Formation and structure of boron nitride conical nanotubes

Nanotubes exhibiting a novel structure - boron nitride (BN) conical nanotub es whose walls consist of conical layers with their cone axis parallel to t he tube axis, as opposed to ordinary nanotubes, composed of concentric cyli ndrical layers with their normal perpendicular to the tube axis - were synt hesized simultaneously with BN nanotubes by using carbon nanotubes (CNTs) a s templates. The diameters of the BN conical nanotubes are typically about 15 nm, which is similar to those of the starting CNTs. Apex angles and inne r diameters of most BN conical nanotubes are about 40 degrees and 1 nm, res pectively. The lengths of the BN conical nanotubes range from 50 nm to up t o several micrometers. PACS: 81.05.Tp; 81.20.-n.