Novel aspects of graphite intercalation by fluorine and fluorides and new B/C, C/N and B/C/N materials based on the graphite network

Materials of composition BC3, C5N and BC2N have been prepared by reactions which are driven by favorable TΔS values associated with HC1 elimination. X-Ray and electron diffraction, electron microscopy, EELS and Auger spectroscopy all establish that these materials have their atoms in graphite-like networks. BC3 is a semi-metal, and BC2N is a small bandgap semiconductor. C5N is best formed at 680°C and is characterized by an interlayer spacing of 3.52 Å. At higher reaction temperatures (CN)2 is lost and at 980°C the composition is ∼ C14N and the average interlayer spacing is 3.43 Å. The C/N material becomes more graphite-like dimensionally and the electrical conductivity increases towards that of graphite as the nitrogen content falls. These observations suggest that the N atoms may not be in the same plane as the C atoms. Each of the B/C, C/N and B/C/N materials has a unique intercalation chemistry, which will be compared with that of graphite. The graphite network is also preserved in graphite fluorinated by F− carriers at ∼ 20°C. A remarkably inert material of composition C1.3F and its CXF relatives (in which the sp2 carbon of graphite is preserved) will be described. At composition C1.3F the interlayer spacing is 6.4 Å but the graphite-like ao parameter (ao = 2.478 Å) is only slightly larger than that in graphite itself, therefore most F atoms in C1.3F must have F atom neighbors at only 2.48 Å.