Crystal Structures of the High Pressure Phases ZnAs and CdAs

Abstract

The structure of the high pressure compounds ZnAs and CdAs have been determined using Guinier film and counter methods. The compounds are orthorhombic, (space group Pbca; Z = 8), with α = 5.679(2) Å, b = 7.277(4) Å, c = 7.559(4) Å and α = 5.993(4) Å, b = 7.819(6) Å, c = 8.011(6) Å respectively. ZnAs and CdAs are isostructural with the normal pressure phases ZnSb and CdSb, which are related to the high pressure phase Si III. Structural relationships are discussed including the Si III-diamond structure relationship.