FORMATION MECHANISM OF QUASI-SPHERICAL CARBON PARTICLES INDUCED BY ELECTRON-BOMBARDMENT

A detailed study of the transformation of graphitic structures into spherical onion-like particles under electron bombardment is presented. This evolution has been monitored up to the atomic details in a high-resolution electron microscope. The transformation from a tubular or polyhedral graphitic particle into a quasi-spherical onion is made in several steps, firstly the innermost shell collapses, then the regraphitization begins in the surface and follows towards the center by a sort of internal epitaxy.