An investigation of the walls of defective multi-wall carbon nanotube suggested a possible mechanism for the formation of defective structures. A generalized model was proposed for the multi-walled carbon nanotube, which consisted of a catalyst part, an embryo part and a fully-grown part. It was claimed that the weak embryo portion of the multi-walled carbon nanotube was structurally undeveloped. The stress due to pressure imbalance between the inside and the outside of the multi-walled carbon nanotube during growth, together with axial loads at the embryo portion caused distortion, which was the source of bending and made the walls of the multi-walled carbon nanotube non-concentric. In the later stage, the stressed embryo retained the distorted structure and was transformed into a fully-grown defective carbon nanotube.

Origin of Structural Defects in Multiwall Carbon Nanotube. K.P.S.S.Hembram, G.M.Rao: Materials Letters, 2012, 72, 68-70