STRUCTURE AND PHYSICAL-PROPERTIES OF IODINE-DOPED FULLERENES

The crystal structure in C60Ix and C70Ix has been studied using X-ray diffraction measurement as a function of the reaction temperature. C60I2 has a base-centered orthorhombic structure. The electrical resistance measurement under high pressure showed that it had a semiconducting behavior with a gap of 0.3 eV at around room temperature. C70Ix has two different structures, depending on the iodine concentration: a body-centered tetragonal structure for x nearly equal to two and an unknown structure for x nearly equal to four. This structure is tentatively assigned as being a body-centered tetragonal structure. These compounds were not superconducting down to 1.3 K, as was checked using a.c. magnetic susceptibility measurements.