Diffraction Line Profiles in the Rietveld Method

The present work traces the evolution of the modeling of the diffraction line profiles in the Rietveld method, starting from the early and most schematic description with Gaussian curves to the most modern approaches based on the convolution of the line profiles from all contributing effects. Basic theory and applications demonstrate the advantages, in terms of improved results quality and microstructural information made accessible, of a careful but still flexible approach to the instrumental and sample-related diffraction line profile. The instrumental profile function is discussed in some detail for the most common powder diffraction measurement geometries. Examples of applications show the advantages of adopting a convolutive approach for the line profile modeling.