Effects of Voigt diffraction peak profiles on the pair distribution function

Powder diffraction and pair distribution function (PDF) analysis are well established techniques for investigation of atomic configurations in crystalline materials, and the two are related by a Fourier transformation. In diffraction experiments, structural information, such as crystallite size and...

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Bibliographic Details
Published in:Acta crystallographica. Section A, Foundations and advances Foundations and advances, 2022-01, Vol.78 (1), p.10-20
Main Authors: Beyer, Jonas, Roth, Nikolaj, Brummerstedt Iversen, Bo
Format: Article
Language:English
Subjects:
Crystallites
Crystals
Diffraction
Distribution functions
Fourier analysis
Fourier transforms
Microstrain
pair distribution function
peak profile
Powder
size effects
strain effects
Voigt function
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Summary:Powder diffraction and pair distribution function (PDF) analysis are well established techniques for investigation of atomic configurations in crystalline materials, and the two are related by a Fourier transformation. In diffraction experiments, structural information, such as crystallite size and microstrain, is contained within the peak profile function of the diffraction peaks. However, the effects of the PXRD (powder X‐ray diffraction) peak profile function on the PDF are not fully understood. Here, all the effects from a Voigt diffraction peak profile are solved analytically, and verified experimentally through a high‐quality X‐ray total scattering measurement on Ni powder. The Lorentzian contribution to the microstrain broadening is found to result in Voigt‐shaped PDF peaks. Furthermore, it is demonstrated that an improper description of the Voigt shape during model refinement leads to overestimation of the atomic displacement parameter. General expressions for peak broadening in reciprocal and direct space are derived based on the Voigt function.
ISSN:2053-2733
0108-7673
2053-2733
DOI:10.1107/S2053273321011840