Atmosphere-induced change of microhardness and plasticity of C60 single crystals and polycrystalline films Original Research Article

The effect of air exposure and visible light illumination on the microhardness, plasticity and dislocation mobility in the C60 single crystals was investigated. Microhardness values for defined structural states of the fullerene (pristine, oxygen-intercalated, photo-oxidized) are reported. It has been shown that oxygen intercalation in the fullerene lattice during air-aging in the dark results in the suppression of dislocation mobility. However, only a slight increase in the hardness of oxygenated samples was observed. A remarkable increase in the hardness and decrease in the plasticity of the C60 crystals under illumination-assisted air exposure was noted. Photochemical transformation was found to be localized in the nearsurface layer of 1–5 μm. The data on the recovery of the micromechanical properties of the photo-oxidized surface layer under heating in air are presented.