Liquidus projection and phase equilibria isothermal section of Se–Sn–Te system

Abstract

Ternary Se–Sn–Te alloys have important applications in thermoelectricity, optical recording and infrared devices. Air-cooled and 250°C-equilibrated ternary Se–Sn–Te alloys were prepared in this study. The primary solidification phases were determined for the air-cooled alloys and these were used to construct the liquidus projection. The liquidus projection contains seven primary phase regions and three ternary invariant reactions. The temperatures of the invariant reaction were determined by thermal analysis as occurring at 230°C, 400°C and 420°C, respectively. Using the equilibrium phases of the thermally equilibrated ternary alloys determined in this study and the phase diagram information of the three binary constituent systems, the 250°C isothermal section of the Se–Sn–Te ternary system was constructed. The equilibrated solubility of Se in SnTe is about 4at%Se and is less than that of Te in SnSe, which is about 10at%Te. No ternary compound was found in either the liquidus projection or the isothermal section.