Sodium diffusion in an artificially frozen silica glass,

Philippe Jund (1) , Emmanuel Sunyer (2) , Rémi Jullien (2)

1 ICGM ICMMM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
2 LCVN - Laboratoire des colloïdes, verres et nanomatériaux

We investigate the diffusion of sodium ions in an artificially frozen amorphous silica matrix via molecular dynamics simulations. The motion of the Si and O atoms is stopped at different temperatures Tfr and we study the activation energy Ea of the diffusing Na atoms. We observe an abrupt change in Ea around the glass transition temperature Tg: for Tfr < Tg high values of Ea are found whereas low values of Ea exist for Tfr > Tg. By studying the probability of the available sodium volume to percolate we show that due to the closing of the intertetrahedral SiOSi angle with increasing Tfr, this volume percolates for the high values of Tfr which explains thus the easy diffusion of the sodium ions.

Domaines: Matériaux

Philippe Jund, Emmanuel Sunyer, Rémi Jullien. Sodium diffusion in an artificially frozen silica glass,. Journal of Non-Crystalline Solids, 2006, pp.5188. ⟨10.1016/j.jnoncrysol.2006.01.163⟩. ⟨hal-00583921⟩