Phase equilibrium and thermodynamic properties of silver-saturated compounds BiSI and Bi19S27I3 of the AgI–Bi–Bi2S3–BiSI system

Abstract

The phase composition of alloys in the Ag–Bi–S–I system (in the region AgI–Bi–Bi2S3–BiSI) for Т ≤ 550 K was studied by physicochemical analysis methods. Equations of overall potential-forming reactions involving the BiSI and Bi₁₉S₂₇I₃ phases were composed. The reactions were performed in the C|Ag|glass Ag₃GeS₃I|D|C electrochemical cells (C are inert (graphite) electrodes; Ag, D are the cell electrodes; D are the four-phase alloys of the system; and glass Ag₃GeS₃I is a membrane with pure Ag⁺ ion conductivity). The linear dependences of EMF of the cells in the range 485–525 K were used for calculating the standard thermodynamic properties of saturated solid solutions of the compounds BiSI and Bi₁₉S₂₇I₃ in the AgI–Bi–Bi₂S₃–BiSI system.