VANADIUM (Vanadium), V (EN: vanadium; DE: Vanadin; FR: vanadium; ES: vanadio; RU: ванадий), is the chemical element of the group V of the Periodic System by Dmitri Mendeleev, the atomic number is 23, the atomic mass is 50.94. Within the nature, there are known two stable isotopes of vanadium, namely, 50V (0.25%), and 51V (99.75%). Vanadium has been discovered by the Mexican mineralogist A. M. del Rio during the 1801.
Vanadium is the metal of the silvery-gray colour, malleable in the pure form. Vanadium has the body-centered cubic lattice with the period a = 3.0282 Ångström. The density is 6110 kilograms per cubic metre; the temperature of the melting point is 1900 ± 25 degrees Celsius; the temperature of the boiling point is 3400 degrees Celsius; the specific heat capacity is 0.5 kilojoules per kilogram-kelvin (at the temperature of 0-100 degrees Celsius); the specific electrical resistivity (at the temperature of 20 degrees Celsius) is 24.8 • 10^-8 ohm-metres, the temperature coefficient of the electrical resistivity (at the temperature of 0-100 degrees Celsius) is 2.8 • 10^-3 per degree Celsius. Vanadium has the paramagnetic properties. Vanadium is the superconductor at the temperature below -268.7 degrees Celsius. The oxidation states of vanadium are +2, +3, +4, +5. The V2+ and V3+ compounds are unstable, and are the strong reducing agents. There are most characteristic the V5+ compounds. The vanadium pentoxide is easily soluble within alkalis, with the forming of vanadates (there are known the ortho-, pyro-, and metavanadates).
Vanadium distinguishes itself with the resistivity to the aqueous solutions of the mineral salts, dissolves itself within the hydrofluoric acid, and within the aqua regia, and during the heating, dissolves itself within the concentrated nitric and sulfuric acids. During the heating, the powder of vanadium vigorously combines with oxygen, sulfur, and chlorine. The compounds of vanadium are toxic. The average content within the Earth's crust is 0.02% in terms of mass.
Vanadium is the quite common element, but is scattered within the rocks and minerals. Among the erupted rocks, the greatest concentrations of vanadium have been noted within gabbroids, and among the sedimentary rocks, the greatest concentrations have been noted within the clayish formations. There are known approximately 80 minerals of vanadium, namely, of the natural vanadates. The majority of these minerals are of the exogenous origin. The major minerals are: vanadinite, carnotite, descloizite. In the form of the impurity, vanadium is contained within many minerals, mainly within oxides and silicates.
Vanadium has the geochemical affinity with Fe, and also with Mn, Cr, Al, Ti. There assist to the wide scattering of vanadium within the endogenous formations the proximity of the crystal-chemical properties of V3+ and Fe3+. Within the exogenous formations, vanadium is contained prevalently in the form of V5+. There plays the great role for the migration of vanadium within the mineralized waters and hydrothermal solutions the stability of its complex compounds. There is characteristic the ability of vanadium to precipitate itself onto the different geochemical barriers. About the major genetic types of the deposits, and about the methods for the extraction from the ores, see within the "Vanadium ores" article.
They obtain the metallic vanadium (95-99% of V), using the carbonate, calcium, and magnesium-thermal reduction of the technical V2O5 compound, or using the thermal dissociation of the vanadium iodide. For the obtainment of the high-purity vanadium, there is used the refining of vanadium: the electrolysis of the molten vanadium halides, the simple and zoned inductive, electric arc, and electron-beam melting within vacuum. There consumes approximately 90% of vanadium the ferrous metallurgy, where it is used as the alloying additive for the steel and cast iron. There are also created on the base of vanadium various alloys, which, along with the metallic vanadium, are used as the structural material within the nuclear reactors, and the alloys on the base of Ti with the additives of vanadium are used within the aviation and rocket machinery. Within the chemical industry, the compounds of vanadium are used as the catalysts for the contact production of the sulfuric acid; they are used within the paint, rubber, textile, ceramic, and other productions.
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