Improvements in Sintering Behavior and Grain-Boundary Conductivity of Ceria-Based Electrolytes by a Small Addition of Fe[sub 2]O[sub 3]

Abstract

The small addition of [e.g., 0.5 atom % (atom percent)] reduced sintering temperature (by ∼200°C), promoted the densification rate and grain growth, for the ceria-based powders. The measurements of lattice parameter indicated that the addition could also enhance the dissolution of in at lower sintering temperatures. The 0.5 atom % -doped sintered at 1450°C for 5 h had a maximum total conductivity, as compared to the undoped one sintered at 1600°C for 5 h. Moreover, a remarkable improvement in grain boundary conductivity was achieved in the ceramics with small additions of (<3 atom %). The two possible mechanisms, that is, attracted to the interface or/and a change in the viscosity and wetting nature of due to the dissolution of have been considered to be responsible for the scavenging effect of on impurity. It was also found that the optimum scavenging was achieved in the ceramics with 0.5 atom % and sintered at 1400 to 1500°C, with a negligible effect on the grain interior conductivity. At 550°C, the total conductivity of ceramics was increased by more than 22% by adding 0.5 atom % when sintered at 1450°C for 5 h. Therefore, the addition of is a feasible and promising way for improving the densification behavior and grain boundary conductivity of ceria-based electrolytes. © 2004 The Electrochemical Society. All rights reserved.