Condensed phase growth of single-wall carbon nanotubes from laser annealednanoparticulates

Single-wall carbon nanotubes (SWNT) were grown to micron lengths by laser-a nnealing nanoparticulate soot containing short (similar to 50 nm long) nano tube "seeds." The "seeded" nanoparticulate soot was produced by restricting the time spent by an ablation plume inside an 800 degreesC oven following laser vaporization of a C-Ni-Co target. The soot collected from the laser v aporization apparatus was placed inside graphite crucibles under argon, and heated by a CO2 laser. In situ pyrometry was used to estimate the sample t emperature. Length distributions of SWNT bundles in the unannealed and anne aled samples were measured by transmission electron microscopy and field em ission scanning electron microscopy. Annealing treatments exceeding 1600 de greesC produced no increase in nanotube length, while lower temperatures in the 1000-1300 degreesC range were optimal for growth. These experiments in dicate that SWNT grow by the conversion of condensed phase nanomaterial dur ing annealing, a similar mechanism to that proposed for growth during norma l laser-vaporization production. (C) 2001 American Institute of Physics.