Influence of Triple Sintering Additives (BaO-CuO-B₂O₃) on the Sintering Behavior and Conductivity of the Proton-Conducting BaZr_0.1Ce_0.7Y_0.2O_3−δ Electrolyte Sintered at 1150 °C

The effects of multiple sintering additives BaO-CuO-B₂O₃ on the sintering behavior, microstructure, and electrochemical performance of BaZr_0.1Ce_0.7Y_0.2O_3−δ (BZCY) as an electrolyte were investigated for intermediate temperature solid oxide fuel cell application. BZCY was prepared by adding 0, 1, 2, and 3 mol % sintering additives through the freeze-drying method. Microstructure analysis and shrinkage measurement reveal that BZCY with 3 mol % sintering additive effectively reduces the sintering temperature to 1150 °C. BZCY pellets with 3 mol % sintering additives sintered at 1150 °C for 8 h increased the linear shrinkage from 2.6 to 17.0%. Thermochemical analysis reveals that the low melting temperature eutectic phase formation resulted in liquid-phase sintering, which supports the rearrangement and densification of BZCY particles. BZCY with 3 mol % sintering additives presented a proton conductivity of 0.016 S cm^-1 and good durability at 600 °C with a low activation energy of 0.44 eV and low grain boundary resistance.