| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 101 === Samarium doped ceria (SDC) is good candidate for application in intermediate temperature solid oxide fuel cells (IT-SOFC) due to the ability of high oxygen ionic conductivity.
SDC powders Ce1-xSmxO2-x/2 (x=0, 0.2, 0.4) is synthesized by traditional solid state reaction method and sintered to densify in conventional sintering and two-step sintering. The sample were characterized by XRD, SEM, EBSD, TEM and AC-impedance in the temperature range of 500~700oC.
The uniformly particle size (1~4?慆) of the SDC mixed powders allows the sintering of the samples into highly dense (≅95%) pellet at 1600oC. All powders and pellet were found to be pure CeO2 or ceria-based solutions with fluorite-type structure in X-ray diffractometer. The microstructure of grain size (≅ 8~15?慆) and grain boundaries in sintered pellets was observed under the SEM and EBSD. The morphology of grain boundaries were defined by high resolution transmission electron microscopy. All the solid oxide electrolytes were characterized by impedance spectroscopy to distinguish the grain and grain boundary electrical properties. The sample 0SDC-1600-1500-20h has the best electrical properties under 800 oC (σgb =1.38×10-3 S/cm, σg =1.41×10-2 S/cm, σeff =1.26×10-2 S/cm, Q =0.89 eV).
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