The conductivity of the system: ZrO2-Ln2O3, where Ln was a lanthanide, was measured as a function of dopant concentration at temperatures ranging from 350 to 1000C. Arrhenius plots of the conductivity revealed a distinct curvature around 600 to 700C. The migration enthalpy of oxide ions, and the association enthalpy of oxide-ion vacancies with dopant lanthanide ions, were deduced from the difference in activation energies for conduction in the high and low temperature ranges. The electrical conductivity of the system depended upon the composition and the dopant-ion radius. That is, the conductivity decreased with increasing dopant-ion radius, and the composition which had the maximum conductivity decreased with increasing dopant-ion radius. The highest conductivity (0.3S/cm at 1000C) was found for ZrO2-11mol%Sc2O3. The migration enthalpy in the ZrO2-Ln2O3 system increased, and the association enthalpy decreased, with increasing dopant-ion radius.

Electrical Conductivity of the ZrO2-Ln2O3 System. Y.Arachi, H.Sakai, O.Yamamoto, Y.Takeda, N.Imanishai: Solid State Ionics, 1999, 121[1-4], 133-9