Glass formation in simulated high-density Al2O 3·2SiO2

Abstract

Glass formation in octahedral phase of Al2O3· 2SiO2 has been investigated via Molecular Dynamics (MD) simulation in a model containing 3025 atoms with the Born-Mayer type pair potentials under periodic boundary conditions. The system has been cooled from 7000 K to 350 K at a cooling rate γ = 4.375 × 1013 K/s and at a fixed density of 4.00 g/cm3 corresponding to the octahedral network structure phase of the system. Glass transition temperature Tg has been obtained via temperature dependence of the system potential energy. Evolution of structure upon cooling from the melt has been found and discussed. Structural properties of an amorphous model obtained at the temperature of 350 K have been analyzed in detail through the partial radial distribution functions (PRDF), coordination number distributions, bond-angle distributions and interatomic distances, compared with those for the model at the same temperature and density obtained by compression of the initial 2.60 g/cm3 amorphous one. The local environment of oxygen and the problem of triclusters in high-density phase has been calculated and discussed. © 2008 World Scientific Publishing Company.