Tearing, folding and deformation of a carbon-carbon sp2-bonded network

A monolayer and a few layers of carbon sp(2)-bonded networks were torn and folded by the tip of an atomic force microscope at the steps on newly cleaved highly oriented pyrolytic graphite. It was found that the preferential breaking directions and folding axes are along the symmetry directions of the graphite hexagonal structure. Depending on the force exerted by the tip, breaking may occur along other directions. The torn part of the graphene sheet can even be stretched and deformed, and does not resume its original shape after release from the tip. (C) 2006 Elsevier Ltd. All rights reserved.