Sodium diffusion in alkali silicate glass by molecular dynamics

Sodium ion diffusion in a sodium silicate glass (22Na2O ⋅ 53SiO2) was studied by molecular dynamics. Sodium diffuses by hopping from one interstitial site to another. At high temperatures reliable sodium diffusion coefficients and activation energies are determined. These are in good agreement with those extrapolated from experimental data. It is suggest that simple Born–Mayer potentials to describe ionic bonding can be used for estimating transport properties. Glass forming is followed as the temperature is lowered in simulated cooling schedules.