Phase Diagram of the Pb-Se-Sn System

Abstract

The Pb-Se-Sn ternary system is of interest to thermoelectric applications. Nevertheless, no phase diagram exists for the entire compositional regime at any temperature. Ternary Pb-Se-Sn alloys are equilibrated at 350°C and 500°C, and their equilibrium phases are determined. The isothermal sections of the equilibrium Pb-Se-Sn phase diagram at 350°C and 500°C are proposed based on the phase diagrams of the three constituent binary systems and ternary phase equilibria results in the literature and those determined in this study. No ternary compound is found. The phase relationships are similar at 350°C and 500°C. At both temperatures, binary compounds, α-PbSe and γ-SeSn, have very significant ternary solubility, but the ternary solubility of Pb in the Se2Sn phase is negligible. There are still unresolved questions about the type and shape of the liquid phase at the Se corner.