A comparative Raman study of some transition metal fullerides

Fe–C 60 films were obtained using co-evaporation of metal and C 60 from separate sources at UHV conditions. A new Fe x C 60 compound was identified based on the analysis of Raman spectra, which showed many new peaks as a well as a split, and shift of original C 60 modes. Fe x C 60 exhibits no homogeneity range and the composition was estimated to be approximately Fe 3–4C 60. The Fe-fulleride phase is stable in air, not soluble in toluene and most probably has a polymeric structure similar to known fullerides with Pt and Pd. Raman spectra of fulleride compounds with Nb, Fe, Pt and Pd were compared and found to exhibit strong similarities including characteristic peaks below 250 cm −1, which can be attributed to intercage vibrations of a polymeric structure. In contrast, Raman data as well as properties of a previously described Ti x C 60 phase suggest a different type of bonding in this compound.