Analysis of chemical interactions between stabilized zirconia and perovskites

LaMnO₃-based perovskites are used as cathode materials in solid oxide fuel cells (SOFC). A major aspect for their applicability is their chemical inertness in connection with the electrolyte material YSZ (Zr_0.85Y_0.15O_1.93) against zirconate formations. Perovskites with the composition La_y-x(Sr, Ca)_xMn_1-uCo_uO₃ (y = 1.0 and 0.95; x = 0– 0.2 and 1; u = 0 and 0.2) were investigated with regard to their reactivity with YSZ at different reaction times and temperatures. Powder mixtures and double-layer reaction couples were used for the investigations. XRD phase analyses, SEM/EDX and EPMA were applied for the characterization of the annealed samples. La-deficient perovskites (y = 0.95) partially substituted by Sr and Ca improve the chemical compatibility of perovskite compositions towards YSZ. Sr-containing perovskites were found to have a higher reactivity than Ca perovskites for La₂Zr₂O₇ formation. On the other hand enhanced Ca diffusion into YSZ was observed. Co substitution on Mn lattice sites decreased the chemical compatibility, especially for Sr containing perovskites.