Effect of the Stone–Wales defect on the structure and mechanical properties of single-wall carbon nanotubes in axial stretch and twist

Abstract

The effect of the Stone–Wales defect due to the rotation of a pair of neighboring atoms on the equilibrium structure and mechanical properties of single-wall carbon nanotubes in axial stretch and twist is considered. The position of carbon atoms in a test section consisting of a number of repeated units hosting a solitary Stone–Wales defect is computed by minimizing the Tersoff–Brenner potential. The energy invested in the defect is found to decrease as the radius of the nanotube becomes smaller. Numerical computations for nanotubes with zigzag and armchair chiralities show that inclined, axial, and circumferential defect orientations have a strong influence on the mechanical response in axial stretch and twist. Stretching may cause the defect energy to become negative, revealing the possibility of spontaneous defect formation leading to failure. In some cases, stretching may eliminate the defect and purify the nanotube. When the tube is twisted around its axis, a neck develops at the location of the defect, signaling possible disintegration.