Abstract
Calculations based on an atomistic model have been carried out to determine interaction energies of cation and anion vacancies in a region approximately 26 by 46 (where 6 is the magnitude of the dislocation's Burgers vector) surrounding an α/2 [110] edge dislocation in a model MgO crystal. The atomistic results are compared to predictions of a model based on linear isotropic elasticity theory. Throughout most of the core region investigated, the atomistic results differ both qualitatively and quantitatively from the predictions of the linear elastic model. At the furthest defect separation distances investigated, the predictions of the two theories show qualitative—though generally not quantitative—agreement. The variation of the interaction energy as a function of local equilibrium vacancy position from the centre of the dislocation is complex, depending on both angle, θ, and defect separation, R. Ignoring the θ-dependence, the steepest part of the spatial variation of the binding energy has an approximately R −2 dependence. This is in disagreement with an R −9 dependence inferred from an internal-friction study of neutron-irradiated MgO. Possible reasons for this disagreement are discussed.
