THE PHASE-DIAGRAM OF THE QUASI-TERNARY SYSTEM (SN,PB) (S,TE)

The phase diagram of the quasiternary system (SnkPb1-k)(SlTe1-l) for 9 00K is determined by X-ray diffraction and by electron microprobe anal ysis. Moreover, the free enthalpy faces g(k,l) for the phases with cub ic rocksalt structure (cub) or with the orthorhombic SnS structure (or h) are calculated from the interaction parameters and from the orh --> cub transition data of the 4 quasibinary subsystems. The interaction parameters are also used to calculate the termodynamic factor for inte rdiffusion along quasibinary sections through the phase square and to calculate the energies of four-particle clusters. By application of th e cluster model one obtains information on the local environment of th e mixing particles and on the cluster processes that have effect upon interdiffusion.