Irreversible amorphization of tetragonal two-dimensional polymeric C60 under high pressure

The pressure dependence of the cell parameters of tetragonal two-dimensional polymeric C60 has been determined by angle-dispersive, X-ray diffraction in a diamond anvil cell. The compression of the c parameter, the interlayer distance, is typical of a weak Van der Waals interaction, whereas the compression of the a parameter indicates strong covalent interactions. Amorphization was observed to occur gradually between 10 and 29 GPa when inter- and intra-layer distances become similar. No transition to another crystalline phase was observed up to 41 GPa or on decompression.