PREPARATION OF HIGH-YIELD HIGHER FULLERENES

The fullerenes synthesized by vaporizing graphite anodes filled with W C, SiC, clay, CaC2, TiC, B4C, Zr and the oxides of La and Yb were stud ied. With the doped materials the relative content of higher fullerene s in the extract increased considerably, while the total yield of Full erenes in soot decreased greatly except when WC, SiC and clay were use d. 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 fulle renes. Use of an ordinary graphite rod containing ca 1% impurity can a lso lead to an increase in the relative content of higher fullerenes w ith the overall yield of fullerenes being unaffected. Doping the graph ite anode favors formation of higher fullerenes while many doped mater ials lower the total yield. The doped materials act as heat carriers w hich sustain the growth of higher fullerenes. (C) 1998 Elsevier Scienc e Ltd. All rights reserved.