Preparation of La, Sr, Ag and Mn oxidesand their use as the possible cathode of solid oxide fuel cells

Chemical co-precipitation between two solutions of nitrate salts and potassium hydroxide was studied to prepare the precursors, which were then calcined to form La_0.7Sr_0.3-xAg_xMnO₃ (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 La_0.7Sr_0.3-xAg_xMnO₃ (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.