Optimization of the Thermodynamic Properties and Phase Diagrams of the Na 2 O–SiO 2 and K 2 O–SiO 2 Systems

Available thermodynamic and phase diagram data have been evaluated for all phases in the Na 2 O‐SiO 2 and K 2 O‐SiO 2 systems at 1 bar pressure from 298 K to above the liq‐uidus temperatures. All reliable thermodynamic and phase diagram data have been simultaneously optimized in order to obtain one set of model equations for the Gibbs energies of all phases as functions of temperature and composition. The thermodynamic properties and phase diagrams calculated from these parameters are self‐consistent. The modified quasi‐chemical model was used to represent the Gibbs energies of the molten slag phases.