Pressure-induced dimerization of C-60 fullerene

The dimerization of C-60 fullerene under conditions of quasi-hydrostatic co mpression at temperatures above 293 K is investigated by IR spectroscopy, R aman scattering (RS) spectroscopy, and x-ray diffraction. The measured dime r (C-60)(2) content in the products of the polymerization of fullerite as a function of the pressure, temperature, and treatment time shows that dimer ization occurs even at room temperature in the entire pressure range above similar to 1.0 GPa. However, at least at temperatures above 400 K dimerizat ion does not result in the formation of a dimer phase as a stable modificat ion of the system, since the dimer is an intermediate product of the transf ormation. It is shown that increasing the holding time at 423 K decreases t he content of the dimer fraction in the samples and results in the formatio n of linear (at 1.5 GPa) and two-dimensional (at 6.0 GPa) polymers, which a re structure-forming elements of the orthorhombic and rhombohedral polymeri zed phases. (C) 1998 American Institute of Physics. [S0021-3640(98)00624-0] .