Local environments of oxygen in Al2O3-SiO2 melts

Local environments of oxygen in Al2O3-SiO2 melts have been investigated via Molecular Dynamics (MD) simulation in a model containing about 3000 atoms with the Born-Mayer type pair potentials under periodic boundary conditions. The study has been carried out via determination of temperature and composition dependences of fraction of [n]O at temperatures ranged from 2100 to 7000 K in the system containing 33.33, 50.00 and 66.67 mol% Al2O3. In addition, fraction of [n]O in liquid Al2O3.2SiO2 at the density ranged from 2.60 to 4.20 g/cm3 has been estimated in order to observe the pressure dependence. The label [n]O refers to the number (n) of T atoms that are nearest neighbors to a given O (i.e. T=Al, Si and n=0,1,2, etc.). The possible relation between local environments of oxygen and dynamics of the system has been discussed. In addition, evolution of triclusters (O atoms surrounded by three cations) and their composition caused by varying temperature, composition and density of liquids has been found and presented