Solar production of carbon nanotubes; structure evolution with experimental conditions

In this work we report the production of carbon nanotubes by direct vapouri zation of graphite targets containing different couples of catalysts using a 2 kW solar furnace. With this small-scale experimental set-up we observed the evolution of the structure of the produced nanotubes with experimental conditions, pressure and flow rate of the inert gas (argon) and target com position. High pressure favours the production of bundles of single-wall na notubes (SWNTs) and the purity of the produced material depends on the targ et temperature and the cooling rate of the vapour. We also discuss the infl uence of the target composition. (C) 2000 Kluwer Academic Publishers.