Text this: Chemical Degradation of the La<sub>0.6</sub>Sr<sub>0.4</sub>Co<sub>0.2</sub>Fe<sub>0.8</sub>O<sub>3−δ</sub>/Ce<sub>0.8</sub>Sm<sub>0.2</sub>O<sub>2−δ</sub> Interface during Sintering and Cell Operation