Atomistic simulation studies on the effect of pressure on diffusion at the MgO 410/[001] tilt grain boundary

We have used atomistic simulation techniques to examine the effect of pressure on atom transport in the 410/[001] tilt grain boundary of MgO. The approach was to compare the diffusion pathways and migration energies for cation and anion vacancy migration at 0 and 40 GPa. The effect of pressure was to increase the migration energies and to increase the preference for vacancies to reside at the boundary rather than at bulk lattice sited. Furthermore, if present in any significant concentration, the vacancies will be bound and remain bound during diffusion, which results in the migration energies being similar to those found for diffusion in the bulk. Hence the results suggest that, as expected, the boundary has higher diffusivities than the bulk but that this is a result of the larger number of mobile species rather than lower migration energies.