Determination of Physically Based Pseudo-Voigt Powder Diffraction Profile Terms from the Fundamental Parameters Approach

Published

April 4, 2022

Author(s)

Jonathan Denney, Gerard Mattei, Marcus Mendenhall, James Cline, Peter Khalifah, Brian Toby

Abstract

Abstract Abstract A methodology is developed where a fundamental parameters approach (FPA) description of a laboratory powder diffraction instrument (configured in divergent beam Bragg-Brentano geometry) is used to determine GSAS-II profile parameters for peak asymmetry and instrumental peak widths. This allows the instrumental contribution to peak shapes to be robustly determined directly from a physical description of the instrument, even though GSAS-II does not directly implement FPA for peak shape computation. The FPA-derived parameters can be used as the starting point for instrument characterization, or to characterize sample broadening without the use of a standard to determine the instrument profile function. This new method can facilitate generation of training sets for machine learning. A plot is generated that shows the differences between the two approaches, demonstrating upper bounds for the accuracy of the GSAS-II profile model for a particular instrumental configuration.

Citation

Journal of Applied Crystallography

Pub Type

Journals

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https://doi.org/10.1107/S1600576722001169

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Keywords

powder diffraction, fundamental parameters, Rietveld analysis

Citation

Denney, J. , Mattei, G. , Mendenhall, M. , Cline, J. , Khalifah, P. and Toby, B. (2022), Determination of Physically Based Pseudo-Voigt Powder Diffraction Profile Terms from the Fundamental Parameters Approach, Journal of Applied Crystallography, [online], https://doi.org/10.1107/S1600576722001169, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932871 (Accessed October 9, 2025)