SOLID-STATE PHASE-DIAGRAM OF THE ZINC-SULFIDE - CADMIUM-SULFIDE SYSTEM

Structures and phase relations in the ZnS-CdS system were investigated in the temperature range 150-700-degrees-C and the boundaries describing the equilibria between the zinc-blende and wurtzite CdxZn1-xS solid solutions were determined by examining the ion exchange processes Cd2+ --> Zn2+ In the ZnS powder. The complete thermodynamical description of the ZnS-CdS system is proposed. It was found, that CdxZn1-xS solid solutions of both modifications obey a regular solution model. Enthalpies of the zinc-blende-to-wurtzite structural phase transition in CdS (550+/-50 J/mol) and in ZnS ( 1700+/-100 J/mol ) were defined. The solid-state phase diagram calculated from defined thermodynamical parameters agrees well with the experimental data.