Fullerenes dissolve gold in a sequence of phase transformations

We present the observation of gold intercalation into the polycrystalline C60 and c70 thin films by a dry electrolysis of the electrode, detected by in situ and space resolved conductivity measurements at different temperatures and applied voltages. The time resistivity behavior is described on the basis of electric field stimulated diffusion of metal ions from the contact into the interstitials of crystal lattice. The resistivity minima correspond to a local formation of Au3C60 and respectively Au1C70 and Au4C70 phases. In contrast to AuxC60, the AuxC70 phases are stable only in the applied electric field.