Calculation of thermodynamic properties and phase diagrams for the CaO-CaF 2, BaO-CaO and BaO-CaF 2 systems by molecular dynamics simulation

Abstract

The thermodynamic properties for the CaO-CaF 2, BaO-CaO and BaO-CaF 2 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 CaF 2. The calculated thermodynamic properties for CaO, BaO and CaF 2 were in good agreement with measured results, and the superionic conductivity on the solid-solid phase transition of CaF 2 has also been successfully assessed by MD simulation. The ΔH M, ΔS M and ΔG M 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-CaF 2 system represented the possibility of formation of the compounds such as BaO·CaF 2 in the BaO-CaF 2 system. The calculated phase diagrams for the CaO-CaF 2 and BaO-CaO systems were in good agreement with experimentally measured and CALPHAD method results. The calculated eutectic points for the CaO-CaF 2 and BaO-CaO systems were about 20mol% CaO at 1650 K and about 20mol% CaO at 2050 K, respectively. The BaO-CaF 2 system has also been estimated the liquidus lines in the CaF 2-rich and BaO-rich region by MD simulation. © 2005 The Mining and Materials Processing Institute of Japan.