A new route to the successful arc-discharge synthesis of pure boron nitride (BN) nanotubes is presented. The carbon-free plasma is established between HfB₂ electrodes in a nitrogen atmosphere. This technique leads to the formation of BN nanotubes with very few layers including single- and double-layer tubes. Electron-energy-loss spectroscopy yields a B: N ratio of approximately 1. Most tube ends are closed by flat layers perpendicular to the tube axis. A closure by a triangular facet, resulting from three 120^ disclinations, is proposed to account for this specific shape.
Loiseau et al. (Mon,) studied this question.