Improvement of Grain-Boundary Conduction in SiO[sub 2]-Doped GDC by BaO Addition

Abstract

Barium oxide (BaO) was suggested as a scavenger material to mitigate the harmful siliceous intergranular phase in gadolinia-doped ceria (GDC). The addition of 1–5 mol % BaO to GDC specimens containing 500 ppm enhanced the grain-boundary conduction by times. Transmission electron microscopy and electron probe microanalysis attributed this enhancement to the scavenging of the siliceous phase by the Ba-rich phase. In contrast, the grain-boundary conduction was significantly deteriorated when doped with 0.1–0.2 mol % BaO, which was attributed to the dissolution of BaO into the intergranular phase and the consequent increase in the ion-blocking effect at the grain boundary.