Understanding anisotropic microstrain broadening in Rietveld refinement

Abstract

Abstract Anisotropic, i.e. hkl-dependent microstrain broadening of Bragg peaks as observed in powder-diffraction measurements often obstructs finding a good description of the peak profiles during Rietveld refinement. This review describes strategies to model this type of structural line broadening. Emphasis is put, further, on the possible physical background of the refined width parameters in terms of compositional, thermal and elastic microstrain. Methods are described to extract thus quantitative microstructural information. Moreover, it is shown how the anisotropy of the microstrain broadening can reveal the anisotropy of intrinsic properties of the solid, which may otherwise be difficult to determine, e.g. compositional lattice-parameter changes or elastic compliance.