摻雜異價離子(Sm3+、Ca2+ )對CeO2基電解質的顯微結構和性質之分析

The microstructure and property analysis of aliovalent cations (Sm3+, Ca2+) doped ceria-base electroyte

李明翰(Ming-hen Lee)

指導教授 ： 吳玉娟

國立臺北科技大學/工程學院/材料科學與工程研究所/碩士(2010年)

摘要

本研究為發展中溫型SOFC電解質以取代高溫型之YSZ (yttria stabilized zirconia)電解質。故本研究選擇CeO2基之電解質，因螢石(fluorite)結構具有高的氧離子導電率，且純CeO2從室溫到熔點皆為穩定之結構，是好的SOFC電解質材料。利用固態反應法於燒結溫度1450oC/4 h和1550oC/4 h下製備Ce1-XCaXO2-δ (X = 0.10~0.20)、Ce1-XSmXO2-δ (X = 0.10~0.20)和(SmXCa0.2-X)Ce0.8O2-δ (X = 0.05~0.15)試片，並利用XRD、SEM、TEM、Raman、熱膨脹分析儀、直流電性及交流阻抗等儀器，分析試片之晶體結構、顯微組織、原子鍵結、緻密度及離子傳導性。
各成份配比試片在燒結後皆為立方螢石結構，且隨燒結溫度提高會增加緻密性，但同時也增加平均晶粒尺寸。各配比試片在頻率~465 cm-1處為螢石結構之F2g震動模式波峰，且在頻率~570 cm-1處有一寬的波峰出現，是由Ca2+、Sm3+置換Ce4+所產生之氧空位鍵結。在500∼800oC範圍，以(Sm0.15Ca0.05)Ce0.8O2-δ (1550oC/4 h)具有最高離子導電率，在800 oC導電率為7.38×10-2 S/cm。

關鍵字

固態氧化燃料電池

並列摘要

This study was to develop ceria-based solid electrolytes with high ionic conductivity for intermediate temperature SOFC (Solid Oxide Fuel Cell). Fluorite structure with the higher oxygen ionic conductivity is the major electrolyte materials in SOFC. The CeO2 is stable cubic fluorite structure from the room temperature to melting point. Beside, as compared to the commercial YSZ (yttria stabilized zirconia) solid electrolyte, it has higher ionic conductivity and lower active energy, so it is applied to as the electrolyte material of intermediate temperature SOFC.
The CaXCe1-XO2-δ (X = 0~0.2), SmXCe1-XO2-δ (X = 0~0.2) and (SmXCa0.2-X) Ce0.8O2-δ (X = 0.05~0.15) electrolytes were sintered at 1450oC and 1550oC for 4 hr by solid-state reaction. All samples were analyzed for crystal structure, appearance, atomic bonding, densification, and ionic conductivity by XRD, SEM, Raman, thermal expansion analyzer and ion conductivity.
All samples are cubic fluorite structure. The densification and average grain size will increase with increasing the sintering temperature. The Raman line (at ~465 cm-1) broadens and becomes asymmetric with a low frequency tail, and a new broad feature appears at 〜570 cm-1 in the spectrum for all samples. These changes are attributed to O vacancies, which were caused by Sm3+, and Ca2+ ions are substituted for Ce4+. The (Sm0.15Ca0.05)Ce0.8O2-δ specimens possess the highest conductivity during 500∼800oC and ionic conductivity is 7.38×10-2 S/cm at 800oC.

並列關鍵字

SOFC ； ceria

參考文獻

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