The conductivity enhancement mechanism in this composite solid electrolyte was investigated. It was found that the degree of enhancement increased with an increasing content of tetragonal BaTiO3 particles. A dependence of the alternating-current conductivity upon frequency indicated that the enhancement was due to an increase in the hopping rate, rather than in the concentration of mobile Na ions.

T.Takeuchi, K.Ado, Y.Saito, M.Tabuchi, H.Kageyama, O.Nakamura: Solid State Ionics, 1996, 89[3-4], 345-9