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Computer simulation of diffusion in silica liquid under temperature and pressure
1Department of Computational Physics, Hanoi University of Science and Technology, 1 Dai Co Viet, Hanoi, Viet Nam. pkhung@fpt.vn
The European Physical Journal. E, Soft Matter
|June 25, 2013
Summary
We investigated silica liquid diffusion using a novel approach. We found that the rate of SiO(x) → SiO(x±1) changes with temperature and pressure, impacting diffusion dynamics.
Area of Science:
- Materials Science
- Physical Chemistry
- Computational Physics
Background:
- Understanding diffusion mechanisms in silica liquid is crucial for materials science.
- Previous studies have not fully elucidated the role of local structural changes on diffusion.
Purpose of the Study:
- To investigate the diffusion mechanism in silica liquid by analyzing the rate of SiO(x) → SiO(x±1) and mean square displacement.
- To explore the influence of temperature and pressure on diffusion dynamics.
Main Methods:
- Employed molecular dynamics simulations on a 1998-particle model.
- Simulations were conducted across a wide range of temperatures (3000-4500 K) and pressures (0-25.75 GPa).
Main Results:
- The rate of SiO(x) → SiO(x±1) increases with temperature and pressure.
- SiO(x) → SiO(x±1) distribution is heterogeneous, concentrating in specific regions under low temperature and ambient pressure.
- Stable units shift from SiO4 (low pressure) to SiO6 (high pressure), altering diffusion mechanisms.
Conclusions:
- Spatial localization of SiO(x) → SiO(x±1) drives diffusion heterogeneity and anomalous dynamics in silica liquid.
- This localization explains the drop in diffusivity and slow dynamics near the glass transition temperature.
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