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

The phase diagrams of the two quasibinary systems (Pb1-kGek)Te and (Ge1-kSn k)Te were calculated from Gibbs energy functions. The concentration and tem perature dependent interaction parameters used in these functions were dete rmined by adjusting the calculated equilibrium curves to data taken from th e literature. From the interaction parameters also the thermodynamic factor for interdiffusion could be calculated. Using this thermodynamic factor an d the experimentally determined composition dependence of the interdiffusio n coefficient of Ge and Pb in (Pb1-kGek)Te the dependence of the tracer dif fusion coefficients on composition will be discussed. Moreover, by use of a cluster model, the variation of the local arrangement of clusters as a fun ction of the mole fraction k was determined and will be used to explain dif ferences in the thermodynamic behaviour of the two systems. (C) 2000 Elsevi er Science B.V. All rights reserved.