Formation of Na-THF-graphite intercalation compounds

The intercalation process of sodium-tetrahydrofuran (Na-THF) complexes was investigated on hosts with a graphitization degree P-1 of 0.1-0.2, and crystallite thickness of 20-30 nm; two cokes heat-treated at 1500-1900 degrees C and two as-received pyrolytic carbons. The reaction of the cokes with Na-THF complexes was completed within 5 h and no unreacted hosts remained, but the products only gave broadened X-ray diffraction peaks. The pyrolytic carbons with comparable values of structural parameters gave a stage-1 structure, but the reaction was very slow and the unreacted host material was detected even after 16 days. This intercalation behavior was the same as that of all hosts with a high degree of graphitization, including the present cokes heat-treated above 2000 degrees C. The two different behaviors are discussed, taking the magnetoresistance value into account.