Insights into the structure of BN nanotubes

The following features of multiwalled BN nanotubes were discovered using a field emission high-resolution analytical transmission electron microscope: (i) coexistence of hexagonal and rhombohedral stacking in nanotube shell assembly; (ii) flattening of nanotube cross section, which makes possible clear atomic resolution of the core structure in a three-shelled nanotube; and (iii) change in chirality of tubular layers from armchair to zigzag arrangement in a 30 degrees double-walled nanotube kink, as revealed by atomically resolved images of tube wall segments. (C) 2000 American Institute of Physics. [S0003-6951(00)04339-4].