Chemical Expansion and Change in Lattice Constant of Y‐Doped BaZrO ₃ by Hydration/Dehydration Reaction and Final Heat‐Treating Temperature

Knowledge of thermal behavior of electrolyte is important for fuel cell fabrication. In this study, using high‐temperature X ‐ray diffraction analysis ( HT ‐ XRD ) and thermo‐mechanical analysis ( TMA ), a systematic investigation of lattice constants was performed on Y‐doped BaZrO 3 , which is a promising candidate for electrolyte in protonic ceramic fuel cells. The results revealed that a chemical expansion was observed between 300°C and 450°C during the heating process in HT ‐ XRD , and was attributed to the dehydration of BZY . Furthermore, it was found that the lattice constants of the samples doped with Y, Sm, Eu, and Dy were larger for the ones finally heat‐treated at 1600°C for sintering than those heat‐treated at 1300°C for synthesizing. The similar behavior was not observed in Sc‐doped samples.