INPLANE PHONON DENSITY-OF-STATES OF LI-GRAPHITE INTERCALATION COMPOUNDS

The in-plane phonon densities of states of Li-graphite intercalation compounds of stage-1 and stage-2 are obtained from neutron time-of-flight spectra. For the stage-2 the ordered compound LiC12 which has the same inplane structure as the stage-1 compound LiC6 as well as the dilute compound LiC16 which only reveals short range order were studied, The temperature in the measurements was extended above expected phase transitions for both stages and the density of states is analysed in terms of the effective temperatures T-parallel to for the in-plane vibrational energies. T-parallel to shows characteristic changes at the thermodynamic temperatures of the phase tansitions. Comparison of the T-parallel to values shows similar in-plane dynamics of all Li-compounds at the highest temperatures.