Growth of Metal Carbide Nanotubes and Nanorods

Transition-metal carbide nanorods have been prepared by reacting carbon nanotubes with volatile Ti and Nb iodides. Systematic temperature-dependent growth studies of TiC nanorods produced from spatially separated Ti metal and carbon nanotubes in the presence of iodine have shown that reaction proceeds initially via the formation of a thin, uniform carbide coating and that further reaction proceeds via inward growth of this coating with a concomitant consumption of the carbon nanotube until a solid nanorod is formed. Transmission electron microscopy, selected area diffraction, and X-ray powder diffraction have been used to show that the coatings and nanorods are polycrystalline, cubic TiC. Similar results were also obtained in growth studies of of NbC nanorods from Nb metal and carbon nanotubes. These data show that the growth of TiC and NbC nanorods involves a template mechanism in which the carbon nanotubes define the overall morphology and, furthermore, demonstrate that new TiC and NbC nanotubes can be prepared by controlling the growth conditions.