Search for new physical properties in fullerides and nanotubes by intercalation of various substances and by their microstructure control under high pressure

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We have tried to intercalate various substances into fullerenes and carbon nanotubes and search new physical properties with adjusting positions of intercalants by heat treatment, pressurization, co-intercalation and film evaporation. The x-ray diffraction, electrical resistivity and magnetization measurements were used.(1) Potassium fullerides K_xC_<70>(x=1,2,3,4,6,9) haye been synthesized and found x=3, 4, and 9 phases to be metallic and x=1, 2 and 6 phases to be insulating. The compounds around x=3 have a superconducting transition at 0.5 K, but other phases are not superconductor down to 40 mK(2) Sodium fullerides Na_xC_<70> have face-centered cubic structures at 1≦x≦8 and has simple cubic structure at x=11. The x=8 and 11 phases are found to be metallic, but are not superconducting down to 2 K.(3) Lithium-saturated fulleride Li_<14>C_<70> has an insulating face-centered orthorhombic structure, and Li_xC_<70> with 1≦x≦14 have face-centered cubic structures. Li_<14>C_<70> could be s … More ynthesized under pressure at room temperature.(4) C_<70>S_x(x=48 and 16) and Mg_xC_<70> were successfully synthesized.(5) Superconductivity with T_c=8.8K was newly found in Li_xC_<60>. Mg_xC_<60> was newly synthesized.(6) The effect of K intercalation and hydrogen adsorption to single wall carbon nanotubes was investigated. But the results are not clear due to a fairly large amount of ferromagnetic impurity in the tubes.(7) The x-ray diffraction measurements were performed for K_xC_<70> as a function of temperature and pressure. Noticeable sructural transitions were not found. Superconductivity under pressure was searched for Cs_3C_<60>.(8) The cryostatic ultra-high vacuum evaporation system had been constructed with a scanning tunneling microscope incorporated. The electrical conductivity with increasing intercalant concentration was measured together with a morphology and a gap observation of the film. But clear results have not been obtained. The results (1), (2), and (3) have been partly published and others are now in submission or preparation. Less