Correction for powder diffraction peak asymmetry due to axial divergence

L. W. Finger, D. E. Cox, A. P. Jephcoat

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Abstract

Analysis of a crystal structure using the Rietveld profile technique requires a suitable description of the shape of the peaks. In general, modern refinement codes include accurate formulations for most effects; however, the functions used for peak asymmetry are semi-empirical and take very little account of diffraction optics. The deficiencies in these methods are most obvious for high-resolution instruments. This study describes the implementation of powder diffraction peak profile formulations devised by van Laar & Yelon. This formalism, which describes the asymmetry due to axial divergence in terms of finite sample and detector sizes, does not require any free parameters and contains intrinsic corrections for the angular dependence of the peak shape. The method results in an accurate description of the observed profiles for a variety of geometries, including conventional X-ray diffractometers, synchrotron instruments with or without crystal analyzers and neutron diffractometers.

Original languageEnglish
Pages (from-to)892-900
Number of pages9
JournalJournal of Applied Crystallography
Volume27
Issue numberpt 6
DOIs
Publication statusPublished - Dec 1 1994
Externally publishedYes

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ASJC Scopus subject areas

  • Structural Biology
  • Condensed Matter Physics

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