The effect of interionic forces upon mobile defects were investigated by determining the far-infrared reflectivity spectra of sintered material as a function of temperature below 300K. An anomalous increase was observed in the phonon damping constant and the long-range Coulomb force. From this temperature dependence, and a small increase in the effective charge with temperature, the effective role of the ionic character of the interionic force in ionic conduction was deduced.

Temperature Dependence of Dielectric and Phonon Properties in Superionic Conductor CuI. K.Wakamura, H.Hiraoka: Solid State Ionics, 2000, 136-137, 399-402