Phase Equilibria Study in Ga-Sn-Te System Using Thermodynamic Modeling and Experimental Validation

Phase equilibria in Ga-Sn-Te system plays a key role in designing multiphase thermoelectric materials. SnTe is a promising alternative to the well-known PbTe (toxic) thermoelectric phase in the Ga-Sn-Te system. In the present study, various compositions have been selected using the thermodynamically developed database of the Ga-Sn-Te system to understand the phase equilibria and microstructural features. The alloys with multiphase combinations of SnTe, Ga₆SnTe₁₀, GaTe, and Te were produced using vacuum induction melting. In addition, the developed microstructures were characterized using x-ray diffraction, optical and Scanning Electron Microscopy techniques. The microstructures reveal interesting eutectic morphologies of Ga₆SnTe₁₀/Te, Ga₆SnTe₁₀/SnTe, and GaTe/SnTe. The microstructural features were explained using Scheil-Gulliver cooling calculations. Moreover, the thermal analysis of the investigated alloys was also performed to validate the thermodynamically predicted liquidus temperatures and various phase transitions in the investigated alloys.