Solid-state equilibria and thermodynamic properties of compounds in the Bi-Te-I system

Abstract

The Bi-Te-I system has been studied by differential thermal analysis, x-ray diffraction, and emf measurements in the temperature range 300–400 K using concentration cells of the type (−)Bi(s) | glycerol + KI + BiI3 | Bi-Te-I(s)(+). The results have been used to construct the 300-K section of the Bi-Te-I phase diagram. The existence of the ternary compounds BiTeI, Bi2TeI, and Bi4TeI1.25 has been confirmed, and the position of the phase fields involving these compounds has been accurately determined. Using emf data, we have evaluated the partial thermodynamic functions (Δ $$ \bar G $$ , Δ $$ \bar H $$ , and Δ $$ \bar S $$ ) of the bismuth in the alloys studied, the standard thermodynamic functions of formation of the ternary compounds, and their standard entropies.