Open AccessXANES and EXAFS Modelling of Configurational Disorder in Silver Borate Glasses
Author(s) -
G. Dalba,
P. Fornasini,
Alexei Kuzmin,
Francesca Monti,
Andrea Sanson,
O. Šipr,
F. Rocca
Publication year - 2005
Publication title -
physica scripta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.415
H-Index - 83
eISSN - 1402-4896
pISSN - 0031-8949
DOI - 10.1238/physica.topical.115a00149
Subject(s) - xanes , extended x ray absorption fine structure , boron , materials science , absorption spectroscopy , optics , spectroscopy , physics , nuclear physics , quantum mechanics
The sensitivity of X-ray absorption spectroscopy (XAS) to the local structurearound a selected atomic species (symmetry, distances and angles) is commonlyexploited to quantitatively describe systems where all the configurations aroundthe absorbing atoms may be approximated by the mean one. However, in manycases of disordered systems a simple description of the local structure with singleconfigurationmodels cannot be reconciled with experimental spectra.In this paper the necessity to analyse the XAS spectra by considering amultiplicity of atomic structural configurations is demonstrated in the case ofsilver borate glasses.The local coordination around Ag cations in (Ag2O.nB2O3) glasses has beenstudied by comparing the XAS experimental spectra at the Ag K edge withtheoretical XANES and EXAFS spectra obtained by a configurational averageof model structures.In order to provide a reasonable agreement with experiment, these models haveto take into account that there are many geometrically distinctAg neighbourhoodspresent in the system, and that the measured XANES and EXAFS signals are infact averages over spectra originated at all the non-equivalent photoabsorbing sites(multi-configuration approach)