Preparation and Mechanism of Formation of Spherical Submicron ZnS Powders

摘要

Zinc sulfide is an attractive infrared window material as it possesses good IR transmittance in the 8-12 micrometer range as well as high melting temperature. When a polycrystalline material is used for applications such as this, a uniform final microstructure is needed. Spherical, submicron particles of zinc sulfide were homogeneously precipitated by thermal decomposition of thioacetamide in acidic aqueous solutions. Rate of sulfide ion generation, determined by various combinations of temperature, pH, and initial concentrations of zinc ions and of thioacetamide, as related to particle growth rate had the paramount effect on the particle size distribution. Monosized, bimodal or narrow size distribution powders were obtained under certain combinations of experimental variables. Particles were found to be porous agglomerates of approx. 10 nm sphalerite crystallites. Particle growth was determined to proceed through diffusion-controlled aggregation of crystallites.