ABSTRACT
I. INTRODUCTION Graphite reacts with fluorine gas in a wide range of temperatures, yielding two kinds of fluorine-graphite compounds: a fluorine-graphite intercalation com pound (GIC), QF, and the graphite fluorides (CF)„ and (QF)« [1,2]. The former is synthesized at a temperature below about 100°C, usually at ambient temper atures, in the presence of various fluorides. The sp2 bonding (i.e., planarity of carbon sheet) is maintained through the fluorine intercalation reaction in graph ite. The important point is that the nature of C -F bonding changes from ionic to semicovalent or semi-ionic with increasing fluorine content and decreasing stage number in CXF. In accordance with the change of C -F bonding with com position and stage number, Q F varies from a metallic conductor to a semicon ductor. On the other hand, the latter are completely different compounds from CXF in structure, C -F bonding, and physicochemical properties. The graphite fluorides (CF)„ and (C2F)n, which are white to almost black in color, are prepared by high-temperature fluorination at 300 to 600°C. Their carbon skeletons are no more planar but consist of trans-linked cyclohexane chairs with sp3 bonding. The C -F bonding is completely covalent; therefore, graphite fluorides are elec tric insulators.
