Chemical Modification of Carbon Materials and Transport Properties of the Resulting Compounds

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Carbon 1s spectra were determined as a function of the composition, K/C,for potassium intercalated graphite. The C1s spectra shifted towards higher energy and broadened with the increase of K/C.The shift was explained on the basis of the fact that the Fermi level shift increases with the increase of K/C as a result of the charge transger from potassium to carbon pi bands.Alkali metal-graphite intercalation compounds such as CsC_<24> can accomodate various molecules in its interlayr nano-spaces. It is very interesting to know the interaction between alkali metal ions and the penetrating molecules. It was found that the electrical conductivity of CsC_<24> changed remarkably and the effect of sorption temperature on the electical conductivity change was large for the system CsC_<24>-C_2H_2. On the other hand, the change of the electrical conductivity of CsC_<24> was less than 10%, and the temperature effect was small in the case of CsC_<24>-C_2H_4. Those results were discussed from the viewpoint that Cs ions can interact with pi electrons of C_2H_2, but not for C_2H_4.Effect of the degree of graphitization on the electrical conductivity, magnetoresistance and Hall coefficient of potassium intercalated carbon materials was also determined. Large values of the electrical conductivity and the magnetoresistance were observed for well graphitized material. For poorly graphitized materials, the temperature dependence of the electrical conductivity did not change to metallic one even if the intercalation of potassium took place.