Phase Equilibria and Thermodynamic Basis for the Cd-Se and Pb-Se Binary Systems

Using the CALculation of PHAse Diagrams (CALPHAD) method, the phase equilibria and thermodynamic basis for the Cd-Se and Pb-Se binary systems are critically studied in this work. The associated solution model is adopted for the liquid phases so as to reflect the V-shaped enthalpies of mixing, the abrupt change in activity plots, and the sharp maxima for the liquidus around intermediate phases. Due to the negligible solubilities in CdSe and PbSe, these two binary compounds are treated as stoichiometric phases. Solid Se, which has a hexagonal structure, is considered to be free of solubility with respect to Cd and Pb. The thermodynamic description provided in this work allows the experimental data to be well represented, thus providing a fundamental basis for semiconductor research.