Molecular dynamics simulations were used to study by the effect of vacancy defects upon mechanical properties of double-walled carbon nanotubes under compression and bending. The results showed that the critical buckling strain under compression, and the critical buckling angle under bending, generally decreased with increasing defect density, but the detailed buckling behavior was sensitive to the defect distribution pattern (e.g., whether the vacancies were on the inner or outer wall, at separate sites or clustered together). Upon high-temperature annealing, vacancy defects underwent structural reconstruction and, in particular, formed interlayer bonds that significantly improved the load-carrying capability of the double-walled carbon nanotubes under compressive and bending deformation. These results provided new insights into the role of vacancy defects in determining the buckling behavior of multi-walled carbon nanotubes. They also suggested that high-temperature annealing was an effective tool for defect engineering by improving the mechanical properties of multi-walled carbon nanotubes. The present study revealed trends and underlying mechanisms regarding the buckling of multi-walled carbon nanotubes under various loading conditions.

Buckling of Double-Walled Carbon Nanotubes under Compression and Bending: Influence of Vacancy Defects and Effect of High-Temperature Annealing. W.Wolfs, C.Tang, C.Chen: Journal of Applied Physics, 2013, 114[17], 174308