Sm置換BiFeO3の相転移挙動

概要

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The compositional and thermal evolution of the crystal structure of the Bi1-xSmxFeO3 solid solution synthesized under a high pressure was investigated. Samples with 0.10≤×≤0.20 had an antipolar PbZrO3-type structure with a √2a×2√2a×4a perovskite superstructure at room temperature, while the sample with x=0.05 had a rhombohedral BiFeO3-type structure. Among them, the samples with 0.10≤x≤0.12 transformed from an antipolar PbZrO3-type structure to a polar BiFeO3-type structure and finally to a nonpolar GdFeO3-type structure on heating, which is similar to Zr-rich Pb(Zr,Ti)O3. On the other hand, the samples with 0.15≤x≤0.20 transformed directly to a nonpolar GdFeO3-type structure. The ferroelectric Curie temperature of BiFeO3 was markedly lowered by the Sm substitution.