New fullerenes in the B-C-N system:: synthesis and analysis by an electron beam

Numerous fullerenes were synthesized in various B-C-N materials by in-situ electron beam irradiation in a high-resolution transmission analytical electron microscope JEM-3000F. Boron-doped graphitic carbons, hexagonal and rhombohedral boron nitrides, and ternary B-C-N turbostratic materials served as the starting materials for irradiation. The transformation to fullerene-like morphology from originally flat or curled and jumbled graphene-like sheets or polygonal particles takes place through a solid-state phase transition by rearrangement of atoms, which is drastically enhanced by thermal and irradiation-induced diffusion. The scale of generated fullerenes ranges from similar to 1 nm (single-shelled objects) to 50 nm (giant nested objects having up to 75 shells). Fullerene symmetry and chemical composition were clarified by high-resolution transmission electron microscopy and electron energy loss spectroscopy, respectively. Finally, 3-D fullerene models were developed which particularly emphasize icosahedral symmetry for B-C and B-C-N fullerenes, and octahedral symmetry for BN fullerenes.