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 molecula r units in Li12C60 Obtained by INS and QENS experiments performed on IN6 (a t 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 tem perature tetragonal structure of Li12C60 is accompanied by significant chan ges in the vibrational density of states (v-DOS). The role of the Li+ vibra tional and diffusional motion in determining the changes in the overall v-D OS is investigated.