Open Access

ABSTRACT

Crystallite Size Distribution Determination By X-Ray Diffraction

D. Balzar¹

1 Department of Physics and Astronomy, University of Denver, Denver, CO 80208, USA

The International Conference on Computational & Experimental Engineering and Sciences 2009, 10(1), 7-8. https://doi.org/10.3970/icces.2009.010.007

Abstract

X-ray diffraction is a useful technique for the estimation of size distributions of smaller crystallites. With the constant improvement of experimental techniques, especially with the advent of new-generation synchrotron and neutron sources with superior resolution, these size distributions can be precisely determined. Furthermore, modern methods for the analysis of X-ray diffraction patterns, such as Rietveld refinement, increasingly go beyond the determination of structural parameters and include refinable parameters for a physical crystallite size distribution.

Several common size distributions (such as lognormal and gamma) will be considered. Particularly, a lognormal distribution of both ellipsoidal and cylindrical crystals with elliptical cross-sections can be used to successfully model anisotropic size broadening. In an example (ZnO powder), the apparent crystallite most closely resembling the shape obtained by the spherical-harmonics model was obtained by usinga bimodal lognormal distribution of ellipsoidal crystallites with two different shapes, corresponding to two size-distribution modes. This shape of the apparent crystallite is in agreement with those reported earlier from X-ray diffraction line broadening analysis and TEM for this sample.

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