The Co-Sb-Ga System: Isoplethal Section and Thermodynamic Modeling
The Co-Sb-Ga ternary system is an important thermoelectric material system, and its phase equilibria are in need of further understanding. The CoSb3-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 Co3Sb2Ga4 phase. The Ga solution in the CoSb3 compound is described by a dual-site occupation (GaVF)xCo4Sb12−x/2(GaSb)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 CoSb3-GaSb isoplethal section, the liquidus projection, and an isothermal section at 923 K (650 °C). The dual-site occupation (GaVF)xCo4Sb12−x/2(GaSb)x/2 model gives good descriptions of both phase equilibria and thermoelectric properties of the CoSb3 phase with Ga doping.
- 11.S.L. Markovski, J.A. van Beek, R.C.J. Schiepers, A.A. Kodentsov, and F.J.J. van Loo: J. Chim. Phys., 1997, Vol. 94, pp. 992-997.Google Scholar
- 12.S.-W. Chen, Y.-C. Chien, J.-S. Chang, and G.J. Snyder: Unpublished research, 2014.Google Scholar
- 17.L.D. Dudkin, and N.K. Abrikosov: Zh. Neorgan. Khim., 1956, Vol. 1, pp. 2096-2105.Google Scholar
- 18.SGTE Unary Elements Database v.5, Scientific Group Thermodata Europe, 2009.Google Scholar
- 20.Pandat: A Computational Tool Developed on the Basis of the CALPHAD Approach for Multi-component Phase Diagram Calculation by CompuTherm, 2014.Google Scholar
- 21.Termocal: A computational Tool Developed on the Basis of the CALPHAD Approach for Multi-component Phase Diagram Calculation by Thermo-Calc Software, 2013.Google Scholar