Ropes of BN multi-walled nanotubes

Ropes consisting of tens of multi-walled boron nitride (BN) nanotubes and extending up to several μm were synthesized through a chemical reaction involving chemical-vapor-deposited multi-walled carbon (C) nanotube oxidation by B2O3 mixed with either MoO3 or V2O5 in a flowing N2 atmosphere. The ropes were analyzed by high-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS). Tubular shells of BN in the ropes were preferentially assembled in a zigzag form with the [101̄0] direction parallel to the tube/rope axis. Oxidation-induced C nanotube opening at the tip and at wall defects, followed by substitution of C atoms with B and N atoms, and consecutive crystallization of BN shells on the seed nanotubes is thought to underlie the formation mechanism.