化学制御による負の熱膨張の対称性交換
Mark S Senn1, Claire A Murray2, Xuan Luo3
1Department of Chemistry, University of Oxford , Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, U.K.
Journal of the American Chemical Society
|March 2, 2016
まとめ
研究者たちは 層状のペロブスキットで 負の熱膨張を制御する 化学的方法を発見しました Ca3-xSrxMn2O7の組成を調整することで 熱膨張の性質をマイナスとプラスに切り替えることができます これは素材のデザインに 新たな可能性をもたらします
科学分野:
- 材料科学
- 固体化学
- クリスタルグラフィー
背景:
- 層状ペロフスキットは,ユニークな構造と電子特性を有する材料のクラスです.
- 熱膨張は,温度によって物質のサイズが変化する方法を説明します.
- 負の熱膨張 (NTE) は,加熱時に物質が収縮する異常な性質です.
研究 の 目的:
- Ca3-xSrxMn2O7層のペロブスキート系における熱膨張の切り替える振る舞いを調査する.
- 材料の対称性と負の熱膨張 (NTE) の関係を理解する.
- 固体溶液の組成を調整することで,NTEに対する化学的制御を証明する.
主な方法:
- 異なるxでCa3-xSrxMn2O7の固体溶液の合成
- 結晶構造と相変化の特徴
- 温度と組成の関数として熱膨張の性質の測定.
主要な成果:
- ストロンチウム (Sr) 含有量 (x) の関数として,単軸負の熱膨張から正の熱膨張への切り替えが観察された.
- このスイッチングは,異なる結晶的対称性を持つ2つの競合する相の存在に関連しています.
- 負の熱膨張 (NTE) 効果は相変化領域の近くで最大化し,それを越えると急に減少します.
結論:
- この研究は,層状のペロブスキットにおける負の熱膨張 (NTE) に対する前例のない化学制御を示しています.
- 競合する相の対称性を理解することは この異常な性質を操作する鍵です
- この研究により 熱膨張特性を持つ素材を 設計する道が開けています
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