Correlation between the defect structure, conductivity and chemical stability of La1–ySryFe1–xAlxO3–δ cathodes for SOFC

The chemical compatibility of a La1–ySryFe1–xAlxO3-δ cathode and an yttria-stabilised ZrO2 electrolyte (YSZ) was studied for solid-oxide fuel cell (SOFC) applications. The Al addition to the LaFe1–xAlxO3 reduces the reactivity with the YSZ associated with increasing tolerance factor. The Sr addition to the LaFe1–xAlxO3 leads to Fe4+ and anion-vacancy formation. The Sr addition hinders the formation of La2Zr2O7, but at y⩾0.2 promotes the formation of SrZrO3 at the La1–ySryFe1–xAlxO3–δ/YSZ interface. At low p(O2) the formation of secondary phases is pronounced what could be related to the formation of anion vacancy.