Molecular dynamics study of aging effects in supercooled Al2 O3

Using molecular dynamics simulations we investigated the effect of aging on static and dynamic properties of supercooled Al2 O3 models at the temperatures of 2100 K and 5600 K . Simulations were done in the basic cube under periodic boundary conditions containing 3000 ions with Born-Mayer type pair potentials. We obtain the changes as a function of time for the total energy and density of the system. The aging time dependence of partial radial distribution functions (PRDFs), coordination number distributions and bond-angle distributions has been studied. We compare the PRDFs for the 10% most mobile Al or O atoms with the corresponding mean PRDFs. We find the effect of aging on the dynamical heterogeneities in the system. Al and O atoms show similar dynamical heterogeneities but with a differing rate of changes during aging. Furthermore, we also find significant aging effects in mean-squared atomic displacement and diffusion constant.