アモルフォの氷のいくつかの異なったメタステーブル形態の構造的研究
C A Tulk1, C J Benmore, J Urquidi
1Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
Science (New York, N.Y.)
|August 24, 2002
まとめ
高密度の無形氷の解熱は,複雑な一連の中間構造的形態を明らかにします. これらの発見は,低温の液体水相変換が,これまで理解されていたよりも複雑であることを示唆しています.
科学分野:
- マテリアルサイエンス 材料科学
- 凝縮物質物理学 凝縮物質物理学
- 物理化学 物理化学
背景:
- アモルフな氷,特に高密度のアモルフな氷 (HDA) は,水の性質を理解するための重要なモデルシステムです.
- 以前の研究では,異なる無形水相の存在が示唆されていましたが,それらの間の構造的移行は,まだ十分に理解されていません.
研究 の 目的:
- 解熱中の高密度無形氷の構造的進化を調査する.
- 低密度無形氷 (LDA) への変換中に形成された中間無形相を特定し,特徴づけること.
- 低温での水の複雑な相行動についての洞察を得るために.
主な方法:
- 中性子 difraktionとX線 difraktionは原子構造を調査するために使用されました.
- 最初の difrraction peak は,さまざまな annealing 温度で,体系的にモニタリングされました.
- 構造変化を分析するために,半径分布関数を計算した.
主要な成果:
- HDAの氷からLDAの氷への構造的移行は,一系列の異なった,転移安定した中間無形形状を通じて起こります.
- 5つの特定の無形な相が特定され,中性子散乱を用いて特徴づけられました.
- 4~8アングストロムの間の放射分布関数において,体系的な構造的進化が観察された.
結論:
- 無形氷の化には,複数の中間状態を持つ複雑な経路が伴う.
- 低温水における相変換は,現在のモデルが示唆しているよりもはるかに複雑である.
- 水のさまざまな無形な相を完全に解明するには,さらなる研究が必要である.
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