地球の内核にある鉄の体中心立方相の安定性

Anatoly B Belonoshko¹, Rajeev Ahuja, Börje Johansson

¹Applied Materials Physics, Department of Materials Science and Engineering, The Royal Institute of Technology, SE-100 44 Stockholm, Sweden. anatoly@fysik.uu.se

Nature

|August 29, 2003

まとめ

分子ダイナミクスシミュレーションでは,体中心の立方体 (b.c.c.) を明らかにしています. 鉄は地球の内核で安定している. この発見は,鉄の高圧相図と融解曲線の不一致を解決している.

科学分野:

地質物理学地質物理学とは地質物理学です.
マテリアルサイエンス材料科学
計算物理学の物理

背景:

鉄は地球の核の主要な構成要素であり,その高圧および高温特性を研究する必要がある.
鉄相図に関する既存の研究は,特に極端な条件下での融解曲線に関する矛盾を示している.

研究の目的:

地球の核条件下における鉄の安定相を調査する.
確立された鉄相図と融解行動の不一致を解決するために.

主な方法:

鉄の分子動力学シミュレーションを利用した.
密度関数理論の計算から派生した組み込み原子モデルを使用した.
発見の信頼性を確保するために,2つの異なるモデル近似をテストしました.

主要な成果:

テストされた両方のモデルは,体中心立方体 (b.c.c.) の安定性を示しています. 鉄相は,高圧と高温で発生する.
計算した融解曲線は",高"の融解曲線と一致する.
六角密集型 (h.c.p.) の間の計算された相境界. そしてb.c.c.c. 鉄は"低"の融解曲線とよく相関する.

結論:

h.c.p. - b.c.c.c. を使っている. 鉄の移行は,以前は溶融の移行として誤って識別されていたかもしれません.
b.c.c. のb.c.c. がやってきました. 鉄相は,地球の内核内の安定した形態として提案されています.
この研究は,鉄の高圧相行動における矛盾するデータを調和させています.

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