2007 NSTI Nanotechnology Conference and Trade Show - Nanotech 2007 - 10th Annual

High pressure behavior of amorphous Al2O3: a molecular dynamics study

Gonzalo Gutierrez
Universidad de Chile, CL

Glasses; structural transformation; computer simulation

We investigate the high pressure behavior of amorphous Al2O3, or alumina, by means of classical molecular dynamics. The simulations were carried out on five systems up to 1800 particles, using a pairwise potential, and cover a range of mass densities from 3.175 to 4.2 g/cm3. A detailed analysis of the interatomic distances reveals that in the low density systems there is a short range order defined essentially by a somewhat distorted (AlO5- )4 tetrahedron, in agreement with recent experimental measurement. As the density increases from 3.175 to 4.2 g/cm3, the Al-O bond length increases, the peak of Al-O coordination changes from 4 to 6 and the O-Al-O bond angle changes from 105o to 90o . These results provide firm evidence of a structural transition from a tetrahedral to an octahedral network. According to our simulation, these pressure-induced structural changes occur at pressures between 15 to 25 GPa.

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