Synthesis of diamond at high pressure and high temperature from C₆₀ fullerene

The C₆₀ fullerene was used as the carbon source to carry out the catalyzed synthesis of diamond, at 6.7 GPa and temperatures between 1200 and 1850 °C; the catalysts used were Ni, Co and a Co alloy. Under these conditions, the graphite used as the carbon source gave a diamond yield of about 90%, the yield with C₆₀ depended on the catalyst. With Co about the same quantity of diamond was obtained from C₆₀ as from graphite, whereas almost no diamond was synthesized when pure C₆₀ was used as the carbon source with Ni and the Co alloy as catalysts. The diamond yield recovered to a high level with these two catalysts when a small quantity (about 10%) of graphite was added to the C₆₀ fullerene. This effect of the addition of graphite to a non‐graphite carbon in the synthesis of diamond is different from that observed with amorphous carbons. In all these experiments under high pressure and high temperature with Ni, Co, or Co alloy the C₆₀ fullerne was destroyed and transformed into diamond, graphite, or poorly crystallized carbon.