The electrical properties of 2-phase mixtures with an alumina mole fraction of less than 0.3 were investigated by means of impedance spectroscopy. An enhancement of the conductivity, as compared with the pure bromide, was explained in terms of a so-called brick-layer space-charge model. Scanning electron microscopic observations confirmed the presence of continuous layers of alumina particles around grains of the solid ionic conductor. Bulk and short-circuiting so-called parallel pathways were detected in a high-frequency semi-circle. The low-frequency response was attributed to current-path narrowing by so-called perpendicular alumina layers.

M.A.Desvals, P.Knauth: Journal of the Physics and Chemistry of Solids, 1997, 58[2], 319-24