BORON-NITRIDE NANOTUBE GROWTH DEFECTS AND THEIR ANNEALING-OUT UNDER ELECTRON-IRRADIATION

Growth defects, namely undulating, dangling B-N sheets, dislocation ed ges, and local irregularities in B-N hexagonal sheet spacing have been observed in boron nitride multi-walled nanotubes produced by laser he ating of hexagonal BN in a diamond anvil cell at a nitrogen pressure o f 10.1 GPa. Most of these defects may be annealed in situ after just a few minutes of electron irradiation in a 300 kV electron microscope ( electron dose of 10-20 A/cm(2)), while almost complete ordering of the nanotubular shells occurs. These results imply that there is not suff icient time for annealing-out of defects during BN nanotube formation. (C) 1997 Elsevier Science B.V.