Influence of synthesis procedure on the formation and properties of zinc oxide

Formation and properties of zinc oxide were investigated in dependence on the synthesis procedure. Zinc oxide did not crystallize upon hydrothermal treatment of Zn(NO3)(2) aqueous solutions containing urea, up to 160 C. Hydrozincite was formed instead. Changes in the X-ray diffraction patterns and Fourier transform infrared (FT-IR) spectra were interpreted in terms of stacking disorder in hydrozincite crystals. Zinc oxide powder was obtained by thermal treatment in air of precipitated hydrozincite. The conditions for instantaneous synthesis of very fine zinc oxide particles were found. This procedure is based on addition of TMAH (tetramethylammonium hydroxide) solution to an ethanolic solution of zinc acetate dihydrate, up to pHsimilar to14. On the other hand, addition of an equivalent volume of water to the ethanolic solution of zinc acetate dihydrate, prior to the addition of TMAH solution up to pHsimilar to14, yielded ZnO flakes without any specific shape. All zinc oxide particles produced upon heating at 600 C in air showed similar morphology and tendency to aggregation due to the sintering effect. The features of the FT-IR spectra of zinc oxide particles were related to their shapes. (C) 2002 Elsevier Science B.V. All rights reserved.