IMPROVING CONDITIONS TOWARDS ISOLATING SINGLE-SHELL CARBON NANOTUBES

We report on some of the conditions during carbon sublimation which pr omote single-shell carbon nanotube formation. Using as a catalyst a mi xture of two metals (Co and Pt) in the anode, we observe a higher dens ity of single-shell carbon nanotubes than that found with cobalt alone . Using other mixtures (Co and Fe), the nanotube yield is always lower , and their formation is even hindered (Co and Ru). First attempts of vacuum annealing at high temperature on samples containing cobalt-cata lyzed single-shell carbon nanotubes suggest that this might be a good way to eliminate the catalyst particles. We present high-resolution tr ansmission electron microscopy images of samples obtained by such proc edures.