Electrical and Mechanical Properties of C₇₀ Fullerene and Graphite under High Pressures Studied Using Designer Diamond Anvils

We compare electrical and mechanical properties of C₇₀ fullerene with high purity graphite to 48GPa at room temperature using designer diamond anvils with embedded electrical microprobes. The electrical resistance of C₇₀ shows a minimum at 20GPa with transformation to an amorphous insulating phase complete above 35GPa, while graphite remains conducting. Nanoindentation shows hardness values 220 times larger for the pressure quenched amorphous phase than for similarly treated graphite. Our studies establish that the amorphous carbon phase produced from C₇₀ has unique properties not attainable from graphite.