Controlling defects: growing longer nanotubes

Nanotubes have remarkable electrical properties due to their specific hexagonal lattice structure. When trying to grow these tubes -- which are 50,000 times thinner than a human hair -- defects can form in the perfect lattice structure and alter these properties. Last week, researchers released calculations showing that growth up to 100cm is possible, free of topological defects. They have determined that iron is the best catalyst for the nanotube-forming reactions, and that it serves to "heal" defects in nanotube rings as they crop up, removing carbon atoms from rings that have too many, and replacing them in rings that have too few. This research is remarkable given the number of carbon atoms involved: as many as ten billion, assembled at millions per second. This research could have important implications in bringing the wonders of carbon nanotubes into pracital usage.