Fluorine or Fluoride-Graphite Intercalation Compounds as New Electroconductive Materials

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The structures, chemical bond and electrical conductivities have been investigated on titanium fluoride, vanadium fluoride, niobium fluoride or tantalum fluoride-graphite intercalation compound prepared in fluorine atmosphere. Titanium fluoride and vanadium fluoride gave mainly stage 2 compounds in which fluoride is inserted in every other layer of graphite, however, niobium fluoride and tantalum fluoride easily produce the stage 1 in which fluoride is inserted in every graphite layer. Elemental analysis, XPS and X-ray diffraction have indicated that titanium fluoride takes a bridged chain structure in which TiF^2-_ share fluoride ions, and vanadium fluoride anion easily gets into the hexagons of graphite layer(nestling). These structures give high stagility to the compounds by preventing diffusion of hexa-fluoroanion between graphite layers. On the other hand, the nestling of NbF^-_ and TaF^-_ is difficult because they have larger cations than vanadium ion. The compounds of NbF^-_ and TaF^-_ are therefore unstagle. XPS has also shown that the host graphite and intercalated fluoride has ionic bond.The electrical conductivities of these compounds have been measured by contact -less Wien bridge. The conductivities were 1.7-2.0x10^5 Scm^<-1>, being 10-12 times that of pristine graphite(HOPG, highly oriented pyrolytic graphite).Especially those for titanium fluoride or vanadium fluoride intercalated graphite were almost unchanged for several to 8 months in air.