| Summary: | 碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 101 === The CeO2-base specimens were prepared by solid state reaction in intermedium temperate solid oxide fuel cell (IT-SOFC) electrolyte, and it can to replace the YSZ (yttria stabilized zirconia) which was used in high temperature SOFC. In the study, it shows the conductivity of the CeO2-base materals have higher conductivity in 500oC ~ 800oC by doping aliovalent cations (Sm3+, Mg2+&;#172;, Ca2+, Sr2+, Ba2+). The oxygen ionic conductivity increase with increasing oxygen vacancies that induced from chage compensation.
The XRD and EDS analysis show secondery phase CaO was produced from Ce0.8Ca0.2O2-δ specimens which sintered at 1550oC for 4 hours, and the MgO and BaCeO3 were also produced from Ce0.8Sm1-xMgxO2-δ (x > 0.05) and Ce0.8Sm1-xBaxO2-δ (x > 0.05) specimens. The grain size was inhibited by doping Sm3+ ion and improved by doping Ca2+ and Sr2+ from SEM analysis. From the DC analysis, the ionic conductivity of Ce0.8Sm0.15Ca0.05O2-δ specimens is higher and about 0.0837 S/cm at 800oC among CeO2-based specimens. After the aging testings for holding 500 and 1000 hours at 700oC, the conductivity of Ce0.8Sm0.15Ca0.05O2-δ specimen decreased from 0.0837 to 0.0581 S/cm and the grain size will also grow. The conductivity of the CeO2-based specimens were also measured under 5% H2/N2 atmosphere, and the conductivity increase in the reducing atmosphere because Ce4+ ions reduced to Ce3+ ions.
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