Fluorine or Fluoride-Graphite Intercalation Compounds as New Electroconductive Materials

研究了氟气氛下制备的氟化钛、氟化钒、氟化Nb和氟化钽-石墨层间化合物的结构、化学键和导电性。氟化钛和氟化钒主要形成2级化合物，氟化物在石墨层间插入，而氟化Nb和氟化钽则容易产生1级化合物，即在石墨层中插入氟化物。元素分析、XPS和X-射线衍射分析表明，氟化钛是一种桥链结构，其中TiF~(2-)分享氟离子，氟化钒阴离子容易进入石墨层的六角形(嵌套)。这些结构阻止了六氟阴离子在石墨层之间的扩散，从而使化合物具有高度的稳定性。另一方面，NbF^-_和TaF^-_的成巢困难，因为它们的阳离子比钒离子大。因此，NbF^-_和Taf^-_的化合物是平缓的。XPS还表明主体石墨和插层氟化物具有离子键，用非接触式维恩电桥测量了这些化合物的电导率。其电导率为1.7~2.0×10~(-5)Scm~(-1)~(-1)，是原始石墨(HOPG)的10~12倍，尤其是氟化钛或氟化钒插层石墨，在空气中几个月至八个月几乎不变。

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.