Raman scattering study of FeCl3 based graphite bi-intercalation compounds

FeCl3-IBr, -ICl, and -SbCl5 - graphite bi-intercalation compounds (GBC's) have been synthesized from a stage 4 FeCl3 - graphite intercalation compound (GIC), and their lattice dynamics has been investigated by Raman spectroscopy. First, layer sequences of these GBC's were determined by x-ray diffraction, and the sequence was determined to be G(FeCl3)G(1)G(2)(I)G(3)G(4)(FeCl3)G, where G(n), (FeCl3), and (I) refer to the nth graphite, FeCl3, and bi-intercalate layers, respectively. The sequences were the same irrespective of bi-intercalated species. These GBC's give only one peak identified as Raman active mode frequency in the Raman spectra. The peak frequencies were found to be affected by bi-intercalated species, and the frequencies were in the order of IBr < ICl < SbCl5. From this result, the degree of charge transfer was determined to be in the order of IBr < ICl < SbCl5.