A theoretical investigation of the mechanical stability of single-walled carbon nanotube 3-D junctions

The deformation behavior of five types of X-junctions made from ultrathin single-walled carbon nanotubes (SWCNTs) was investigated using molecular dynamics (MD) simulation. Three deformation modes were observed in the X-junctions under uni-axial or bi-axial tensile stresses. If the junction is strong, as is the case with certain (3,3)-(3,3) junctions, then the bonds break at individual nanotubes, rather than at the junction region, and the original bonding structures around the junctions remain. However, for some (3,3)–(3,3) junctions and X-junctions formed by (5,0)–(5,0) nanotubes, the bonds at the junction region break and are reconstructed, which results in the transformation of a 3-D junction into a 2-D type. Either one neck or two necks may be nucleated near the junction. The use of random seed numbers in MD simulations plays an important role in the outcome of the deformation process due to the small number of carbon atoms involved in the junction regions.