Structure/microstructure analysis of nanocrystalline and layered materials

In the powder diffractionist's life it is not infrequent to meet patterns showing unexpected or unexplained features such as odd profile shapes or anisotropic line profile broadening. Even apparently well-behaving data lead sometimes to questionable refinement results (e.g. unexpected polymorphism in transformations, unrealistic thermal parameters) in which materials' physics contrasts with the hypotheses on which the analysis method is based (e.g. perfect three dimensional lattice). Complementary information is usually needed in those cases, together with new analysis tools able to cope with the real physical environment in which the problem is framed. A couple of such tools are the Whole Powder Pattern Method that can provide microstructure information in simple cases, and the DIFFaX+ approach, able to deal with traditional, layered/interlayered and modular structures showing a local or global reduction of the lattice symmetry due to the presence of defects. Basics and examples of both methods will be shown and commented.