Porous Spherical Particles of ZnS Nanocrystallites

Abstract ZnS particles consisting of nanocrystallites have potential applications as light emitters for displays. The possibility of encapsulating chemicals into porous particles and the temperature-controlled release of them could also be of interest in chemical engineering. The objective of this study is to determine the size distribution, shape and morphology of ZnS particles synthesized under different conditions, since they strongly influence the optical and electric properties. The ZnS powders were prepared by precipitation from homogeneous aqueous solutions, following a procedure described elsewhere1-3 The initial solution consists of a zincsalt precursor dissolved in ultrapure water under acidic pH conditions. Adding Thioacetamide (TAA: CH3C(S)NH2) to this acidic solution at elevated temperature leads to the precipitation of ZnS nanocrystals. Four different types of zincsalt precursors were used to study their influence on the precipitation process and the final powder morphology: acetate (CH3COO), chloride (Cl-), trifluoromethanesulfonate (tFMS: CF3SO3 -) and dimethyldithiocarbamate (dMdTC: S4N2C6H12 -). The dried powder were subjected to 350°C and 700°C heat treatments, respectively.