Purification and characterization of buckminsterfullerene, nanotubes and their by-products

Buckminsterfullerene, C-60, has been purified by the sublimation technique using a closed quartz ampoule. Carbon nanotubes have been purified by eliminating the nanoparticles through oxidation at 725 degrees C using oxygen as a carrier gas. A pure form of C-60, nanotubes and their by-products have been characterized with thermogravimetric and powder X-ray diffraction analyses. The temperature for the maximum rare of oxidation is 830 degrees C for nanotubes and 515 degrees C for C-60 when heated at the rate of 20 degrees C/min in air. The outershells of carbon deposit prepared in an argon atmosphere are more resistant to oxidation (840 degrees C) compared with the oxidation temperature of outershells prepared in helium gas (760 degrees) under similar conditions. The powder X-ray diffraction study of nanotubes reveals that the interlayer distances have been enhanced by a few percent more than those in bulk graphite. Copyright (C) 1996 Elsevier Science Ltd