鑭、鍶、銀、錳氧化物之製備與其作為固態氧化物燃料電池陰極可行性研究

Preparation of La, Sr, Ag and Mn Oxides and their Use as the Possible Cathode of Solid Oxide Fuel Cells

本論文以化學沉澱法製備鑭、鍶、銀、錳固態氧化物La0.7Sr0.3-xAgxMnO3 （x = 0, 0.1, 0.2, 0.3）之前驅物，經煆燒後製成燃料電池之陰極。探討沉澱過程溶液中，鍶與銀莫耳比、前驅物煆燒溫度等條件對陰極材料之表面形貌、組成、結晶構造、熱性質等影響，以評估作為燃料電池陰極的可行性。氧化物表面形貌與半定量組成分析採用配備EDS之掃描式電子顯微鏡（SEM）來觀察。有關氧化物之結晶結構以X光繞射儀（X-ray diffractometer, XRD）進行分析，進而使用結晶解析（Total pattern analysis solution, TOPAS）商用軟體來探索結晶定性與定量之數據。氧化物之表面組成則用X光光電子能譜儀（XPS）進行分析，探討銀在價態上之變化。研究結果顯示：La0.7Sr0.3-xAgxMnO3氧化物中x = 0.00 ~ 0.20間均可形成鈣鈦礦結構，然而在x≥0.20後，會出現元素態銀的雜相。

Chemical co-precipitation between two solutions of nitrate salts and potassium hydroxide was studied to prepare the precursors, which were then calcined to form La0.7Sr0.3-xAgxMnO3 (x = 0, 0.1, 0.2, 0.3) for preparation of cathode catalysts used in solid oxide fuel cells (SOFC). The effects of Sr/Ag molar ratio in the nitrate solutions as well as calcination temperature on the morphology, composition, crystalline structure of the catalysts and on the cathodic behavior applied in SOFC were focused. The surface morphology of the oxide powders was examined through field emission scanning electron microscope (FE-SEM) and their composition was analyzed by the equipped energy dispersive spectrophotometer (EDS). The crystal structure was determined by X-ray diffractmeter (XRD) and further delineated in detail with the commercial software named as total pattern analysis solution (TOPAS). The surface composition on the oxides was explored by X-ray photoelectron spectroscopy (XPS) verifying the chemical states such as Ag-component. Resulting from various tests, the oxides La0.7Sr0.3-xAgxMnO3 (x = 0, 0.1, 0.2, 0.3) still retained in a perovskite structure with silver content ranging in x = 0.00 ~ 0.20. However, an impurity phase of metallic silver was present if x ≥ 0.20.