Infrared spectra of high-temperature and high-pressure LinC60 phases

Lithium fullerides LinC60 prepared by liquid-phase intercalation, solid-sta te reaction, and a mixed process were studied by IR spectroscopy. The fulle rides obtained by liquid-phase intercalation can be divided, according to t heir structure, into three groups: solid solutions (n = 1-4), polymerized p hases containing lithium clusters between fullerene chains (n = 4-12), and partially depolymerized phases with two inequivalent types of lithium atoms (n = 12-30). The spect a of the fullerides with a = 2-3 prepared by solid- stare reaction are similar to those of the polymerized fullerides with n mu ch greater than 4 prepared by liquid-phase intercalation. The structure of the fullerides produced by the mixed process varies from that of photopolym erized C-60 films (n similar or equal to 1) to orthorhombic (n similar or e qual to 4).