Molecular dynamics simulation studies of displacement cascade induced defects in gold nanotubes

In order to investigate the defects induced by displacement cascade in gold nanotubes, primary knock-on atoms with kinetic energies of 1 keV were introduced at the exterior surface of the nanotubes. The evolution of the collision cascade as well as the defects generated in the nanotube were studied using molecular dynamics simulation. We found that point defects and stacking faults were induced by the cascade. The interior surface of the nanotube acts as the sinks to absorb the point defects as the same as the exterior surface does, especially when the distance between them is decreased. Consequently, both the two surfaces influence the time evolution and the residual number of point defects in the nanotubes. In the gold nanotubes with fixed external diameter, the number of interstitials is decreased with the internal diameter increasing, while the number of vacancies does not show a clear trend with the variation of the internal diameters. The probability of formation of stacking faults is higher in gold nanotubes with larger internal diameters which caused by the fact that the formation of stacking faults is facilitated by the interior surface. The results show that, due to the specific geometry of the nanotubes, the evolution and the production of the cascade-induced damage has its own features.