Structure and physical properties of Cs_3+αC₆₀ (α=0.0-1.0) under ambient and high pressures

The intermediate phases Cs_3+αC₆₀ (α=0.0-1.0), have been prepared, and their structure and physical properties are studied by x-ray powder diffraction, Raman, ESR, electric conductivity, and ac susceptibility measurements under ambient and high pressures. The x-ray powder diffraction pattern of Cs_3+αC₆₀ (α =0.0-1.0) can be indexed as a mixture of the body-centered-orthorhombic (bco) and cubic (A15) phases. The A15 phase diminishes above 30 kbar. The broad ESR peak due to the conduction electron (c-ESR) is observed only for the phases around α=0.0 in Cs_3+αC₆₀. The resistivity of the Cs_3+αC₆₀ (α≠0) sample follows the granular metal theory and/or Sheng model even in the sample exhibiting a broad ESR peak. No superconducting transition is observed up to 10.6 kbar in (Cs_3+αC₆₀ (α≠0). These results present that bco phase of Cs_3+αC₆₀ (α=0) is a final candidate for a pressure-induced superconductor.