Diffraction line broadening due to lattice-parameter variations caused by a spatially varying scalar variable: its orientation dependence caused by locally varying nitrogen content in ∊-FeN 0.433
2004; Wiley; Volume: 37; Issue: 1 Linguagem: Inglês
10.1107/s0021889803026906
ISSN1600-5767
AutoresAndreas Leineweber, E. J. Mittemeijer,
Tópico(s)Machine Learning in Materials Science
ResumoThe diffraction line broadening due to lattice-parameter variations caused by a position-dependent (spatial) scalar variable ( e.g. the composition) was analysed theoretically. It was shown that the anisotropy of the resulting microstrain-like line broadening depends on the symmetry of the crystal system of the phase concerned. This model provides a physical basis for a special case of a previously reported phenomenological description of anisotropic microstrain broadening [Stephens (1999). J. Appl. Cryst . 32 , 281–289], which is widely used in Rietveld refinement. The model presented was used to analyse the hkl dependence of the X-ray diffraction line broadening of a sample of hexagonal ∊-iron nitride, FeN y 0 with the average N content y 0 = 0.433. The observed anisotropy of the line broadening was shown to be compatible with the known composition dependencies of the lattice parameters a ( y ) and c ( y ). From the extent of the line broadening, the standard deviation of y 0 could be determined very well, as 0.008.
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