Heterogeneous growth of B-C-N nanotubes by laser ablation

Multi-wall nanotubes have been synthesized by metal catalyzed laser ablation of a BN and carbon composite target in a tube furnace heated to 1000 degrees C or 1200 degrees C and flowing with nitrogen gas. The products are characterized by scanning transmission electron microscopy and electron energy-loss spectroscopy. No single-wall nanotube has been found in the products. Thinner nanotubes with a few layers are usually composed of pure carbon. B-C-N layers exist at the outer surface of thicker nanotubes. The layer number and chemical composition vary along the tube axis, The growth mechanism of the heterogeneous nanotubes is discussed. (C) 1997 Elsevier Science B.V.