BiCoO3における圧力誘発のスピン状態の移行
Kengo Oka1, Masaki Azuma, Wei-tin Chen
1Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan. oka@issp.u-tokyo.ac.jp
Journal of the American Chemical Society
|June 24, 2010
まとめ
高圧ではビスムートコバルト酸化物 (BiCoO3) の構造が変化し,体積の減少と電気抵抗力の低下を引き起こします. これは,コバルトイオンのスピン状態の変化を明らかにし,その電子特性を理解するために不可欠です.
科学分野:
- 材料科学 材料科学とは
- 固体物理 固体物理学
- クリスタログラフィーです.
背景:
- ビスムートコバルト酸化物 (BiCoO3) は,複雑な構造および電子特性を有しています.
- 圧力下での相変化を理解することは,新材料の応用の鍵です.
研究 の 目的:
- 高圧下におけるBiCoO3の構造的および電子的振る舞いを調査する.
- 圧力誘発の相変化と関連する性質の変化を決定する.
主な方法:
- 構造変化を分析するために,シンクロトロンX線と中性子粉の difraktion が採用されました.
- 電気抵抗の測定は,様々な圧力条件下で行われました.
- 電子とスピン状態の移行を検知するために,X線放射スペクトロスコピーを用いた.
主要な成果:
- 3GPa以上では,極性PbTiO3型から中心対称性GdFeO3型への構造的相変化が起こります.
- 室温で13%の大幅な体積減少が観察され,これはスピン状態の変化に関連しています.
- 電気抵抗は,第1次相移行時に急激に低下する.
- 構造データは,高圧下でのCo3+の低スピン状態を示しているが,X線放射スペクトルは中間のスピン状態を示唆している.
結論:
- 高圧によりBiCoO3.3の構造と電子が変化します.
- コバルトイオンにおける観測されたスピン状態の変化は,圧力に対する材料の反応における重要な要因である.
- 構築された圧力-温度相図は,材料の安定性と移行温度に関する洞察を提供します.
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