Grain Boundary Space Charge Effect and Proton Dynamics in Chemically Stable Perovskite-Type Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3- (BSCZGY): A Case Study on Effect of Sintering Temperature

The present study reports the effect of sintering temperature on the proton dynamics of perovskite-type Ba0.5Sr0.5Ce0.6Zr0.2Gd0.1Y0.1O3- (BSCZGY) by establishing a co-relation between the grain-boundary (GB) space charge effect, electrical conductivity and dielectric loss of the BSCZGY samples sintered at 1300 degrees C, 1400 degrees C, and 1550 degrees C for 20 h in air. Although, the GBs are the main source of resistance in BaZrO3 based ceramic proton conductors, we show that the GB impedance disappeared above 450 degrees C and 300 degrees C, respectively, for BSCZGY samples sintered at 1300 degrees C and 1400 degrees C. Interestingly, the BSCZGY sample sintered at 1550 degrees C showed absence of GB contribution to total conductivity even at 200 degrees C. The GB electrostatic potential [phi(0)] was found to vary between 0.35-0.38 V and 0.4-0.45 V, respectively, for the samples sintered at 1300 degrees C and 1400 degrees C at 200 degrees C-300 degrees C. The migration energy (E-m) of the protons was found to be 0.71, 0.65 and 0.58 eV for the sample sintered at 1300 degrees C, 1400 degrees C and 1550 degrees C, respectively.