Sammendrag
The chemistry and microstructure of the interface between calcium sub stituted lanthanum manganite and cubic calcia stabilized zirconia hav e been studied. The aim was to investigate the chemical stability of these materials as a model system for, respectively, the cathode and the electrolyte in solid oxide fuel cells. The relative amounts and t ime dependence of the formation of secondary phases (La2Zr2O7 and CaZ rO3)and inter-diffusion between the primary phases were obser ved to d epand on temperature, partial pressure of oxygen, and composi tion of the manganite. 30 mole % Ca on La-site and A-site deficiency of the m anganite were shown to stabilize the heterophase inte rface in air. Re ducing conditions were shown to destabilize the prima ry phases and in crease the rate of formation of secondary phases. Por e-coarseing with increasing amount of Ca in the manganite was the most striking featu re in the time dependence of the microstructure. The present findings are discussed in relation to the thermodynamic and ki netic stability of the cathode/electrolyte interface of conventional solid oxide fue l cells consisting of yttria stabilized zirconia and strontium substi tuted lanthanum manganite.
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