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Reversible phase transformations between Pb nanocrystals and a viscous liquid-like phase.
Wenjing Zheng1, Jun Kang2,3, Kaiyang Niu4
1School of Energy and Power Engineering, North University of China, Taiyuan 030051, China.
Science Advances
|June 19, 2024
Summary
Researchers observed reversible phase transformations between lead (Pb) nanocrystals and a liquid-like phase. This discovery, achieved using advanced microscopy, offers new insights into material behavior under electron beams.
Area of Science:
- Materials Science
- Nanotechnology
- Physical Chemistry
Background:
- Phase transformations are crucial in materials science but challenging to study, especially when induced by solid-liquid reactions.
- Understanding the mechanisms of these transformations is vital for both fundamental science and applied engineering.
Purpose of the Study:
- To investigate and characterize reversible phase transformations between metal nanocrystals and a liquid-like phase.
- To elucidate the mechanisms driving these transformations under specific conditions.
Main Methods:
- In situ liquid cell transmission electron microscopy (LC-TEM) was employed to observe the transformations in real-time.
- Electron current density was modulated to induce and control the reversible phase changes.
- Density functional theory (DFT) and molecular dynamics (MD) calculations were used to support experimental observations.
Main Results:
- Reversible phase transformations between lead (Pb) nanocrystals and a viscous liquid-like phase were successfully demonstrated.
- The transformations were controlled by varying electron current density (1000–3000 e- Å-2 s-1).
- The liquid-like phase exhibited short-range ordering with a Pb-Pb distance of 0.5 nm and was identified as a metal-organic product.
Conclusions:
- The viscous liquid-like phase arises from the reaction of Pb with CH3O fragments from the triethylene glycol solution under electron beam irradiation.
- This study reveals a novel mechanism for reversible phase transformation in metal nanocrystals.
- The findings suggest potential broad applications in materials engineering and nanotechnology.
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