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.