A Study of Mixed Alkali Effect of Na2O-K2O-SiO2 Glasses by Molecular Dynamics Simulation

The mechanism of the mixed alkali effect of 0.25{xK2O-(1−x) Na2O}-0.75SiO2 glasses was studied by using the molecular dynamics (MD) simulation. MD simulations of this work reproduced the mixed alkali effect. In addition, the tendency of molar volume with temperature change by this work was reproduced in the experimental tendency. The mixing of alkali was independent to the network structure of Si and O. The free volume in the glass systems indicated that high condensed packing occurred by alkali mixing. The results of 39K133KSi3O7 glass showed that the mass difference from one alkali metal ion decreased the diffusion of the other alkali metal ion. The mixed alkali effect was considered to relate to both the size- and the mass-differences of the coexisting alkali metal ions.