The conductivity of compositions in the ZrO2-Ln2O3 and ZrO2-MO2-Ln2O3 systems, where M was Hf or Ce and Ln was a lanthanide, was studied. The highest conductivity (0.3S/cm at 1000C) was found for the ZrO2-Sc2O3 system. The addition of MO2 to ZrO2-Ln2O3 systems decreased the conductivity. The conduction mechanism in ZrO2-based oxide ion conductors was explained in terms of the dopant ionic radius. The aging effect of the conductivity in ZrO2-Ln2O3 systems was measured at 800 to 1000C. Compositions with a high Ln2O3 content did not exhibit any significant conductivity degradation.

Zirconia-Based Oxide Ion Conductors for Solid Oxide Fuel Cells. O.Yamamoto, Y.Arachi, H.Sakai, Y.Takeda, N.Imanishi, Y.Mizutani, M.Kawai, Y.Nakamura: Ionics, 1998, 4[5-6], 403-8