EARLY STAGES OF CRYSTALLITE GROWTH OF ZNO OBTAINED FROM AN OXALATE PRECURSOR

A detailed analysis of the microstructure of zinc oxide produced by thermal decomposition of zinc oxalate at temperatures in the range 328 degrees to 650 degrees C is described. Parameters describing the breadth and shape of X-ray diffraction line profiles mere obtained by means of pattern decomposition, and a method based on the Voigt function was used to obtain information on the temperature dependence of the microstructure. It was found that the crystallites are prismatic, the dimensions increasing significantly with formation temperature, and that each contains one stacking fault, on average. The results of size determinations are in broad agreement with TEM and SEM measurements. The specific surface area of the crystallites, obtained by the BET method, is compared with the results of X-ray diffraction line-profile analysis, leading to a determination of the variation of ''packing factor'' with temperature. Results suggest a homogeneous crystallite growth in the initial sintering of the loosely packed zinc oxide powder.