Boron Nitride Nanotubes with Reduced Numbers of Layers Synthesized by Arc Discharge

A new route to the successful arc-discharge synthesis of pure boron nitride (BN) nanotubes is presented. The carbon-free plasma is established between ${\mathrm{HfB}}_{2}$ 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\ifmmode^\circ\else\textdegree\fi{} disclinations, is proposed to account for this specific shape.