Accurate knowledge of the diffusion mechanism of network-forming elements (NFs) in silicate liquids is essential for modeling transport properties such as the shear viscosity. Previous studies focusing on alkali diffusion in silicate liquids/glasses have revealed that alkali ions diffuse via thermal hopping event. However, the diffusion mechanism for NFs remains poorly understood. Herein, molecular dynamics simulations and various analysis methods based on chemical species and bond-breaking events are presented. The analysis results reveal the following diffusion mechanism of NF. Oxygen atoms diffuse similar to a site exchange through the non-bridging oxygen (NBO) state. By contrast, Si diffusion is unlike the exchange regime, and occurs gradually through a bond-exchange event, deforming the network. The dominant mechanism is a rare long flight during Si—O bond breaking, and most bond-breaking events do not contribute, similar to local events. The supporting mechanism is network deformation after a bond-exchange event.

准确了解网络形成元素（NFs）在硅酸盐液体中的扩散机理对于建模运输特性（例如剪切粘度）至关重要。先前针对碱在硅酸盐液体/玻璃中扩散的研究表明，碱离子通过热跳跃事件扩散。但是，对于NFs的扩散机制仍然知之甚少。本文介绍了基于化学物种和键断裂事件的分子动力学模拟和各种分析方法。分析结果揭示了NF的以下扩散机理。氧原子通过非桥接氧（NBO）状态扩散，类似于位点交换。相比之下，Si扩散与交换机制不同，而是通过键交换事件逐渐发生，从而使网络变形。占主导地位的机制是在Si-O键断裂期间发生罕见的长途飞行，并且与本地事件类似，大多数键断裂事件没有贡献。支撑机制是键交换事件后的网络变形。