A large amplitude rattling-type anharmonic vibration of Li is possible without guest-host type structure, as we report here for tetragonal LiNH 2 crystal. The low temperature (0.4-300 K) specific heat capacity and Raman spectroscopy support the phonon model of site-specific Li activities governed by the symmetry of the potential energy distribution around the Li atoms in LiNH 2, which yields the anharmonic Li3 vibration (optical) in one direction (either X or Y axis of the crystal), while the Li1 and Li2 atoms remain silent. Our finding may help to correlate ionic conductivity, thermal, and hydrogenation properties of LiNH 2.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)