Onions carbon

Hollow carbon nanostructures are exciting new systems for research and for the design of potential nano-electronic devices. Their atomic structures are closely related to their outer shapes and are described by hex-agonal/pentagonal network configttrations. The surfaces of such structures are atomically smooth and perfect. The most prominent of these objects are ftil-lerenes and nanotubesjl]. Other such novel structures are carbon onions[2] and nanocones[3]. 

Fig. 4.15 Carbon onion. After [59]. Image credit http //www.staff.uni-mainz.de/banhart/ c-nano-structures/onions. Note compression of interlayer distances - from 0.335 nm for ordered graphite to less than 0.3 nm this is in contrast to the swelling of planes in turbostatic graphite and in carbon nanoshells [60]...

F. Banhart, T. Fuller, P.FI. Redlich, P.M. Ajayan, The formation and self-compression of carbon onions. Chem. Phys. Lett., 269 (1997) 349-355. 

H. Abe, Nucleation of carbon onions and nanocapsules under ion implantation at high temperature. DiamondRelat. Mater, 10 (2001) 1201. 

A. Hirata, M. Igarashi, T. Kaito, Study on solid lubricant properties of carbon onions produced by heat treatment of diamond clusters and particles. Tribology Int., 37(11-12) (2004) 899-905. 

Sano N, Wang H, Chhowalla M et al (2001) Synthesis of carbon onions in water. Nature 414 506-507... 

Alexandrou I, Wang H, Sano N et al (2004) Structure of carbon onions and nanotubes formed by arc in liquids. J Chem Phys 120 1055-1058... 

Fig. 3.3 Carbon toroids formed simultaneously with the growth of carbon nanotubes and carbon onions...

Amorphous carbon is a general term that covers non-crystalline forms of carbon such as coal, coke, charcoal, carbon black (soot), activated carbon, vitreous carbon, glassy carbon, carbon fiber, carbon nanotubes, and carbon onions, which are important materials and widely used in industry. The arrangements of the carbon atoms in amorphous carbon are different from those in diamond, graphite, and fullerenes, but the bond types of carbon atoms are the same as in these three crystalline allotropes. Most forms of amorphous carbon consist of graphite scraps in irregularly packing. 

From observations in transmission electron micrography (TEM), carbon soot particles are found to have an idealized onion-like shelled structure, as shown in Fig. 14.1.8. Carbon onions varying from 3 to 1000 nm in diameter have been observed experimentally. In an idealized model of a carbon onion, the first shell is a C6o core of /h symmetry, the second shell is C240 (comprising 22 x 60... 

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