Synthesis and characterization of carbide nanorods

THE properties and potential applications of carbon nanotubes filled with other materials have aroused much speculation1–5. Strategies for filling nanotubes include in situ growth in an arc reactor using metal/carbon composites2,5 and the capillarity-driven filling of open nanotubes using liquid reagents3,4. Here we report an alternative approach to the synthesis of nanoscale structures based on nanotubes, in which the tubes are converted to carbide rods by reaction with volatile oxide and/or halide species. In this way we have been able to prepare solid carbide nanoscale rods of TiC, NbC, Fe3C, SiC and BCx in high yield with typical diameters of between 2 and 30 nm and lengths of up to 20 urn. Preliminary studies show that these rods share the properties of the bulk materials (such as magnetism and superconductivity), suggesting that they might allow the investigation of the effects of confinement and reduced dimensionality on such solid-state properties. These carbide nanorods might also find technological applications in nanostructured composite materials.