Ion-Exchange Strengthening of Glasses: Atomic Topology Matters

2015/05/28 by Mengyi Wang, Wang, Mengyi, Mathieu Bauchy +1
Materials Science · Physics and Astronomy · #Glass properties and applications #Material Dynamics and Properties #Photonic Crystals and Applications

paper · pdf · doi:10.48550/arxiv.1505.07880

Abstract

Ion-exchange is commonly used to chemically strengthen glasses, by replacing small atoms by larger ones at sub T_g temperature, thereby inducing a compressive stress. However, the resulting expansion of the glass remains lower than that predicted by the difference of molar volumes of the as-cooled glasses, an anomaly that remains poorly understood. Here, based on molecular dynamcis simulations of permanently densified sodium silicate glasses coupled with topological constraint theory, we show that the rigidity of the network controls the extent of the dilatation. Isostatic networks, which are rigid but free of eigenstress, show maximal expansion and, therefore, appear to be an attractive option to improve the toughness of glass.

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