BaCe0.45Zr0.45M0.1O3–δ (M=Y, In) and BaCe0.9Y0.1O3–δ were prepared through the conventional solid state reaction route. The chemical stability was investigated in hydrogen, carbon dioxide, and boiling water. Crystalline phase and microstructure of the proton conductor before and after stability test were measured with X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results showed that all materials were quite stable in H2 atmosphere. In CO2 atmosphere, BaCe0.45Zr0.45M0.1O3–δ (M=Y, In) were rela- tively stable, while BaCe0.9Y0.1O3–δ decomposed. In boiling water, BaCe0.9Y0.1O3–δ was quickly decomposed into Ba(OH)2 and corresponding oxide. BaCe0.45Zr0.45M0.1O3–δ slightly reacted with boiling water and some amorphous phases were formed. However, BaCe0.45Zr0.45In0.1O3–δ was observed to exhibit better stability than BaCe0.45Zr0.45Y0.1O3–δ in water. The experimental results were interpreted in terms of thermodynamic data and tolerance factor.
