Structural properties of liquidAl2O3:A molecular dynamics study

Molecular dynamics (MD) simulations of liquid aluminum oxide $\left({\mathrm{Al}}_2{\mathrm{O}}_3\right)$ were carried out on a system with up to 1800 particles, using a pairwise potential. All simulations were done in the microcanonical ensemble, for two densities, $3.0$ and $3.175\hspace{0.5em}\mathrm{g}/{\mathrm{cm}}^3,$ at temperatures of 2200, 2600, and 3000 K. A detailed analysis of the interatomic distances, given by the partial pair-distribution functions and the bond-angles distribution, reveals that in the liquid state there is a short range order dominated by a somewhat distorted $({\mathrm{AlO}}_4{)}^{5-}$ tetrahedron, in agreement with recent experimental measurements. This conclusion is supported by the distribution of nearest-neighbor coordinations, where more than 60% of Al atoms have four O as nearest neighbors. This finding does not change over the explored temperature range. Because of the presence of twofold rings, the connectivity of $({\mathrm{AlO}}_4{)}^{5-}$ units consists of corner, edge, and face sharing tetrahedra. Based in this structural information, i.e., bond lengths, coordination numbers, bond-angle distributions, and ring statistics, our MD simulation allows us to put forward a possible structure of liquid ${\mathrm{Al}}_2{\mathrm{O}}_3.$