Synthesis and structure of the fluorine-graphite intercalation compound, C xF

Abstract

The fluorine-graphite intercalation compound C xF has been synthesized at room temperature in the presence of liquid and gaseous HF, a Lewis acid (SbF 5 or WF 6) or metal fluoride (AgF). The compounds were analyzed by X-ray and electron diffractometries, IR spectroscopy and XPS. The fluorine intercalation rate in graphite increases with increasing HF coexisting in the reaction system. The products were stage 1–3 with composition of C 2F to C 10F. The c-axis repeat distance is 10.5–-12 Å for all the stage 1 compounds prepared under various conditions. This has been interpreted by the formation of a bi-intercalation phase in which ionically and semi-ionically bonded fluorine (6 Å and 4.7–6 Å including the thickness of one carbon sheet, respectively) are inserted in every other carbon layer. The in-plane structures are different according to the fluorine intercalation rate. The compounds prepared in the presence of AgF (intercalation rate is low) have a supcrlattice with a lattice parameter a 0=2a g at stage 2 and 3, but no superlattice at stage 1. Those prepared in liquid HF or gaseous HF (intercalation rate is high) show no in-plane superlattice in any stage.