Micro Structural and Electrical Properties of Ceria-Yttria Stabilized Zirconia Nanocomposites

Yttria stabilized zirconia (YSZ) is widely accepted nanomaterial electrolyte for solid oxide fuel cells (SOFCs). But, high operational temperature (~1000^oC) is required in 8 mol. % YSZ (8YSZ) electrolytes for achieving acceptable levels of ionic conductivity (~0.1S/cm). Alternately, doped cerium-oxide (ceria) show promise as electrolytes capable of operating at reduced temperatures (~600^oC). Enhanced ionic conductive interface is observed in doped ceria and YSZ composites in comparison to that of YSZ alone. Thus, it would be advantageous to synthesize ceria-8YSZ composites nanomaterials with 0, 5 and 10 wt. % ceria addition in 8YSZ, for attaining enhanced ionic conductivity. The novelty of current proposal is to synthesize ceria-8YSZ nanocomposite via spark plasma sintering (SPS, 1200 and 1300^oC, 5min. 30 MPa), and compare the resulting properties (mechanical properties, ionic conduction, etc) of ceria-8YSZ composites. This will allow correlation of processing temperature, microstructure, and ionic conduction of ceria-8YSZ, so that a mechanism for enhanced ionic conductivity can be explained. XRD analysis revealed that all samples exhibit both cubic and tetragonal structuressynthesized via SPS. The impedance spectroscopy analysis shows that ionic conductivity isincreased by the increasing CeO₂content in 8YSZ (which gave the clear evidence for ionic conduction not electronic as ceria content increases); this is also attributed to the nano size effect, high ionic conducting pathways in dense CeO₂-YSZ nanocomposite to promoting fast oxygen ion transportation. Thus optimal selection (physical, micro structural, mechanical and ionic conduction) of ceria-YSZ electrolytes will strongly assist in designing solid oxide fuel cells with enhanced performance.