STRUCTURAL STUDIES OF IONICALLY CONDUCTIVE GLASSES BY EXAFS

A good knowledge of the local structure is necessary for a better understanding of the high conductivity shown by some ions in oxide glasses. The ability of X-Ray Absorption Spectroscopy (XAS) to select a single atomic species makes this technique very useful in this field: XANES and EXAFS can give information not only on radial distribution function of atoms around the absorbing species but also on their geometrical arrangement. The experience of the last years shows that peculiar information can be extracted by studying multiple-scattering contributions and evaluating the influence of static and thermal disorder. The results of XAS studies on AgI-containing silver borate glasses are presented and discussed, with particular emphasis on the role of temperature dependent measurements in EXAFS. The comparison with results concerning other similar systems offers the possibility of discussing strengths and limits of XAS.