FREQUENCY-DEPENDENT CONDUCTIVITIES OF RBAG4I5 AND NA-BETA''-ALUMINA FROM RADIO TO FIR FREQUENCIES

The electric conductivities of the two fast ionic conductors RbAg4I5 and Na-beta"-alumina have been determined at various temperatures and frequencies from 4 MHz to 105 GHz. - The conductivity of RbAg4I5 is found to display a dispersion as expected by the so-called "universal dynamic" response, a high-frequency plateau in the range of 100 GHz and an Arrhenius behaviour at both low and high frequencies. - The spectra of Na-beta"-alumima show a different behaviour. In addition to the "universal dynamic" response dispersion, a faster and thermally less activated relaxation process is observed at high frequencies and low temperatures. Up to 60 GHz, a high-frequency plateau has not been encountered.