Mixed reactions: Glass durability and the mixed-alkali effect

Multiple-component oxide silicate glasses possess a complex network backbone, which results in manifolded composition property relationships. The relation between the chemical composition and durability of silicate glasses is not linear, however, this relation has always been considered somewhat relevant. Several contradicting observations on the mixed-alkali effect and its relation with their chemical alteration have been reported. Here, laboratory results and historical evidence show that the often good state of preservation of aged mixed modifier glasses is in good agreement with the influence of a mixed-modifier cation effect (MMCE) such as had been observed for other mobility- and bulk-related properties. This concordance supports the proposals made through this work concerning pore closure and lower diffusivity of mobile species under the MMCE.