Nguyen Thi Thanh Ha, Tran Thuy Duong, Nguyen Hoai Anh

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Molecular dynamics simulation of sodium-silicate has been carried out to investigate the microstructural transformation and diffusion mechanism. The microstructure of sodium silicate is studied by the pair radial distribution function, distribution of SiOx (x=4,5,6), OSiy (y=2,3) basic unit, bond angle distribution. The simulation results show that the structure of sodium silicate occurs the transformation from a tetrahedral structure to an octahedral structure under pressure. The additional network-modifying cation oxide breaking up this network by the generation of non-bridging O atoms and it has a slight effect on the topology of SiOx and OSiy units. Moreover, the diffusion of network- former atom in sodium-silicate melt is anomaly and diffusion coefficient for sodium atom is much larger than for oxygen or silicon atom. The simulation proves two diffusion mechanisms of the network-former atoms and modifier atoms.

Keywords: Molecular dynamics, microstructural transformation, mechanism diffusion, sodium-silicate


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