Structures and stabilities of multi-terminal carbon nanotube junctions

A variety of multi-terminal junctions, including Y-, T- and X-type carbon nanotubes, were generated by connecting individual single-walled carbon nanotubes with different size and helicity. By optimizing these hetero-structures with different geometric features, the energetically favored structures were proposed. The corresponding energy features of the junctions indicate that the tube diameter, the helicity, and the distribution of defects, play an important role on the stability of junctions. The most stable Y-, T- and X-junctions contain six, six, and twelve heptagons, respectively. These defect rings tend to distributed at the corners of the junctions. The zigzag-type junctions are more stable than the armchair ones. Moreover, the average energy of individual atom for Y-, T-, and X-junction is found to be a function of the tube diameter.