Melting and liquid structure of aluminum oxide using a molecular-dynamics simulation

The radial distribution function G(r) for liquid aluminum oxide (corundum) is calculated by means of the two-phase molecular-dynamics method utilizing a previously developed pairwise interatomic potential. Our results agree very well with the recent experimental results of Ansell et al. [Phys. Rev. Lett. 78, 464 (1997)], confirming a tetrahedral aluminum coordination in the liquid phase. The calculated melting curve is in good agreement with existing experimental data up to 25 GPa. The melting is calculated to involve a radical change from octahedral to tetrahedral coordination and an accompanying large volume expansion of about 20%, in good agreement with experiment.