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

Keywords:
Glasses; structural transformation; computer simulation

Abstract:
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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