Computer simulation of noncrystalline ionic-covalent oxides in the SiO2-CaO-FeO system

Molecular dynamics simulations were used to study self-diffusion in noncrystalline SiO2-CaO-Feo oxides at 1873 K. The simulations were carried out in the purely ionic and ionic-covalent approximations. In the latter case, use was made of the "semiclassical" molecular dynamics simulation method proposed earlier for studying ionic-covalent oxide systems. At SiO2 contents below 40 mol %, the self-diffusion coefficients of the constituent ions depend little on the oxide composition and the assumed character of bonding. As the SiO2 content increases to 40 mol % and above, the ion mobility drops sharply. The thermodynamic and structural parameters derived from the ionic-covalent simulations of the ternary oxides are in reasonable agreement with experimental data.