Coupled experimental phase diagram study and thermodynamic optimization of the Li 2 O–MgO–SiO 2 system

Abstract A coupled key phase diagram study and critical evaluation and optimization of all available experimental data of the Li 2 O–MgO–SiO 2 system was performed to obtain a set of Gibbs energy functions to reproduce all the reliable phase equilibria and thermodynamic data. Differential scanning calorimetry measurements and equilibration/quenching experiments were performed in the Li 2 SiO 3 –MgO and Li 4 SiO 4 –Mg 2 SiO 4 sections, respectively, using sealed Pt capsules to prevent the volatile loss of Li. According to the present experimental results, Li 2 MgSiO 4 is the only compound present in the Li 4 SiO 4 –Mg 2 SiO 4 isopleth, which shows a peritectic melting at 1465 ± 6°C (1738 ± 6 K). The Modified Quasichemical Model, which considers short‐range ordering in the melt, was employed to describe the thermodynamic properties of the liquid phase. The Li 4 SiO 4 –Li 2 MgSiO 4 and Mg 2 SiO 4 ‐rich solid solutions were modeled using the Compound Energy Formalism.