Sc2S3–Cu2S phase diagram

Abstract

A phase diagram is constructed for the Sc2S3–Cu2S system. The system forms two incongruently melting complex sulfides: hexagonal CuScS2 (1Cu2S: 1Sc2S3): a = 0.3734 nm, c = 0.6102 nm, space group P3m1, Т m = 1635 K, ΔH m = 1670 kJ/mol; and cubic CuSc3S5 (1Cu2S: 3Sc2S3), a = 1.0481 nm, space group Fd3m, Т m = 1835 K. In the 45–62 mol % Cu2S solid solution (ss) range, there is a singular point corresponding to the composition of compound CuScS2 (50 mol % Cu2S). The Sc2S3-based solubility at 1070 K is 14 mol % Cu2S. In the γ-Cu2S-based solid solution range, there is a peritectic point at 7 mol % Sc2S3, 1423 K.