固態電解質La1-xSrxGa1-yMgyO3-δ之電性及微觀結構分析

The electrical and microstructure analysis of solid electrolyte La1-xSrxGa1-yMgyO3-δ ceramic

李明澤(Ming-Ze Lee)

指導教授 ： 吳玉娟

國立臺北科技大學/工程學院/材料及資源工程系研究所/碩士(2011年)

https://doi.org/10.6841/NTUT.2011.00487

摘要

本研究利用固態合成法製備中溫型固態氧化物燃料電池之電解質La1-xSrxGa1-yMgyO3-δ試片。LaGaO3鈣鈦礦結構微量摻雜二價的Sr和Mg，在中溫範圍(600oC ~ 800oC)具有高氧離子導電率，並且造成相結構的轉變。本實驗經由XRD、SEM、TEM、Raman、直流電性、交流阻抗及熱膨脹等分析儀器，分析試片之顯微組織、晶體結構、離子導電性。主要討論在不同添加量下其微觀結構變化和電性之關係。
結果顯示共摻雜後晶體結構會從正交晶系轉變成菱方晶系，並觀察到有微量二次相SrLaGa3O7於晶界析出。拉曼在674、738 cm-1會產生額外峰值，推測是由Sr2+置換La3+、Mg2+置換Ga3+所產生之氧空位鍵結。利用SEM觀察試片表面結構，觀察到LaGaO3的平均晶粒大小為10 μm，並隨著摻雜量的增加而提升。於操作溫度500oC ~ 800oC之DC電性量測，當共摻雜量達0.35 mol以上，在800oC時有高離子導電率σ約0.16 S/cm。以TEM觀察可以發現低摻雜之LSGM1010試片表面，有明顯且密集之板狀微結構。隨著摻雜量的增加，此微結構有減少甚至消失的趨勢，推測此與結構轉換有關聯。

關鍵字

固態氧化物燃料電池 ； 固態反應法 ； 固態電解質 ； 鈣鈦礦結構

並列摘要

This study was to develop La1-xSrxGa1-yMgyO3-δ solid electrolytes with high ionic conductivity for intermediate temperature SOFC (Solid Oxide Fuel Cell).The perovskite solid solution formed by the substitution of La and Ga by Sr and Mg had a superior oxide ion conuctivity at intermediate temperature of 600oC ~ 800oC. The LSGM ceramics had studied correlations between the crystal structures and oxide ion conduction properties of LaGaO3-based compound systems by XRD, SEM, TEM, Raman and conductivity. The crystal structure was changed from the orthorhombic to the rhombohedral with dopimg Sr and Mg was odserved. The second phase SrLaGa3O7 was identified by XRD and EDS. The extra aman bands at 674 cm-1, 738 cm-1 were observed, probably due to oxygen vacancy inducing by doping. The average grain size will increase with increasing by Sr and Mg site dopant content. The ionic conductivity of LSGM was enhanced with increase of both the Sr and Mg doped. When the total dopant concentration was more than 0.35 mol, the conductivity was higher than 0.16 S/cm. The lamellar-like microstructure was observed in LSGM1010, LSGM1020 specimens, and decreased with increasing dopant content.

並列關鍵字

Solid Oxide Fuel Cell ； Solid state reaction ； Solid electrolyte ； Perovskite structure

參考文獻

[1] W. R. Grove, “On Voltaic Series and the Combination of Gases by Platinum”, Philosophical Magazine and Journal of Science, 14, 127-130 (1839).

[2] R. M. Ormerod, “Solid Oxide Fuel Cells”, The Royal Society of Chemistry, 32, 17-28 (2003).

[4] T. Ishihara, H. Matsuda, Y. Takita, “Doped LaGaO3 Perovskite Type Oxide as a New Oxide Ionic Conductor”, Journal of the American Chemical Society, 116, 3801-3803 (1994).

[5] M. S. Khan, M. S. Islam, “Dopant Substitution and Ion Migration in the LaGaO3-Based Oxygen Ion Conductor”, Journal of the American Chemical Society, B 102, 3099-3104 (1998).

[6] K. Huang, R. S. Tichy, J. B. Goodenough, “Superior Perovskite Oxide-Ion Conductor; Strontium- and Magnesium-Doped LaGaO3:Ⅰ, Phase Relationships and Electrical Properties”, Journal of the American Ceramic Society, 81[10], 2565-2575 (1998).