Structural transformation of graphite by passage of electric current

The passage of an electric current through graphite, or few-layer graphene, at high temperatures can produce dramatic structural transformations. These involve the formation of carbon structures with highly irregular morphologies, displaying many unusual features, including nanotube–graphene junctions. A number of studies of the transformed carbon have been carried out, but many aspects of its structure and formation mechanism are still not understood. This paper summarises the studies that have been made on this phenomenon, drawing mainly on the author’s own work. It is shown, using high-tilt transmission electron microscopy imaging, that the transformed carbon is largely flat, and not three-dimensional as suggested in previous papers. The possible mechanism of the transformations is discussed