Thermodynamic descriptions of the BaO-CaO, BaO-SrO, BaO-SiO2 and SrO-SiO2 systems

In order to provide an adequate basis for extrapolation into higher order oxide systems, a thermodynamic assessment was performed on the BaO-CaO, BaO-SrO, BaO-SiO2 and SrO-SiO2 binary systems by critically evaluating the available experimental data and previous thermodynamic modeling. Associate solution model was applied to describe the molten phase in the BaO-SiO2 and SrO-SiO2 systems. Two associates, Ba2SiO4 and BaSiO3, were tested and compared with the previous assessment with only one associate Ba2SiO4. A set of self-consistent thermodynamic parameters for the descriptions of each oxide system is presented. The phase diagrams, thermodynamic properties including activities, standard enthalpies of formation at 298.15 K and enthalpy increments were calculated according to the thermodynamic parameters acquired in the present work. For the BaO-SiO2 and SrO-SiO2 systems, the site fractions of species in the liquid were calculated to illustrate the chemical short-range order tendency of the compound(s) in the liquid phase.