LUMINESCENT-GRADE ZINC-SULFIDE PREPARED BY THIOSULFATE METHOD .4. THEEFFECT OF THE THERMAL-TREATMENT ON SOME PROPERTIES OF ZNS-TYPES

By thiosulphate method, two series of ZnS-samples were prepared at pre -calcination temperatures between 600 degrees C and 1100 degrees C in an intermediate and weakly sulphurated local firing atmosphere. They w ere characterized by degree of whiteness, crystalline structure, parti cle size distribution and especially by their luminescence ability. Th e last was estimated on the basis of the emission spectra of ZnS:Cl an d ZnS:Ag,Cl phosphor samples prepared from the two ZnS-sample series. It was revealed that the properties of the ZnS-samples strongly depend on both the pre-calcination temperature and the composition of the lo cal firing atmosphere.