Modified Scherrer Equation for Small Crystallites

INTRODUCTION

Based on the 2D X-ray diffraction theory, for the profile analysis, the new intensity model (rather than the existing convolution and deconvolution model), is developed. In the present model, it is considered that the observed intensities are additive from those X-ray intensities scattering from small-size and distorted crystallites, as well as the other non- Bragg scattering from the instrument, cosmic radisation, etc. As a result, the observed profile is additive from the individual profiles of the size-strain profiles and the unwanted profile. On the basis of Scherrer equation, the termed Weighted-mean dimension (W-md) is first defined to evaluate the broadening due to small-size crystallites, combining with the Weighted-mean breadth (W-mb) to deal with broadening due to small-size crystallites. The effect of the instrumental broadening is effectively eliminated by using relative- intensities method in data processing.....