The core structures of basal dislocations in graphite in a nanoscale continuum framework were calculated. The model consisted of a stack of buffered Kirchhoff plates where the plates represented the covalent interactions within individual graphene sheets and the buffer layers represented the secondary interactions between them. In the mid-plane of the buffer layers, cohesive surfaces were introduced to account for the nonlinear deformations due to basal dislocations. The cohesive surface separation was governed by using an empirical 4-8 Lennard-Jones potential. Meanwhile, their relative shear sliding was governed by using a newly proposed empirical periodic stacking-fault potential. With these potentials, the core structures of full dislocations and partials were calculated and examined. It was shown that the full dislocations automatically split into partials that repel each other. The core sizes of individual partials, measured between peak stresses, were about 5 nm wide for the edge component and slightly narrower for the screw component. Since these sizes were about 10 times the lattice constant, they lend credence to the continuum model of basal dislocation cores in graphite. It was also shown that when the dislocations were densely packed on the same glide plane, i.e. in a pile-up, with spacing one to two times the core size, the split partials retain their individual identity with well-defined and well-separated stress peaks. Meanwhile, the membrane normal stresses in the graphene sheets rise considerably at the pile-up tips which, in turn, may provoke further deformation and damage modes such as kinking and delamination.

Nanoscale Continuum Calculation of Basal Dislocation Core Structures in Graphite. B.Yang, M.W.Barsoum, R.M.Rethinam: Philosophical Magazine, 2011, 91[10], 1441-14