Abstract
Bundles of single-walled boron-doped carbon (BxC1 - x), boron- and nitrogen-doped carbon (BxC1 - x - yNy) and boron nitride (BN) nanotubes were prepared by thermal treatment of a mixture of boron trioxide and bundles of single-walled carbon nanotubes at 1523-1623 K in a nitrogen flow. The (BxC1 - x + BxC1 - x - yNy)/BN nanotube yield ratio increased with decreasing temperature in the reaction zone, The nanotubes were characterised by using high-resolution transmission electron microscopy and electron energy loss spectroscopy. The diameter of the individual nanotubes in the resultant bundles was 1.2-1.4 nm, which was similar to the diameter of the starting C-nanotubes. The B/C ratio of the B-doped carbon nanotubes was of less than or equal to 0.1, whereas the BN nanotubes exhibited a B/N stoichiometry of similar to 1.0. (C) 1999 Elsevier Science B.V. All rights reserved.