Plasticity in carbon nanotubes: Cooperative conservative dislocation motion

Monte Carlo simulations are used to study dislocation glide mediated plasticity in carbon nanostructures. A detailed analysis of the simulations leads to identification of a type of defect, a dislocation screened by multiple dislocation dipoles, as the mediator of plastic deformation. The defects appear under high stress conditions. The appearance of these defects is rationalized in terms of the competition between dislocation core energy and the buckling inherent to dislocation motion within an essentially two-dimensional membrane. These defects thus represent a deformation mechanism that is uniquely found in nominally two-dimensional nanostructures. The influence of these defects on the predicted mechanical properties of carbon nanostructures is discussed.