CVD growth of boron nitride nanotubes

Multiwalled BN nanotubes are grown from nickel boride catalyst particles by chemical vapor deposition at 1000-1100 degrees C using borazine, B3N3H6, a s the precursor. This precursor is generated in situ from molten salt that forms from mixtures of (NH4)(2)SO4, NaBH4, and Co3O4 at 300-400 degrees C. The BN nanotubes have concentric-tube structures, are free of internal clos ures, have crystalline walls, and exhibit lengths of up to similar to 5 mu m. The nanotubes often possess bulbous, flag-like, or club-like tip closure s. A root-growth mechanism is proposed for the catalyzed process.