Dopant Site Occupancy and Chemical Expansion in Rare Earth‐Doped Barium Zirconate

Rare earth‐doped BaZrO 3 is a very attractive material in electrochemical applications due to its proton conductive property. In this work, powder X ‐ray diffraction patterns of BaZr 0.8 M 0.2 O 3−δ (M = Sc, Eu, Sm, Dy) were collected using synchrotron radiation, and also using characteristic X ‐ray of Cu K α in dry and wet atmospheres at high temperature. Then, a combined interpretation of the diffraction patterns was established by using Rietveld refinement. The results revealed that an obvious lattice expansion was observed for BaZr 0.8 M 0.2 O 3−δ (M = Sc, Eu, Sm, Dy) in wet O 2 compared with the case in dry condition, indicating a chemical expansion effect on lattice volume by incorporating water into lattice. Eu, Sm, and Dy cations occupied both A‐ and B‐sites of BaZrO 3 crystalline lattice, whereas Sc cations were determined to occupy B‐site only. These results indicate clearly an increasing tendency toward A‐site occupation for the rare earth cations in BaZrO 3 with an increasing radius.