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Hafnium(IV) Bromide
Hafnium tetrabromide is the inorganic compound with the formula HfBr4. It is the most common bromide of hafnium. It is a colorless, diamagnetic moisture sensitive solid that sublimes in vacuum. It adopts a structure very similar to that of zirconium tetrabromide, featuring tetrahedral Hf centers, in contrast to the polymeric nature of hafnium tetrachloride Hafnium(IV) chloride is the inorganic compound with the chemical formula, formula HfCl4. This colourless solid is the Precursor (chemistry), precursor to most hafnium organometallic compounds. It has a variety of highly specialized applications, m ....Berdonosov, S. S.; Berdonosova, D. G.; Lapitskii, A. V.; Vlasov, L. G. "X-ray study of hafnium tetrabromide" Zhurnal Neorganicheskoi Khimii, 1963, vol. 8, 531-2. References {{Bromides Bromides Hafnium compounds Metal halides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inorganic Compound
In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemistry''. Inorganic compounds comprise most of the Earth's crust, although the compositions of the deep mantle remain active areas of investigation. Some simple carbon compounds are often considered inorganic. Examples include the allotropes of carbon (graphite, diamond, buckminsterfullerene, etc.), carbon monoxide, carbon dioxide, carbides, and the following salts of inorganic anions: carbonates, cyanides, cyanates, and thiocyanates. Many of these are normal parts of mostly organic systems, including organisms; describing a chemical as inorganic does not necessarily mean that it does not occur within living things. History Friedrich Wöhler's conversion of ammonium cyanate into urea in 1828 is often cited as the starting point of modern ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hafnium
Hafnium is a chemical element with the symbol Hf and atomic number 72. A lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Its existence was predicted by Dmitri Mendeleev in 1869, though it was not identified until 1923, by Dirk Coster and George de Hevesy, making it the penultimate stable element to be discovered (the last being rhenium in 1925). Hafnium is named after , the Latin name for Copenhagen, where it was discovered. Hafnium is used in filaments and electrodes. Some semiconductor fabrication processes use its oxide for integrated circuits at 45 nanometers and smaller feature lengths. Some superalloys used for special applications contain hafnium in combination with niobium, titanium, or tungsten. Hafnium's large neutron capture cross section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zirconium Tetrabromide
Zirconium(IV) bromide is the inorganic compound with the formula ZrBr4. This colourless solid is the principal precursor to other Zr–Br compounds. Preparation and properties ZrBr4 is prepared by the action of bromine on zirconium oxide via a carbothermic reaction: : ZrO2 + 2C + 2Br2 → ZrBr4 + 2CO Like many related tetrahalides, it is purified by sublimation. It can also be prepared by treatment of the borohydride complex with hydrogen bromide: : Zr(BH4)4 + 4HBr → ZrBr4 + 4H2 + 2B2H6 Like related tetrabromides of Ti and Hf, ZrBr4 hydrolyzes readily to give oxy-bromide, with release of hydrogen bromide Hydrogen bromide is the inorganic compound with the formula . It is a hydrogen halide consisting of hydrogen and bromine. A colorless gas, it dissolves in water, forming hydrobromic acid, which is saturated at 68.85% HBr by weight at room temper .... Structure No single crystal X-ray study of ZrBr4 has been described. Some reports suggest that it is is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hafnium Tetrachloride
Hafnium(IV) chloride is the inorganic compound with the chemical formula, formula HfCl4. This colourless solid is the Precursor (chemistry), precursor to most hafnium organometallic compounds. It has a variety of highly specialized applications, mainly in materials science and as a catalyst. Preparation HfCl4 can be produced by several related procedures: *The reaction of carbon tetrachloride and hafnium oxide at above 450 °C; :HfO2 + 2 CCl4 → HfCl4 + 2 COCl2 *Chlorination of a mixture of HfO2 and charcoal, carbon above 600 °C using chlorine gas or sulfur monochloride: :HfO2 + 2 Cl2 + C → HfCl4 + CO2 *halogenation, Chlorination of hafnium carbide above 250 °C. Separation of Zr and Hf Hafnium and zirconium occur together in minerals such as zircon, cyrtolite and baddeleyite. Zircon contains 0.05% to 2.0% hafnium dioxide HfO2, cyrtolite with 5.5% to 17% HfO2 and baddeleyite contains 1.0 to 1.8 percent HfO2.Newnham, Ivan Edgar "Purification of H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bromides
A bromide ion is the negatively charged form (Br−) of the element bromine, a member of the halogens group on the periodic table. Most bromides are colorless. Bromides have many practical roles, being found in anticonvulsants, flame-retardant materials, and cell stains. Although uncommon, chronic toxicity from bromide can result in bromism, a syndrome with multiple neurological symptoms. Bromide toxicity can also cause a type of skin eruption, see potassium bromide. The bromide ion has an ionic radius of 196 pm. Natural occurrence Bromide is present in typical seawater (35 PSU) with a concentration of around 65 mg/L, which is about 0.2% of all dissolved salts. Seafood and deep sea plants generally have higher levels than land-derived foods. Bromargyrite—natural, crystalline silver bromide—is the most common bromide mineral known but is still very rare. In addition to silver, bromine is also in minerals combined with mercury and copper. Formation and react ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hafnium Compounds
Hafnium compounds are compounds containing the element hafnium (Hf). Due to the lanthanide contraction, the ionic radius of hafnium(IV) (0.78 ångström) is almost the same as that of zirconium(IV) (0.79 angstroms). Consequently, compounds of hafnium(IV) and zirconium(IV) have very similar chemical and physical properties. Hafnium and zirconium tend to occur together in nature and the similarity of their ionic radii makes their chemical separation rather difficult. Hafnium tends to form inorganic compounds in the oxidation state of +4. Halogens react with it to form hafnium tetrahalides. At higher temperatures, hafnium reacts with oxygen, nitrogen, carbon, boron, sulfur, and silicon. Some compounds of hafnium in lower oxidation states are known. Halides Hafnium(IV) fluoride (HfF4) is a white crystalline powder. It has a monoclinic crystal structure, with space group C2/c (No.15), and lattice constants ''a'' = 1.17 nm, ''b'' = 0.986 nm and ''c'' = 0.764 nm. Hafnium(IV) c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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