The phase diagrams of the quasibinary systems (Pb,Ge)Te and (Ge,Sn)Te

Abstract

The phase diagrams of the two quasibinary systems (Pb 1− k Ge k )Te and (Ge 1− k Sn k )Te were calculated from Gibbs energy functions. The concentration and temperature dependent interaction parameters used in these functions were determined by adjusting the calculated equilibrium curves to data taken from the literature. From the interaction parameters also the thermodynamic factor for interdiffusion could be calculated. Using this thermodynamic factor and the experimentally determined composition dependence of the interdiffusion coefficient of Ge and Pb in (Pb 1− k Ge k )Te the dependence of the tracer diffusion coefficients on composition will be discussed. Moreover, by use of a cluster model, the variation of the local arrangement of clusters as a function of the mole fraction k was determined and will be used to explain differences in the thermodynamic behaviour of the two systems.