Single-walled carbon nanotubes produced at high yield by mixed catalysts

We report here on the high-density preparation of single-wall tubes in the presence of mixed catalysts of the types Fe/Ni and Co/Ni, in the soot as well as in the weblike deposits forming in the chamber. The yield is much higher than previously reported, and gram quantities can be obtained. Diameters cover the range from 0.9 to 3.1 nm, larger than previously reported, with the histogram showing only one peak at 1.7 nm. Evidence of an epitaxial action between C ₆₀ and single-walled nanotubes is presented. Results from the mixed catalysts Co/Cu, Ni/Mg, and Ni/Ti are also reported.