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Structural and dynamical properties of sodium silicate melts: an investigation by molecular dynamics computer simulation

机译：硅酸钠熔体的结构和动力学性质：分子动力学计算机模拟研究

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We present the results of large-scale computer simulations in which we investigate the static and dynamic properties of sodium disilicate and sodium trisilicate melts. We study in detail the static properties of these systems, namely the coordination numbers, the temperature dependence of the Q((n)) species and the static structure factor, and compare them with experiments. We show that the structure is described by a partially destroyed tetrahedral SiO4 network and the homogeneously distributed sodium atoms, which are surrounded on average by 16 silicon and other sodium atoms as nearest neighbors. We compare the diffusion of the atoms in the sodium silicate systems with that in pure silica and show that it is much slower in the latter. The sodium diffusion is characterized by an activated hopping through the Si-O matrix, which is frozen with respect to the movement of the sodium atoms. We identify the elementary diffusion steps for the sodium and the oxygen diffusion and find that in the case of sodium they are related to the breaking of a Na-Na bond and in the case of oxygen to that of a Si-O bond. From the self-part of the van Hove correlation function, we recognize that at least two successive diffusion steps of a sodium atom are spatially highly correlated with each other. With the same quantity, we show that at low temperatures also the oxygen diffusion is characterized by activated hopping events. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 33]
机译：我们提供了大规模计算机仿真的结果，其中我们研究了二硅酸钠和三硅酸钠熔体的静态和动态特性。我们详细研究了这些系统的静态特性，即配位数，Q（（n））物种的温度依赖性和静态结构因子，并将它们与实验进行比较。我们表明，该结构由部分破坏的四面体SiO4网络和均匀分布的钠原子描述，钠原子平均被16个硅和其他钠原子作为最近邻居包围。我们将原子在硅酸钠体系中的扩散与在纯二氧化硅中的扩散进行了比较，并表明在后者中它的扩散要慢得多。钠扩散的特征是通过Si-O基质的活化跃变，该跃迁相对于钠原子的运动是冻结的。我们确定了钠和氧扩散的基本扩散步骤，发现在钠的情况下，它们与Na-Na键的断裂有关，在氧的情况下与Si-O键的断裂有关。从范霍夫相关函数的自已部分，我们认识到钠原子的至少两个连续扩散步骤在空间上彼此高度相关。在相同的数量下，我们表明在低温下，氧的扩散也以活化的跳跃事件为特征。 （C）2001 Elsevier Science B.V.保留所有权利。 [参考：33]

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