2005 Volume 46 Issue 3 Pages 643-650
The thermodynamic properties for the CaO-CaF2, BaO-CaO and BaO-CaF2 systems were calculated by molecular dynamics (MD) simulation using the simple Born-Mayer-Huggins type potential model. The interatomic potential parameters were determined by fitting the thermodynamic properties of pure CaO, BaO and CaF2. The calculated thermodynamic properties for CaO, BaO and CaF2 were in good agreement with measured results, and the superionic conductivity on the solid-solid phase transition of CaF2 has also been successfully assessed by MD simulation. The ΔHM, ΔSM and ΔGM for each binary system were calculated based on the thermodynamic parameters obtained by MD simulation and thermodynamic solution model. The calculated enthalpy interaction parameters for the BaO-CaF2 system represented the possibility of formation of the compounds such as BaO·CaF2 in the BaO-CaF2 system. The calculated phase diagrams for the CaO-CaF2 and BaO-CaO systems were in good agreement with experimentally measured and CALPHAD method results. The calculated eutectic points for the CaO-CaF2 and BaO-CaO systems were about 20 mol% CaO at 1650 K and about 20 mol% CaO at 2050 K, respectively. The BaO-CaF2 system has also been estimated the liquidus lines in the CaF2-rich and BaO-rich region by MD simulation.