Superconductivity in NaH intercalated C60

We have found a new superconducting (SC) phase with the nominal composition (NaH) 4 C 60 , which was prepared by direct intercalation of sodium hydride (NaH) in C 60 . In a SQUID magnetization measurement, the SC transition temperature was found to be 15 K and the SC volume fraction was estimated to be 65%. The large value of the volume fraction suggests the creation of a single phase. This was confirmed by the powder X-ray profile showing a single f.c.c. phase with a lattice constant a=14.356(3) A . Hydrogen in the SC sample was analyzed by thermal desorption spectroscopy.