Eur. Phys. J. B (2017) 90: 185
https://doi.org/10.1140/epjb/e2017-80169-5

Regular Article

Study of diffusion and local structure of sodium-silicate liquid: the molecular dynamic simulation

¹ Simulation in Materials Science Research Group, Ton Duc Thang University, Ho Chi Minh City, Vietnam
² Faculty of Electrical and Electronics Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam
³ Graduate Faculty of Interdisciplinary Research, University of Yamanashi, Yamanashi City, Japan
⁴ Computational Astrophysics Laboratory, RIKEN, Saitama City, Japan
⁵ Department of Computational Physics, Hanoi University of Science and Technology, Hanoi City, Vietnam

^a e-mail: phamkhachung@tdt.edu.vn
^b e-mail: lethevinh@tdt.edu.vn

Received: 22 March 2017
Received in final form: 28 May 2017
Published online: 9 October 2017

Abstract

A systematic analysis on sodium-silicate melt with various silica contents was carried out. The simulation revealed two diffusion mechanisms occurred in the melt: the bond-breaking and hopping between sites. The local structure was analyzed through T-simplexes. It was revealed that T-clusters have a non-spherical shape and represent the diffusion channel, in which Na atoms are dominant, but no any O atoms are located. The SiO₂-poor melt acquires a long channel. In contrast, the SiO₂-rich melt consists of unconnected short channels. The simulation also revealed the immobile and mobile regions which differ in local structure and constituent composition. We propose a new CL-function to characterizing the spatial distribution of different atom component. The spatial distribution of mobile and immobile atoms is found quite different. In particular, the immobile atoms are concentrated in high-density regions possessing very large density of immobile atoms. The spatial distribution of mobile atoms in contrast is more homogeneous.