Microstructures and electrical properties of zirconium doped barium cerate perovskite proton conductors

In this work, we vary the Zr to Ce ratio to investigate the microstructures and electrical properties of zirconium doped barium cerates. The solid state reaction is used in synthesizing the BaCe_0.8-xZr_xY_0.2O₃ (X = 0.1–0.5). The electron backscatter diffraction (EBSD) is successfully applied to identify the crystal structure of the barium cerates. EBSD results indicate that all samples have the orthorhombic structure. Conductivity measurement results show that for temperatures below 700 °C, Zr-doped barium cerates have higher protonic conductivities than oxygen-ion/electron-hole conductivities. The protonic conductivity increases with the Zr content initially, but decreases after the Zr content is higher than 0.3. The protonic conductivity of BCZY0.3 reaches 8.8 mS/cm at 700 °C in dry hydrogen atmosphere. Stability test results show that, for stable operation in CO₂ atmosphere, the Zr content in barium cerates should be greater than 0.2.