原子電子トモグラフィを用いて四次元で結晶の核形成を観察する

Jihan Zhou^1,2, Yongsoo Yang^1,2,3, Yao Yang^1,2

¹Department of Physics and Astronomy, University of California, Los Angeles, CA, USA.

Nature

|June 28, 2019

まとめ

原子電子トモグラフィーは,4Dの原子構造と初期段階の原子核のダイナミクスを明らかにしますこの突破は原子スケールでの核形成プロセスと相変異に関する新たな洞察をもたらします

科学分野:

材料科学
ナノ科学
凝縮物質物理学
化学について

背景:

核化は結晶化や病気の形成を含む様々な物理的,生物学的プロセスに不可欠です.
原子レベルでの初期核形成の研究は実験的に難しい.
これまでの方法では新生原子核の3次元構造と動態を決定する解像度が不足していました

研究の目的:

原子解像度で4次元 (4D) で初期核形成を調査する.
核の形成と進化の過程における原子構造と動態を決定する.
核化理論の精錬のための実験的証拠を提供すること.

主な方法:

4D原子解像度イメージングを達成するために原子電子トモグラフィーを利用しました.
FePtナノ粒子を核化研究のためのモデルシステムとして使用した.
Pt核の分子ダイナミクスシミュレーションで証明された結果

主要な成果:

初期段階の原子核は不規則な形状で,1〜3個の原子が最大限の秩序を示しています.
オーダーパラメータのグラデーションは,核からその境界まで導きます.
成長,解消,結合,分裂を含む原子核のダイナミックな振る舞いを観察し,捕捉した.

結論:

原子電子トモグラフィーは前例のない4D原子解像度を提供します.
初期段階の核のダイナミクスは,順序パラメータ分布とグラデーションによって支配される.
古典的な核形成理論は,原子規模の核形成過程を記述するために改訂を必要とする.
このアプローチにより,相変換や原子解像度での原子拡散などの様々な現象を研究することができます.

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