Carbon nanofoam

Carbon nanofoam is the fifth known allotrope of carbon discovered in 1997 by Andrei V. Rode and co-workers at the Australian National University in Canberra^[1]. It consists of a low-density cluster-assembly of carbon atoms strung together in a loose three-dimensional web.

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Each cluster is about 6 nanometers wide and consists of about 4000 carbon atoms linked in graphite-like sheets that are given negative curvature by the inclusion of heptagons among the regular hexagonal pattern. This is the opposite of what happens in the case of buckminsterfullerenes, in which carbon sheets are given positive curvature by the inclusion of pentagons.

The large-scale structure of carbon nanofoam is similar to that of an aerogel, but with 1% of the density of previously-produced carbon aerogels—or only a few times the density of air at sea level. Unlike carbon aerogels, carbon nanofoam is a poor electrical conductor. The nanofoam contains numerous unpaired electrons, which Rode and colleagues propose is due to carbon atoms with only three bonds that are found at topological and bonding defects. This gives rise to what is perhaps carbon nanofoam's most unusual feature; it is attracted to magnets, and below −183 °C can itself be made magnetic.

References

1. D. Rode, Andrei; Gamaly, Eugene; Luther-Davies, Barry. "Method for deposition of thin films", International Patent Application No. PCT/AU98/00739, priority date 11 September, 1997; "Method of deposition of thin films of amorphous and crystalline microstructures based on ultrafast pulsed laser deposition", US Patent US6312760 (2001).

2. A. V. Rode, S. T. Hyde ST, E. G. Gamaly, et al., "Structural analysis of a carbon foam formed by high pulse-rate laser ablation", APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 69, S755-S758 (1999).

3. A. V. Rode, E. G. Gamaly, and B. Luther-Davies, "Formation of cluster-assembled carbon nano-foam by high-repetition-rate laser ablation", Appl. Phys. A 70, 135-144 (2000).

4. A. V. Rode, R. G. Elliman, E. G. Gamaly, A. I. Veinger, A. G. Christy, S. T. Hyde, B. Luther-Davies, "Electronic and magnetic properties of carbon nanofoam produced by high-repetition-rate laser ablation", Applied Surface Science 197-198, 644-649 (2002).

5. A. V. Rode, E. G. Gamaly, A. G. Christy, J. D. Fitz Gerald, S. T. Hyde, R. G. Elliman, B. Luther-Davies, A. I. Veinger, J. Androulakis, J. Giapintzakis, "Unconventional magnetism in all-carbon nanofoam", Phys. Rev. B, 70, 054407 (2004).

6. E. G. Gamaly, A. V. Rode, "Nanostructures created by lasers", in: Encyclopaedia of Nanoscience and Nanotechnology, Ed. H. S. Nalwa, (American Scientific Publishers, Stevenson Range, 2004), v. 7, 783-809.

7. A. V. Rode, E. G. Gamaly, A. G. Christy, J. D. Fitz Gerald, S. T. Hyde, R. G. Elliman, B. Luther-Davies, A. I. Veinger, J. Androulakis, J. Giapintzakis, "Strong paramagnetism and possible ferromagnetism in pure carbon nanofoam produced by laser ablation", Journal of Magnetism and Magnetic Materials, 290-291, 298-301 (2005).

8. D. Arčon, Z. Jagličič, A. Zorko, A. V. Rode, A. G. Christy, N. R Madsen, E. G. Gamaly, B. Luther-Davies, "Origin of Magnetic Moments in Carbon Nanofoam", Phys Rev B, 74, 014438 (1-9) (2006).

9. R. Blinc, P. Cevc, D. Arcon, B. Zalar, A. Zorko, T. Apih, F. Milia, N. R. Madsen, A. G. Christy, A. V. Rode, "13C NMR and EPR of carbon nanofoam", Physica Status Solidi B: Basic Solid State Physics 243, 3069-3072 (2006).

10. A. V. Rode, A. G. Christy, E. G. Gamaly, S. T. Hyde, B. Luther-Davies, Magnetic properties of novel carbon allotropes, in: “Carbon-based magnetism”, Eds. T. Makarova, F. Palacio, (Elsevier, Amsterdam, 2006) 463-482.

11. D.W.M. Lau, D.G. McCulloch, N.A. Marks, N.R. Madsen, A.V. Rode, "High-Temperature Formation of Carbon Onions within Nanofoam: An Experimental and Simulation Study", Phys Rev B, 75, 233408 (2007).

1. ^ Rode AV, Hyde ST, Gamaly EG, et al. (1999) Structural analysis of a carbon foam formed by high pulse-rate laser ablation. APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 69, S755-S758