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Perovskite
Perovskite (pronunciation: ) is a calcium titanium oxide mineral composed of calcium titanate (chemical formula ). Its name is also applied to the class of compounds which have the same type of crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns t ... as (XIIA2+VIB4+X2−3), known as the perovskite (structure), perovskite structure. Many different cations can be embedded in this structure, allowing the development of diverse engineered materials. History The mineral was discovered in the Ural Mountains of Russia by Gustav Rose in 1839 and is named after Russian mineralogist Lev Perovski (1792–1856). Perovskite's notable crystal structure was first described by Victor Goldschmidt in 1926 in his work on tolerance factors. The crystal structure was later published ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perovskite (structure)
A perovskite is any material with a crystal structure following the formula ABX3, which was first discovered as the Perovskite, mineral called perovskite, which consists of calcium titanium oxide (CaTiO3). The mineral was first discovered in the Ural Mountains, Ural mountains of Russia by Gustav Rose in 1839 and named after Russian mineralogist L. A. Perovski (1792–1856). 'A' and 'B' are two positively charged ions (i.e. cations), often of very different sizes, and X is a negatively charged ion (an anion, frequently oxide) that bonds to both cations. The 'A' atoms are generally larger than the 'B' atoms. The ideal Cubic crystal system, cubic structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedron, cuboctahedral coordination. Additional perovskite forms may exist where either/both the A and B sites have a configuration of A1x-1A2x and/or B1y-1B2y and the X may deviate from the ideal coordination configu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium Titanate
Calcium titanate is an inorganic compound with the chemical formula Ca Ti O3. As a mineral, it is called perovskite, named after Russian mineralogist, L. A. Perovski (1792-1856). It is a colourless, diamagnetic solid, although the mineral is often coloured owing to impurities. Synthesis CaTiO3 can be prepared by the combination of CaO and TiO2 at temperatures >1300 °C. Sol-gel processes has been used to make a more pure substance, as well as lowering the synthesis temperature. These compounds synthesized are more compressible due to the powders from the sol-gel process as well and bring it closer to its calculated density (~4.04 g/ml). Structure Calcium titanate is obtained as orthorhombic crystals, more specifically perovskite structure. In this motif, the Ti(IV) centers are octahedral and the Ca2+ centers occupy a cage of 12 oxygen centres. Many useful materials adopt related structures, e.g. barium titanate or variations of the structure, e.g. yttrium barium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helen Dick Megaw
Helen Dick Megaw (1 June 1907 – 26 February 2002) was an Irish crystallographer who was a pioneer in X-ray crystallography. She made measurements of the cell dimensions of ice and established the Perovskite crystal structure. Education and career Megaw was born in Dublin as the daughter of the Irish judge and politician Robert Megaw. She was educated at the Roedean in Dublin. While still at school, Megaw read Bragg's ''X-rays and Crystal Structure.'' She spent a year Queen's University, Belfast before moving to Girton College, Cambridge to study Natural Sciences in 1926. She graduated in 1930 and was a research student in crystallography under J. D. Bernal. Megaw's first speciality was the structure of ice, and she was awarded her PhD in 1934,Personal papers of Helen Megaw' and Girton awarded her a Hertha Ayrton research scholarship which she used to study in Vienna in 1934-1935 under Hermann Francis Mark. In 1935 Megaw co-published with Bernal an influential method for f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barium Titanate
Barium titanate (BTO) is an inorganic compound with chemical formula BaTiO3. Barium titanate appears white as a powder and is transparent when prepared as large crystals. It is a ferroelectric, pyroelectric, and piezoelectric ceramic material that exhibits the photorefractive effect. It is used in capacitors, electromechanical transducers and nonlinear optics. Structure 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. All of these phases exhibit the ferroelectric effect apart from the cubic phase. The high temperature cubic phase is easiest to describe, as it consists of regular corner-sharing octahedral TiO6 units that define a cube with O vertices and Ti-O-Ti edges. In the cubic phase, Ba2+ is located at the center of the cube, with a nominal coordination number of 12. Lower symmetry phases are stabili ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Titanium
Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in sea water, aqua regia, and chlorine. Titanium was discovered in Cornwall, Kingdom of Great Britain, Great Britain, by William Gregor in 1791 and was named by Martin Heinrich Klaproth after the Titan (mythology), Titans of Greek mythology. The element occurs within a number of minerals, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere; it is found in almost all living things, as well as bodies of water, rocks, and soils. The metal is extracted from its principal mineral ores by the Kroll process, Kroll and Hunter process, Hunter processes. The most common compound, titanium dioxide, is a popular photocatalysis, photocatalyst and is used in the manufacture of white pigments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxide Minerals
The oxide mineral class includes those minerals in which the oxide anion (O2−) is bonded to one or more metal alloys. The hydroxide-bearing minerals are typically included in the oxide class. The minerals with complex anion groups such as the silicates, sulfates, carbonates and phosphates are classed separately. Simple oxides: *XO **Periclase group *** Periclase *** Manganosite **Zincite group *** Zincite *** Bromellite *** Tenorite *** Litharge * ** Cuprite ** Ice * **Hematite group ***Corundum ***Hematite *** Ilmenite * **Rutile group *** Rutile *** Pyrolusite *** Cassiterite ** Baddeleyite ** Uraninite ** Thorianite * **Spinel group *** Spinel *** Gahnite ***Magnetite ***Franklinite *** Chromite ** Chrysoberyl ** Columbite *Hydroxide subgroup: ** Brucite ** Manganite **Romanèchite **Goethite group: *** Diaspore *** Goethite Nickel–Strunz Classification -04- Oxides IMA-CNMNC proposes a new hierarchical scheme (Mills et al., 2009). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gustav Rose
Prof Gustavus ("Gustav") Rose FRSFor HFRSE (18 March 1798 – 15 July 1873) was a German mineralogist who was a native of Berlin. He was President of the German Geological Society from 1863 to 1873. Life He was born in Berlin the son of pharmacologist Valentin Rose. Rose was a graduate of the University of Berlin, where he was a student of mineralogist Christian Samuel Weiss (1780–1856). He also studied under Swedish physical chemist Jöns Jakob Berzelius (1779–1848) in Stockholm. While studying with Berzelius, Rose met German chemist Eilhard Mitscherlich (1794–1863), with whom he maintained a lifelong friendship. Rose provided assistance to Mitscherlich's development of the law of isomorphism. In 1826 he became an associate professor of mineralogy in Berlin. In 1829, with German naturalists Alexander von Humboldt (1769–1859) and Christian Gottfried Ehrenberg (1795–1876), Rose took part in a scientific expedition throughout Imperial Russia. In Russia he performed m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnet Cove Igneous Complex
The Magnet Cove igneous complex is a small alkalic ring complex lying to the west of the town of Magnet Cove in Hot Spring County, Arkansas.Geology of Titanium-Mineral Deposits, Eric R. Force, Geological Society of America, 1991,Google Books/ref> It and the adjacent town are so named due to the existence of magnetite and the terrain being a cove, a basin-shaped valley. The complex is of Mesozoic age, intruded into Paleozoic sediments. Mapping was conducted by the geologists Erickson and Blade in 1963. Units within the complex include carbonatite, nepheline syenite, phonolite, and ijolite. In addition to the magnetite which forms both massive lodestone and crystals, the complex is strewn with odd and rare minerals, and is the type locality for five mineral species. Over 100 different minerals have been identified from the area. There are many titanium minerals such as rutile, anatase, brookite, and perovskite, as well as some vanadium Vanadium is a chemical element with th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxide Mineral
The oxide mineral class includes those minerals in which the oxide anion (O2−) is bonded to one or more metal alloys. The hydroxide-bearing minerals are typically included in the oxide class. The minerals with complex anion groups such as the silicates, sulfates, carbonates and phosphates are classed separately. Simple oxides: *XO **Periclase group *** Periclase *** Manganosite **Zincite group *** Zincite *** Bromellite *** Tenorite *** Litharge * ** Cuprite ** Ice * **Hematite group ***Corundum ***Hematite *** Ilmenite * **Rutile group ***Rutile *** Pyrolusite *** Cassiterite ** Baddeleyite ** Uraninite ** Thorianite * **Spinel group *** Spinel *** Gahnite ***Magnetite ***Franklinite *** Chromite ** Chrysoberyl ** Columbite *Hydroxide subgroup: ** Brucite ** Manganite **Romanèchite **Goethite group: *** Diaspore *** Goethite Nickel–Strunz Classification -04- Oxides IMA-CNMNC proposes a new hierarchical scheme (Mills et al., 2009). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal Structure
In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns that repeat along the principal directions of three-dimensional space in matter. The smallest group of particles in the material that constitutes this repeating pattern is the unit cell of the structure. The unit cell completely reflects the symmetry and structure of the entire crystal, which is built up by repetitive translation of the unit cell along its principal axes. The translation vectors define the nodes of the Bravais lattice. The lengths of the principal axes, or edges, of the unit cell and the angles between them are the lattice constants, also called ''lattice parameters'' or ''cell parameters''. The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of partic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lev Perovski
Count Lev Alekseyevich von Perovski (russian: Лев Алексе́евич Перо́вский, also transliterated as Perofsky, Perovskii, Perovskiy, Perovsky, Perowski, and Perowsky; also credited as L.A. Perovski) (9 September 1792 – 21 November 1856) was a Russian nobleman and mineralogist who also served as Minister of Internal Affairs under Nicholas I of Russia. In 1845, he proposed the creation of the Russian Geographical Society. The mineral perovskite Perovskite (pronunciation: ) is a calcium titanium oxide mineral composed of calcium titanate (chemical formula ). Its name is also applied to the class of compounds which have the same type of crystal structure In crystallography, crystal ... is named for him. References Interior ministers of Russia Politicians of the Russian Empire Russian mineralogists 1792 births 1856 deaths Burials at Lazarevskoe Cemetery (Saint Petersburg) Imperial Moscow University alumni {{Russia-scientist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paragenesis
Paragenesis is a petrologic concept meaning an ''equilibrium sequence of mineral phases''. It is used in studies of igneous and metamorphic rock genesis and importantly in studies of the hydrothermal deposition of ore minerals and the rock alteration (vein metasomatism) associated with ore mineral deposits. The concept and application of paragenesis, from the Greek for ''born beside'', was first applied by August Breithaupt in 1849 in his work ''Die Paragenesis der Mineralien''. The paragenetic sequence in mineral formation is an important concept in deciphering the detailed geologic history of ore deposits and metamorphic events. The sequence is worked out through detailed microscopic studies in polished ore mineral section, petrologic thin section and fluid inclusion image:Inclumed.gif, 250px, Trapped in a time capsule the same size as the diameter of a human hair, the ore-forming liquid in this inclusion was so hot and contained so much dissolved solids that when it cooled, cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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