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

The densification of Ba3Ca1.18Nb1.82O8.73 (BCN18) at 1325 degrees C has been improved by the addition of ZnO, resulting in the new proton conducting material, Ba-3(Ca1.18Nb1.70Zn0.12)O-8.55 (BCNZ18). As for Ba3Ca1.18Nb1.82O8.73, Ba-3(Ca1.18Nb1.70Zn0.12) 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 Ba-3(Ca1.18Nb1.70Zn0.12)O-8.55, the total conductivity has increased by decreasing the grain boundary contribution. Once the sample is hydrated under wet 5% H-2/Ar, Ba-3(Ca1.18Nb1.70Zn0.12)O-8.55 behaves as a pure ionic conductor below 550 degrees C, due mainly to proton conduction. At 500 degrees C the value of conductivity measured for Ba-3(Ca1.18Nb1.70Zn0.12)O-8.55 under 5% H-2/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.