氷の多形変異の伝播と液体-液体の臨界点

Osamu Mishima¹, Yoshiharu Suzuki

¹Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, 305-0044 Japan. mishima.osamu@nims.go.jp

Nature

|October 11, 2002

まとめ

この研究は,高密度と低密度のアモルフ氷の間の移行が不連続の相移行であることを明らかにしています. この発見は,水が水であることを示唆しています.

科学分野:

物理化学物理化学
マテリアルサイエンス材料科学
熱力学は熱力学である.

背景:

水は,高密度と低密度のアモルフな氷と超冷却液体の間の移行を含む複雑なメタステーブルフェーズ行動を示す.
これらの移行は,結晶氷が熱力学的に安定している条件下で発生し,直接的な実験調査を困難にします.
液体の水の移行の性質 (連続か不連続) と第2の臨界点の存在については,依然として議論されている.

研究の目的:

高密度無形氷 (HDA) と低密度無形氷 (LDA) の間の相変化の熱力学的性質を調査する.
変形氷の研究に基づいて超冷却液体の水の相行動に関する洞察を提供するため.
アモルフの氷における多形変異の移行が連続か不連続かを明確にするために.

主な方法:

ラーマン光譜を用いて,HDAからLDAへの変換中の構造変化を分析した.
視覚検査は,相変化の物理的特徴を観察するために使用されました.
実験は,相界の伝播と進化の特徴に重点を置いた.

主要な成果:

HDAからLDAへの変換は,両方の氷の形態の混合物を含む明確な相境界の伝播を伴う.
この相界は,変化の進行と温度が増加するにつれて狭くなることが観察されました.
観測された境界ダイナミクスは断続的な相変化を強く示している.

結論:

HDAとLDAの間の多形変異は不連続であり,伝播相境界によって特徴付けられます.
無形氷と超冷却液体の構造的類似性は,液体の水も不連続の移行を経験することを示唆しています.
これらの発見は,水の液体-液体臨界点理論を支持する.

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