FW1/5/4/5M method for determination of the grain size distibution form powder diffraction line profile

Well-established Scherrer method allows for determination of the average grain size (R) of a crystalline powder by measurement of full width at half maximum (FWHM) of the diffraction peak profile. We propose an enhancement of this classical method. Measurement of two widths of the same peak, allows for two parameters to be distinguished: the average grain size (R) and dispersion of sizes or. These parameters are sufficient to draw grain size distribution (GSD) curve, that is much more informative than a single size parameter (R). We propose to measure widths at 1/5 and 4/5 of the peak maximum (FW1/5 M and FW4/5 M, respectively). A simple algebraic formula that 5 5 converts measured FW1/5 M and FW4/5M values into (R) and sigma is presented. The FW1/5 / 4/5 M method proposed in this paper is especially sensitive in case of a broad diffraction maxima, i.e. for nano-sized polycrystals. (C) 2004 Elsevier B.V. All rights reserved.