| Abstract
| - Mesoporous niobium oxide potassium fulleride composites were synthesized by thetreatment of mesoporous niobium oxide with 0.3, 0.6, or 1.0 equiv of potassium naphthalenefollowed by stirring with either excess K3C60 or C60. The reaction of potassium-reducedmesoporous niobium oxide with neutral C60 is the first reported example of a mesoporousoxide functioning as an electron donor to a guest molecule. These new routes allow for greaterflexibility in the K:Nb and C:Nb ratios in the composite than our previous method and forthis reason enables a more comprehensive study of the effect of absolute carbon andpotassium content on electron transport properties. Materials were characterized byelemental analysis, nitrogen adsorption, XRD, XPS, SQUID magnetometry, and room-temperature conductivity measurements in an effort to relate density of states at the Fermilevel, temperature-independent paramagnetism, and conductivity patterns to the compositionof the composite. Variable temperature resistivity measurements showed that the compositesare metallic, semiconducting, or insulating, depending on the composition. The main factorsgoverning conductivity were the absolute carbon content and the oxidation state of theintercalated fulleride, while the absolute potassium content had little effect on the electronicproperties.
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