X-ray characterization for the charge ordering on β(β')-vanadium oxide bronzes

The vanadium oxide bronzes β(β')-AxV2O5 were studied by X-ray diffraction for A=Ag,Pb and Ca at low temperature and for A=Na and Cu under pressure. We identify that the superlattice formations with the charge ordering are strongly related to the conducting properties. Moreover, the increase of dimensionality in the ab-plane made by the V1 and V2 unit was detected with applying pressure, which probably introduces the pressure-induced superconductivity with the dissolution of the charge ordering on the V2 ladder