The effect of FeO1.5 addition on the densification behavior and electrical properties of Ce0.8Gd0.2O2-delta ceramics was examined. The small addition of FeO1.5 (e.g., 0.5 at.%) reduced sintering temperature (by similar to 200 degreesC) and promoted densification rate. When sintered at 1300degreesC for 5 h, the 0.5 at.% FeO1.5-doped Ce0.8Gd0.2O2-delta has similar to 95% relative density, as compared to similar to 82% relative density for the undoped one. The measurement of lattice parameter indicated that the FeO1.5 addition also promoted the dissolution of Gd2O3 in CeO2 at lower sintering temperatures. On the other hand, the grain boundary (GB) conductivity could be significantly improved by small addition of FeO1.5. The optimum scavenging effect on SiO2 impurity was achieved by adding 0.5 at.% FeO1.5 to Ce0.8Gd0.2O2-delta ceramics and sintered at 1400-1500 degreesC. (C) 2004 Elsevier B.V. All rights reserved.