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水は,火力発電材料の正と負の電荷を持つ表面で異なった凍結をします

David Ehre¹, Etay Lavert, Meir Lahav

¹Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 76100, Israel.

Science (New York, N.Y.)

|February 6, 2010

まとめ

電気場は水の凍結に大きく影響する. 陽性電荷の表面は氷の核形成を促進し,陰性電荷の表面はそれを阻害し,超冷却水の振る舞いに影響を及ぼします.

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
クリスタルグラフィーです.

背景:

水は,特定の条件下で0°C以下の超冷却液体として存在することができます.
水の凍結 (electrofreezing) に対する電場の影響は,自然と人工のプロセスにとって極めて重要です.

研究の目的:

超冷却水の凍結温度に対する表面電荷の影響を調査する.
熱電材料の電荷のある表面での氷核形成のメカニズムを探求する.

主な方法:

ピロエレクトリックのリチウムタンタラート (LiTaO3) クリスタルとストロンチウムチタナート (SrTiO3) の薄膜を用いて,表面電荷が制御されています.
水滴の凍結行動を,異なる表面電荷条件下で,零下温度で観察する.
粉末X線 difraktionを用いて,氷の核形成部位を分析した.

主要な成果:

LiTaO3とSrTiO3の陽性電荷の表面は,超冷却水における氷核形成を促進する.
負の電荷を持つ表面は凍結温度を下げ,氷の形成を遅らせます.
表面電荷を負から正に切り替えると,超冷却水の即時凍結が起こります.
X線 difraktionにより,氷の核形成は,陽性表面の固体/水界面,陰性表面の空気/水界面で始まることが明らかになった.

結論:

表面電荷の極性は,超冷凍水の電気凍結を決定的に制御する.
発見は,大気科学と材料工学に関連する氷の形成機構の洞察を提供します.
パイロ電気材料は,氷の核化を研究し,潜在的に制御するための調整可能なプラットフォームを提供します.

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