Coupled experimental phase diagram study and thermodynamic optimization of the Li2O–MgO–SiO2 system

Abstract

AbstractA coupled key phase diagram study and critical evaluation and optimization of all available experimental data of the Li2O–MgO–SiO2 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 Li2SiO3–MgO and Li4SiO4–Mg2SiO4 sections, respectively, using sealed Pt capsules to prevent the volatile loss of Li. According to the present experimental results, Li2MgSiO4 is the only compound present in the Li4SiO4–Mg2SiO4 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 Li4SiO4–Li2MgSiO4 and Mg2SiO4‐rich solid solutions were modeled using the Compound Energy Formalism.