THERMODYNAMIC INVESTIGATIONS OF LIQUID-TE-SATURATED CDTE ZNTE SOLID-SOLUTIONS

The activity of ZnTe in liquid-Te-saturated CdTe-ZnTe solid solutions in the range 743-848 K was measured by an electrochemical technique using LiCl-KCl + 5 wt% ZnCl2 as the molten salt electrolyte. The activity of CdTe was calculated by Gibbs-Duhem integration using the alpha function. From the e.m.f. values of the cell measured at different temperatures, the partial, integral and excess molar thermodynamic quantities have been calculated. All the excess partial molar thermodynamic parameters at infinite dilution have been accurately estimated by Chiotti's method. The thermodynamic properties of the system have been analysed in terms of Darken's stability and excess stability parameters. The continuous variation of the activity and activity coefficients of both the components, and the smooth, gradual variation of the values of stability and excess stability with composition indicate that the CdTe-ZnTe system is completely miscible and consists of a single-phase field throughout the entire range of composition in the range 743-848 K.