Determination of crystallite size distribution histogram in nanocrystalline anatase powders by XRD

摘要

The whole powder pattern modelling (WPPM) method developed by Scardi & Leoni (2002) is used for determination of a crystallite size distribution in TiO_2 nanocrystal line powders. The distribution is represented by a histogram. The histogram frequencies are refined from X-ray diffraction (XRD) data. The method is slightly modified by introduction of the distribution regularisation. It is applied on (ⅰ) two reference TiO_2 samples synthesized by a sol-gel process at different temperatures (ⅱ) and on a series of well defined mixtures of these reference samples. The refined size distributions of both reference samples can be well approximated by a log-normal distribution. The volume fractions of the reference samples in the mixtures are derived from the determined crystallite size histograms. The difficulties with an uncertainty of the distribution shape in the case of small volume fractions of small crystal lites at the presence of majority of large crystallites are discussed.