It was shown that pentagon-heptagon (5-7) pair defects in carbon nanotube play an important role as the center of vacancy reconstruction using tight-binding molecular dynamics simulations and ab initio total energy calculations. Single vacancy defect diffuses toward and coalesces with 5-7 pair defects and the coalescence structure was reconstructed into a new and more stable 5-7 pair defect plus an adatom by an exchange mechanism. In the case of four single vacancy defects, the vacancy defects coalesce with 5-7 pair defects and form defect structures with non-hexagonal rings. Finally, these defective structures reconstruct into two new 5-7 pair defects.

The Role of Pentagon-Heptagon Pair Defect in Carbon Nanotube: the Center of Vacancy Reconstruction. G.D.Lee, C.Z.Wang, E.Yoon, N.M.Hwang, K.M.Ho: Applied Physics Letters, 2010, 97[9], 093106