Carbon Onions and Related Materials

After having made the acquaintance of fuUerenes and of single- and multiwalled carbon nanotubes, the question arises on the existence of multiwalled fullerenes. Such carbon cages concentrically arranged one inside another are also called carbon onions. In comparison to other new carbon materials, they have by far been studied less. Chiefly this is because only small amounts of those are available. Still they represent an interesting structural variant of carbon. This chapter deals with their structure, different methods of preparation, and first results regarding their properties. 

The carbon onions present a Unk between the fullerenes and the multiwalled nanotubes. From one point of view, they may be considered fullerene cages concentrically contained one inside another and constantly increasing in size toward the outside. On the other hand, they might just as weU be interpreted as multiwalled nanotubes with length zero so only the caps of the constituent tubes remain. With irregular caps, carbon nanoparticles of uneven shape result. 

Copyright 2010 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim 

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Numerous spectroscopic methods have been applied to examine the physical properties and to elucidate the structure of carbon onions. They include IR- and Raman spectroscopy. X-ray diffraction, electron energy loss spectroscopy (EELS), absorption, and photoluminescence spectroscopy and NMR-spectroscopy. Each of these methods gives account of certain aspects of the geometric and electronic structure, so altogether quite a detailed picture is obtained of the situation in carbon onions and related materials. There is, however, a strong dependency on... 

Further Spectroscopic Properties of Carbon Onions and Related Materials... 

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