Compositional effect of Cr contamination susceptibility of La9.83Si6−x−yAlxFeyO26±δ apatite-type SOFC electrolytes in contact with CROFER 22 APU
Apatite-type lanthanum silicates (ATLS) are attracting great interest as a new class of solid electrolytes possessing high oxide-ion conductivity at relatively low temperatures for solid oxide fuel cells (SOFC). In this study, doped ATLS of the composition La9.83Si6−x−yAlxFeyO26±δ (x: 0, 0.25, 0.75, 1.5 and/or y: 0, 0.25, 0.75, 1.5) were successfully prepared by solid state chemistry. They were brought into direct contact with CROFER-22 interconnector alloy in order to study Cr migration into the electrolyte. Due to inconclusive SEM-EDX results, a depth profile was acquired by Laser Induced Breakdown Spectroscopy (LIBS) and the results showed that the increase of Fe concentration in the apatite oxide's composition enhanced Cr uptake. At the same time, lower conductivity values were measured for the materials after Cr contamination i.e. in Fe containing ATLS. No significant change in conductivity was found for Fe-free ATLS sample.