Onionlike structures and small nested fullerenes formation under electron irradiation of turbostratic BC2N

Turbostratic BC2N samples were exposed to intense irradiation regimes in a high resolution electron microscope equipped with a field emission gun. Electron energy loss spectroscopy (EELS) analysis was used to check the sp2-bonding type and the composition of the starting materials. In highly crystalline areas, we observed a tendency for the basal planes to curl and form large “open” onionlike features. According to EELS quantification, no change of the composition occurs during their formation. Very occasionally, small nested fullerenes of less than 10 shells each with dimensions of the very internal shell close to that of a C60 were observed. These onions are thought to arise from the bending of a few basal planes of the planar starting material.