Growth, morphology, and structure of boron nitride nanotubes

Multiwalled BN nanotubes were synthesized via a chemical vapor deposition (CVD) route from a B4N3O2H precursor. Their morphological and structural features have been studied. It was suggested that the tips encapsulate boron oxynitride nanoclusters, which incorporate silicon, aluminum, and calcium and serve as the effective promoters for CVD growth of the BN nanotubes. An alternative open-end growth mechanism is also applied for the occasional formation of nanotubes with open or flat tip ends. Local three-dimensional ordering in the nanotube shell assembly was often observed. BN nanotubes synthesized in the current CVD process exhibit a dominant near zigzag arrangement and a rhombohedral (r-BN) stacking order. The results of initial efforts to grow arrays of aligned BN nanotubes are also described.