Pressure- and temperature-induced structural changes in simulated amorphous Al2O3·2SiO2

Abstract

We investigated the pressure- and temperature-induced structural changes in amorphous Al2O3·2SiO2 by a molecular dynamics method. Simulations were done in a basic cube under periodic boundary conditions containing 3025 ions with the Born-Mayer type pair potentials. In order to study the structural changes, nine models of amorphous Al 2O3·2SiO2 at 350 K and at densities ranging from 2.6 g/cm-3 to 4.2 g/cm-3 have been built. The microstructure of the amorphous Al2O3·2SiO 2 has been analyzed through the pair radial distribution functions, coordination number, bond-angle distributions, and interatomic distances. Moreover, we found clear evidence of structural changes from a tetrahedral to an octahedral network structure in the system upon compression. We also found that the changes reverse from an octahedral to a tetrahedral network structure by subsequent heating of an octahedral structure model from 350 K to 1610 K at constant external pressure P = 0 GPa. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.