Laser vaporization synthesis of single wall carbon nanotubes

The effects of five experimental parameters in pulsed laser vaporization (PLV) synthesis of single wall carbon nanotubes (SWNTs) were examined. Parameters investigated include the laser beam raster pattern, reactor chamber temperature, graphite particle size in the target, reactor chamber configuration, and incident laser beam power density. The type and quality of resultant SWNTs synthesized were strongly influenced by altering these experimental conditions. This information can then be utilized to allow the experimentalist to exhibit a considerable degree of control over the physical and chemical properties of the as-produced SWNT materials. Characterization of the SWNT products was achieved using a combination of Raman spectroscopy, thermogravimetric analysis, UV-Vis-NIR spectroscopy and scanning electron microscopy. SWNTs synthesized using the corner to corner type laser beam raster pattern have pronounced differences in contrast to those synthesized using a linear type raster pattern. Smaller SWNT diameters result from use of a corner to corner raster pattern. Production rate of SWNT material is doubled using a one shot corner to corner raster pattern versus a one shot move linear raster pattern. These results indicate that there is a diminution of metal enrichment at the target surface was observed using the corner to corner raster pattern due to a reduction of induced localized heating of the target. Increasing reactor chamber temperature produces SWNTs with larger diameters. SWNT yields within the as-produced material increase with increasing temperature up to 1100°C. Defect densities are decreased with increasing temperature. Smaller graphite particle sizes give higher SWNT yields. An increase in reactor chamber volume increases SWNT yield. Increasing power densities result in a decrease in SWNT diameters. By carefully controlling the power density in combination with raster pattern the amount of graphite in the final product can be minimized