C60 FULLERENE AS CARBON SOURCE FOR DIAMOND SYNTHESIS

The C60 fullerene was used as the carbon source to carry out the catal yzed synthesis of diamond, at 6.7 GPa and temperatures between 1200 an d 1850-degrees-C; the catalysts used were Ni, Co, and a Co alloy. Unde r these conditions, the graphite used as the carbon source gave a diam ond yield of about 90%; the yield with C60 depended on the catalyst. W ith Co, about the same quantity of diamond was obtained from C60 as fr om graphite, whereas almost no diamond was synthesized when pure C60 w as used as the carbon source with Ni and the Co alloy as catalysts. Th e diamond yield recovered to a high level with these two catalysts whe n a small quantity (about 10%) of graphite was added to the C60 fuller ene. This effect of the addition of graphite to a non-graphite carbon in the synthesis of diamond is different from that observed with amorp hous carbons. In all these experiments under high pressure and high te mperature with Ni, Co, or Co alloy, the C60 fullerene was destroyed an d transformed into diamond, graphite, or poorly crystallized carbon.