| Summary: | 碩士 === 元智大學 === 化學工程與材料科學學系 === 97 === The objective of this study was to promote ion and electronic conductivity and decrease the polarization of cathodes with Ba0.5Sr0.5CoO3-based cathode material. Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) were prepared by solid-state reaction methode, Pechini process and citrate-EDTA complexing method. From the results of XRD and conductivity, it was formed that BSCF prepared by citrate-EDTA complexing method have the best electrochemistry property.
Although the samples prepared from different pH solution have similar structure and microstructure morphologies. The optimized composition of BSCF electrode was prepared from the precursor solution with a pH value of 6 and showed highest conductivity of 50.2 S/cm at 400℃, which is 1.3 times higher than the sample prepared from the precursor solution with a pH value of 9.
The (Ba0.5Sr0.5)La0.2Co1-xCuxO3-δ (x=0~0.45, BSLCCu) were prepared with pH values of 6 by citrate-EDTA complexing method. X-ray diffraction results of all samples sintered at 1050℃ revealed that the single phase cubic structure of perovskite was formed. The grain size of BSLCCu (X=0~0.15) is in the range of 1~5 μm, and the grain size grow up to about 10μm as x≧0.2. The open porosity of BSLCCu was decrease with increase of x value. Coefficient(CTE) of thermal expansion (CTE) and conductivity of BSLCCu was also decrease with increase of x value. BSLCCu with x=0 showed the highest conductivity of 689 S/cm at 300℃, which is 3.1 times higher than that of BSLCCu with x=0.45. From the result of AC impedance, it was formed that the gas diffuses resistance of BSLCCu much lower than that of BSLC.
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