It was noted that the mechanisms of ionic conduction in solid electrolytes were best studied by obtaining conductivity spectra (frequency- and temperature-dependent conductivities ranging from the direct-current to the far-infrared regime). The spectra of solid electrolytes exhibited characteristic patterns which could be interpreted in terms of dynamic processes. Only non-vibrational types of motion were considered; some of which were strictly localized while others contributed to translational diffusion. In particular, jump relaxation provided a consistent explanation for the familiar power-law conductivity.

K.Funke: Zeitschrift für Physikalische Chemie, 1995, 188[I-II], 243-57