寒冷圧縮下でのsp3-ハイブリッド化された炭素の多形相
1Department of Chemistry and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, USA.
Journal of the American Chemical Society
|April 12, 2012
まとめ
研究者らは,冷圧圧縮グラファイットを計算的に探求することによって,新しい超硬質炭素構造を発見しました. これらの新しいsp(3) -ハイブリッド化された炭素アロトロップは,高硬度と光学透明性を示し,実験結果を説明する可能性がある.
科学分野:
- 材料科学 材料科学とは
- 固体物理 固体物理学
- コンピューティング・ケミストリー
背景:
- グラファイトは冷圧で超硬い炭素に変身する.
- これらの超硬い炭素の正確な構造は,実験的に未決定のままである.
研究 の 目的:
- 炭素の高圧結晶相に対する広範な構造的探求を行う.
- 新しく予測されたsp(3) -ハイブリッド化された炭素構造を分類し,特徴づけること.
主な方法:
- 進化的アルゴリズムを用いて,偏りのない構造的検索を行いました.
- エネルギーと特性分析のための密度関数理論の計算を採用した.
- 実験データとの比較のために,X線 difraktion (XRD) のシミュレーションスペクトル.
主要な成果:
- 9つの低エネルギー,sp(3) -ハイブリッド化された炭素多形構造を特定しました.
- グラフェン層を重ね合わせた構造を基に分類された構造.
- 7つの新しい構造は,Cco-C(8) (Z-炭素) よりも,0〜25GPaの間,より安定しています.
- いくつかの予測された構造は,弾性モジュールと立方ダイヤモンドに匹敵する硬さを示しています.
- Z-炭素-4は,予測された硬度 (93.4) で最も高い硬さを示しています.
- ほとんどの構造は光学的に透明です.
- シミュレーションされたXRDスペクトルは,冷圧グラフィートの実験データと一致しています.
結論:
- 分類スキームは,新しいsp(3) -ハイブリッド化された炭素アロトロプの設計戦略を提供します.
- 新しく予測された構造は,エネルギー的に好ましいものであり,望ましい機械的性質を有しています.
- 冷圧圧縮グラフィートの実験サンプルには,sp(3) -ハイブリッド化された炭素の複数のポリモルフ相が含まれることがあります.
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