Preparation of NaC60 and its physical properties revealed by differential scanning calorimetry, 23Na-NMR and ESR

NaC60 was prepared and identified by Raman spectroscopy. Differential scanning calorimetry showed the existence of two stable phases above and below 280 K. The high-temperature phase was supercooled down to 205 K and further transformed to a glass state below 205 K. X-ray diffraction at 295 K could be indexed by a face-centered cubic lattice. The 23Na-NMR spectra below 252 K exhibited the second-order nuclear quadrupole effect accompanied by a descent in symmetry at the site occupied by the Na+ ion. An ESR study has shown that the fcc NaC60 becomes nonmagnetic below 180 K.