Nanobamboo

By annealing peapods the fullerenes within the host nanotube slowly coalesce and transform into an inner nanotube. The formation of the inner tubes has been confirmed by Raman spectroscopy. However, there is a major difference between such peapod-grown DWCNTs and other (e.g. CVD grown) DWCNTs.

All of the experimentally observed features can be explained by the presence of a special kind of defect which could in principle appear in the inner walls during the growth process. For a given outer tube there are several different inner tubes which could grow during the annealing, since the van der Waals distance only restricts the diameter of the inner shell, and not its chirality. At the very least, left- and right-handed varieties of the same chiral nanotube could grow in a given outer tube at the same time, e.g. (6,4) and (4,6). Furthermore, there is no reason why the inner shell could not start to grow in multiple places along the tube axis simultaneously. Therefore it is possible that during the annealing process the fullerenes start to coalesce at different places at the same time and inner tubes with different chiralities or with the same chirality but different handedness emerge. When these tubes of different chiralities come into contact, a junction will be formed. Such a junction is illustrated in the figure below, showing the case of the contact of a (6,4) and a (4,6) nanotube. We refer to these junctions as bamboo defects and we call a nanotube with such defects nanobamboo.

The geometry of the bamboo defect in a (6,4)-(4,6) nanotube junction.
The geometry of the bamboo defect in a (6,4)-(4,6) nanotube junction. The top and bottom panels are different views of the same geometry. Pentagons and heptagons are highlighted within the junction. The diameter of the tube expands near the pentagon defects and contracts near the heptagon defects. There are two non-equivalent junctions in the unit cell, the length of which depends on the density of junctions (65 Å in this case).

Publications on this topic

[1] Rusznyák, Á., Koltai, J., Zólyomi, V. and Kürti, J., "Carbon nanobamboo: Junctions between left and right handed single walled carbon nanotubes", in Phys. Status Solidi B, 249: 2652–2655 (2012). DOI

[2] V. Zólyomi, J. Koltai, D. Visontai, L. Oroszlány, Á. Rusznyák, I. László, and J. Kürti, "Characteristics of bamboo defects in peapod-grown double-walled carbon nanotubes", In Phys. Rev. B 82, 195423 (2010) DOI

[3] Koltai, J., Rusznyák, Á., Zólyomi, V., Kürti, J. and László, I., "Junctions of left- and right-handed chiral carbon nanotubes – nanobamboo", In Phys. Status Solidi B, 246: 2671–2674 (2009). DOI

[4] Poster at IWEPNM'2010 (PDF),

[5] Poster at IWEPNM'2009 (PDF).

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nanotube