Affiliation:
1. University of Illinois at Chicago, Department of Mechanical Engineering, Chicago, IL 60607, USA.
2. Tokyo Institute of Technology, Materials and Structures Laboratory, 4259 Nagatsuta, Midori-ku, Yokohama 226, Japan.
Abstract
Polyhedral nano- and microstructures with shapes of faceted needles, rods, rings, barrels, and double-tipped pyramids, which we call graphite polyhedral crystals (GPCs), have been discovered. They were found in pores of glassy carbon. They have nanotube cores and graphite faces, and they can exhibit unusual sevenfold, ninefold, or more complex axial symmetry. Although some are giant radially extended nanotubes, Raman spectroscopy and transmission electron microscopy suggest GPCs have a degree of perfection higher than in multiwall nanotubes of similar size. The crystals are up to 1 micrometer in cross section and 5 micrometers in length, and they can probably be grown in much larger sizes. Preliminary results suggest a high electrical conductivity, strength, and chemical stability of GPC.
Publisher
American Association for the Advancement of Science (AAAS)
Reference28 articles.
1. Bacon R., J. Appl. Phys. 31, 283 (1960).
2. Helical microtubules of graphitic carbon
3. Polyhedral carbon nanotubes have been reported (4–7) but did not receive much attention. Faceting of vapor-grown carbon fibers occurs after heating to 3000°C (8). Of all carbon fibers those are the closest to crystalline graphite in crystal structure and properties. However faceted carbon whiskers have not been reported. Partial graphitization and formation of polygons was observed after heat treatment of carbon black at 2800°C (8). Polyhedral nanoparticles (5 to 30 nm) made of concentric layers of closed graphene sheets with a nanoscale cavity in the center were produced at very high temperatures in arc plasma (9). They provide further evidence that nonplanar graphite crystals can exist. However transformation of carbon polyhedra to onions under electron irradiation (9) suggested their instability. No other polyhedral carbon structures have been reported so far.
4. P. M. Ajayan in Carbon Nanotubes: Preparation and Properties T. W. Ebbesen Ed. (CRC Press Boca Raton FL 1997) pp. 111–138.
5. M. S. Dresselhaus G. Dresselhaus P. C. Eklund Science of Fullerenes and Carbon Nanotubes (Academic Press Burlington MA 1996).
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