Abstract
This study focuses on the mechanisms of pipe diffusion and the kinetic of point defect diffusion along dislocation line in MgO. We developed a numerical approach, based on atomic scale calculations and the use of the elasticity theory, to determine the migration energies of point defects. The kinetic of diffusion along the dislocation is then evaluated according to a on-lattice atomistic kinetic Monte Carlo algorithm informed by atomistic simulations. We show that edge dislocation in MgO behaves as a strong sink for vacancies which, combined with a lower migration energy at dislocation core region, strongly enhances the diffusion of point defect in the vicinity of the dislocation with respect to the bulk material. At low and intermediate temperatures, pipe diffusion results in an increase of the diffusivity of several order of magnitude. Accounting more precisely for the effect of pipe diffusion may therefore be a key to reconcile the experimentally measured scattering of diffusivity in MgO.
NSTL
Elsevier