Arsenides

compounds of arsenic with metals. They are solids and melt, as a rule, at high temperatures. They can be divided into two groups according to their composition and properties: derivatives of arseniuretted hydrogen (arsine), AsH₃, which are decomposed by water and acids (arsenides of alkaline, alkaline earth, and several other metals—for example, K₃As, Na₃As, Ca₃ As₂, and Zn₃As₂); and intermetallic compounds, which are acid-resistant (for example, FeAs₂, MnAs, Fe₃ As₂, and Ni₅ As₂). Arsenides are obtained by the reaction of elements, precipitation from solutions of metallic salts by arseniuretted hydrogen, and the reduction of arsenates. Several arsenides have semiconducting properties. The arsenides of the metals of Group III of the Mendeleev periodic system have acquired special significance; they crystallize in the structure of sphalerite (zincblende). Laser crystals (GaAs, InAs, Gajn, _ _xAs), rectifiers, and tonal diodes and triodes (GaAs) are made from these arsenides.

Upon hydrometallurgical processing of several ores containing arsenides, the highly poisonous arseniuretted hydrogen (arsine) is released.