges of tetragonal disphenoid represent a regular zig-zag skew quadrilateral A non-planar quadrilateral is called a skew quadrilateral. Formulas to compute its dihedral angles from the edge lengths and the angle between two adjacent edges were derived for work on the properties of molecules such as cyclobutane that contain a "puckered" ring of four atoms. Historically the term gauche quadrilateral was also used to mean a skew quadrilateral. A skew quadrilateral together with its diagonals form a (possibly non-regular) tetrahedron, and conversely every skew quadrilateral comes from a tetrahedron where a pair of opposite edges is removed.
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Tantalum exists in two crystalline phases, alpha and beta. The alpha phase is relatively ductile and soft; it has body-centered cubic structure (space group Im3m, lattice constant a = 0.33058 nm), Knoop hardness 200–400 HN and electrical resistivity 15–60 µΩ⋅cm. The beta phase is hard and brittle; its crystal symmetry is tetragonal (space group P42/mnm, a = 1.0194 nm, c = 0.5313 nm), Knoop hardness is 1000–1300 HN and electrical resistivity is relatively high at 170–210 µΩ⋅cm. The beta phase is metastable and converts to the alpha phase upon heating to 750–775 °C.
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Iron–platinum nanoparticles (FePt NPs) are 3D superlattices composed of an approximately equal atomic ratio of Fe and Pt. Under standard conditions, FePt NPs exist in the face-centered cubic phase but can change to a chemically ordered face-centered tetragonal phase as a result of thermal annealing. Currently there are many synthetic methods such as water-in-oil microemulsion, one-step thermal synthesis with metal precursors, and exchanged-coupled assembly for making FePt NPs.Hyie, K. M.(2010). “Synthesis of Iron-Platinum Nanoparticles in Water-in-Oil Microemulsions for High-Density Storage Media Application”. 1-9.
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When an edge forms one of the two equal sides of its adjacent isosceles triangle faces, the six disphenoids surrounding the edge form a special type of parallelepiped called a trigonal trapezohedron. : 300px An orientation of the tetragonal disphenoid honeycomb can be obtained by starting with a cubic honeycomb, subdividing it at the planes x=y, x=z, and y=z (i.e. subdividing each cube into path-tetrahedra), then squashing it along the main diagonal until the distance between the points (0, 0, 0) and (1, 1, 1) becomes the same as the distance between the points (0, 0, 0) and (0, 0, 1).
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CeCoIn5 is a member of a rich family of heavy-fermion compounds. CeIn3 is heavy-fermion metal with cubic crystal structure that orders antiferromagnetically below 10K. With applying external pressure, antiferromagnetism in CeIn3 is continuously suppressed, and a superconducting dome emerges in the phase diagram near the antiferromagnetic quantum critical point. CeCoIn5 has a tetragonal crystal structure, and the unit cell of CeCoIn5 can be considered as 'CeIn3 with an additional CoIn2 layer per unit cell'. Closely related to CeCoIn5 is the heavy-fermion material CeRhIn5, which has the same crystal structure and which orders antiferromagnetically below 4K, but does not become superconducting at ambient pressure.
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Some pairs of minerals that are not related structurally or compositionally may also exhibit epitaxy. A common example is rutile TiO2 on hematite Fe2O3. Rutile is tetragonal and hematite is trigonal, but there are directions of similar spacing between the atoms in the (100) plane of rutile (perpendicular to the a axis) and the (001) plane of hematite (perpendicular to the c axis). In epitaxy these directions tend to line up with each other, resulting in the axis of the rutile overgrowth being parallel to the c axis of hematite, and the c axis of rutile being parallel to one of the axes of hematite.
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Leucite is a rock-forming mineral of the feldspathoid group, silica- undersaturated and composed of potassium and aluminium tectosilicate KAlSi2O6. Crystals have the form of cubic icositetrahedra but, as first observed by Sir David Brewster in 1821, they are not optically isotropic, and are therefore pseudo-cubic. Goniometric measurements made by Gerhard vom Rath in 1873 led him to refer the crystals to the tetragonal system. Optical investigations have since proved the crystals to be still more complex in character, and to consist of several orthorhombic or monoclinic individuals, which are optically biaxial and repeatedly twinned, giving rise to twin-lamellae and to striations on the faces.
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As austenite cools, the carbon diffuses out of the austenite and forms carbon rich iron-carbide (cementite) and leaves behind carbon poor ferrite. Depending on alloy composition, a layering of ferrite and cementite, called pearlite, may form. If the rate of cooling is very swift, the carbon does not have time enough to diffuse and the alloy may experience a large lattice distortion known as martensitic transformation in which it transforms into martensite, a body centered tetragonal structure (BCT).The rate of cooling determines the relative proportions of martensite, ferrite, and cementite, and therefore determines the mechanical properties of the resulting steel, such as hardness and tensile strength.
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Most commercial bismuth vanadate pigments are now based on pure bismuth vanadate with monoclinic (clinobisvanite) or tetragonal (dreyerite) structure though in the past two phase systems involving a 4:3 relationship between bismuth vanadate and bismuth molybdate (Bi2MoO6) have been used. In the monoclinic phase, BiVO4 is an n-type photoactive semiconductor with a bandgap of 2.4 eV, which has been investigated for water splitting after doping with W and Mo. BiVO4 photoanodes have demonstrated record solar-to- hydrogen (STH) conversion efficiencies of 5.2% for flat films and 8.2% for WO3@BiVO4 core-shell nanorods (highest for metal-oxide photo-electrode) with the advantage of a very simple and cheap material.
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TaN is often prepared as thin films. Methods of depositing the films include RF-magnetron-reactive sputtering, Direct current (DC) sputtering, Self-propagating high-temperature synthesis (SHS) via 'combustion' of Tantalum powder in Nitrogen, low‐pressure metalorganic chemical vapor deposition (LP‐MOCVD), ion beam assisted deposition (IBAD), and by electron beam evaporation of tantalum in concert with high energy nitrogen ions. Depending on the relative amount of N2, the deposited film can vary from (fcc) TaN to (hexagonal) Ta2N as nitrogen decreases. A variety of other phases have also been reported from deposition including bcc and hexagonal TaN; hexagonal Ta5N6; tetragonal Ta4N5; orthorhombic Ta6N2.5, Ta4N, or Ta3N5.
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The strong bond between the copper ion and the cysteine sulfur allows for the non-bonded electron on the cysteine sulfur to be present on both the low/high spin state copper ion, dx2-dy2 orbital and the p-orbital of the cysteine sulfur. Most copper (II) complexes will exhibit the Jahn-Teller effect when the complex forms a tetragonal distortion of an octahedral complex geometry. With blue copper proteins, a distorted tetrahedral complex will be formed due to the strong equatorial cysteine ligand and the weak axial methionine ligand. The two neutral histidine ligands are positioned by the protein ligand so the geometry is distorted tetrahedral.
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Crystallising in the tetragonal (I41/amd) crystal system, xenotime is typically translucent to opaque (rarely transparent) in shades of brown to brownish yellow (most common) but also reddish to greenish brown and gray. Xenotime has a variable habit: It may be prismatic (stubby or slender and elongate) with dipyramidal terminations, in radial or granular aggregates, or rosettes. A soft mineral (Mohs hardness 4.5), xenotime is--in comparison to most other translucent minerals--fairly dense, with a specific gravity between 4.4-5.1. Its lustre, which may be vitreous to resinous, together with its crystal system, may lead to a confusion with zircon (ZrSiO4), the latter having a similar crystal structure and with which xenotime may sometimes occur.
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When observing the phase diagram the cubic phase will crystallize first as the solution is cooled down no matter the concentration of Y2O3. If the concentration of Y2O3 is not high enough the cubic structure will start to break down into the tetragonal state which will then break down into a monoclinic phase. If the concentration of Y2O3 is between 2.5-5% the resulting product will be PSZ (partially stabilized zirconia) while monophasic cubic crystals will form from around 8-40%. Below 14% at low growth rates tend to be opaque indicating partial phase separation in the solid solution (likely due to diffusion in the crystals remaining in the high temperature region for a longer time).
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An important category is generating a hex mesh conforming to a fixed quad surface mesh; a research subarea is studying the existence and generation of meshes of specific small configurations, such as the tetragonal trapezohedron. Because of the difficulty of this problem, the existence of combinatorial hex meshes has been studied apart from the problem of generating good geometric realizations. While known algorithms generate simplicial meshes with guaranteed minimum quality, such guarantees are rare for cubical meshes, and many popular implementations generate inverted (inside-out) hexes from some inputs. Meshes are often created in serial on workstations, even when subsequent calculations over the mesh will be done in parallel on super-computers.
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CuCl2 reacts with HCl or other chloride sources to form complex ions: the red CuCl3− (it is a dimer in reality, Cu2Cl62−, a couple of tetrahedrons that share an edge), and the green or yellow CuCl42−. : + : + 2 Some of these complexes can be crystallized from aqueous solution, and they adopt a wide variety of structures. Copper(II) chloride also forms a variety of coordination complexes with ligands such as ammonia, pyridine and triphenylphosphine oxide: :CuCl2 \+ 2 C5H5N → [CuCl2(C5H5N)2] (tetragonal) :CuCl2 \+ 2 (C6H5)3PO → [CuCl2((C6H5)3PO)2] (tetrahedral) However "soft" ligands such as phosphines (e.g., triphenylphosphine), iodide, and cyanide as well as some tertiary amines induce reduction to give copper(I) complexes.
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Above Tc, the structure is tetragonal, like rutile . In the monoclinic phase, the V4+ ions form pairs along the c axis, leading to alternate short and long V-V distances of 2.65 Å and 3.12 Å. In comparison, in the rutile phase the V4+ ions are separated by a fixed distance of 2.96 Å. As a result, the number of V4+ ions in the crystallographic unit cell doubles from the rutile to the monoclinic phase. The equilibrium morphology of rutile particles is acicular, laterally confined by (110) surfaces, which are the most stable termination planes. The surface tends to be oxidized with respect to the stoichiometric composition, with the oxygen adsorbed on the (110) surface forming vanadyl species.
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Nickel-plated neodymium magnet on a bracket from a hard disk drive Nickel- plated neodymium magnet cubes Left: high-resolution transmission electron microscopy image of Nd2Fe14B; right: crystal structure with unit cell marked A neodymium magnet (also known as NdFeB, NIB or Neo magnet) is the most widely used type of rare-earth magnet. It is a permanent magnet made from an alloy of neodymium, iron, and boron to form the Nd2Fe14B tetragonal crystalline structure. Developed independently in 1984 by General Motors and Sumitomo Special Metals, neodymium magnets are the strongest type of permanent magnet available commercially. Because of different manufacturing processes, they are divided into two subcategories, namely sintered NdFeB magnets and bonded NdFeB magnets.
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Neodymium is a metal which is ferromagnetic (more specifically it shows antiferromagnetic properties), meaning that like iron it can be magnetized to become a magnet, but its Curie temperature (the temperature above which its ferromagnetism disappears) is , so in pure form its magnetism only appears at extremely low temperatures. However, compounds of neodymium with transition metals such as iron can have Curie temperatures well above room temperature, and these are used to make neodymium magnets. The strength of neodymium magnets is the result of several factors. The most important is that the tetragonal Nd2Fe14B crystal structure has exceptionally high uniaxial magnetocrystalline anisotropy (HA ≈ 7T – magnetic field strength H in units of A/m versus magnetic moment in A·m2).
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In all these cases, cooling on the upper and lower surfaces of the solidified lava resulted in contraction and fracturing, starting in a blocky tetragonal pattern and transitioning to a regular hexagonal fracture pattern with fractures perpendicular to the cooling surfaces.Atilla Aydin and James M. Degraff (1988) "Evolution of Polygonal Fracture Patterns in Lava Flows," Science 29 January 1988: 239 (4839), 471-476. As cooling continued these cracks gradually extended toward the centre of the flow, forming the long hexagonal columns we see in the wave- eroded cross-section today. Similar hexagonal fracture patterns are found in desiccation cracks in mud where contraction is due to loss of water instead of cooling.
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Diffraction pattern of the protein thaumatin in its tetragonal crystal form, recorded on a PILATUS 6M at the HZB MX beamline BL14.1. PILATUS is the name of a series of x-ray detectors originally developed by the Paul Scherrer Institute at the Swiss Light Source and further developed and commercialized by DECTRIS. The PILATUS detectors are based on hybrid photon counting (HPC) technology, by which X-rays are converted to electrical signals by the photoelectric effect in a semiconductor sensor layer--either silicon or cadmium telluride--which is subject to a substantial bias voltage. The electric signals are counted directly by a series of cells in an ASIC bonded to the sensor.
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In the isometric system, the most common types of twins are the Spinel Law (twin plane, parallel to an octahedron), [111] where the twin axis is perpendicular to an octahedral face, and the Iron Cross [001] which is the interpenetration of two pyritohedrons a subtype of dodecahedron. In the hexagonal system, calcite shows the contact twin laws {0001} and {0112}. Quartz shows the Brazil Law {1120}, and Dauphiné Law [0001] which are penetration twins caused by transformation and Japan Law {1122} which is often caused by accidents during growth. In the tetragonal system, cyclical contact twins are the most commonly observed type of twin, such as in rutile titanium dioxide and cassiterite tin oxide.
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Nanosized titanium dioxide, particularly in the anatase form, exhibits photocatalytic activity under ultraviolet (UV) irradiation. This photoactivity is reportedly most pronounced at the {001} planes of anatase, although the {101} planes are thermodynamically more stable and thus more prominent in most synthesised and natural anatase, as evident by the often observed tetragonal dipyramidal growth habit. Interfaces between rutile and anatase are further considered to improve photocatalytic activity by facilitating charge carrier separation and as a result, biphasic titanium dioxide is often considered to possess enhanced functionality as a photocatalyst. It has been reported that titanium dioxide, when doped with nitrogen ions or doped with metal oxide like tungsten trioxide, exhibits excitation also under visible light.
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Crystal structure of the tetragonal (superconductive) phase of La2CuO4: top view (top-right) and CuO6 octahedron (bottom-right). It was known that the high-temperature cuprate superconductors have a complex lattice structure. In 1993 it was proposed that these materials belong to a particular class of materials called heterostructures at atomic limit made of a superlattice of superconducting atomic layers intercalated by a different material with the role of spacer. All new high-temperature superconducting materials discovered in the years 2001–2013 are heterostructures at atomic limit made of the active atomic layers: honeycomb boron layer in diborides, graphene in intercalated graphite, CoO2 atomic bbc monolayers in cobaltates, FeAs atomic fluorite monolayers in pnictides, FeSe atomic fluorite monolayers in selenides.
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Cross Section view of the structures that can be formed by phospholipids in aqueous solutions Polymorphism in biophysics is the ability of lipids to aggregate in a variety of ways, giving rise to structures of different shapes, known as "phases". This can be in the form of sphere of lipid molecules (micelles), pairs of layers that face one another (lamellar phase, observed in biological systems as a lipid bilayer), a tubular arrangement (hexagonal), or various cubic phases (Fdm, Imm, Iam, Pnm, and Pmm being those discovered so far). More complicated aggregations have also been observed, such as rhombohedral, tetragonal and orthorhombic phases. It forms an important part of current academic research in the fields of membrane biophysics (polymorphism), biochemistry (biological impact) and organic chemistry (synthesis).
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The tetragonal γ form exists at low temperatures below 44.5 K between about 0.3 GPa and 3 GPa pressure. The triple point for α/β/γ2 is at 0.47 GPa and 44.5 K. The space group of the γ phase is P42/mnm and its unit cell has lattice constants a=3.957 Å, c=5.109 Å at 20 K and 4000 bar. The 15N isotope converts at a pressure 400 atmospheres lower to the γ form than natural nitrogen, at 20 K. In the γ form, nitrogen molecules appear to have the shape of a prolate spheroid, 4.34 Å in the long dimension, and 3.39 Å in the short diameter. The boundary of the molecule appears at an electron density of 0.0135 eÅ−3.
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The crystal structure adopted by ceria-zirconia depends on the Zr/Ce ratio and temperature. At very low Zr concentrations, ceria-zirconia exhibits the cubic fluorite structure, which is common to both pure ceria and cubic zirconia (pure zirconia normally only adopts a cubic structure at high temperatures). However, at higher Zr contents, other crystal structures are formed, including two different tetragonal phases at intermediate Zr concentrations, and a monoclinic phase at very high Zr concentrations. There is both experimental and theoretical evidence showing that the decomposition of ceria-zirconia into Ce-rich and Zr-rich oxides is thermodynamically favorable in a wide range of solid solution compositions, which means that ceria-zirconia is metastable with respect to phase separation.
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Martensite is formed in carbon steels by the rapid cooling (quenching) of the austenite form of iron at such a high rate that carbon atoms do not have time to diffuse out of the crystal structure in large enough quantities to form cementite (Fe3C). Austenite is gamma-phase iron (γ-Fe), a solid solution of iron and alloying elements. As a result of the quenching, the face-centered cubic austenite transforms to a highly strained body- centered tetragonal form called martensite that is supersaturated with carbon. The shear deformations that result produce a large number of dislocations, which is a primary strengthening mechanism of steels. The highest hardness of a pearlitic steel is 400 Brinell, whereas martensite can achieve 700 Brinell.
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This shape has been used as a test case for hexahedral mesh generation,..... simplifying an earlier test case posited by mathematician Robert Schneiders in the form of a square pyramid with its boundary subdivided into 16 quadrilaterals. In this context the tetragonal trapezohedron has also been called the cubical octahedron, quadrilateral octahedron, or octagonal spindle, because it has eight quadrilateral faces and is uniquely defined as a combinatorial polyhedron by that property. Adding four cuboids to a mesh for the cubical octahedron would also give a mesh for Schneiders' pyramid. As a simply-connected polyhedron with an even number of quadrilateral faces, the cubical octahedron can be decomposed into topological cuboids with curved faces that meet face-to-face without subdividing the boundary quadrilaterals,.
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Thorium is a moderately soft, paramagnetic, bright silvery radioactive actinide metal. In the periodic table, it lies to the right of actinium, to the left of protactinium, and below cerium. Pure thorium is very ductile and, as normal for metals, can be cold-rolled, swaged, and drawn. At room temperature, thorium metal has a face-centred cubic crystal structure; it has two other forms, one at high temperature (over 1360 °C; body-centred cubic) and one at high pressure (around 100 GPa; body-centred tetragonal). Thorium metal has a bulk modulus (a measure of resistance to compression of a material) of 54 GPa, about the same as tin's (58.2 GPa). Aluminium's is 75.2 GPa; copper's 137.8 GPa; and mild steel's is 160–169 GPa.
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Cooperative PJTE in BaTiO3-type crystals and ferroelectricity. In crystals with PJTE centers the interaction between the local distortions may lead to their ordering to produce a phase transition to a regular crystal phase with lower symmetry. Such cooperative PJTE is quite similar to the cooperative JTE; it was shown in one of the first studies of the PJTE in solid state systems that in the case of ABO3 crystals with perovskite structure the local dipolar PJTE distortions at the transition metal B center and their cooperative interactions lead to ferroelectric phase transitions. Provided the criterion for PJTE is met, each [BO6] center has an APES with eight equivalent minima along the trigonal axes, six orthorhombic, and (higher) twelve tetragonal saddle-points between them.
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It was found later that iron can be substituted for zinc. The mineral is opaque and has a steel-gray yellow tint in reflected light, similar to native platinum. Isotropic sections are light blue whereas anisotropic ones are blue to creamy pink. Strong optical anisotropy is observed when the crystals are viewed in polarized light. Khatyrkite forms dendritic, rounded or irregular grains, typically below 0.5 millimeter in size, which are intergrown with cupalite. They have a tetragonal symmetry with point group 4/m 2/m 2/m, space group I4/mcm and lattice constants a = 0.607(1) nm, c = 0.489(1) nm and four formula units per unit cell. The crystalline structure parameters are the same for khatyrkite and synthetic CuAl2 alloy. The density, as calculated from XRD the lattice parameters, is 4.42 g/cm3.
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The powders are cooled, reground and calcined again. This process is repeated several times to get homogeneous material. The powders are subsequently compacted to pellets and sintered. The sintering environment such as temperature, annealing time, atmosphere and cooling rate play a very important role in getting good high-Tc superconducting materials. The YBa2Cu3O7−x compound is prepared by calcination and sintering of a homogeneous mixture of Y2O3, BaCO3 and CuO in the appropriate atomic ratio. Calcination is done at 900–950 °C, whereas sintering is done at 950 °C in an oxygen atmosphere. The oxygen stoichiometry in this material is very crucial for obtaining a superconducting YBa2Cu3O7−x compound. At the time of sintering, the semiconducting tetragonal YBa2Cu3O6 compound is formed, which, on slow cooling in oxygen atmosphere, turns into superconducting YBa2Cu3O7−x.
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It contains as an induced subgraph the Grötzsch graph, the smallest triangle-free four-chromatic graph, and every four-chromatic induced subgraph of the Clebsch graph is a supergraph of the Grötzsch graph. More strongly, every triangle-free four-chromatic graph with no induced path of length six or more is an induced subgraph of the Clebsch graph and an induced supergraph of the Grötzsch graph.. The 5-regular Clebsch graph is the Keller graph of dimension two, part of a family of graphs used to find tilings of high- dimensional Euclidean spaces by hypercubes no two of which meet face-to-face. The 5-regular Clebsch graph can be embedded as a regular map in the orientable manifold of genus 5, forming pentagonal faces; and in the non-orientable surface of genus 6, forming tetragonal faces.
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Bismuth oxide, Bi2O3 has five crystallographic polymorphs. The room temperature phase, α-Bi2O3 has a monoclinic crystal structure. There are three high temperature phases, a tetragonal β-phase, a body-centred cubic γ-phase, a cubic δ-Bi2O3 phase and an ε- phase. The room temperature α-phase has a complex structure with layers of oxygen atoms with layers of bismuth atoms between them. The bismuth atoms are in two different environments which can be described as distorted 6 and 5 coordinate respectively. β-Bi2O3 has a structure related to fluorite. γ-Bi2O3 has a structure related to that of Bi12SiO20 (sillenite), where a fraction of the Bi atoms occupy the position occupied by SiIV, and may be written as Bi12Bi0.8O19.2. δ- Bi2O3 has a defective fluorite-type crystal structure in which two of the eight oxygen sites in the unit cell are vacant.
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Phase III ranges from 21 °C to 90 °C with a transition temperature of 90 °C to 100 °C between phase III and phase II. Phase II ranges from 90 °C to 140 °C. At 140 °C, CsHSO4 undergoes a phase shift from phase II to phase I. Phase III (21 °C to 90 °C) and Phase II (90 °C to 140 °C) are referred to as the monoclinic phases, in which CsHSO4 exhibits its lowest proton conductivity. As the crystalline structure’s temperature is raised, it will show variations in the unit cell volume and the arrangement of its hydrogen bonds, which will alter the ability of a CsHSO4 crystalline structure to allow the displacement of protons. At 141 °C, the CsHSO4 crystal structure experiences a structural change from monoclinic phase II to a tetragonal phase, becoming phase I. Phase I has more elevated crystal symmetry and widened lattice dimensions.
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Greenwood and Earnshaw, p. 222 The density of indium, 7.31 g/cm3, is also greater than gallium, but lower than thallium. Below the critical temperature, 3.41 K, indium becomes a superconductor. Indium crystallizes in the body-centered tetragonal crystal system in the space group I4/mmm (lattice parameters: a = 325 pm, c = 495 pm): this is a slightly distorted face-centered cubic structure, where each indium atom has four neighbours at 324 pm distance and eight neighbours slightly further (336 pm).Greenwood and Earnshaw, p. 252 Indium has greater solubility in liquid mercury than any other metal (more than 50 mass percent of indium at 0 °C). Indium displays a ductile viscoplastic response, found to be size-independent in tension and compression. However it does have a size effect in bending and indentation, associated to a length-scale of order 50–100 µm, significantly large when compared with other metals.
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The snub disphenoid is 4-connected, meaning that it takes the removal of four vertices to disconnect the remaining vertices. It is one of only four 4-connected simplicial well- covered polyhedra, meaning that all of the maximal independent sets of its vertices have the same size. The other three polyhedra with this property are the regular octahedron, the pentagonal bipyramid, and an irregular polyhedron with 12 vertices and 20 triangular faces.. The snub disphenoid has the same symmetries as a tetragonal disphenoid: it has an axis of 180° rotational symmetry through the midpoints of its two opposite edges, two perpendicular planes of reflection symmetry through this axis, and four additional symmetry operations given by a reflection perpendicular to the axis followed by a quarter-turn and possibly another reflection parallel to the axis.. That is, it has antiprismatic symmetry, a symmetry group of order 8\. Spheres centered at the vertices of the snub disphenoid form a cluster that, according to numerical experiments, has the minimum possible Lennard-Jones potential among all eight-sphere clusters.. Up to symmetries and parallel translation, the snub disphenoid has five types of simple (non-self-crossing) closed geodesics.
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