Thermodynamic analysis of binary liquid silicates and prediction of ternary solution properties by modified quasichemical equations
Abstract
Modified quasichemical equations, developed for the analysis of the thermodynamic properties of structurally ordered liquid solutions, are shown to be well-suited for use with molten silicates. For binary systems, these equations have been coupled with a least-squares optimization computer program to analyse simultaneously all thermodynamic data including phase diagrams, Gibbs energies and enthalpies of formation of compounds, activities, enthalpies of mixing, entropies of fusion, miscibility gaps, etc. In this manner, data for several binary systems have been analysed and represented with a small number of parameters. In the present article, results for the SiO 2-MgO, SiO 2-Na 2O and MgO-CaO systems are presented. The resulting equations represent all the binary data, including the phase diagrams, within or virtually within experimental error limits. From the modified quasichemical equations for ternary systems, ternary thermodynamic properties can be approximated solely from data from the subsidiary binary systems. Results for the SiO 2-CaO-Na 2O, SiO 2-CaO-MgO, and SiO 2-MgO-FeO systems are in excellent agreement with measured ternary data. Predictions for the quaternary system SiO 2-MgO-CaO-Na 2O are also presented.
- Publication:
-
Geochimica et Cosmochimica Acta
- Pub Date:
- January 1987
- DOI:
- 10.1016/0016-7037(87)90009-3
- Bibcode:
- 1987GeCoA..51...85B