Proton Conduction in New Brownmillerite Ba2(Zn, B')2O5 systems (B'=Nb, Ta, W)

Ba2(Zn, B')2O5 systems with B'=Nb, Ta and W which were synthesized by solid state reaction, showed cubic, hexagonal perovskite-type structure and cubic double-perovskite-type structure, respectively. The adsorption of a large amount of H2O in Ba2(Zn, B')2O5 suggests the generation of proton conduction. The electrical conductivity increased remarkably in humid Ar atmosphere, confirming that the proton conduction generated. Especially, Ba2(Zn, Nb)2O5 exhibited the electrical conductivity of 8.7 x 10-3 (S/cm) at 673 K in humid Ar atmosphere. Therefore, the new proton conductor can be expected as the electrolyte materials for SOFCs working at lower temperature.