A XANES study of the valence state of vanadium in lithium vanadate phosphate glasses

Valence states of vanadium in Li2O-V2O5-P2O5 electronic-ionic conducting glasses have been studied by X-ray absorption spectroscopy. The composition dependence of the XANES range of the spectra has been used to estimate relative abundance of the vanadium atoms in V4+ or V5+ charge states. This information is important for analysis of electronic transport in these glasses, which occurs via electronic hopping between aliovalent vanadium centers. It was found that in samples with the lowest V2O5 contents (10 mole% of V2O5) a vast majority of vanadium ions are in V4+ charge state. At higher V2O5 contents the proportion of V4+ ions decreases at the expense of V5+ ones, but remains substantial even in glasses with the highest contents of V2O5. C 2005 Springer Science + Business Media, Inc.