Molecular dynamics study of CaO-Al2O3 melts

Molecular dynamics simulations with Born-Mayer pair potentials taking into account the effective dipole-dipole interaction were used to study CaO-Al2O3 oxides at 1873 K. In each simulation, the system included about 500 ions in a cubic central box with periodic boundary conditions. The thermodynamic, structural, and topological properties of the system were calculated. The inclusion of the dipole-dipole interaction allowed reasonable agreement with the experimental heats of formation to be achieved. According to the simulation results, all of the oxides have a loose structure. At Al2O3 contents of up to 50 mol %, the Al ions are predominantly in tetrahedral coordination. In the melts containing greater than or equal to 25 mol % Al2O3, the Al3+ subsystem is fully polymerized. The electrical conductivity of the melts exceeds the error of determination only for CaO-rich compositions. The self-diffusion coefficients of the ions are very low.