High surface area composite electrolytes were studied by using the alternating-current admittance method at temperatures of between 25 and 300C. The composition ranged from 20 to 70mol% Al2O3. Maxima were observed, in the isothermal conductivity versus composition plots, at 40 to 50mol%Al2O3. At 25C, the best material had a specific conductivity of 3.75 x 10-5S/cm. This was a factor of 100 to 1000 better than that of LiI at the same temperature. The enhanced conductivity resulted from an increase in the frequency factor, and a minimum in the overall activation energy, for conduction which occurred between 40 and 50mol% Al2O3.

F.W.Poulson, N.H.Andersen, B.Kindl, J.Schoonman: Solid State Ionics, 1983, 9-10, 119-22