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Microstructure and Interdiffusion Phenomena in YSZ-CGO Composite Electrolyte
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1999
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Materials ScienceElectroactive MaterialChemical EngineeringSinteringHigh Temperature MaterialsEngineeringYttria-stabilized ZirconiaElectrode-electrolyte InterfaceOxide ElectronicsApplied PhysicsDouble-layer Ceria-zirconia ElectrolyteCeramics MaterialsYsz-cgo Composite ElectrolyteCo-firing FeasibilityMicrostructureMaterial Preparation
In order to investigate the co-firing feasibility of a double-layer ceria-zirconia electrolyte for low-temperature Solid Oxide Fuel Cells (SOFCs), interdiffusion phenomena between yttria-stabilized zirconia (YSZ) and cerium-gadolinium oxide (CGO) were studied in the temperature range 1200°C to 1500°C with the aid of SEM/EDX-WDS. Significant solid state reaction and interdiffusion phenomena across the YSZ-CGO interface were found to occur already at 1200°C. The extent of the interdiffusion zone formed at the interface as well as the elemental distributions in this zone showed no dependence on sintering temperature and holding time. The difference of the diffusivity of Ce 4+ and Gd 3+ into YSZ and Y 3+ and Zr 4+ into CGO resulted in porosity emerging at the YSZ/CGO interface. The use of a microstructure with a graded YSZ/CGO 0.5 YSZ 0.5 /CGO composition was found to reduce the cation diffusion rates across the interface. However, the low conductivity of the CGO 0.5 YSZ 0.5 solid solution phase used requires further optimization of the composition of the interlayer to be used.