X-ray absorption fine structure: characterization of thermal and structural disorder in non-crystalline solids

A great progress has been made in the last years in the XAFS studies of thermal and structural disorder, due to the increased quality of measurements allowed by the intense third generation synchrotron radiation sources, and the refinement of the analysis techniques. A description of XAFS strengths and limits is given and some paradigmatic investigations on thermal and structural characterization of crystalline and non-crystalline solids are reported. In particular, the environments of the nearest neighbors of selected species in some germanium based compounds and silver borate glasses are described in terms of radial distribution functions and their main parameters, such as mean distance, variance and asymmetry. The determination of local thermal expansion coefficients in crystalline and non-crystalline solids by temperature dependent studies is shown.