Surface structure and structural point defects of liquid and amorphous aluminosilicate nanoparticles

Abstract

The surface structure of liquid and amorphous aluminosilicate nanoparticles of composition Al2O32SiO2 has been investigated in a model of different sizes ranging from 2.0 to 5.0nm with the Born-Mayer type pair potential under non-periodic boundary conditions. Models have been obtained by cooling from the melts at a constant density of 2.6gcm-3 via molecular dynamics (MD) simulation. The surface structure has been investigated via the coordination number, bond-angle distributions and structural point defects. Calculations show that surface effects on surface static and thermodynamic properties of models are significant according to the change in the number of Al atoms in the surface layers. Evolution of the local environment of oxygen in the surface shell of nanoparticles upon cooling from the melt toward the glassy state was also found and discussed. In addition, the nanosize dependence of the glass transition temperature was presented. © 2008 IOP Publishing Ltd.