The development and structure of carbon nanotubes

The first carbon filament possessing a very small diameter (less than 10 nm) was produced in the 1970s by the decomposition of hydrocarbon at high temperature using transition metal catalysts. The 1985 discovery of the third allotropy form of ordered carbon (after the graphite and diamond forms. 

The discovery of these nano-elements and nanostructures offered the opportunity to understand how carbon atoms bond with other carbon atoms, and how carbon reacts with other elements under specific conditions of temperature and pressure. With the benefit of theoretical models and 

1 SEM micrograph of carbon nanotube bundles deposited on the cathode eiectrode surface.  

The studies of Kroto, Smalley and coworkers (at Rice University) showed that carbon nanotubes constitute a particular case of the fullerene family. The most famous and most stable of the fullerene molecules is C60, with a computer-simulated image very similar in appearance to a soccer ball. This molecule consists of 20 hexagonal and 12 pentagonal faces, with the carbon atoms at each corner of the individual polygons. C60 stability has been attributed to the pentagon rule and the satisfaction of all valences when the pentagon faces lead to the closure of individual C60 molecules. 

The coimection between carbon nanotubes and other fullerenes has been defined by the observation that the nanotubes were closed by fullerene-like caps or hemispheres. It is interesting to observe that the smallest reported carbon nanotube diameter is the same as the diameter of C60. This is important in evaluating the minimum dimension of carbon nanostructures. It is necessary to identify all types of nanoparticles and nanostructures of the fullerene family (multiwall and/or single-wall nanotubes, carbon-encapsulated metal nanoparticles, fullerene black and soot, carbon onion, nanowhiskers, etc.). For each nanostructure it is possible to define a set of physical and chemical properties and subsequent applications. It is also interesting to explore the interrelationships between the various nanostructured carbon forms, as well as their relation to the traditional forms of ordered carbon atoms such as diamond and graphite. Carbon is a unique material and can be a good metallic 

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