Structure and formation of raft-like bundles of single-walled helical carbon nanotubes produced by laser evaporation

Laser ablation of graphite powders mixed with catalysts of Ni and/or Co produces single-walled carbon nanotubes at high yield. The distribution of tubule diameters has a narrow peak at d = 1.22 nm. These tubules of single diameter often form bundles of raft-like structures in which they are aligned and stacked together in hexagonal packing with lattice constant of about 1.59 nm. In the present study, less than 20% examined bundles had the armchair structure of single-helicity, while in most cases the helicity was found to be distributed quite uniformly between the zigzag and armchair structures.