Abstract
We have measured the longitudinal (00 q) and transverse ( q00) modes in LiC 6 by inelastic neutron scattering, including the observation of a very high-energy phonon branch, tentatively assigned to an optic mode. Analysis of the longitudinal (00 q) modes by a one dimensional shell model yields force constants which are considerably larger than those of the heavy alkali-metal stage 1 compounds. Also, the interlayer shear constant C 44 is found to be distinctly larger than in the other stage 1 compounds. Yet, LiC 6 still shows an ω ∼ q 2 dispersion of the transverse branch characteristic for layered materials. Low temperature measurements on KC 24 revealed a mode splitting in the longitudinal acoustic (00 q) branch, which persists at temperatures above the alkali order-disorder phase transition at 123 K. The splitting may be caused by an Einstein-like in-band mode, which seems also to hybridize the ( q00) transverse branch.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call