Thermodynamic behaviour of the SnTe, PbTe, SnSe and PbSe melts according to the associated model

Calculations derived from a previously reported model involve the standard enthalpy ( Delta H deg ) and entropy ( Delta S deg ) of formation of the known compounds ("associates") and three interaction parameters (W sub ij ) between the different elements. Each of these four systems has a high temperature, congruently melting, equiatomic compound; the agreement between experimental and calculated values of thermodynamic quantities is good. In the Sn--Se system there is possibly another compound, for which the fit between experimental and calculated values is poor. The Se-based alloys are more associated than the Te-based alloys; the main difference is due to the strongly positive (Se) or negative (Te) values of the standard entropy of formation of the compounds. Plotted curves of thermodynamic functions and thermodynamic data are provided. Graphs. 17 ref.--J.J.P.