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

Abstract

Rare earth‐doped BaZrO3 is a very attractive material in electrochemical applications due to its proton conductive property. In this work, powder X‐ray diffraction patterns of BaZr0.8M0.2O3−δ (M = Sc, Eu, Sm, Dy) were collected using synchrotron radiation, and also using characteristic X‐ray of CuKα 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 BaZr0.8M0.2O3−δ (M = Sc, Eu, Sm, Dy) in wet O2 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 BaZrO3 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 BaZrO3 with an increasing radius.