Preparation, Purification and Densification of Zinc Sulfide Powder from Organometallics

摘要

Zinc sulfide powders were prepared from diethylzinc and hydrogen sulfide in toluene solution at-20 C. The powder consisted of agglomerates of 0.1-micrometer-sized particles. The residual zinc ethyl group content was determined by acid hydrolysis followed by gas chromatography and varied from 10-4 to 3 mol% depending on reaction conditions. Reactivity varies with alkyl group as di-t-butylzinc > diethylzinc > dimethylzinc. Toluene and isopropylthiol were identified as organic impurities with isopropylthiol originating in the H2S reagent. Adventitious tetrahydrofuran impurity was converted to tetrahydrothiophene upon heating at 137 to 159 C. Organic impurities were oxidized by treatment of the powder with O2 at 400 C or 1 mol% O3 in O2 at 25 C. Particle growth was evident in the O2-treated sample but not in the O3-treated sample. The oxidized samples contained about 2 mol% ZnSO4 and EPR spectra provided evidence for SO2- radicals. The ZnSO4 impurity was converted to ZnO by heating at 800 C. Hot isostatic pressing of the treated powders at 775 C produced fragmented opaque compacts with grain sizes varying from 0.1 to 0.5 micrometers. The densified samples exhibited about twice the hardness of commercial RAYTRAN ZnS but only half the fracture toughness. (aw)