Oxidation states of cations in a perovskite structure play an important role for conductivity in solid oxide electrochemical cells. For bulk materials oxidation states can be calculated for specific conditions, but is not well understood for micro−/nanostructured materials and at interfaces between materials. We present a fundamental study of interfaces between La_0.6Sr_0.4CoO_3-δ (LSC) and yttria-stabilized zirconia (YSZ) in symmetric model solid oxide electrochemical cells. Nanoscale morphology as well as the chemical state of the LSC are investigated by scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS). The experiments were performed in situ at temperatures up to 600 °C in high vacuum (ca. 10⁻⁷ mbar) and in 2 mbar oxygen. The measured LSC Co oxidation at room temperature is lower than that expected for bulk LSC, indicating a high oxygen vacancy density and possibly high ionic conductivity. However, the Co oxidation state increases with increasing temperature, both in oxygen and in vacuum. The results shows that the Co oxidation state approach that expected for bulk LSC for typical solid oxide fuel or electrolysis cell operation temperatures.

钙钛矿结构中阳离子的氧化态对于固体氧化物电化学电池中的电导率起着重要作用。对于散装材料，可以针对特定条件计算氧化态，但对于微/纳米结构材料以及材料之间的界面尚不了解。我们目前对对称模型固体氧化物电化学电池中La _0.6 Sr _0.4 CoO3 _-δ（LSC）和氧化钇稳定的氧化锆（YSZ）之间的界面进行基础研究。通过扫描透射电子显微镜（STEM）和电子能量损失谱（EELS）研究了LSC的纳米级形态和化学状态。实验是在高达600°C的高真空下（约10 ^-7 mbar）和2 mbar氧气。室温下测得的LSC Co氧化程度低于大体积LSC所预期的氧化程度，表明高的氧空位密度和可能的高离子电导率。然而，在氧气和真空中，Co的氧化态都随着温度的升高而增加。结果表明，对于典型的固体氧化物燃料或电解池工作温度，对于大体积LSC来说，Co氧化态方法是可以预期的。