IUCr journals

Line profile analysis: pattern modelling versus profile fitting

J. Appl. Cryst. (2006). 39, 24–31 [doi: 10.1107/S0021889805032978]

[WPPM graph]WPPM results for a nanocrystalline ceria sample. In the inset, TEM grain diameter distribution (full column) with WPPM final results (open column) and starting (prior) distribution (dashed column).
Grain size determination is a primary issue in the study of nanocrystalline materials. The recently developed Whole Powder Pattern Modelling (WPPM) was applied to data collected on a nanocrystalline ceria sample. Unlike traditional profile fitting, WPPM makes no use of arbitrary analytical profile functions: diffraction profiles are directly modelled in terms of microstructural parameters, like, e.g., grain shape and size distribution, dislocation density, effective outer cut-off radius, faulting and anti-phase domain boundary probabilities. The results are in close agreement with those of transmission electron microscopy.

P. Scardi and M. Leoni