B-C-N, C-N and B-N nanotubes produced by the pyrolysis of precursor molecules over Co catalysts

B-C-N, C-N and B-N nanotubes, prepared by the pyrolysis of the appropriate precursor compounds around 1000 degrees C in an atmosphere of argon. have been examined by electron microscopy and other techniques. The compositions of the nanotubes have been analysed by electron energy loss spectroscopy and X-ray photoelectron spectroscopy. There is significant compositional variation in B-C-N and C-N nanotubes. Properties of the B-C-N and C-N nanotubes have been compared with those of carbon nanotubes, particularly with respect to the I-V characteristics as obtained from UHV-STM studies. The near absence of B-N nanotubes on pyrolysing the appropriate precursor compound, and other observations made in the present study, indicate the crucial role played by carbon in the initial nucleation and growth of nanotubes. (C) 1998 Elsevier Science B.V. All rights reserved.