STUDIES OF STRUCTURAL-CHANGES IN C-60 C-70-NI LAYERS ANNEALED UNDER OXIDATIVE CONDITIONS/

The structural changes in C-60/C-70:Ni layers annealed at a temperatur e of 620 K were observed by Raman spectroscopy, electron diffraction, AFM and HRTEM methods. The 'as grown' C60C/(70):Ni layers exhibit the features of the amorphous structure, which is confirmed by broadened R aman bands of H-g(1) fullerene mode, diffused rings in the electron di ffraction pattern (with 4.8 and 8.7 nm(-1) radius) and HRTEM pictures. The AFM topographies depict grains of 100-200 nm in size, rounded hil locks agglomerated in bigger 'zigzag' objects. The annealed layer cont ains two phases: amorphous and crystalline fcc C-60 with enlarged latt ice parameter (a = 1.44 nm). The changes toward crystalline structure are observed in Raman spectra (sharp H-g(1)mode) and in the electron d iffraction pattern (reflexes (111), (220), (311), (420) and (422) of p ure C-60 fee structure). The AFM topographies show two kinds of object s with different lateral sizes 300 and 100-200 nm and different base t o top height 100-150 and 35 nm, respectively. (C) 1997 Published by El sevier Science Ltd.