Effects of aging conditions on the morphologies of ZnO particles synthesized under hydrothermal conditions from layered zinc hydroxide as a precursor derivered from zinc acetate

Zinc oxide is a useful material for various products. ZnO crystals usually grow in the c-axis direction, on the less exposed (001) plane. However, the (001) plane has high chemical reactivity, and plate-like ZnO crystals on large (001) planes have superior UV-lasing and other properties. In this study, layered zinc hydroxide acetate (ZHA), a precursor of ZnO, was aged in deionized water and Zn(OCOCH3)(2) or CH3COONa aqueous solutions of various concentrations under hydrothermal conditions at 90 and 120 degrees C. Aging at above 90 degrees C yielded ZnO in all the solutions, and the concentrations of the CH3COONa aqueous solutions did not affect the form of the ZnO particles. On the other hand, when ZHA was aged in Zn(OCOCH3)(2) aqueous solution, the crystal growth of ZnO in the c-axis direction was suppressed as the Zn(OCOCH3)(2) concentration increased. In the case of aging in 1 molL(-1) Zn(OCOCH3)(2) aqueous solution, plate-like ZnO was obtained, but the yield was about 10% and a large amount of ZHA remained. When the obtained mixture of plate-like ZnO and ZHA was aged again in deionized water at 90 and 120 degrees C after washing, most of the ZHA was transformed into plate-like ZnO after aging for over 72 hours.