Defects and coalescence in carbon nanotubes

Dimensional stability and surface reconstructions are investigated using high-resolution electron transmission microscopy and molecular dynamics simulation. The effect of a high-concentration of defects on the electronic properties of carbon nanotubes is studied, and a new family of sp/sup 2/-like carbon nanotubes, incorporating five-, six-, and seven-membered rings in the lattices, is proposed. The coalescence of single-wall nanotubes is also investigated in situ under electron irradiation at high-temperature in a transmission electron microscope, and the merging process is simulated using theoretical approaches.