Models of oxide–fluorides CaO–CaF
2 with additions of MeO and MeF
2 were constructed and investigated by molecular dynamics method at 1873 K. It was found out that the CaO–CaF
2 system is close to the ideal solution. Structure of oxide–fluorides is topologically dense, total coordination number for Ca
2+ 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 Ca
2+ ions by the same number of Me
2+ ions. Activity coefficients of MeO and MeF
2 solutes in the CaO–CaF
2 system were calculated and discussed in terms of basicity (acidity) of the solution. Analysis of MeO and MeF
2 activity coefficients in the CaO–CaF
2 system showed that with respect to MeO oxides, the CaO–CaF
2 system could be considered as a basic solution for CaO mole fraction above 0.8–0.9. At lower CaO concentration the CaO–CaF
2 system behaves as an acidic solution. With respect to MeF
2 solutes, the CaO–CaF
2 system may be regarded as a basic solution at about all compositions except the vicinity of pure CaF
2.
View full abstract