Li diffusion and fullerene dynamics in lithium fulleride Li12C60 from inelastic neutron scattering experiments

We present results on the dynamics of the Li+ ions and of the C-60 molecular units in Li12C60 Obtained by INS and QENS experiments performed on IN6 (at the Institut Laue-Langevin) covering the temperature range 150 K to 600 K. The transition from the high temperature Fm (3) over bar m to the low temperature tetragonal structure of Li12C60 is accompanied by significant changes in the vibrational density of states (v-DOS). The role of the Li+ vibrational and diffusional motion in determining the changes in the overall v-DOS is investigated.