Composition dependence of static and dynamic heterogeneities in simulated liquid aluminum silicates

Abstract

We study the composition dependence of static and dynamic heterogeneities in simulated Al2 O3 -Si O2 melts containing 33.33, 50, and 66.67 mol % Al2 O3 in a model containing about 3000 atoms under periodic boundary conditions with the Born-Mayer-type interatomic potentials via molecular-dynamics simulations. We found composition dependence of coordination number distributions, bond-angle distributions, partial radial distribution functions, mean interatomic distances, triclusters, and microphases of Al-O and Si-O local networks in the system at different temperatures. Moreover, the composition dependence of dynamical heterogeneity in the system has been found via the non-Gaussian parameter of particles, the spatial correlations of the 10% most mobile and immobile particles, and the temperature dependence of the mean cluster size of the most mobile or immobile particles. The temperature dependence of the mean cluster size of most mobile and immobile particles in the system shows different laws. We found no relations between particle mobility and local particle environment in the system. Calculations showed that dynamical heterogeneity in multicomponent liquids has specific features different from those in simple oxides. In addition, the composition dependence of diffusion constant has been observed and discussed. © 2007 The American Physical Society.