Application of deconvolutional treatment to powder diffraction data collected with a Bragg-Brentano diffractometer with a contaminated Cu target and a Ni filter

A deconvolutional method for preprocessing powder diffraction data has been improved. The cumulants of instrumental aberration functions of Bragg-Brentano (Parrish) diffractometer calculated up to the fourth order are presented. The treatments of axial-divergence aberration and the effective spectroscopic profile of the source X-ray have been simplified from those used in previous methods. The current method has been applied to powder diffraction data collected with a Cu-target X-ray tube, used over 20 years, and a Ni-foil Kβ filter.

Aberration corrections for non-Bragg–Brentano diffraction geometries

The construction of peak intensity, profile and displacement aberration functions based on the geometry of a powder diffraction measurement allows for physically realistic corrections to be applied in Rietveld modelling through a fundamental parameters approach. Parallel-beam corrections for asymmetric reflection and Debye–Scherrer geometry are summarized, and corrections for thin-plate transmission are derived and validated. Geometrically correct implementations of preferred orientation models are also summarized.