Fullerene nanowires

Abstract

A method has been found which produces nanowires in high yield. These wires are cylindrical single-walled fullerenes: hollow carbon tubes 1.2-1.4 nm in diameter, >20 μm in length, constructed of a single hexagonally-bonded graphene sheet wrapped into a cylinder, with hemispherical endcaps involving 6 pentagons. They are produced by laser vaporization of a composite rod of graphite with 1-2 atom percent of a catalyst such as 1/1 Ni/Co, inside a quartz tube at 1200°C, in a 1 cm sec-1 flow of argon at 500 Torr. The yield is greater than 50% of all the carbon vaporized. The wires are found to be aligned to form ropes of 10-100 parallel tubes held together in a closed-packed hexagonal array by van der Waals forces. The ropes are often found with overall length greater than 0.1 mm. Due to their expected high electrical conductivity, especially when doped with metals either down the hollow inside region or on the outside, intercalated in the triangular gaps between the adjacent tubes, these new materials may provide the first source of wires on the nanometer scale whose electrical conduction is truly metallic. It may also be possible to make them much longer.