Influence of Oxygen Impurities on Electrical Properties of Fullerene C60 |
| T. Rabenau, S. Roth and R.K. Kremer Max-Planck-Institut f. Festkörperforschung, Heisenbergstr. 1, D-70569 Stuttgart, Germany |
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| We present high temperature dc, ac and contactless microwave conductivity results on solid-state C60 (films and crystals) from room temperature up to 850 K. Heating pristine samples, which were exposed to the ambient atmosphere, under dynamic vacuum at first leads to a reduction of the electrical resistance and finally, above ≈700 K, to an increase in the resistance. The decrease is ascribed to oxygen desorption and the increase to the chemical reactivity of residual chemisorbed oxygen with the C60 host molecules, respectively. Samples, annealed above 800 K, display a reversible temperature dependence of the resistance. The high temperature regime of their resistance exhibits an activated behaviour with an universal activation energy of 2Ea = 1.85 ± 0.04 eV for crystals and films, which is identical to the HOMO-LUMO splitting of the C60-molecules. |
| DOI: 10.12693/APhysPolA.87.881 PACS numbers: 72.20.-i, 72.20.Jv, 72.80.Le |