The attempt frequency for ion diffusion in the superionic conductors sodium and silver $\beta$-alumina is directly observed as a resonance in the far infrared dielectric response. Correlation of the measured attempt frequency with the observed diffusion coefficient suggests that the best conductors, Na and Ag $\beta$-alumina, can be described by a single ion hopping motion despite the relatively high density of diffusing species.

• Received 14 August 1974

DOI:https://doi.org/10.1103/PhysRevLett.33.1478