The small addition of FeO1.5 [e.g., 0.5 atom % (atom percent)] reduced sintering temperature (by similar to200degreesC), promoted the densification rate and grain growth, for the ceria-based powders. The measurements of lattice parameter indicated that the FeO1.5 addition could also enhance the dissolution of Gd2O3 in CeO2 at lower sintering temperatures. The 0.5 atom % FeO1.5-doped Ce08Gd0.2-O2-delta sintered at 1450degreesC for 5 h had a maximum total conductivity, as compared to the undoped one sintered at 1600degreesC for 5 It. Moreover, a remarkable improvement in grain boundary conductivity was achieved in the Ce08Gd0.2O2-delta ceramics with small additions of FeO1.5 (<3 atom %). The two possible mechanisms, that is, SiO2 attracted to the Fe2O3 interface or/and a change in the viscosity and wetting nature of SiO2 due to the dissolution of Fe2O3, have been considered to be responsible for the scavenging effect of Fe2O3 on SiO2 impurity. It was also found that the optimum scavenging was achieved in the Ce0.8Gd0.2O2-δ ceramics with 0.5 atom % FeO1.5, and sintered at 1400 to 1500&DEG;C, with a negligible effect on the grain interior conductivity. At 550&DEG;C, the total conductivity of Ce0.8Gd0.2O2-δ ceramics was increased by more than 22% by adding 0.5 atom % FeO1.5, when sintered at 1450&DEG;C for 5 h. Therefore, the addition of Fe2O3 is a feasible and promising way for improving the densification behavior and grain boundary conductivity of ceria-based electrolytes. (C) 2004 The Electrochemical Society.