Origins of long-term oxygen reduction activity degradation at 700 °C in polymeric precursor-derived La_0.6Sr_0.4FeO₃ (LSF) thin film cathodes were investigated. Electrochemical impedance spectroscopy measurements revealed that the LSF thin films pre-calcined at 900 °C (LSF-900) exhibited much faster electrochemical activity loss than did LSF pre-calcined at 700 °C (LSF-700). As similar losses in surface area were determined upon scanning electron microscopy image analyses of samples, microstructure evolution was excluded as a possible reason for the difference in degradation rates. Upon X-ray diffraction analyses and comparison of results with literature, it was suggested that small amounts of Ruddlesden-Popper type (La, Sr)₂FeO₄ (214) phases were present throughout the 100 hour exposure of both LSF-700 and LSF-900 to 700 °C, thus not affecting the long-term performance degradation rates. X-ray photoelectron spectroscopy analyses revealed that the ratio of surface-bound Sr to the lattice-bound one increased significantly in LSF-900, suggesting electrochemically inactive SrO/Sr(OH)₂/SrCO₃ rich layer formation and thus contributing to fast activity loss. Overall, it was established that microstructural evolution was not the sole source of degradation in LSF-based cathodes. Since LSF thin films deposited by a solution precursor onto YSZ electrolytes constitute a model structure, the results obtained in the present study can also provide useful information on the degradation of LSF-YSZ composite cathodes prepared by LSF infiltration into YSZ scaffolds.

研究了聚合前体衍生的La _0.6 Sr _0.4 FeO ₃（LSF）薄膜阴极在700°C下长期氧还原活性下降的原因。电化学阻抗谱测量显示，在900°C下预煅烧的LSF薄膜（LSF-900）比在700°C下预煅烧的LSF（LSF-700）表现出更快的电化学活性损失。由于在样品的扫描电子显微镜图像分析中确定了类似的表面积损失，因此排除了微观结构演变作为降解速率差异的可能原因。通过X射线衍射分析和与文献的结果比较，表明少量的Ruddlesden-Popper型（La，Sr）₂ FeOLSF-700和LSF-900暴露于700°C的整个100小时中都存在₄（214）个相，因此不影响长期性能下降率。X射线光电子能谱分析表明，在LSF-900中，表面结合的Sr与晶格结合的Sr的比例显着增加，表明电化学上无活性的SrO / Sr（OH）₂ / SrCO ₃丰富的层形成，从而导致快速的活动损失。总的来说，已经确定，微结构演变并不是基于LSF的阴极降解的唯一来源。由于由溶液前体沉积到YSZ电解质上的LSF薄膜构成模型结构，因此本研究中获得的结果还可提供有关通过LSF渗入YSZ支架制备的LSF-YSZ复合阴极降解的有用信息。