It was recalled that the C layers of graphite slid easily against each other due to the layered structure and its weak interlayer interaction. However, the exact nature of the interlayer interaction was still unclear. Ultrasonic atomic force microscopy was applied here to highly oriented pyrolytic graphite. This revealed edge dislocations which were associated with extra half-planes. By observing dislocation behaviour under various loads, it was found that the dislocation moved laterally by 20nm as the load was increased by 80nN, and returned to its original position as the load was decreased. In order to explain this, a model was proposed for lateral motion of the dislocations. This included a spring and pinning point. The observation of a large lateral motion confirmed the very easy movement, between C layers, which explained the behaviour of the material as a solid lubricant.

Observation by Ultrasonic Atomic Force Microscopy of Reversible Displacement of Sub-Surface Dislocations in Highly Oriented Pyrolytic Graphite. T.Tsuji, K.Yamanaka: Nanotechnology, 2001, 12[3], 301-7