Pressure-induced superhard phase of C60

The superhard phase of C60 has been found at non-hydrostatic high pressure 22.4 GPa at room temperature by in situ X-ray diffraction study. This phase exists at the pressure up to 32.7 GPa. At the higher pressure there is a random network of fullerene molecules. The crystal structure has been determined by Rietveld analysis of the high-pressure diffractogram. The best fit profile has been simulated by a 3D polymerized structure with (2+2) cycloaddition along a and b axes and (3+3) type of cycloaddition along the space diagonal of orthorhombic structure. The bulk modulus B0 is tentatively determined by the compressibility up to 32.7 GPa, and its value is approximately equal to 530±80 GPa.