Abstract
Flakes of CVD grown BxC1-x (x<0.2) films were exposed to intense electron irradiation (flux density up to similar to 100 A/cm(2)) in a 300 kV high resolution electron microscope equipped with a field emission gun. The starting flakes revealed a turbostratic BxC1-x structure, The composition of the starting materials and irradiated products was determined by using electron energy loss spectroscopy (EELS). Depending on the electron dose applied, irradiation of the turbostratic material led to formation of soap-bubble-like irregularly-shaped objects (linear dimensions of similar to 2-5 nm), onion- and semi-onion-like structures (d similar to 10nm), nested fullerenes (3-14 shells) and elementary fullerene-type cages (d similar to 0.7 nm). It is thought that these curled and closed nanostructures arise from a continuous bending of the hexagonal BxC1-x sheets under electron irradiation. Finally, some possible structural models of BxC1-x fullerenes are considered.