Diffusion of Sulfur on the Crystallization of Zinc Sulfide in Atmosphere of Hydrogen Sulfide

The mechanism of the diffusion of sulfur atom of hydrogen sulfide into zinc sulfide (amorphous and crystalline) in the temperature range from 500°to 1150°C has been investigated by a tracer technique using H235S. The results showed that for both amorphous and crystalline zinc sulfide samples, the diffusion rates (number of atoms/m2) of sulfur atom from hydrogen sulfide to zinc sulfide increased rapidly at about 1000°C. From these facts it was suggested that the diffusion rate at the solid-gas interface related to the phase-transition of solid (i.e. Hedvall effect) . To estimate the distribution state in the bulk of the sulfur atom diffusing from gas-phase (hydrogen sulfide) to solid-phase (fired zinc sulfide) on firing, the fired zinc sulfide sample was successively dissolved in hydrochloric acid and then the disappearance state of the sulfiur atom diffused was measured. As a result, it was found that in the case of amorphous sample, the diffused sulfur atom distributed uniformly throughout the bulk; while in the case of crystalline sample it was not uniform but localized mostly on the surface region of zinc sulfide particles.