Pressure-induced irreversible amorphization of C70 fullerene

We report Raman scattering study of C70 fullerene polycrystals undertaken at high static pressures up to 51 GPa using a diamond-anvil cell. Above 12 GPa, a majority of the intramolecular vibrational modes lost their intensities and only one broad peak initially centered at 1567 cm−1 was found to persist, indicating an occurrence of amorphization. Analysis of the line width of the 1567 cm−1 peak showed the amorphization to be completed by about 18 GPa. The amorphous phase was irreversibly retained to the ambient pressure after pressures higher than 35 GPa were applied.