Structural and impedance studies of TiIV and NbV co-doped bismuth vanadate system

Oxygen ion conductor with formula unit Bi2V0.875Ti0.125-xNbxO5.5-δ (0≤x≤0.1) (BITIIVNBVVOX) and Bi4V2O11 (for comparison) were synthesized through solid state reaction technique. The effect of simultaneous doping at V-site of Bi4V2O11 with TiIV and NbV on stabilization of high oxygen ionic conducting ϒ-phase and ionic conductivity has been investigated in the current study. These specimens were subjected to X-ray diffraction (XRD) for phase determination. The phase stability was further confirmed by FT-IR spectroscopy. Surface morphology was studied by SEM. Ionic conductivity of all prepared compositions of BITINBVOX was studied by electrochemical impedance spectroscopy (EIS) as a function of frequency and temperature for different dopant concentrations. The ionic conductivity was found to be higher for the composition Bi2V0.875Ti0.075Nb0.050O5.4625 as compared to the only Ti or Nb-doped and parent compounds.