The superhard crystalline three-dimensional polymerized C60 phase

The profile analysis of the diffraction patterns, obtained for C-60 samples quenched from high pressure 13 GPa and temperature 670-820 K, yields proof of the formation of three-dimensional (3D) polymerized C-60 phase. The superhard phase manufactured after 13 GPa, 820 K treatment is characterized by common four-sided ring and (2 + 2) interfullerene cycloadditions in the layer, and (3 + 3) bondings between layers. The unit cell parameters of its body-centred orthorhombic 1mmm crystal structure refined by Rietveld program are equal to: a = 0.867(4), b = 0.881(1), and c = 1.26(0) nm. Lattice dynamics simulation of 3D polymerized C-60 has shown that sound velocities, bulk modulus and broad bands in Raman spectra agree well with the measurements. (C) 2000 Elsevier Science B.V. All rights reserved.