Doped fullerenes preliminaries

Small amounts of the individual fullerenes ( 0.5mg) were placed in quartz tubes with alkali metals and sealed under vacuum. These samples were subjected to a series of heat treatments and tests for superconductivity by 9-GHz microwave-loss experiments. Preliminary tests indicated that only the K-doped Cfto showed a response consistent with a superconducting transition (Fig. 1). For this reason, together with the fact that K Cgo showed the highest film conductivity, we focused our studies on the K-doped compound. 

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