Elaboration and characterization of various carbon nanostructures

Evaporation of carbon in the presence of helium produces a large variety of carbon cage molecules with quasi-spherical (fullerenes), tubular (carbon nanotubes) and polyhedral (graphitic nanoparticles) morphologies. Co-evaporation of carbon with another element (or mixture of elements) of the periodic table in the presence of helium yields interesting modifications of those structures. The nanotubes can be single- or multi-walled depending on the nature of the additional element and on the experimental conditions. In some caes, the nanotubes as well as the polyhedral particles can be filled with cylindrical single crystals of the element, while in some other cases an encapsulated carbide is formed. Another way of modifying carbon nanostructures is the substitution of B and N into the carbon network. These variations lead to changes in the physical properties of the nanostructures.