Correlation between catalyst particle and single-walled carbon nanotube diameters

Single-walled carbon nanotubes (CNTs) were synthesised at different conditions by a novel aerosol method based on the introduction of pre-formed iron catalyst particles into conditions leading to CNT formation. The results of statistical measurements of individual CNT dimensions based on high-resolution TEM images showed the effects of the residence time and temperature in the reactor. The ratio between catalyst particle and CNT diameters was close to 1.6 and independent of the experimental conditions, thus revealing an astonishing “universality” in the growth process. A proposed geometric model of heptagon defect formation, which initiates and maintains the CNT growth, allowed us to theoretically explain the phenomenon.