NaSbO3における多形性:金属酸化物における構造と結合
Hiroshi Mizoguchi1, Patrick M Woodward, Song-Ho Byeon
1Department of Chemistry, Ohio State University, Columbus, Ohio 43210-1185, USA.
Journal of the American Chemical Society
|March 12, 2004
まとめ
ペロブスキート構造を持つ新しいナトリウムアンチモナート (NaSbO(3)) ポリモルフは,高圧下で合成されました. この発見は,三次性アンチモナート化合物の複雑な結合と構造的好みを明らかにします.
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:
- テナリペロブスキットは材料科学において極めて重要であるが,その構造的多様性と圧力下での安定性は十分に理解されていない.
- ナトリウムアンチモナート (NaSbO(3) は,環境条件下でイルメナイトポリモルフで存在することが知られている.
研究 の 目的:
- NaSbOの新しい高圧ポリモルフを合成し,特徴づけること.
- この新しい材料の構造,電子,結合特性について調査する.
- 異なるNaSbO ((3) ポリモルフの安定性を支配する要因を理解する.
主な方法:
- 10.5 GPaと1150°Cでユニアキアル・スプリット・スフィア・アンビル型プレス (USSA-2000) を使用した高圧合成.
- クリスタル構造の決定のためのX線 difraktion.
- バンドギャップを判別するための光学測定.
主要な成果:
- NaSbO(3) の新しいオーソロンビックに歪んだペロブスキートポリモルフが合成され,環境条件に回復することが成功しました.
- 構造 (空間群Pnma) は,イオン半径によって予測されるよりも大きい,重要な八面形の傾斜歪みを表しています.
- この化合物は,光学帯のギャップが3.4 eVの白い断熱体であり,オクターエドール部位にSb(5+) を含む最初の三元ペロブスキットを表しています.
結論:
- 観測された歪みは,強いSb-O共性結合によって引き起こされる酸素に対する二次的なJahn-Teller効果に起因する.
- Sb-O共性結合とNa-O排斥相互作用の間の衝突は,環境条件下でのペロブスキート構造を不安定化し,イルメナイトポリモルフを好む.
- 結合の分析は,ASbO ((3)) とABiO ((3)) の化合物において,ポーリングの規則に違反する構造の有病性を説明する.
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