シンプルな構造から発せられた負の熱膨張:立方ScF ((3))
Benjamin K Greve1, Kenneth L Martin, Peter L Lee
1School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
Journal of the American Chemical Society
|October 21, 2010
まとめ
スカンジウムトリフッ化物は,低温で有意な負の熱膨張を示す. この研究は,立方体ReO ((3) 構造の固体構造ユニットの熱誘発振動のメカニズムを実験的に確認し,そのユニークな熱特性を説明しています.
科学分野:
- マテリアルサイエンス 材料科学
- 固体化学 固体化学
- クリスタログラフィーです.
背景:
- スカンジウムトリフッ化物 (ScF3) は立方体ReO(3) 型構造を有する.
- 負の熱膨張 (NTE) は,特定の材料で観察される現象で,加熱すると収縮する.
- ReO(3) 構造は,理論的には"固体ユニットモード"メカニズムを通じてNTEとリンクされています.
研究 の 目的:
- 低温でのスカンジウムトリフッ化物の構造的および熱膨張特性を調査する.
- ScF3.3における負の熱膨張のための提案されたメカニズムを実験的に検証する.
- 温度と圧力の変動条件下でのScF3の相変化行動を特徴づけるために.
主な方法:
- 変数温度と圧力のX線 difraktion研究.
- 熱膨張係数を測定するための膨張計測定.
- 構造変化と段階移行の分析.
主要な成果:
- スカンジウムトリフッ化物は,10Kまで立方体ReO(3) 構造を保持する.
- 強い負の熱膨張 (α(l) ≈ -14 ppm K(-1)) は60-110 Kの間で観察されました.
- キュービックからロンボエドルの相移行圧力は温度に依存し,低温で著しく低下します.
- 室温CTEはZrW(2)O(8) と比較され,1100K以上で正熱膨張が認められる.
結論:
- スカンジウムトリフッ化物は,負の熱膨張のための硬いユニットモードメカニズムの明確な実験的実証を提供します.
- NTEと調節可能な相変化を含むユニークな熱的振る舞いにより,さらなる研究のための重要な材料となっています.
- この発見は,ReO ((3) 構造の材料におけるNTE現象の理解に貢献する.
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