Line profile analysis in Rietveld method and Whole-Powder-Pattern Fitting

Analytical profiles are used in most programs for Whole Powder Pattern Fitting (WPPF) and Reitveld method used in microstructural as well as in structural studies. The present work deals with the effect of microstructure and lattice defects on the shape, width and position of diffraction profiles, and their role in WPPF. Suitable models of domain size and shape, planar and linear defects can be incorporated in a fast and efficient least squares algorithm for pattern fitting with Voigt functions, currently working on fcc materials. WPPF is then compared with Whole Powder Pattern Modelling, a new approach that gets rid of analytical profiles to fit data, and allows a direct comparison of microstructural models with experimental diffraction data.