Electrical properties of gadolinia doped ceria electrolytes fabricated by infiltration aided sintering

Abstract

Common solid oxide fuel cell (SOFC) electrolyte materials (e.g., gadolinia doped ceria - GDC) demand temperatures exceeding 1400 degrees C for densification by conventional solid state sintering. It is very desirable to reduce the densification of the SOFC electroltytes to i) avoid microstructural coarsening of the composite anode layers, which are co-sintered with the electolyte layer in the anode supported SOFC fabrication scheme and ii) reduce energy consumption during SOFC manufacturing. We have recently demostrated a novel infiltration-aided sintering route to densify GDC ceramics at 1200 degrees C. In the present work, we present the electrical properties of GDC ceramics fabricated thusly. Comparison of high density (>= 95%) samples fabricated by conventional or infiltration-aided sintering reveal that at 700 degrees C, similar total electrical conductivities are obtained, while at 300 degrees C, specific grain boundary resistivity is smaller in the latter. Bulk (grain) conductivity is higher in porous GDC ceramics (relative density <= 90%) fabricated by infiltration-aided sintering than the conventionally sintered ones with similar porosities. Finally, open circuit voltage of 0.84 V at 700 degrees C, obtained under dilute hydrogen and stagnant air conditions suggests that GDC ceramics densified by infiltration-aided sintering are suitable for use as SOFC electrolytes.