Study of thin films of NaxC60: Electrochemical intercalation and physical properties

Electrochemical intercalation of Na into C-60 has been carried out in all solid-state cells in order to probe the phase diagram from the potential-composition curve. Experiments are performed in potentiodynamic mode on thin films deposited on Na-beta Al2O3 pellets at 350 K. Intercalation becomes noticeable below 1.305(5) V versus Na+-Na-0 and evidence is given for a large two-phase domain characterized by an equilibrium voltage plateau at 1.190(5) V, a smaller intercalation event near 0.95(5) V, and a solid solution domain at about 0.15<V<0.35 V. Na+ diffusion coefficients have been determined and films have been characterized by X-ray diffraction and Raman spectroscopy.