Free energy of mixing and vapour pressure of liquid Ga-As, In-As, Ga-P and In-P alloys

The change of the Gibbs energy of the reaction between group IIIA and VA elements to form a liquid III-V alloy was derived for the Ga-As, In-As, Ga-P and In-P systems by combining the heat content of the alloy with the heat and entropy of formation of the equiatomic compound at a reference temperature. The obtained data were analysed by using a Redlich-Kister polynomial equation and the optimized parameters were derived for a temperature range between 873 and 1523 K and a composition range between x_v = 0 and 0.5 (for the Ga-P system between x_p = 0 and 0.1). The partial pressures of these liquid alloys were expressed as a function of alloy composition and temperature. Partial pressure and total pressure-composition-temperature diagrams were constructed.