Warren-Averbach technique

MudMaster MudMaster A program for calculating crystallite size distributions and strain from the shapes of X ray diffraction peaks. D. D. Eberl, V. Drits, J. Srodon, and R. Nuesch, U.S. Geological Survey Open File Report 96 171, (1996) 46 pp and XRD measurement of mean thickness, thickness distribution and strain for illite and illite/ smectite crystallites by the Bertaut Warren Averbach technique. 

Lanson B, (Champion D (1991) The I/S-to-illite reaction in the late stage diagenesis. Am J Sci 291 473-596 Lanson B, Kibler B (1994) Experimental determinations of the coherent scattering domain size distribution of natural mica-like phases with the Warren-Averbach technique. Clays Clay Minerals 42 489-494 Li G, Peacor DR, Merriman RJ, Roberts B (1994) The diagenetic to low grade metamorphic evolution of matrix white micas in the system muscovite-paragonite in a mudrock from Central Wales, U.K. Clays Clay Minerals 42 369-381... 

We will give here a short overview of the most common XRPD techniques used to study the microstructure of materials, starting from the most used and simple Scherrer method to the quite complex Warren-Averbach method, which is able to extract all the information available on sample microstructure and defects. 

B. E. Warren and B. L. Averbach. Pages 95-130 of Modern Research Techniques in Physical Metallurgy (Cleveland American Society for Metals, 1953). 

Instrumentation for studies of this nature are usually variations of the normal powder X-ray diffractometer. Except for faulting and strain in single crystals, which are better treated as defects, the very nature of the material limits studies to powders or aggregates. X-ray powder patterns of simple metals can be analyzed to yield information on particle size, deformation fault probability, mean-square strain, and twinning. The theory and techniques used to study diffraction line broadening, peak shifts, and line profile asymmetry have been derived and applied by Warren, " and Warren and Averbach. To assess faulting probability, certain drastic assumptions are necessary, reducing the detectability limit to approximately one faulted layer in 200. 

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