STRUCTURE OF FLUORINE-GRAPHITE INTERCALATION COMPOUNDS SYNTHESIZED IN GASEOUS AND ANHYDROUS LIQUID-HYDROGEN FLUORIDE WITH FLUORINE-GAS

The fluorination of highly oriented pyrolytic graphite (HOPG), powdery and flaky natural graphites, and carbon fiber (P 100) has been performed in a fluorine atmosphere with HF gas (5.3 x 10(3)-4.8 x 10(4) Pa), or by flowing fluorine gas in anhydrous liquid hydrogen fluoride (AHF) at ambient temperature. The obtained C(x)Fs were the stage 1 to 2 compounds with composition of C1.9F to C7.0F. The stage 1 phases prepared from HOPG and pyrolytic graphite have shown large I(C) values of 1.12 nm to 1.18 nm. This result has coincided with the model that the stage 1 phase with large I(C) values is a bi-intercalation phase in which two kinds of almost ionically and semi-covalently bonded fluorine atoms with different C-F bond lengths are inserted in every other carbon layer. However, stage 1 C(x)F samples prepared from natural graphite powder and carbon fiber showed only one strong (001) diffraction line in most cases. X-ray powder diffraction and electron diffraction have revealed the absence of an in-plane superlattice at all stages.