Studies of structural changes in layers annealed under oxidative conditions

Abstract The structural changes in C 60 C 70 :Ni layers annealed at a temperature of 620 K were observed by Raman spectroscopy, electron diffraction, AFM and HRTEM methods. The ‘as grown’ C 60 C 70 :Ni layers exhibit the features of the amorphous structure, which is confirmed by broadened Raman bands of Hg(1) fullerene mode, diffused rings in the electron diffraction pattern (with 4.8 and 8.7 nm−1 radius) and HRTEM pictures. The AFM topographies depict grains of 100–200nm in size, rounded hillocks agglomerated in bigger ‘zigzag’ objects. The annealed layer contains two phases: amorphous and crystalline fcc C60 with enlarged lattice parameter (a = 1.44 nm). The changes toward crystalline structure are observed in Raman spectra (sharp Hg(1)mode) and in the electron diffraction pattern (reflexes (111), (220), (311), (420) and (422) of pure C60 fcc structure). The AFM topographies show two kinds of objects with different lateral sizes 300 and 100–200 nm and different base to top height 100–150 and 35 nm, respectively.