Using typical armchair (5,5) and (10,10) single-walled carbon nanotubes as examples, a molecular dynamics study was made of the vacancy defect reconstruction and elastic properties of these single-walled carbon nanotubes of various defect ratio. The results showed that single vacancies and di-vacancies in single-walled carbon nanotubes have different reconstructions. A single vacancy reconstructs into a 5-1DB configuration when the temperature was about or higher than 2400K, and a di-vacancy reconstructed into a 5-8-5 configuration when the temperature was about, or higher than, 2600K. At room temperature, the Young’s moduli of armchair (5,5) and (10,10) single-walled carbon nanotubes with no defects were 948 and 901GPa, respectively. When the vacancy defect achieves a certain ratio, there was a sudden slow down in the curves of the Young’s moduli versus the vacancy defect ratio and a platform phenomenon emerges. The reconstruction of vacancy defects could be carried out by way of not only temperature but also the defect ratios in single-walled carbon nanotubes because of the activity of dangling bonds and their spaces. Vacancy defects will bring about a decrease in the Young’s modulus, but their reconstruction will be an important factor in stabilizing the modulus.

Effects of Vacancy Defect Reconstruction on the Elastic Properties of Carbon Nanotubes. J.Yuan, K.M.Liew: Carbon, 2009, 47[6], 1526-3