Synthesis of single-walled carbon nanotubes by dual laser vaporization : the CSIR at 60

• Published in: South African journal of science Vol. 102; no. 7; pp. 364 - 368
• Main Authors: Holloway, B.C., Maaza, M., Moodley, M.K., Coville, N.J.
• Format: Journal Article
• Language: English
• Published: Academy of Science for South Africa (ASSAf) 01.07.2006
• ISSN: 0038-2353; 1996-7489

Single-walled carbon nanotubes were synthesized by the laser vaporization of graphite composite targets in a tube furnace. Two pulsed Nd:YAG lasers operating at fundamental (1064 nm) and 2nd harmonic (532 nm) frequencies were combined, focussed and evaporated targets in an inert argon atmosphere at a pressure of 500 mbar. Furnace temperatures of either 1200 or 1000°C were used. The targets were either pure graphite or graphite doped with catalysts. The as-evaporated material was collected and characterized by transmission electron microscopy, scanning electron microscopy and Raman spectroscopy. TEM analysis showed individual single-walled tubes with diameters of 1.31 + 0.02 nm and bundles of single-walled tubes up to 10 nm in diameter. Raman spectroscopy revealed a distribution of chiral, metallic and semiconducting nanotubes, all with a very low defect concentration. Most of the identified tubes were semiconducting. The addition of Fe as catalyst changed the diameter distribution fractionally from 1.30-1.46 nm to 1.33-1.49 nm and significantly lowered the defect concentration. The concentration of metallic nanotubes was also found to have decreased.