Y. Yu, M. Wang, N.M. Anoop Krishnan, M.M. Smedskjaer, K. Deenamma Vargheese, J.C. Mauro, M. Balonis, and M. Bauchy
Journal of Non-Crystalline Solids 489, 16 (2018)
Publication year: 2018

The origin of the various manifestations of the mixed modifier effect in silicate glasses remains poorly under- stood. Here, based on molecular dynamics simulations, we investigate the origin of a negative deviation from linearity in the hardness of a series of mixed alkaline earth aluminosilicate glasses. The minimum of hardness is shown to arise from a maximum propensity for shear flow deformations in mixed compositions. We demonstrate that this anomalous behavior originates from the existence of local structural instabilities in mixed compositions arising from a mismatch between the modifiers and the rest of the silicate network. Overall, we suggest that the mixed modifier effect manifests itself as a competition between the thermodynamic driving force for structural relaxation and the kinetics thereof.