Local electric properties of β-Ag0.33V2O5 studied by 51V NMR

The local electric properties of β-Ag0.33 V2O5, a pressure-induced superconductor, were studied at ambient pressure using a nuclear magnetic resonance (NMR) technique. Three crystallographically inequivalent Vi sites (i=1, 2, and 3) were identified from 51V-NMR spectra. We determined the principal axes of the electric-field-gradient (EFG) tensor, electric quadrupole frequency, asymmetric parameter, and Knight shift for each Vi site in the metallic phase and the subsequent charge-ordering (CO) phase at low temperatures. The results suggest that the electric properties for the VI sites are similar to those for the V3 sites, whereas those for the V2 sites are different from those for the V1 and V3 sites. The peculiarity in the metallic phase reflects the electric properties in the CO phase and is attributable to the diagonal structure of the Vi orbitals. (author)