Effect of H2S gas flow rate on the stoichiometric ratio of S:Zn and transparency of ZnS nanostructure ceramic in IR region

Abstract

In this research, zinc sulfide (ZnS) nanostructure powder was successfully synthesized via two-stage annealing (Ar + H2S). The annealing under argon medium was responsible for eliminating impurities such as SO4, SO3 and SO2. The annealing under hydrogen sulfide (H2S) medium also led to compensation of sulfur and establishment of Zn to S stoichiometric ratio following sintering. Investigation of different flow rates of H2S gas indicated that 30 mL/min would contribute to optimal Zn to S stoichiometric ratio. The Zn to S stoichiometric ratio before sintering under H2S medium was 1.28, which increased to 1.55 after annealing under H2S medium. The ceramic obtained from ZnS powder annealed under H2S medium at 30 mL/min had density of 99.98% and IR transmission of 62% within 8–12 μm range (wavenumbers of 1250–850 cm−1).