X-ray absorption study of the short range order of tungsten and molybdenum ions in BaO-P2O5-WO3 and CaO-P2O5-MoO3 glasses

The analysis of XANES and EXAFS in BaO-P2O5-WO3 and CaO-P2O5-MoO3 glasses at the W L-1,L-3 and Mo K edges was performed in comparison with a number of crystalline WO3, CaWO4, Na0.66WO3, alpha-MoO3, beta-MoO3 and amorphous a-WO3, a-MoO3 compounds. The results of the EXAFS modelling by two different methods ((1) multi-shell single-scattering model within harmonic approximation and (2) model-independent radial distribution function (RDF) approach) allowed us to extract detailed structural information on the first coordination shell of metal (W or Mo) ion. Using the obtained data together with the information given by other experimental techniques, we propose a structural model of the local environment distortion around tungsten and molybdenum ions in phosphate glasses.