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Titanate
In chemistry, titanate usually refers to inorganic compounds composed of titanium oxides, or oxides containing the titanium element. Together with niobate, titanate salts form the Perovskite group. In some cases, the term is used more generally for any titanium-containing anion, e.g. iCl6sup>2− and i(CO)6sup>2−. This article focuses on the oxides. Many kinds of titanium oxides are known, and some are commercially important. Typically these materials are white, diamagnetic, high-melting, and insoluble in water. They are often prepared at high temperatures, e.g. using tube furnaces, from titanium dioxide. In virtually all cases, titanium achieves octahedral coordination geometry.. Orthotitanates Orthotitanates have the formula M2TiO4, where M is divalent. An example of such a material is magnesium titanate (Mg2TiO4), which adopts the spinel structure. Li2TiO3 is not considered an orthotitanate since it adopts the rock-salt structure and does not feature an identifiable t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Barium Titanate
Barium titanate (BTO) is an inorganic compound with chemical formula BaTiO3. It is the barium salt of metatitanic acid. Barium titanate appears white as a powder and is transparent when prepared as large crystals. It is a Ferroelectricity, ferroelectric, Pyroelectricity, pyroelectric, and Piezoelectricity, 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 crystal system, cubic, Tetragonal crystal system, tetragonal, Orthorhombic crystal system, orthorhombic and Trigonal crystal system, 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Barium Orthotitanate
Barium orthotitanate is the inorganic compound with the chemical formula Ba2TiO4. It is a colourless solid that is of interest because of its relationship to barium titanate, a useful electroceramic. Structure The solid has two known phases: a low-temperature (β) phase with ''P''21/''n'' symmetry and a high-temperature (α) phase with ''P''21''nb'' symmetry. The structure of Ba2TiO4 is unusual among the titanates because its titanium atoms sit in a four-oxygen tetrahedron rather than a six-oxygen octahedron. Production It forms as white crystals from a melt of BaCl2, BaCO3 and TiO2 or from just sintering BaCO3 and TiO2. Another method of preparation is heating pellets of Ba(OH)2 and TiO2. Additionally, there are polymer precursor, sol-gel and reverse micellar routes to Ba2TiO4 synthesis. Ba2TiO4 has also been successfully grown as a thin film with chemical vapor deposition. Properties * Room temperature entropy – 47.0 cal/deg. mol * Dielectric constant – 20 (at 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Ferroelectric
In physics and materials science, ferroelectricity is a characteristic of certain materials that have a spontaneous electric polarization that can be reversed by the application of an external electric field. All ferroelectrics are also piezoelectric and pyroelectric, with the additional property that their natural electrical polarization is reversible. The term is used in analogy to ferromagnetism, in which a material exhibits a permanent magnetic moment. Ferromagnetism was already known when ferroelectricity was discovered in 1920 in Rochelle salt by American physicist Joseph Valasek.See and Thus, the prefix ''ferro'', meaning iron, was used to describe the property despite the fact that most ferroelectric materials do not contain iron. Materials that are both ferroelectric ''and'' ferromagnetic are known as multiferroics. Polarization When most materials are electrically polarized, the polarization induced, ''P'', is almost exactly proportional to the applied extern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Titanium Isopropoxide
Titanium isopropoxide, also commonly referred to as titanium tetraisopropoxide or TTIP, is a chemical compound with the formula . This alkoxide of titanium(IV) is used in organic synthesis and materials science. It is a diamagnetic tetrahedral molecule. Titanium isopropoxide is a component of the Sharpless epoxidation, a method for the synthesis of chiral epoxides. The structures of the titanium alkoxides are often complex. Crystalline titanium methoxide is tetrameric with the molecular formula . Alkoxides derived from bulkier alcohols such as isopropyl alcohol aggregate less. Titanium isopropoxide is mainly a monomer in nonpolar solvents. Preparation It is prepared by treating titanium tetrachloride with isopropanol in presence of ammonia. Hydrogen chloride is formed as a coproduct: : TiCl4 + 4 (CH3)2CHOH → Ti4 + 4 HCl Properties Titanium isopropoxide reacts with water to deposit titanium dioxide: :Ti4 + 2 H2O → TiO2 + 4 (CH3)2CHOH This reaction is employed in the sol-g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Bismuth Titanate
Bismuth titanate or bismuth titanium oxide is a solid inorganic compound of bismuth, titanium and oxygen with the chemical formula of Bi12TiO20, Bi 4Ti3O12 or Bi2Ti2O7. Synthesis Bismuth titanate ceramics can be produced by heating a mixture of bismuth and titanium oxides. Bi12TiO20 forms at 730–850 °C, and melts when the temperature is raised above 875 °C, decomposing in the melt to Bi4Ti3O12 and Bi2O3. Millimeter-sized single crystals of Bi12TiO20 can be grown by the Czochralski process, from the molten phase at 880–900 °C. Properties and applications Bismuth titanates exhibit electrooptical effect and photorefractive effect, that is, a reversible change in the refractive index under applied electric field or illumination, respectively. Consequently, they have potential applications in reversible recording media for real-time holography Holography is a technique that allows a wavefront to be recorded and later reconstructed. It is best known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Perovskite (structure)
A perovskite is a crystalline material of formula ABX3 with a crystal structure similar to that of the mineral perovskite, this latter consisting of calcium titanium oxide (CaTiO3). The mineral was first discovered in the Ural mountains of Russia by Gustav Rose in 1839 and named after Russian mineralogist L. A. Perovski (1792–1856). In addition to being one of the most abundant structural families, perovskites have wide-ranging properties and applications. Structure Perovskite structures are adopted by many compounds that have the chemical formula ABX3. 'A' and 'B' are 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 structure has the B cation in 6-fold coordination, surrounded by an octahedron of anions, and the A cation in 12-fold cuboctahedral coordination. Additional perovskite for ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
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, Lev 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 cop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Titanium
Titanium is a chemical element; it has 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, Great Britain, by William Gregor in 1791 and was named by Martin Heinrich Klaproth after the 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 and Hunter processes. The most common compound, titanium dioxide (TiO2), is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride (TiCl4), a component of smoke screens and cata ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Esters
In chemistry, an ester is a chemical compound, compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a Functional group#Groups containing oxygen , distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well (e.g. amides), but not according to the IUPAC. Glycerides are fatty acid esters of glycerol; they are important in biology, being one of the main classes of lipids and comprising the bulk of animal fats and vegetable oils. Lactones are cyclic carboxylic esters; naturally occurring lactones are mainly 5- and 6-membered ring lactones. Lactones contribute to the aroma of fruits, butter, cheese, vegetables like celery and other foods. Esters can be formed from oxoa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Corundum
Corundum is a crystalline form of aluminium oxide () typically containing traces of iron, titanium, vanadium, and chromium. It is a rock (geology), rock-forming mineral. It is a naturally transparency and translucency, transparent material, but can have different colors depending on the presence of transition metal impurities in its crystalline structure. Corundum has two primary gemstone, gem varieties: ruby and sapphire. Rubies are red due to the presence of chromium, and sapphires exhibit a range of colors depending on what transition metal is present. A rare type of sapphire, Sapphire#Padparadscha, padparadscha sapphire, is pink-orange. The name "corundum" is derived from the Tamil language, Tamil-Dravidian languages, Dravidian word ''kurundam'' (ruby-sapphire) (appearing in Sanskrit as ''kuruvinda''). Because of corundum's hardness (pure corundum is defined to have 9.0 on the Mohs scale), it can scratch almost all other minerals. Emery (rock), Emery, a variety of corundum w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
