Synthesis, HRTEM and electron diffraction studies of B/N-doped C and BN nanotubes

Large-scale synthesis of multi-walled BN and single-walled B/N-doped C nano tubes (NT) from C nanotube templates was carried out. The NTs were produced through heating of C templates with B2O3 in a flowing N-2 atmosphere at 15 03-1773 K. The NTs were analyzed by means of a JEM-3000F high-resolution fi eld emission transmission electron microscope operated at 300 kV and equipp ed with a parallel detection electron energy loss spectrometer. Particular attention was given to the effects of C template morphology, synthesis temp erature and metal oxide promoters on the yield and chemical composition of NTs. Ropes consisting of tens of multi-walled BN NTs were synthesized at 17 73 K using MoO3 and PbO promoters. Ropes of single-walled B/N-doped C NTs w ere produced at high yields by synthesis at 1553 K. Packing of NTs in the r opes and nanotube helicities were studied by electron diffraction. B/N-dope d C and BN NT morphologies, formation mechanism and atomic structures are d iscussed in this paper. (C) 2001 Elsevier Science B.V. All rights reserved.