We report on the extraordinary superionic conductivity in the fulleride polymer Li4C60, a crystalline material with no disorder. 7Li, NMR, and dc frequency dependent conductivity show uncorrelated ionic hopping across small energy barriers (DeltaE_{a} approximately 200 meV) and an ionic conductivity of 10;{-2} S/cm at room temperature, higher than in "standard" ionic conductors. Ab initio calculations of the molecular structure find intrinsic unoccupied interstitial sites that can be filled by Li+ cations in stoichiometric Li4C60 even at low temperatures. The low energy required for the occupation of these sites allows a sizable Li+ diffusion above 130 K. The results suggest novel application of lithium intercalated fullerides as electrodes in Li ions batteries.

We studied the temperature stability of the endohedral fullerene molecule, N@C60, inside singlewall carbon nanotubes using electron spin resonance spectroscopy. We found that the nitrogen escapes at higher temperatures in the encapsulated material as compared to its pristine, crystalline form. The temperature dependent spin-lattice relaxation time, T1, of the encapsulated molecule is significantly shorter than that of the crystalline material, which is explained by the interaction of the nitrogen spin with the conduction electrons of the nanotubes.

Na 2 C 60 is believed to be an electron-hole counterpart of the Mott-Jahn-Teller insulator A 4 C 60 salts. We present a study of infrared, ESR, NMR spectroscopy, x-ray diffraction, chemical composition and neutron scattering on this compound. Our spectroscopic results at room temperature can be reconciled in a picture of segregated regions of the size 3 -10 nm. We observe a significant insulating C 60 phase and at least two more phases, one of which we assign to metallic Na 3 C 60 . The separation disappears on heating by jump diffusion of the sodium ions, which we followed by neutron scattering. Above ϳ460 K we see infrared spectroscopic evidence of a Jahn-Teller distorted C 60 2− anion.