Melt speciation in the system Na2O-SiO2

The applicability of a speciation model to quantify the thermodynamic properties of silicate liquids was evaluated in the Na2O-SiO2 system. Based on spectroscopic data, four sodium-silicate species with various numbers of bridging oxygen atoms were considered. We used a thermodynamic model that assumed ideal mixing between the species and temperature-independent, additive heat capacities of the species.