衝撃圧縮された超離子水氷のナノ秒X線 difraktion
Marius Millot1, Federica Coppari2, J Ryan Rygg3,4
1Lawrence Livermore National Laboratory, Livermore, CA, USA. millot1@llnl.gov.
Nature
|May 10, 2019
まとめ
研究者達は 極度の圧力と温度下で 新しい超離子氷相"氷XVIII"を生み出しました この発見は 超離子水氷の結晶構造の 最初の直接的な実験的証拠です
科学分野:
- 凝縮物質物理学
- 材料科学
- 高圧物理学
背景:
- 水 (H2O) は17以上の結晶といくつかの無形氷の構造を持つ複雑な多形性を表しています.
- 極端な圧力 (>100 GPa) と温度 (>2,000 K) は,陽子が固体酸素の格子を通して拡散するH2Oのスーパーイオン行動を誘導すると予測されています.
- この超イオン状態は,高いイオン伝導性,高融解温度,新しい酸素格子構造によって特徴付けられています.
研究 の 目的:
- 極限条件下での水氷の形成と構造を実験的に調査する.
- 水の氷の予測された超音波の直接的な証拠を提供するために.
- ギガパスカルの圧力とキロケルビンの温度で水氷の相変換と圧縮性を特徴付ける.
主な方法:
- 液体の水のサンプルを 100~400 GPa と 2,000~3,000 K に圧縮して加熱するためにレーザー駆動の衝撃波が使用されました.
- 氷の構造を決定するために,衝撃を受けたサンプルにX線散離測定を行いました.
- 分離パターンの分析により,結晶酸素の格子と相変換が特定されました.
主要な成果:
- 水は極度の条件下で ナノメートルの大きさの氷粒に 急速に固まりました
- 超離子水氷の結晶性酸素格子に対する明確な証拠が得られた.
- 身体中心の立方体 (おそらく氷X) から,新しい顔中心の立方体,スーパーイオン相 (氷XVIII) への相変化が観察された.
- 極限条件下での氷の圧縮性は 文書化されています
結論:
- この研究は,超離子水氷 (氷XVIII) の存在と結晶構造に関する最初の直接的な実験的証拠を提供する.
- この発見は,極端な圧力と温度下での水における超音波の理論的予測を裏付けている.
- この研究は惑星の内部と 極端な条件下での物質の振る舞いを 理解する新しい道を開きます
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