Electrical properties of dense Me-doped bismuth vanadate (Me=Cu, Co) pO2-dependent conductivity determined by impedance spectroscopy

Co- and Cu-substituted Bi4V2O11 compounds were synthesised by means of fine reactive powders with a typical d50 close to 0.5 μm. Appropriate sintering conditions resulted in fine and homogeneous microstructure without any cracks related to large grain size. The total electrical conductivity was measured by complex impedance spectroscopy with respect to temperature, oxygen partial pressure, thermal history, and nature of dopant. The bulk and the grain boundary conductivity were also studied for both compounds. No time-dependence and no thermal hysteresis of the total electrical conductivity were observed and a structure dependence of the electrical properties was noticed. BICUVOX0.10 material can be considered as a pure oxide ion conductor within the investigated experimental conditions whereas BICOVOX0.10 exhibited a p-type conductivity contribution to the bulk conductivity with an ionic transference number greater than 0.97.