Rare-earth-doped ceria powders (Ce0.8R0.2O1.9, R=Yb, Y, Gd, Sm, Nd and La), which may be applied to the oxygen ion electrolyte for solid oxide fuel cells, were prepared by the oxalate coprecipitation method. As-produced powders were calcined at 600oC, then pressed isostatically into disks (8 mm in diameter and 1 mm thickness) and sintered to above 98% relative density at 1600oC for 4 h. The complex impedance of the disk samples with Au electrodes was measured by a two-terminal AC bridge circuit in an oxygen partial pressure range from 0.21 to 1 × 10−23 atm at 336o-866oC. The electrical conductivity of Yb, Y or Sm-doped ceria was independent of the oxygen partial pressure. This result indicates that the conductivity is dominated by the diffusion of oxygen ions and electronic conduction can be ignored in the present case.

Keywords: Rare-earth-doped ceria, Electrical conductivity, Oxygen partial pressure