Complete Conductivity Spectra of Crystalline and Glassy Fast Ion Conductors Up to Far Infrared Frequencies

Abstract

AbstractComplete conductivity spectra have been taken of a lithium ion conducting glass of composition B2O3 · 0.56Li2O · 0.45LiBr and of lithium stabilized Na-β″-alumina, at various temperatures. — In the glass, it has forthe first time been possible to separate the hopping and vibrational contributions to theconductivity. The resulting hopping conductivity spectra display high-frequency plateaux similar to those known to exist in crystalline solid electrolytes like RbAg415 and Na-β-alumina. In the dispersive regime, the spectra are characterized bytwo different power-law exponents, p = 0.6 and q = 1.3. The data are evaluated by combined application of the jump relaxation model and the dynamic structure model. — Na-β″-alumina has pronounced high-frequency plateaux between about 200 GHz and 400 GHz. The hopping observed in the spectra can be decomposed into hops that are a priori unsuccessful and others that can be treated in terms of the jump relaxation model. The latter fraction is found to increase with increasing temperature.