Flattened Multiwalled Carbon Nanotube with Multi-Layered Structure

Fabrication of novel nanostructures based on carbon nanotubes has been a focus of recent interest since they are expected to inherit excellent properties of carbon nanotube. To find new nanotube-based nanostructures, it is important to find a new growth mode or process. This paper reports the formation of a multiwalled carbon nanotube that has bi-layered structure and is partly flattened. Transmission electron microscopy observations suggest that the outer multiwalled layer was formed first from a Fe catalyst nanoparticle, and was partly flattened during the growth. Then the catalyst nanoparticle worked again to form the inner multiwalled tube moving inside the outer tube and became flattened at the same position of the outer tube. It is likely that the inner growth gave an expansion stress against the flattened outer tube; nevertheless, the flattened part of the outer tube remained. This observation evidences that the flattening of the nanotube occurred simultaneously during the growth and was stabilized by structural defect.