Microstructures and proton conductivities of BaZrO₃ modified by BaCeO₃

The dense sintered bodies with >95% theoretical densities were successfully obtained from the BaZrO₃, BaCeO₃, Ba(Zr _0.7Ce_0.3)O₃ solid solution, and core-shell structured 0.7BaZrO₃-0.3BaCeO₃ composite powders prepared by sol-gel methods. The activation energy of Ba(Zr_0.7Ce _0.3)O₃ solid solution calculated from the Arrhenius plot of the proton conductivities was similar to that of BaZrO₃. The activation energy of core-shell structured 0.7BaZrO₃-0.3BaCeO ₃ composite, however, was much lower than that of BaZrO₃ or Ba(Zr_0.7Ce_0.3)O₃ solid solution, and was very similar to that BaCeO₃. These results could be assigned to the Ce-rich grain boundary which was clearly observed by EDX in core-shell structured 0.7BaZrO₃-0.3BaCeO₃ composite.