DETERMINATION OF STRUCTURE AND VALENCE IN VANADIUM BRONZE BY X-RAY ABSORPTION SPECTROSCOPY

We used XANES to determine coordination geometry and charge state in a series of mixed valence vanadium bronzes, NaxV2O5 where x = 0.25, 0.40, and 0.75. Simple chemical arguments suggest that each additional positive charge added to the V2O5 lattice will switch one V5+ to V4+. Our results suggest that this is generally true. The energy position and splitting of the V K-edge prepeak, 1s-to-3d, was a sensitive indicator of V valence(s). The intensity of the prepeak decreased as the first neighbor bonds increased in length.