Abstract
Nanotubular ropes composed of aligned multiwalled nanotubes having electrically insulating BN-rich outer shells and semiconducting B-C-N inner shells were synthesized through the reaction of aligned CNx (xless than or equal to0.1) nanotube mats with boron oxide and nitrogen at similar to2000-2110 K. The atomic structure and chemical composition of the ropes were analyzed by high-resolution transmission and energy-filtered (Omega filter) electron microscopy. Individual ropes display perfect insulating performance of BN-rich outer layers and excellent field emission and thus conductive properties of inner B-C-N layers. A semiconducting nanometer-scale cable with built-in electrical insulation has thus been realized. (C) 2003 American Institute of Physics.