Electrical Conductivity and Diffusion of Oxygen Ions in Rare-Earth-Doped Ceria.

Abstract

An oxalate coprecipitation method was applied to produce rare-earth-doped ceria powders (Ce0.8R0.2O1.9, R=Yb, Y, Gd, Sm, Nd and La). The powders calcined at 600°C were isostatically compacted and sintered at 1600°C in air to reach a relative density exceeding 98%. The electrical conductivity of rare-earth-doped ceria ceramics was dominated by the migration of oxygen ions in the bulk and was in the range of 6.7 to 13.6S·m-1 at 800°C. The activation energies for diffusion of oxygen ions in the bulk ranged from 75.3 to 93.4kJ/mol. The lattice energy theory for the fluorite structure was applied to estimate the activation energy. The calculated activation energy was close to the measured value.