A dislocation mechanism was proposed which explained the formation of multi- and single-sheet nanotubes, and a disclination mechanism which accounted for the formation of nanocones. According to the proposed mechanism, rolling up of a graphite sheet gave rise to elastic stresses which were released via the slip of dislocations having edge and screw components. Each closure of the sheet proceeded via a zipper mechanism, and resulted in the formation of a single-sheet nanotube. The number of dislocation slips was equal to the number of layers in a multi-sheet nanotube.

Dislocation Mechanism of Nanotube Formation. A.V.Pokropivny, V.V.Pokropivny: Technical Physics Letters, 2003, 29[6], 494-5