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Phenomenological model of anisotropic peak broadening in powder diffraction
Author(s) -
Stephens Peter W.
Publication year - 1999
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889898006001
Subject(s) - anisotropy , rubidium , diffraction , rietveld refinement , powder diffraction , materials science , line (geometry) , lattice (music) , pair distribution function , phenomenological model , condensed matter physics , chemistry , crystallography , optics , physics , mathematics , geometry , mathematical analysis , potassium , acoustics , metallurgy
Anisotropic line‐shape broadening (peak width which is not a smooth function of d ‐spacing) is frequently observed in powder diffraction patterns, and can be a source of considerable difficulty for whole‐pattern fitting or Rietveld analysis. A model of the multi‐dimensional distribution of lattice metrics within a powder sample is developed, leading naturally to a few parameters which can be varied to achieve optimal line‐shape fits. Conditions on these parameters are derived for all crystal systems, and the method is illustrated with two examples: sodium p ‐hydroxybenzoate and rubidium fulleride.