Network cavity, spatial distribution of sodium and dynamics in sodium silicate melts
Network cavity, spatial distribution of sodium and dynamics in sodium silicate melts
复制标题
网络空腔、钠的空间分布和硅酸钠熔体的动力学
DOI：
10.1007/s10853-019-04232-x
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发表时间：
2019
影响因子：
4.5
通讯作者：
F. Noritake
中科院分区：
文献类型：
--
作者：
T. B. Van;P. K. Hung;P. K. Hung;L. T. Vinh;N. Ha;L. San;F. Noritake
采用分子动力学模拟方法，对硅酸钠熔体的结构和动力学行为进行了研究。模拟表明，NC包含多达6个Na，其半径从1.4到4.5 μ m不等。位于NC中的Na原子的数目强烈地依赖于NC形成原子的组成含量。模拟还表明Na和O形成化学键。静态结构是不均匀的，不同类型的NC团簇形成单独的贫Na和富Na区域，其数量和大小随SiO2含量而变化。我们还发现Si附近的钠亏损和O附近的钠盈余。随着O原子状态的改变，Na原子在网络形成物（VSNFs）的邻近空间之间重新分布。的动力学结构是异质性的高钠密度原子的NF集群和低钠密度原子的NF集群的数量所占据的单独的区域。在几百皮秒的时间里，钠原子并不是均匀地分布在整个VSNF中，而是倾向于沿着扩散路径移动。在富SiO2模型中，扩散路径清晰地出现，而在贫SiO2模型中，这些扩散路径消失。
Molecular dynamics simulation is carried out for studying the structure and dynamics of sodium silicate melts using the network cavity (NC), NF (network former) cluster and NC cluster. The simulation shows that an NC contains up to six Na, and its radius varies from 1.4 to 4.5 Å. The number of Na atoms located in NC depends strongly on the constituent content of NC-forming atoms. The simulation also reveals that Na and O form the chemical bond. The static structure is found to be heterogeneous with separate Na-poor and Na-rich regions formed by different-type NC clusters, the number and size of which vary with SiO2content. We also find the sodium deficit around Si and sodium surplus around O. As the status of O changes, Na atoms are redistributed between vicinity spaces of network former (VSNFs). The dynamical structure is heterogeneous with separate regions occupied by an NF cluster of high-sodium-density atoms and a number of NF clusters of low-sodium-density atoms. During hundreds of picoseconds, the sodium atoms are not uniformly distributed throughout VSNFs, but they prefer to move along diffusion pathways. In the SiO2-rich model, the diffusion pathways emerge clearly, while in the SiO2-poor model, these diffusion pathways disappear.