Kinetic analyses of the formation of solid solution in the ZnS-CdS system.

The formation of solid solution in the ZnS-CdS system, one of the simplest reaction which involves two or more phases, has been studied by X-ray diffraction and by the observation of ZnS or CdS phosphor in some stages of the solid solution formation.Values of activation energy obtained from the height decrease of diffraction lines ZnS (102) are 35 kcal/mol for ZnS : CdS=1 : 1, and 41 kcal/mot for 7 : 3. The formation process was observed by using the phosphor as one of the starting materials. It was assumed that cadmium sulfide sublimates on the first stage of solid solution formation especially when cadmium sulfide is a form of fine powder. The presence of cadmium sulfide on the outer surface of zinc sulfide was observed by EPMA, these results supporting the above assumption. Thereafter the mutual diffusion proceeded to form solid solution. The result of emission measurement coincided with those by EPMA.