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.