Role of Y-Ni-B mixtures in the formation of carbon nanotubes and encapsulation into carbon clusters

We report on the formation of carbon nanotubes and encapsulated metal nanoparticles produced during the electric are discharge between a graphite cathode and a graphitic anode containing different stoichiometric mixtures of Ni, Y and B. Using these mixtures it can be shown that Ni plays a catalytic role in the formation of single-walled nanotubes (SWTs). However, the active catalytic amount of Ni used in the experiment can be increased by additionally introducing certain other metals in the anode. Their melting point, vapour pressure and their affinity towards carbon seem to have an important influence on the amount of SWTs produced, as well as on the amount of metal particles encapsulated in multi-walled nanotubes (MWTs) and graphitic polyhedral nanoparticles (GNPs).