Compositional control of the photoelastic response of silicate glasses

The stress-induced birefringence (termed photoelastic response) in oxide glasses has important consequences for several applications. In this work, we provide new insights into the structural origins of the photoelastic response of silicate glasses by determining the composition dependence of the stress optic coefficient (C) of forty-nine silicate glasses containing different alkali and alkaline earth oxides. We find that the value of C decreases with increasing modifier-to-silica ratio and increases with alumina-to-silica ratio. The scaling of stress optic coefficient with composition can be predicted based on the average ratio of bond metallicity to cation coordination number in the glass, which varies as a function of composition. This is evidence that the details of the glass network structure need to be considered in order to account accurately for the composition dependence of C, a result that is consistent with a previously proposed empirical model and with topological constraint theory. Our results enable an improved control of the photoelastic response of silicate glasses through compositional design.