Dynamical Properties of Protonic Conductor K3H(SeO4)2

Dynamical properties of protonic conductor K3H(SeO4)2 were examined by using various techniques, Brillouin scattering, quasi elastic, and inelastic neutron scattering. No significant anomaly was observed in longitudinal and transverse acoustic modes. In each experiment, a Lorentzian shaped spectrum was observed at extremely low energy, (less than 0.1 meV). The spectra in Brillouin and inelastic neutron scattering at the zone boundary originate from rotational modes of SeO4 tetrahedra at Г- and L-point, respectively. The peak positions, shapes, and widths of the spectra are consistent with each other, while the integrated intensities show complementary temperature dependence. The lifetimes of those modes, about 10−10 s, agree with the stationary time of conduction protons obtained from Q dependence of width in quasi elastic neutron scattering.