Pressure-induced transformations in two-dimensional polymeric phases of C60

The structural stability of the tetragonal and rhombohedral two-dimensional (2D) polimeric phases of C60 has been studied under pressure up to 27 GPa and room temperature by means of in-situ Raman scattering spectroscopy. The results show that the tetragonal 2D phase undergoes an irreversible transformation in the region of 20 GPa while no pressure-induced transitions were observed for the rhombohedral 2D phase. The obtained data are discussed within the framework of recent numerical calculations, which predict the pressure-induced transformation of the 2D polymeric phases of C60 into three-dimensional (3D) polymers in the pressure range 1420 GPa