Phase Equilibria in BaS–In2S3 System

Abstract

A confined region of solid solution exists in BaS−In2S3 system of eutectic type with incongruent melting compounds of BaIn2S4 and Ba2In2S5 composition based on the α modification of In2S3. Compounds BaIn2S4 and Ba2In2S5 melt incongruently at 1330 and 1497 K, crystallize in rhombic syngony with unit cell parameters а = 2.181 nm, b = 2.165 nm, с = 1.311 nm (space group Fddd) and а = 1.317 nm, b = 1.272 nm, с = 1.178 nm (space group Pbca), respectively. Microhardness H = 2470 MPa for BaIn2S4 and 2250 MPa for Ba2In2S5. Coordinates of BaIn2S4–In2S3 eutectics is 76 mol % In2S3, Tm = 1190 K. Solubility of BaS in α-In2S3 at 1070 K reaches 2 mol % BaS. Solubility of BaS in α-In2S3 decreases with temperature and becomes 1 mol % BaS at 870 K.