Molecular dynamics study of the self-diffusion of ions in B2O3 melt at high pressure

Molecular dynamics (MD) simulations were carried out in order to investigat e the structure and transport properties of boron oxide melt, as a function of pressure. The simulations show a rapid initial increase in the diffusio n coefficients of boron and oxygen ions to similar to5-7 GPa, followed by a slower increase from 7 to 14 GPa, The increase in ion diffusivities is cor related with an increase in the proportion of BO4 to BO3 units. These resul ts can be used to help rationalize an increase in growth rate of boron subo xide (B6O) crystals, observed from B2O3-B6O melts in the 0-4 GPa pressure r ange.