Synthesis, analysis, and electrical property measurements of compound nanotubes in the B-C-N ceramic system

Nanotubular structures in the B-C-N ceramic system represent an intriguing alternative to conventional carbon nanotubes. Because of the ability to widely vary the chemical composition of nanotubes within the B-C-N ternary phase diagram and to change the stacking of C-rich or BN-rich tubular shells in multiwalled structures, a wide horizon opens up for tuning nanostructure electrical properties. Pure carbon nanotubes are metals or narrow-bandgap semiconductors, depending on the helicity and diameter, whereas those of BN are insulators with a ∼5.0 eV gap independent of these parameters. Thus, the relative B/C/N ratios and/or BN-rich and C-rich domain spatial arrangements, rather than tube helicity and diameter, are assumed to primarily determine the B-C-N nanotube electrical response. This characteristic is highly valuable for nanotechnology: while tube diameter and helicity are currently difficult to control, continuous doping of C with BN, or vice versa, proceeds relatively easily due to the isostructural nature of layered C and BN materials. In this article, recent progress in the synthesis, microscopic analysis, and electrical property measurements of a variety of compound nanotubes in the ceramic B-C-N system is documented and discussed.