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Published on: December 20, 2012
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Dynamics and Diffusion Mechanism of Low-Density Liquid Silicon
1Key Laboratory of Micro and Nano Photonic Structures (MoE) and Department of Optical Science and Engineering, Fudan University , Shanghai, 200433, China.
The Journal of Physical Chemistry. B
|November 6, 2015
Summary
Liquid silicon exhibits unique atomic diffusion behaviors, strongly linked to tetrahedral structures. This study reveals hopping diffusion mechanisms in low-density liquid silicon, offering insights into supercooled liquids.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Computational Chemistry
Background:
- A liquid-liquid phase transition (LLPT) in supercooled water explains its anomalies.
- LLPT is hypothesized for supercooled silicon, leading to a low-density, high-viscosity liquid phase.
- Understanding atomic diffusion in this phase is crucial for its characterization.
Purpose of the Study:
- Investigate atomic diffusion mechanisms in low-density liquid silicon.
- Correlate diffusion with local tetrahedral structures.
- Elucidate the role of directional bonding in diffusion.
Main Methods:
- Molecular dynamics simulations.
- Utilized the classical Stillinger-Weber (SW) potential for silicon.
- Analyzed atomic trajectories and structural ordering.
Main Results:
- Atomic diffusion strongly correlates with local tetrahedral geometries.
- Observed short-range hopping diffusion processes accumulating into long-range random motion.
- Identified a relationship between dynamical heterogeneity and hopping diffusion.
- Diffusion mechanism linked to directional bonding in distorted tetrahedral networks.
Conclusions:
- Low-density liquid silicon exhibits unique diffusion behavior driven by tetrahedral ordering.
- Hopping diffusion is a key mechanism, influenced by directional bonding.
- Findings provide insights into highly viscous liquid silicon and suggest similar behavior in other tetrahedral liquids like carbon and germanium.
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