高校地质学报Issue(3)：456-462,7.
熔融SiO2中原子自扩散性质的分子动力学模拟
Molecular Dynamics Study of Self-Diffusion of Silica and Oxygen in Silica Melt
摘要
Abstract
The diffusivity of elements in mineral controls the processes of ion exchange, isotope fractionation, and phase transition. As one of the most important components of silicate melts, SiO2 plays a very important role in the earth mantle structure and the dynamics process. This paper focuses on the ion diffusion mechanism in silica melt and the corresponding pressure when the self-diffusion coefficient reaches its maximum value. We calculated the changing process of Si and O ions, self-diffusion coefficient at temperatures of 3000 K by using the molecular dynamics (MD) simulation which contains 4500 ions in the silica melt with Morse stretch potential. Calculations show that both Si and O self-diffusion coefficients increase at initial compression and reach maximum values at 17.5 GPa. Self-diffusion coefficients for O are slightly greater than that for Si. The Si and O ions , diffusion feature is caused by a defect-controlled transport mechanism and the five-fold coordination structure of Si ion is the main reason for the rise of the diffusion coefficients in accord with the increasing pressure. The fact that the diffusion coefficient reaches its maximum value means the change in the formation of five-fold Si in the liquid silica. This paper also calculated the relationship between the average volume of [SiO2] unit and the pressure, which agrees well with the results of our experiment.关键词
Morse stretch势场/自扩散系数/SiO2/分子动力学Key words
morse stretch potential/self-diffusion coefficient/SiO2/molecular dynamics分类
天文与地球科学引用本文复制引用
孙义程,周会群,尹坤,黄倩,徐士进..熔融SiO2中原子自扩散性质的分子动力学模拟[J].高校地质学报,2013,(3):456-462,7.基金项目
国家自然科学基金项目 （）
