Synthesis of Controlled Spherical Zinc Sulfide Particles by Precipitation from Homogeneous Solutions

Abstract

Zinc sulfide (ZnS) powders have been obtained by precipitation from homogeneous solutions of various zinc salt compounds, with S 2‐ as precipitating anion, formed by decomposition of thioacetamide. Spherical particles with a very narrow size distribution can be obtained by controlling the synthesis parameters. The particle sizes are influenced by the nature of the associated anion. For example, nanometer‐sized ZnS particles are formed using acetate or acetylacetonate anions under acidic pH conditions, controlled by the addition of acetic acid. Although the nucleation is accelerated by the use of acetic acid, limited particle growth occurs because of the formation of complexes with zinc cations that lowers the concentration of free cations in the solution. Also, the complexing‐attachment phenomena of the ZnS particles with acetate and acetylacetonate anions lead to the arrest of particle growth processes. The presence of complexed Zn 2+ species in the acidic solution is demonstrated both theoretically, using a model based on the calculations of the solubility isotherms of the soluble species, and by Fourier‐transform infrared techniques. The nanostructured ZnS particles may provide a suitable semiconductor nanocluster material for optoelectronic applications as well as a phosphor suitable for application in flat‐panel display technology.