Grain Boundary Space Charge Effect and Proton Dynamics in Chemically Stable Perovskite-Type Ba_0.5Sr_0.5Ce_0.6Zr_0.2Gd_0.1Y_0.1O_3-δ (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 Ba_0.5Sr_0.5Ce_0.6Zr_0.2Gd_0.1Y_0.1O_3-δ (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°C, 1400°C, and 1550°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°C and 300°C, respectively, for BSCZGY samples sintered at 1300°C and 1400°C. Interestingly, the BSCZGY sample sintered at 1550°C showed absence of GB contribution to total conductivity even at 200°C. The GB electrostatic potential [φ(0)] was found to vary between 0.35-0.38 V and 0.4-0.45 V, respectively, for the samples sintered at 1300°C and 1400°C at 200°C-300°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°C, 1400°C and 1550°C, respectively.