Joining Nanotubes with Pentagons and Heptagons

These images represent ways of connecting nanotubes using pentagon and heptagon defects. Many thanks to Phillipe Lambin for the atomic coordinates and science, I've just used them to experiment with the raytracing! You can find out more about Phillipe's work here.

The different images show either different orientations of the tube or have the pentagons and heptagons marked in colour to make them easier to spot. Click on an image to see a larger version..

"It is possible to connect two nanotubes with different chiralities by just introducing a pair of heptagon and pentagon in the otherwise perfect hexagonal graphite lattice. Quasi one-dimensional heterojunctions can therefore be realized in this way, including metal-semiconductor hybrids for which interesting properties may be expected."
(9,0)-(5-5) knee
The (9,0)-(5,5) knee illustrated here connects a nanotube with the parallel orientation (bottom) to one with the perpendicular orientation (top). The diameters of the two half nanotubes are close to 0.35 nm.
9055 knee tube 9055 knee tube 9055 knee tube
(10,0)-(6,6) knee
The (10,0)-(6,6) knee is a semiconductor-metal hybdrid. The calculations indicate that the band gap requires a distance of the order of 1 nm to settle in the semiconducing nanotube.
10066 knee tube 10066 knee tube 10066 knee tube
(8,0)-(7,1) knee
A group in Berkley University has investigated the electronic properties of small-bend heterostructures in which the pentagon and heptagon are adjacent. Local densities of states were computed by Green's functions for several systems, including the (8,0)-(7,1) hybrid illustrated on the left (by courtesy of Leonor Chico). The lower half of this hybrid is a semiconductor, the upper part is a metallic chiral nanotube.
8071 knee tube 8071 knee tube 8071 knee tube
(9,0)-(12,0) connection
The (11,0)-(12,0) connection is a semiconductor-metal hybrid. Two nanotubes with the parallel (or zig-zag) orientation are connected with a pair of edge-sharing pentagon (red) and heptagon (blue) oriented parallel to the tubule axis. This results in a straight connection.
120110 knee tube 120110 knee tube 120110 knee tube
If you are interested in using these images please contact me. Please don't use without permission. All images on this site are ©Chris Ewels.

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Last modified November 7, 2006