Zinc Arsenide, Zn₃As₂

Zinc Arsenide, Zn₃As₂, is prepared by melting zinc in arsenic vapour and hydrogen, or by subjecting zinc and arsenic, in appropriate proportions, to a pressure of 6500 atmospheres. It crystallises in octa-hedra or small needles, and evolves arsine with dilute sulphuric acid. The diarsenide and monarsenide, ZnAs₂ and ZnAs, have been prepared by heating zinc and arsenic together in proper proportions. They are greyish, and dissolve in acids with the evolution of arsine. ZnAs is frequently used for preparing arsine.

Heike, from a thermal study of the system Zn-As, concluded that only ZnAs₂ and Zn₃As₂ exist. Both are brittle, and melt at 771° C. and 1015° C. respectively.