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Neodymium(III) Oxide
Neodymium(III) oxide or neodymium sesquioxide is the chemical compound composed of neodymium and oxygen with the formula Nd2O3. It forms very light grayish-blue hexagonal crystals. The rare-earth mixture didymium, previously believed to be an element, partially consists of neodymium(III) oxide. Uses Neodymium(III) oxide is used to dope glass, including sunglasses, to make solid-state lasers, and to color glasses and enamels. Neodymium-doped glass turns purple due to the absorbance of yellow and green light, and is used in welding goggles. Some neodymium-doped glass is dichroic; that is, it changes color depending on the lighting. One kind of glass named for the mineral alexandrite appears blue in sunlight and red in artificial light. About 7000 tonnes of neodymium(III) oxide are produced worldwide each year. Neodymium(III) oxide is also used as a polymerization catalyst. Reactions Neodymium(III) oxide is formed when neodymium(III) nitride or neodymium(III) hydroxide is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hexagonal Crystal System
In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crystal system and the rhombohedral lattice system are not equivalent (see section crystal systems below). In particular, there are crystals that have trigonal symmetry but belong to the hexagonal lattice (such as α-quartz). The hexagonal crystal family consists of the 12 point groups such that at least one of their space groups has the hexagonal lattice as underlying lattice, and is the union of the hexagonal crystal system and the trigonal crystal system. There are 52 space groups associated with it, which are exactly those whose Bravais lattice is either hexagonal or rhombohedral. __TOC__ Lattice systems The hexagonal crystal family consists of two lattice systems: hexagonal and rhombohedral. Each lattice system consists of one Bravais l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solid-state Laser
A solid-state laser is a laser that uses a gain medium that is a solid, rather than a liquid as in dye lasers or a gas as in gas lasers. Semiconductor-based lasers are also in the solid state, but are generally considered as a separate class from solid-state lasers, called laser diodes. Solid-state media Generally, the active medium of a solid-state laser consists of a glass or crystalline "host" material, to which is added a "dopant" such as neodymium, chromium, erbium, thulium or ytterbium.Z. Su, J. D. Bradley, N. Li, E. S. Magden, Purnawirman, D. Coleman, N. Fahrenkopf, C. Baiocco, T. Adam, G. Leake, D. Coolbaugh, D. Vermeulen, and M. R. Watts (2016"Ultra-Compact CMOS-Compatible Ytterbium Microlaser" ''Integrated Photonics Research, Silicon and Nanophotonics 2016'', IW1A.3. Many of the common dopants are rare-earth elements, because the excited states of such ions are not strongly coupled with the thermal vibrations of their crystal lattices (phonons), and their operational t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transactions And Journal Of The British Ceramic Society
Transaction or transactional may refer to: Commerce *Financial transaction, an agreement, communication, or movement carried out between a buyer and a seller to exchange an asset for payment *Debits and credits in a Double-entry bookkeeping system *Electronic funds transfer, the electronic exchange or transfer of money from one account to another *Real estate transaction, the process whereby rights in a unit of property is transferred between two or more parties *Transaction cost, a cost incurred in making an economic exchange *Transactional law, the practice of law concerning business and commerce Computing *Transaction processing, information processing that is divided into individual, indivisible operations *Database transaction, a unit of work performed within a database management system *Atomic transaction, a series of database operations such that either all occur, or nothing occurs Other uses *Transactions, the published proceedings of a learned society: ** *Transaction ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Space Group
In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it unchanged. In three dimensions, space groups are classified into 219 distinct types, or 230 types if chiral copies are considered distinct. Space groups are discrete cocompact groups of isometries of an oriented Euclidean space in any number of dimensions. In dimensions other than 3, they are sometimes called Bieberbach groups. In crystallography, space groups are also called the crystallographic or Fedorov groups, and represent a description of the symmetry of the crystal. A definitive source regarding 3-dimensional space groups is the ''International Tables for Crystallography'' . History Space groups in 2 dimensions are the 17 wallpaper groups which have been known for several centuries, though the proof that the list was complete was only ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphism (materials Science)
In materials science, polymorphism describes the existence of a solid material in more than one form or crystal structure. Polymorphism is a form of isomerism. Any crystalline material can exhibit the phenomenon. Allotropy refers to polymorphism for chemical elements. Polymorphism is of practical relevance to pharmaceuticals, agrochemicals, pigments, dyestuffs, foods, and explosives. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure." According to McCrone, polymorphs are "different in crystal structure but identical in the liquid or vapor states." Materials with two polymorphs are called dimorphic, with three polymorphs, trimorphic, etc. Examples Many compounds exhibit polymorphism. It has been claimed that "every compound has different polymorphic forms, and that, in general, the n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodymium(III) Hydroxide
Neodymium(III) hydroxide is an insoluble inorganic compound with the chemical formula Nd(OH)3. Production Neodymium(III) nitrate and ammonia water will react to produce neodymium(III) hydroxide《无机化合物制备手册》. 朱文祥 主编. 化学工业出版社. 【III-119】氢氧化钕（neodymium hydroxide） : Nd(NO3)3 + 3 NH3·H2O → Nd(OH)3↓ + 3 NH4NO3 If the amount of Nd(NO3)3 is 40g/L, the amount of ammonia water needed is 0.50 mol/L. The ammonia water is mixed into the Nd(NO3)3 solution at the speed of 1.5mL/min, and polyethylene glycol is used to control pH. The process will produce neodymium(III) hydroxide powder with grain size ≤1μm. 刘治平, 王晓铁. 氢氧化镧和氢氧化钕微粉的制备[J]. 《稀土》. Vol.25 No.3 Jun.2004 Chemical properties Neodymium(III) hydroxide can react with acid and produce neodymium salts: : Nd(OH)3 + 3 H+ → Nd3+ + 3 H2O For example, to create neodymium acetate with neodymium(III) hydroxide: :Nd(OH)3 + 3CH3COOH ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neodymium Nitride
Neodymium nitride or neodymium(III) nitride is a chemical compound of neodymium and nitrogen with the formula NdN in which neodymium exhibits the +3 oxidation state and nitrogen exhibits the -3 oxidation state. It is ferromagnetic, like gadolinium(III) nitride, terbium(III) nitride and dysprosium(III) nitride. Neodymium nitride is not usually stoichiometric, and it is very hard to create pure stoichiometric neodymium nitride.Nasirpouri, Farzad and Nogaret, Alain (eds.) (2011) ''Nanomagnetism and Spintronics: Fabrication, Materials, Characterization and Applications''. World Scientific. Preparation Neodymium nitride can be prepared via an exothermic metathesis reaction between lithium nitride and anhydrous neodymium(III) chloride. Lithium chloride formed in the reaction can be removed by THF, a chemical in which lithium chloride dissolves in. : NdCl3 + Li3N → NdN + 3 LiCl It can also be prepared directly when neodymium reacts directly with nitrogen: : 2 Nd + N2 → 2 NdN It c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catalyst
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quickly, very small amounts of catalyst often suffice; mixing, surface area, and temperature are important factors in reaction rate. Catalysts generally react with one or more reactants to form intermediates that subsequently give the final reaction product, in the process of regenerating the catalyst. Catalysis may be classified as either homogeneous, whose components are dispersed in the same phase (usually gaseous or liquid) as the reactant, or heterogeneous, whose components are not in the same phase. Enzymes and other biocatalysts are often considered as a third category. Catalysis is ubiquitous in chemical industry of all kinds. Estimates are that 90% of all commercially produced chemical products involve catalysts at some s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer, monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them. In chemical compounds, polymerization can occur via a variety of reaction mechanisms that vary in complexity due to the functional groups present in the reactants and their inherent steric effects. In more straightforward polymerizations, alkenes form polymers through relatively simple free-radical reaction, radical reactions; in contrast, reactions involving substitution at a carbonyl group require more complex synthesis due to the way in which reactants polymerize. Alkanes can also be polymerized, but only with the help of strong acids. As alkenes can polymerize in somewhat straightforward radical reactions, they form useful compounds such as polyethylene and p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United States customary units), and the long ton ( British imperial units). It is equivalent to approximately 2204.6 pounds, 1.102 short tons, and 0.984 long tons. The official SI unit is the megagram (symbol: Mg), a less common way to express the same mass. Symbol and abbreviations The BIPM symbol for the tonne is t, adopted at the same time as the unit in 1879.Table 6 . BIPM. Retrieved on 2011-07-10. Its use is also official for the metric ton in the United States, having been adopted by the United States |
Alexandrite
The mineral or gemstone chrysoberyl is an aluminate of beryllium with the formula Be Al2 O4. The name chrysoberyl is derived from the Greek words χρυσός ''chrysos'' and βήρυλλος ''beryllos'', meaning "a gold-white spar". Despite the similarity of their names, chrysoberyl and beryl are two completely different gemstones, although they both contain beryllium. Chrysoberyl is the third-hardest frequently encountered natural gemstone and lies at 8.5 on the Mohs scale of mineral hardness, between corundum (9) and topaz (8). An interesting feature of its crystals are the cyclic twins called ''trillings''. These twinned crystals have a hexagonal appearance, but are the result of a triplet of twins with each "twin" oriented at 120° to its neighbors and taking up 120° of the cyclic trilling. If only two of the three possible twin orientations are present, a "V"-shaped twin results. Ordinary chrysoberyl is yellowish-green and transparent to translucent. When the mineral e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dichroic
In optics, a dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths (colours) (not to be confused with dispersion), or one in which light rays having different polarizations are absorbed by different amounts. In beam splitters The original meaning of ''dichroic'', from the Greek ''dikhroos'', two-coloured, refers to any optical device which can split a beam of light into two beams with differing wavelengths. Such devices include mirrors and filters, usually treated with optical coatings, which are designed to reflect light over a certain range of wavelengths and transmit light which is outside that range. An example is the dichroic prism, used in some camcorders, which uses several coatings to split light into red, green and blue components for recording on separate CCD arrays, however it is now more common to have a Bayer filter to filter individual pixels on a single CCD array. This kind of dichroic device does n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
