Composition- and temperature-dependent thermodynamic properties of the Cd, Ge‖Se, Te system, containing CdSe1–хTeх solid solutions

Abstract

The 298-K isothermal section through the phase diagram of the Cd, Ge‖Se, Te system is mapped out and the direction of the stable diagonal CdSe–CdTe is determined using thermodynamic analysis and data for the constituent binary systems CdSe–GeSe₂, CdSe–CdTe, and CdTe–GeTe, in combination with X-ray diffraction and emf measurements. Data are presented on the thermodynamic properties of CdSe_1–хTe_х solid solutions as functions of composition and temperature. The Gibbs free energy of formation of the CdSe_1–хTe_х solid solutions is evaluated as a function of composition in the temperature range 300–1400 K using thermodynamic calculations. The composition dependence of the energy of mixing for CdSe_1–хTe_х is shown to have a negative deviation from ideality in the range x ≈ 0.2–0.6 at temperatures from 1000 to 1400 K. The contributions of each component of the CdSe_1–хTe_х solid solutions to their partial excess thermodynamic functions of mixing are estimated and the interaction parameter of their components in the solid and liquid states has been evaluated. The band gap of alloys in the CdSe–CdTe system is calculated as a function of composition and temperature.