Boron-doped carbon nanotubes have been prepared by the pyrolysis of acetyle
ne-diborane mixtures in a stream of helium and hydrogen. The nanotubes so o
btained have compositions around C35B. The presence of boron favours nanotu
be formation and the boron content does not vary with the depth. Considerin
g that the nitrogen-doped nanotubes, reported recently (Chem. Phys. Lett. 2
87 (1997) 671) have the average composition C35N, it may be possible to use
a combination of these p-type and n-type nanotubes for certain application
s. (C) 1999 Elsevier Science B.V. All rights reserved.