Bi-intercalation of ICl into a stage-5 FeCl3 graphite intercalation compound.

Abstract

X-ray diffraction (XRD) has been used for the study of bi-intercalation of ICl into the stage-5 ${\mathrm{FeCl}}_{3}$ graphite intercalation compound (GIC). The stage-5 ${\mathrm{FeCl}}_{3}$ GIC is obtained when the temperature of graphite is set at 788 K, and the temperature of ${\mathrm{FeCl}}_{3}$ at 573 K in the two-zone system. Since the stage-5 ${\mathrm{FeCl}}_{3}$ GIC has four consecutive vacant galleries in the c-axis direction, the ${\mathrm{FeCl}}_{3}$-ICl graphite bi-intercalation compounds (GBC's) with one and two ICl layers are studied. When the temperature of the stage-5 ${\mathrm{FeCl}}_{3}$ GIC is held at 373 K and the temperature of ICl at 323 K, the ${\mathrm{FeCl}}_{3}$-ICl GBC with one ICl layer is obtained. The layer sequence of the GBC is found to be an admixture of G(${\mathrm{FeCl}}_{3}$)GG(ICl)GGG(${\mathrm{FeCl}}_{3}$)G and G(${\mathrm{FeCl}}_{3}$)GGG(ICl)GG(${\mathrm{FeCl}}_{3}$)G by XRD, where G, (${\mathrm{FeCl}}_{3}$), and (ICl) refer to graphite, ${\mathrm{FeCl}}_{3}$, and ICl layers, respectively. The ${\mathrm{FeCl}}_{3}$-ICl GBC with two ICl layers is prepared with the temperatures of the stage-5 ${\mathrm{FeCl}}_{3}$ GIC and ICl at 333 and 313 K, respectively. Its layer sequence is determined to be G(${\mathrm{FeCl}}_{3}$)GG(ICl)G(ICl)GG(${\mathrm{FeCl}}_{3}$)G. From the result of the layer sequence of the ${\mathrm{FeCl}}_{3}$-ICl GBC with two ICl layers, the order of the degree of the charge transfer is shown to be ${\mathrm{FeCl}}_{3}$ GIC>ICl GIC.