High-yield single-wall carbon nanotubes were produced in large quantity using a Y-Ni alloy composite graphite rod as anode in a dc arc discharge. Termination of the tubes was found to be the most common defect in the arc-discharge-produced single-walled carbon nanotubes. A comparison was made with samples produced by laser ablation. High-resolution transmission electron microscopy was used to investigate the cap structure of the terminated single-walled carbon nanotubes and their relatives. The cap shapes of most single-walled carbon nanotubes with high aspect ratios were hemispherical, while those of highly defective squat single-walled carbon nanotubes were polyhedral. Inclusion of carbon materials in the single-walled carbon nanotubes was also observed. The results provided basic information for understanding the growth mechanism of single-walled carbon nanotubes.

Defects in Arc-Discharge-Produced Single-Walled Carbon Nanotubes. Y.Zhang, S.Iijima, Z.Shi, Z.Gu: Philosophical Magazine Letters, 1999, 79[7], 473-9