BaIrO ((3)) の高圧配列における新しいペロブスキートポリタイプ
Jin-Guang Cheng1, José Antonio Alonso, Emmanuelle Suard
1Texas Materials Institute, ETC 9.102, The University of Texas at Austin, Austin, Texas 78712, USA.
Journal of the American Chemical Society
|May 28, 2009
まとめ
バリウムイリデート (BaIrO3) は,新しい5H構造を含むペロブスキートポリタイプのユニークな高圧配列を示しています. この振る舞いは,強いイリジウム-イリジウム結合と反発により,典型的な移行金属酸化物とは異なる.
科学分野:
- 固体化学 固体化学
- マテリアルサイエンス 材料科学
- クリスタログラフィーです.
背景:
- イリド酸バリウム (BaIrO3) は,様々なペロブスキートポリタイプを持つ複雑な酸化物です.
- 圧力下におけるBaIrO3の構造変化を理解することは,材料科学にとって極めて重要です.
研究 の 目的:
- 10GPaまでのBaIrO3におけるペロブスキートポリタイプの高圧配列を調査する.
- これらのポリタイプの結晶構造を,光技術を用いて特徴づけること.
主な方法:
- 固体反応と環境圧力合成のための遅い冷却.
- 結晶構造の精製のために,X線 difraktion (XRD) と中性子粉の difraktion (NPD) を用いる.
- 構造ソリューションのための Ab initio 計算.
主要な成果:
- 9Rポリタイプ (hhchhcスタッキング) は,最大3GPaまで安定しています.
- 新しい5Hポリタイプ (hchccスタッキング) は,4〜5GPaの間に安定しています.
- 6Hポリタイプ (hcchccスタッキング) は5GPaから10GPaまで安定しており,10GPaで軽微な3Cペロブスキート相が現れます.
結論:
- BaIrO3は,他の過渡金属酸化物とは異なる独特の圧力誘発ポリタイプ配列 (9R-5H-6H-3C) を表しています.
- 9R相の安定性とIr-Ir相互作用は,この新しい配列,特に5Hポリタイプの安定化に影響します.
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