Phase equilibria and the thermodynamic properties of saturated solid solutions of BiTeI, Bi2TeI, and Bi4TeI1.25 compounds of the AgI–Bi–Bi2Te3–BiTeI system

Abstract

The phase equilibria of the Ag–Bi–Te–I system in the part AgI–Bi–Bi₂Te₃–BiTeI is studied in the interval of 500–540 K by means of physicochemical analysis. Thermodynamic properties of phases are determined via EMF. Potential-forming processes occur in electrochemical cells (ECCs) of the C|Ag|glass Ag₃GeS₃I|D|C structure (where C denotes inert (graphite) electrodes; Ag, D denotes ECC electrodes; D denotes four-phase alloys of the AgI–Bi–Bi₂Te₃–BiTeI system; and Ag₃GeS₃I glass is the selective Ag⁺ conducting membrane). Linear dependences of the EMFs of cells Е(Т) in the interval of 505–535 K are used to calculate the values of the thermodynamic functions of BiTeI, Bi₂TeI, and Bi₄TeI_1.25 phases saturated over silver.