Atomic dynamics in liquid KxSb1−x alloys

The atomic dynamics of liquid K_xSb_1−x alloys are studied using cold neutron inelastic scattering. Dynamical properties extracted from the experimental spectra, like the dispersions obtained from the maxima of the longitudinal current correlation function, J_l(Q, ω), and the vibrational spectra, show a strong dependence on concentration. With increasing content of Sb, higher frequency modes are observed in the vibrational spectrum. For the Sb-rich compositions the dispersion is split into two branches. This indicates the de-coupling of the dynamics of the two components, due to the difference in atomic mass, already around the position of the principal peak of the static structure factor, S(Q). The observations are consistent with results from earlier experiments on similar systems and from ab initio molecular dynamics simulations.