Synthesis of zinc aluminate (ZnAl۲O۴) by mechanochemical processing with different molar ratios of ZnS:Al

Zinc aluminate spinel structure (ZnAl۲O۴) was synthesized from mixtures of zinc sulfide (with sphalerite structure) and aluminum. The starting materials with different molar ratios were milled for ۳ hours. The as-milled powders were heated isothermally at ۸۰۰ ⁰C under an air atmosphere for one hour. The heated samples finally were washed out with diluted sulfuric acid and the remained residuals were dried at ۱۱۰ ℃ for two hours. The results showed that aluminium content and the molar ratios of ZnS:Al in the starting materials have significant effect on the formation of ZnAl۲O۴.The as-milled results showed that although the reduction of ZnS by aluminum occurred during milling, the reaction was not completed with increasing the Al content in the starting materials. Except the molar ratio of ۱:۲, no signs of un-reacted Al were observed in other mixtures of ZnS-Al after milling for three hours. The XRD patterns and FT-IR spectra of the acid treated sample revealed that zinc aluminate could be synthesized from mixtures of ZnS-Al and the ZnS-Al mixture with molar ratio of ۴:۲ was the best among all mixtures.

Keywords:

Mechanochemical reaction , Sphalerite , Spinel , ZnAl۲O۴ , Zinc sulfide