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Aluminates
In chemistry, an aluminate is a compound containing an oxyanion of aluminium, such as sodium aluminate. In the naming of inorganic compounds, it is a suffix that indicates a polyatomic anion with a central aluminum atom. Aluminate oxyanions Aluminium oxide (alumina) is amphoteric: it dissolves in both bases and acids. When dissolved in bases it forms hydroxyaluminate ions in the same way as aluminium hydroxide or aluminium salts. The hydroxyaluminate or hydrated aluminate can be precipitated and then calcined to produce anhydrous aluminates. Aluminates are often formulated as a combination of basic oxide and aluminium oxide, for example the formula of anhydrous sodium aluminate NaAlO2 would be shown as Na2O·Al2O3. A number of aluminate oxyanions are known: * The simplest is the approximately tetrahedral found in the compound Na5AlO4, * framework ions in anhydrous sodium aluminate NaAlO2 and monocalcium aluminate, CaAl2O4 made up of corner-sharing tetrahedra. * A ring anion, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tricalcium Aluminate
Tricalcium aluminate Ca3Al2O6, often formulated as 3CaO·Al2O3 to highlight the proportions of the oxides from which it is made, is the most basic of the calcium aluminates. It does not occur in nature, but is an important mineral phase in Portland cement. Properties Pure tricalcium aluminate is formed when the appropriate proportions of finely divided calcium oxide and aluminium oxide are heated together above 1300 °C. The pure form is cubic, with unit cell dimension 1.5263 nm and has density 3064 kg·m−3. It melts with decomposition at 1542 °C. The unit cell contains 8 cyclic Al6O1818− anions, which can be considered to consist of 6 corner sharing AlO4 tetrahedra. The structure of pure liquid tricalcium aluminate contains mostly AlO4 tetrahedra in an infinite network, with a slightly higher concentration of bridging oxygens than expected from the composition and around 10% unconnected AlO4 monomers and Al2O7 dimers. In Portland cement clinker (cement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcium Aluminates
Calcium aluminates are a range of materials obtained by heating calcium oxide and aluminium oxide together at high temperatures. They are encountered in the manufacture of refractories and cements. The stable phases shown in the phase diagram (formed at atmospheric pressure under an atmosphere of normal humidity) are: * Tricalcium aluminate, 3CaO·Al2O3 (C3A) * Dodecacalcium hepta-aluminate, 12CaO·7Al2O3 (C12A7) (once known as mayenite) * Monocalcium aluminate, CaO·Al2O3 (CA) (occurring in nature as krotite and dmitryivanovite - two polymorphs) * Monocalcium dialuminate, CaO·2Al2O3 (CA2) (occurring in nature as grossite ) * Monocalcium hexa-aluminate, CaO·6Al2O3 (CA6) (occurring in nature as hibonite, a representative of magnetoplumbite group) In addition, other phases include: * Dicalcium aluminate, 2CaO·Al2O3 (C2A), which exists only at pressures above 2500 MPa. The crystal is orthorhombic, with density 3480 kg·m−3. The natural dicalcium aluminate, b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aluminium
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has a great affinity towards oxygen, and forms a protective layer of oxide on the surface when exposed to air. Aluminium visually resembles silver, both in its color and in its great ability to reflect light. It is soft, non-magnetic and ductile. It has one stable isotope, 27Al; this isotope is very common, making aluminium the twelfth most common element in the Universe. The radioactivity of 26Al is used in radiodating. Chemically, aluminium is a post-transition metal in the boron group; as is common for the group, aluminium forms compounds primarily in the +3 oxidation state. The aluminium cation Al3+ is small and highly charged; as such, it is polarizing, and bonds aluminium forms tend towards covalency. The strong affinity tow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithium Tetrachloroaluminate
Lithium tetrachloroaluminate (LAC, lithium aluminium chloride) is an inorganic compound, a tetrachloroaluminate of lithium, with the formula LiAlCl4. Solution of lithium tetrachloroaluminate in thionyl chloride is the liquid cathode and electrolyte of some lithium batteries, e.g. the lithium-thionyl chloride cell. Another cathode-electrolyte formulation is lithium tetrachloroaluminate+thionyl chloride+sulfur dioxide+bromine. Other salts used in lithium battery electrolytes are lithium bromide, lithium perchlorate, lithium tetrafluoroborate, and lithium hexafluorophosphate; less common ones are lithium chloride, lithium iodide, lithium chlorate, lithium nitrate, lithium hexafluoroarsenate, lithium hexafluorosilicate (i.e. lithium and hexafluorosilicic acid), lithium bis(trifluoromethanesulfonyl)imide Lithium bis(trifluoromethanesulfonyl)imide, often simply referred to as LiTFSI, is a hydrophilic salt with the chemical formula LiC2F6NO4S2. It is commonly used as Li-ion sourc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monocalcium Aluminate
Monocalcium aluminate (CaAl2O4) is one of the series of calcium aluminates. It does occur in nature, although only very rarely, as two polymorphs known as krotite and dmitryivanovite, both from meteorites. It is important in the composition of calcium aluminate cements. Properties Monocalcium aluminate is formed when the appropriate proportions of calcium carbonate and aluminium oxide are heated together until the mixture melts. It melts incongruently at 1390 °C. The crystal is monoclinic and pseudohexagonal, and has density 2945 kg.m−3. In calcium aluminate cements, it exists as a solid solution in which the amount of minor elements depends upon the bulk composition of the cement A cement is a binder, a chemical substance used for construction that sets, hardens, and adheres to other materials to bind them together. Cement is seldom used on its own, but rather to bind sand and gravel ( aggregate) together. Cement mi .... A typical compositionP. C. Hew ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxyanion
An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determined by the octet rule. The corresponding oxyacid of an oxyanion is the compound . The structures of condensed oxyanions can be rationalized in terms of AO''n'' polyhedral units with sharing of corners or edges between polyhedra. The oxyanions (specifically, phosphate and polyphosphate esters) adenosine monophosphate ( AMP), adenosine diphosphate (ADP) and adenosine triphosphate (ATP) are important in biology. Monomeric oxyanions The formula of monomeric oxyanions, , is dictated by the oxidation state of the element A and its position in the periodic table. Elements of the first row are limited to a maximum coordination number of 4. However, none of the first row elements has a monomeric oxyanion with that coordination number. Instead, ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Garnet
Garnets () are a group of silicate minerals that have been used since the Bronze Age as gemstones and abrasives. All species of garnets possess similar physical properties and crystal forms, but differ in chemical composition. The different species are pyrope, almandine, spessartine, grossular (varieties of which are hessonite or cinnamon-stone and tsavorite), uvarovite and andradite. The garnets make up two solid solution series: pyrope-almandine-spessartine (pyralspite), with the composition range ; and uvarovite-grossular-andradite (ugrandite), with the composition range . Etymology The word ''garnet'' comes from the 14th-century Middle English word ''gernet'', meaning 'dark red'. It is borrowed from Old French ''grenate'' from Latin ''granatus,'' from ''granum'' ('grain, seed'). This is possibly a reference to ''mela granatum'' or even ''pomum granatum'' ('pomegranate', ''Punica granatum''), a plant whose fruits contain abundant and vivid red seed covers ( arils), whic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithium Aluminium Hydride
Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula Li Al H4. It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides. The solid is dangerously reactive toward water, releasing gaseous hydrogen (H2). Some related derivatives have been discussed for hydrogen storage. Properties, structure, preparation LAH is a colourless solid but commercial samples are usually gray due to contamination. This material can be purified by recrystallization from diethyl ether. Large-scale purifications employ a Soxhlet extractor. Commonly, the impure gray material is used in synthesis, since the impurities are innocuous and can be easily separated from the organic products. The pure powdered material is pyrophoric, but not its large crystals. Some commercial materials contain mineral oil to in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Petrochemical Industry
The petrochemical industry is concerned with the production and trade of petrochemicals. A major part is constituted by the plastics (polymer) industry. It directly interfaces with the petroleum industry, especially the downstream sector. Companies The top ten global petrochemical companies based on the 2008 revenues – excludes state-owned companies: Countries and sites *Marun petrochemical complex Technology Conferences *Asia Petrochemical Industry Conference *International Petrochemical Conference by the AFPM Associations *American Fuel and Petrochemical Manufacturers (AFPM) *European Petrochemical Association *Gulf Petrochemicals and Chemicals Association Awards *Medal "For the Tapping of the Subsoil and Expansion of the Petrochemical Complex of Western Siberia" *Petrochemical Heritage Award See also *Aqueous Wastes from Petroleum and Petrochemical Plants ''Aqueous Wastes from Petroleum and Petrochemical Plants'' is a book about the composition and treatment of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mordant
A mordant or dye fixative is a substance used to set (i.e. bind) dyes on fabrics by forming a coordination complex with the dye, which then attaches to the fabric (or tissue). It may be used for dyeing fabrics or for intensifying stains in biological specimen, cell or tissue preparations. Although mordants are still used, especially by small batch dyers, it has been largely displaced in industry by substantive dye, directs.} The term mordant comes from the Latin ''mordere'', "to bite". In the past, it was thought that a mordant helped the dye bite onto the fiber so that it would hold fast during washing. A mordant is often a polyvalency (chemistry), polyvalent metal ion, and one example is chromium (III). The resulting coordination complex of dye and ion is colloidal and can be either acidic or base (chemistry), alkaline. Common dye mordants Mordants include tannic acid, oxalic acid, alum, chrome alum, sodium chloride, and certain salt (chemistry), salts of aluminium, chrom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Aluminate
Sodium aluminate is an inorganic chemical that is used as an effective source of aluminium hydroxide for many industrial and technical applications. Pure sodium aluminate (anhydrous) is a white crystalline solid having a formula variously given as NaAlO2, NaAl(OH)4 (hydrated), Na2O·Al2O3, or Na2Al2O4. Commercial sodium aluminate is available as a solution or a solid. Other related compounds, sometimes called sodium aluminate, prepared by reaction of Na2O and Al2O3 are Na5AlO4 which contains discrete AlO45− anions, Na7Al3O8 and Na17Al5O16 which contain complex polymeric anions, and NaAl11O17, once mistakenly believed to be β-alumina, a phase of aluminium oxide.Egon Wiberg, Arnold Frederick Holleman (2001) ''Inorganic Chemistry'', Elsevier Structure Anhydrous sodium aluminate, NaAlO2, contains a three-dimensional framework of corner linked AlO4 tetrahedra. The hydrated form NaAlO2·5/4H2O has layers of AlO4 tetrahedra joined into rings and the layers are held together by sodi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aerodynamic Levitation
Aerodynamic levitation is the use of gas pressure to levitate materials so that they are no longer in physical contact with any container. In scientific experiments this removes contamination and nucleation issues associated with physical contact with a container. Overview The term aerodynamic levitation could be applied to many objects that use gas pressure to counter the force of gravity, and allow stable levitation. Helicopters and air hockey pucks are two good examples of objects that are aerodynamically levitated. However, more recently this term has also been associated with a scientific technique which uses a cone-shaped nozzle allowing stable levitation of 1-3mm diameter spherical samples without the need for active control mechanisms. Aerodynamic levitation as a scientific tool These systems allow spherical samples to be levitated by passing gas up through a diverging conical nozzle. Combining this with >200W continuous CO2 laser heating allows sample temperatures in e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
