Preparation of high yield higher fullerenes

The fullerenes synthesized by vaporizing graphite anodes filled with WC, SiC, clay, CaC2, TiC, B4C, Zr and the oxides of La and Yb were studied. With the doped materials the relative content of higher fullerenes in the extract increased considerably, while the total yield of Fullerenes in soot decreased greatly except when WC, SiC and clay were used. Doping the graphite anode with WC, SiC or clay lead to an increase not only in the relative but also the absolute content of higher fullerenes. Use of an ordinary graphite rod containing ca 1% impurity can also lead to an increase in the relative content of higher fullerenes with the overall yield of fullerenes being unaffected. Doping the graphite anode favors formation of higher fullerenes while many doped materials lower the total yield. The doped materials act as heat carriers which sustain the growth of higher fullerenes. (C) 1998 Elsevier Science Ltd. All rights reserved.