VALENCE STATES AND HYBRIDIZATION IN VANADIUM-OXIDE SYSTEMS INVESTIGATED BY TRANSMISSION ELECTRON-ENERGY-LOSS SPECTROSCOPY

The electronic structure of vanadium oxides and (VO)2P2O7 is investigated by electron-energy-loss spectroscopy. The O K pre-edge in (VO)2P2O7 is substantially different from that of vanadium oxides, whereas the profiles of V L2/L3 transition show no significant differences between these materials. We attribute the change of the O K pre-edge to the change of local symmetry of oxygen atoms in (VO)2P2O7 and the change of hybridization from pure d-p hybridization in vanadium oxide to mixed d-p-sigma hybridization in (VO)2P2O7. It is also inferred that the V L2/L3 transition ratio Of (VO)2P2O7 is more like that Of V2O3.