LATTICE-DYNAMICS OF GRAPHITE-IRON CHLORIDE INTERCALATION COMPOUNDS FROM MOSSBAUER-SPECTROSCOPY

Mössbauer spectra of graphite-FeCl3 and graphite-FeCl2 intercalation compounds have been measured over the temperature range 4.2 ≤ T ≤ 320 K. The spectrum of the FeCl3 intercalated compound consists of a singletv resonance at an isomer shift characteristic of ferric iron in a cubic symmetry charge site. The spectrum of the FeCl2 intercalated compound showed that there are two crystallographically inequivalent iron sites, described as Fe(I) and Fe(O), in this compound. In single crystal orientation experiments of the graphite-FeCl2 compound, the intensity ratio of the doublet spectrum for the Fe(I) site was angularly dependent but that of the Fe(O) site was not. The Mössbauer lattice temperature, θM, obtained from the temperature dependence of recoil free fraction for the intercalates were smaller than those of the corresponding neat iron chlorides. This result suggests that the iron atoms in the intercalation compounds are more labile than those in the corresponding iron chloride. © 1979.