EXAFS studies of local thermal expansion

Original information on local thermal expansion can be obtained through a cumulant analysis of EXAFS. The different sensitivity to correlation of the first and third EXAFS cumulants, and their comparison with crystallographic distance, can help in disentangling the contribution of potential anharmonicity to thermal expansion from geometrical effects. These possibilities are illustrated by recent experimental results. In germanium, the perpendicular Mean Square Relative Displacement has been obtained from EXAFS. In Ag2O, whose framework structure exhibits negative thermal expansion, a positive expansion of the Ag–O bond has been measured and the deformation of the Ag4O structural units monitored.