Coupled phase diagram experiments and thermodynamic optimization of the binary Li2O-MgO and Li2O-CaO systems and ternary Li2O-MgO-CaO system

A key phase diagram study of the Li2O-MgO and Li2O-CaO systems at 1 atm was performed using equilibration/quenching experiments and differential scanning calorimetry measurements with sealed 90Pt-10Rh crucibles. In particular, the eutectic temperatures of both systems and the solubility of Li2O in solid MgO and CaO were properly measured for the first time. The eutectic temperatures of the Li2O-MgO and Li2O-CaO systems were determined to be 1696 ± 6 K (1423 ± 6 °C) and 1617 ± 6 K (1344 ± 6 °C), respectively. A solubility of 2.6 mol% (1.9 wt%) Li2O in solid MgO was measured at 1743 K (1470 °C) and no detectable solubility of Li2O in solid CaO was determined. The present experimental results were employed for the thermodynamic modeling of the binary Li2O-MgO and Li2O-CaO systems. The phase diagrams for the binary Li2O-MgO and Li2O-CaO systems were constructed for the first time, and the phase diagram of the ternary Li2O-MgO-CaO system was predicted from the binary descriptions.