Molecular Dynamics Simulation of Dilute Solutions of MeO and MeF2 in the CaO–CaF2 System

Models of oxide–fluorides CaO–CaF2 with additions of MeO and MeF2 were constructed and investigated by molecular dynamics method at 1873 K. It was found out that the CaO–CaF2 system is close to the ideal solution. Structure of oxide–fluorides is topologically dense, total coordination number for Ca2+ ions changes from 5.2 to 6.8. The Ca–Me–O–F system (Me=Mg, Fe, Sr and Ba) was simulated by replacement of a few Ca2+ ions by the same number of Me2+ ions. Activity coefficients of MeO and MeF2 solutes in the CaO–CaF2 system were calculated and discussed in terms of basicity (acidity) of the solution. Analysis of MeO and MeF2 activity coefficients in the CaO–CaF2 system showed that with respect to MeO oxides, the CaO–CaF2 system could be considered as a basic solution for CaO mole fraction above 0.8–0.9. At lower CaO concentration the CaO–CaF2 system behaves as an acidic solution. With respect to MeF2 solutes, the CaO–CaF2 system may be regarded as a basic solution at about all compositions except the vicinity of pure CaF2.