Electrical Conductivity and Dielectric Constant of Novel Proton Conductor Ba2(Zn, M)2O6-δ (M = W, Nb) Having Oxygen Deficient Perovskite Structure

Ba2(Zn1-xMx)2O6-δ (M = W, Nb) systems, where the oxygen vacancy concentration can be controlled by the Zn/M ratio, were found to have cubic double-perovskite-type structure for M = W and cubic perovskite-type structure for M=Nb. As it was found by thermogravimetry that the Ba2(Zn1-xMx)2O6-δ samples can uptake the large amount of H2O, we expected that the adsorption of H2O may contribute to a generation of proton conduction. Then, the electrical conductivity was measured in dry and humid Ar atmospheres by the two-probe method. The electrical conductivity remarkably increased in the humid atmosphere, suggesting occurrence of the proton conduction. The numerical calculation of frequency dependences of dielectric constant (ɛr’) were successfully explained by the superposition of Debye-type polarizations and electrolyte-electrode interfacial.