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Selenide
A selenide is a chemical compound containing a selenium anion with oxidation number of −2 (Se2−), much as sulfur does in a sulfide. The chemistry of the selenides and sulfides is similar. Similar to sulfide, in aqueous solution, the selenide ion, Se2−, is prevalent only in very basic conditions. In neutral conditions, hydrogen selenide ion, HSe−, is most common. In acid conditions, hydrogen selenide, H2Se, is formed. Some selenides are reactive to oxidation by air. Owing to the greater reducing power of selenide, metal selenides are more easily decomposed to the elements than are sulfides (tellurides are even more labile). Selenides of electropositive metals: such as aluminium selenide readily hydrolyse, even in moist air, evolving toxic hydrogen selenide gas. Pure selenide minerals are rare, instead selenium tends to partially substitute for sulfide in many sulfide minerals. The degree of substitution is only of commercial interest for copper sulfide ores, in which cas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lead Selenide
Lead selenide (PbSe), or lead(II) selenide, a selenide of lead, is a semiconductor material. It forms cubic crystals of the NaCl structure; it has a direct bandgap of 0.27 eV at room temperature. (Note that incorrectly identifies PbSe and other IV–VI semiconductors as indirect gap materials.) A grey solid, it is used for manufacture of infrared detectors for thermal imaging. The mineral clausthalite is a naturally occurring lead selenide. It may be formed by direct reaction between its constituent elements, lead and selenium. Infrared detection PbSe was one of the first materials found to be sensitive to the infrared radiation used for military applications. Early research works on the material as infrared detector were carried out during the 1930s and the first useful devices were processed by Germans, Americans and British during and just after World War II. Since then, PbSe has been commonly used as an infrared photodetector in multiple applications, from spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen Selenide
Hydrogen selenide is an inorganic compound with the formula H2Se. This hydrogen chalcogenide is the simplest and most commonly encountered hydride of selenium. H2Se is a colorless, flammable gas under standard conditions. It is the most toxic selenium compoundhttp://www.epa.gov/ttnatw01/hlthef/selenium.html, US Environmental Protection Agency, Air Toxins website with an exposure limit of 0.05 ppm over an 8-hour period.https://www.cdc.gov/niosh/idlh/7783075.html, Documentation of Immediately Dangerous to Life or Health Concentrations: Hydrogen Selenide, The National Institute for Occupational Safety and Healthhttps://www.cdc.gov/niosh/docs/81-123/pdfs/0336.pdf Occupational Health Guideline for Hydrogen Selenide, The National Institute for Occupational Safety and Health, 1978 Even at extremely low concentrations, this compound has a very irritating smell resembling that of decayed horseradish or 'leaking gas', but smells of rotten eggs at higher concentrations. Structure and proper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenides
A selenide is a chemical compound containing a selenium anion with oxidation number of −2 (Se2−), much as sulfur does in a sulfide. The chemistry of the selenides and sulfides is similar. Similar to sulfide, in aqueous solution, the selenide ion, Se2−, is prevalent only in very basic conditions. In neutral conditions, hydrogen selenide ion, HSe−, is most common. In acid conditions, hydrogen selenide, H2Se, is formed. Some selenides are reactive to oxidation by air. Owing to the greater reducing power of selenide, metal selenides are more easily decomposed to the elements than are sulfides (tellurides are even more labile). Selenides of electropositive metals: such as aluminium selenide readily hydrolyse, even in moist air, evolving toxic hydrogen selenide gas. Pure selenide minerals are rare, instead selenium tends to partially substitute for sulfide in many sulfide minerals. The degree of substitution is only of commercial interest for copper sulfide ores, in which cas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cadmium Selenide
Cadmium selenide is an inorganic compound with the formula Cd Se. It is a black to red-black solid that is classified as a II-VI semiconductor of the n-type. Much of the current research on this compound is focused on its nanoparticles. Structure Three crystalline forms of CdSe are known which follow the structures of: wurtzite (hexagonal), sphalerite (cubic) and rock-salt (cubic). The sphalerite CdSe structure is unstable and converts to the wurtzite form upon moderate heating. The transition starts at about 130 °C, and at 700 °C it completes within a day. The rock-salt structure is only observed under high pressure. Production The production of cadmium selenide has been carried out in two different ways. The preparation of bulk crystalline CdSe is done by the High-Pressure Vertical Bridgman method or High-Pressure Vertical Zone Melting. Cadmium selenide may also be produced in the form of nanoparticles. (see applications for explanation) Several methods for the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copper Selenide
Copper selenide is an inorganic binary compound consisting of copper and selenium. Its formula is sometimes described as CuSe or Cu2Se. The crystalline structure and electronic behavior is determined by its elemental composition. Stoichiometric copper selenide is a zero bandgap material with metal-like behavior. Copper-deficient Cu2-xSe (non-stoichiometric) is an intrinsic p-type semiconductor with direct and indirect bandgap energies in the range of 2.1–2.3 eV and 1.2–1.4 eV, respectively. It is frequently grown as nanoparticles or other nanostructures. Uses Copper selenide is produced in-situ to form a protective black coating on iron or steel parts in some cold-bluing processes. Bluing solutions that operate in this manner will typically be labeled as containing selenous acid or selenium dioxide. It has also been investigated for use in the treatment of colon cancer. Natural occurrences Copper selenides are the most common selenium minerals. CuSe is known in mine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenide Mineral
Selenide minerals are those minerals that have the selenide anion as a main component. Selenides are similar to sulfides and often grouped with them. Examples include: * achavalite * athabascaite * clausthalite * ferroselite * penroseite * stilleite * tiemannite * umangite Umangite is a copper selenide mineral, Cu3 Se2, discovered in 1891. It occurs only in small grains or fine granular aggregates with other copper minerals of the sulfide group. It has a hardness of 3. It is blue-black to red-violet in color with ... References {{Mineral-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Indium(III) Selenide
Indium(III) selenide is a compound of indium and selenium. It has potential for use in photovoltaic devices and it has been the subject of extensive research. The two most common phases, α and β, have a layered structure, while γ is a "defect wurtzite structure." In all, there are five known forms (α, β, γ, δ, κ). The α- β phase transition is accompanied by a change in electrical conductivity. The band-gap of γ-In2Se3 is approximately 1.9 eV. The crystalline form of a sample can depend on the method of production, for example thin films of pure γ-In2Se3 have been produced from trimethylindium, InMe3, and hydrogen selenide, H2Se, using MOCVD techniques. Indium selenide has been shown to have excellent electronic properties in its two-dimensional (few-layer) form. Because of its air sensitivity, several processes have been developed to encapsulate the material for the integration in electronic devices. See also * Gallium(III) selenide * Indium chalcogenides *Nanoparticle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gallium(II) Selenide
Gallium(II) selenide (Gallium, GaSelenium, Se) is a chemical compound. It has a hexagonal layer structure, similar to that of gallium(II) sulfide, GaS. It is a photoconductor, a second harmonic generation crystal in nonlinear optics, and has been used as a far-infrared conversion material at 14–31 THz and above. Uses It is said to have potential for optical applications but the exploitation of this potential has been limited by the ability to readily grow single crystals Gallium selenide crystals show great promise as a nonlinear optical material and as a photoconductor. Non-linear optical materials are used in the frequency conversion (laser light), frequency conversion of laser light. Frequency conversion involves the shifting of the wavelength of a monochromatic source of light, usually laser light, to a higher or lower wavelength of light that cannot be produced from a conventional laser source. Several methods of frequency conversion using non-linear optical materials exist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyselenide
In chemistry, a polyselenide usually refers to anions of the formula (Sen)2-, where Se is the atomic symbol for the element selenium. Many main group and transition metals form complexes with polyselenide anions. Preparation Conceptually, polyselenides are derived by deprotonation polyselenanes H2Sen, but such species are rare or unstable. Instead, analogous to the preparation of many Zintl ions, polyselenides are produced by reduction of elemental Se with alkali metals. Such reactions can be conducted by heating a mixture of the solids or by dissolving Se metal in amine solutions of alkali metals. Synthesis can also be conducted in high-boiling, polar, aprotic solvents such as DMF, HMPA, and NMP. These reactions appear to proceed by initial formatiion of the alkali metal selenide, followed by the reaction of the latter with additional selenium: :2 Na + Se → Na2Se :Na2Se + ''n'' Se → Na2Se''n''+1 Once generated, alkali metal polyselenides can be converted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Umangite
Umangite is a copper selenide mineral, Cu3 Se2, discovered in 1891. It occurs only in small grains or fine granular aggregates with other copper minerals of the sulfide group. It has a hardness of 3. It is blue-black to red-violet in color with a black streak. It has a metallic luster. Umangite is named after the locality of Sierra de Umango, La Rioja province in Argentina. It also occurs at other localities including the Harz Mountains in Germany, and at Skrickerum, Sweden. See also *List of minerals This is a list of minerals for which there are articles on Wikipedia. Minerals are distinguished by various chemical and physical properties. Differences in chemical composition and crystal structure distinguish the various ''species''. Within a m ... References Copper(I,II) minerals Selenide minerals Tetragonal minerals Minerals in space group 113 {{mineral-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Selenium
Selenium is a chemical element with the symbol Se and atomic number 34. It is a nonmetal (more rarely considered a metalloid) with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. It seldom occurs in its elemental state or as pure ore compounds in the Earth's crust. Selenium – from Greek ( 'Moon') – was discovered in 1817 by , who noted the similarity of the new element to the previously discovered tellurium (named for the Earth). Selenium is found in metal sulfide ores, where it partially replaces the sulfur. Commercially, selenium is produced as a byproduct in the refining of these ores, most often during production. Minerals that are pure selenide or selenate compounds are known but rare. The chief commercial uses for selenium today are glassmaking and pigments. Selenium is a semiconductor and is used in photocells. Applications in electronics, once important, have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferroselite
Orthorhombic ferroselite and its isometric polymorph dzharkenite are iron selenides of general formula FeSe2 precipitated under reducing conditions in anoxic environments. They are a source of selenium in the Rocky Mountains where selenium occurrence is associated with Upper Cretaceous shale deposits. In the frame of safety assessment calculations made for deep disposal of high-level radioactive waste, ferroselite and dzharkenite are also considered in geochemical calculations as one of the mineral phases limiting the solubility of Selenium-79. Names Dzharkenite's type locale is in the Suluchekinskoye Se-U deposit in the Dzharkenskaya Depression of the Middle Ili River, Almaty Province, in southeastern Kazakhstan. It was discovered in 1995 and named after the depression. Ferroselite was first reported in 1955 for an occurrence in the Ust’-Uyuk uranium deposit in Tuva, Siberia. Its name comes from the Latin ''ferro'' (iron) and "sel" for selenium. See also * Coccolithoph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
