Characterisation of lower temperature sintered zinc-doped barium calcium niobate proton conducting electrolytes

摘要

The densification of BasCa_(1.18)Nb_(1.82)O_(8.73) (BCN18) at 1325 °C has been improved by the addition of ZnO, resulting in the new proton conducting material, Ba3(Ca_(1.18)Nb_(1.70)Zn_(0.12))O_(8.55) (BCNZ18). As for Ba3Ca_(1.18)Nb_(1.82)O_(8.73), Ba3(Ca_(1.18)Nb_(1.70)Zn_(0.12))O_(8.55) is found to be a mixed conductor; with both electronic and ionic conductivity under different atmospheres. By increasing the sintered density of Ba3(Ca_(1.18)Nb_(1.70)Zn_(0.12))O_(8.55), the total conductivity has increased by decreasing the grain boundary contribution. Once the sample is hydrated under wet 5% H2/Ar, Ba3(Ca_(1.18)Nb_(1.70)Zn_(0.12))O_(8.55) behaves as a pure ionic conductor below 550 °C, due mainly to proton conduction. At 500 °C the value of conductivity measured for Ba3(Ca_(1.18)Nb_(1.70)Zn_(0.12))O_(8.55) under 5% H2/Ar was 7.32 x 10~(-4) S cm~(-1). Overall, this material has shown to be a promising electrolyte material for high temperature electrochemical devices.