高溫時效對La0.6Sr0.4Co0.2Fe0.8O3-δ結構與性質之影響

本研究利用固態合成法製備La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF6428)陰極材料，探討經過750oC/200~1000小時的高溫時效後的電性與微結構變化。並且製備La0.6Sr0.4FeO3-δ(LSF641)與LSCF6428比較，探討添加鈷之異同。XRD檢測結果顯示部分的時效樣品觀察到LSF641與LSCF6428有二次相析出。但SEM觀察到LSCF6428與 LSF641在燒結後有二次相，隨著時效時間的增加，二次相並沒有增加或晶粒粗大的傾向，推論在時效溫度下析出量有一定之限度。LSF641與LSCF6428經過時效後導電性並沒有太大的改變，推論時效對導電性影響不大。LSF641與LSCF6428顯示皆為菱方晶結構，經過矩陣運算後，菱方晶對稱可以轉換為偽立方晶來表示。藉由TEM觀察LSF641與LSCF6428，皆有微結構的缺陷使晶粒之繞射斑點改變，LSF641藉由TEM分析發現晶粒邊緣有少量LaFeO3導致產生額外繞射點，推論在該時效條件下，LSF641與LSCF6428沒有產生相分離現象。交流阻抗的量測發現LSF641與LSCF6428的電性在一定的程度上隨時效時間而變化。

關鍵字

固態氧化物燃料電池；固態反應法；鐵鈷鍶酸鑭；鈣鈦礦結構

並列摘要

The variations of crystal structure, microstructure and electric properties of La0.6Sr0.4Co0.2 Fe0.8O3-δ (LSCF6428) IT-SOFC cathode material aged at 750oC for 200~1000 hours were investigated in this study. LSF641 was fabricated to compared with LSCF6428. After sintering, second phase precipitates in LSF641 and LSCF6428 were found by SEM, but only a little of CoO precipitation in the specimens of LSCF6428 could be observed by XRD. Moreover, there were no significant trends of increasing of CoO precipitation and crystal growth with increasing aging time. Though the TEM diffraction patterns of LSCF6428 and LSF641 exhibit a rhombohedral structure, which also can be examined by the high angle scanning of XRD. The results of AC-impedance measurement showed the impedance decrease with the increasing of aging time until 1000 hr.

並列關鍵字

Solid Oxide Fuel Cell ； Solid state ； LSCF6428 ； LSF641

參考文獻

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[3] T. Ishihara, "Perovskite Oxide for Solid Oxide Fuel Cells" Springer Science + Business Media, 2009, ch1, pp1-16.

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高溫時效對La0.6Sr0.4Co0.2Fe0.8O3-δ結構與性質之影響

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