The conductivity spectrum of a Li ion conducting glass with the composition, B2O3-0.56Li2O-0.45LiBr, was determined at temperatures ranging from 173 to 573K, for frequencies ranging from a few Hz to about 50THz. Separation of the hopping and vibrational contributions to the spectra was thus achieved for the first time. It was found that the resultant frequency-dependent hopping conductivity exhibited a high-frequency plateau which was similar to those which were known to exist in crystalline solid electrolytes such as Ag4RbI5 and Na -alumina. Within the dispersive regime of the conductivity, there was an increase in the power-law exponent from 0.6 to 1.3. The spectra were explained in terms of the jump relaxation and dynamic structure models. As well as a translational hopping of Li ions via the preferred A-sites, more localized motions were also detected; such as hops into the less-favored C-sites (and usually back again), and smaller displacements of the ions within their local environments.

C.Cramer, K.Funke, T.Saatkamp, D.Wilmer, M.D.Ingram: Zeitschrift für Naturforschung, 1995, 50a[7], 613-23