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 appropr iate precursor compounds around 1000 degrees C in an atmosphere of arg on. have been examined by electron microscopy and other techniques. Th e compositions of the nanotubes have been analysed by electron energy loss spectroscopy and X-ray photoelectron spectroscopy. There is signi ficant 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 ob tained from UHV-STM studies. The near absence of B-N nanotubes on pyro lysing the appropriate precursor compound, and other observations made in the present study, indicate the crucial role played by carbon in t he initial nucleation and growth of nanotubes. (C) 1998 Elsevier Scien ce B.V. All rights reserved.