Abstract
The Co-Sb-Ga ternary system is an important thermoelectric material system, and its phase equilibria are in need of further understanding. The CoSb 3 -GaSb isoplethal section is experimentally determined in this study. Phase equilibria of the ternary Co-Sb-Ga system are assessed, and the system’s thermodynamic models are developed. In addition to the terminal phases and liquid phase, there are six binary intermediate phases and a ternary Co 3 Sb 2 Ga 4 phase. The Ga solution in the CoSb 3 compound is described by a dual-site occupation (Ga VF ) x Co 4 Sb 12−x/2 (Ga Sb ) x/2 model. Phase diagrams are calculated using the developed thermodynamic models, and a reaction scheme is proposed based on the calculation results. The calculated results are in good agreement with the experimentally determined phase diagrams, including the CoSb 3 -GaSb isoplethal section, the liquidus projection, and an isothermal section at 923 K (650 °C). The dual-site occupation (Ga VF ) x Co 4 Sb 12−x/2 (Ga Sb ) x/2 model gives good descriptions of both phase equilibria and thermoelectric properties of the CoSb 3 phase with Ga doping.