The electric field gradient at111Cd in vanadium oxides

摘要: The electric field gradient (efg) of111Cd in polycrystalline V2O5 was studied using perturbed angular correlation (PAC) spectroscopy, with the111In activity ion-implanted at 400 keV. Between the individual steps of an isochronal annealing program, a distinct efg (vQ1=88.1(3) MHz, ν1=0.62(2)) recorded contribution which increased temperature up to 74% 870 K. Corresponding X-ray analysis inactive samples, underwent same treatment, proved that sample always stayed as V2O5. Since has only one equivalent cation site, it is concluded this belongs to111Cd site. Oxidation vanadium foil atT=675 and 800 K at\(p_{{\text{O}}_{\text{2}} } \)=200 mbar also yielded efg. From PAC measurements VO2, two well-defined efg's were found above below metal-semiconductor transition 340 K, are tentatively attributed monoclinic tetragonal phase.