Electrical properties of non-stoichiometric SmBa0.5Sr0.48(Co1-xFex)2.05O5+d (x= 0, 0.3, 0.5, 0.7) layered perovskite cathodes for SOFC

Park, Jeong Yun and Hong, Yu Taek and Lim, Yu Ri and Ryu, Bohyun and Schlegl, Harald and Kim, Jung Hyun (2025) Electrical properties of non-stoichiometric SmBa0.5Sr0.48(Co1-xFex)2.05O5+d (x= 0, 0.3, 0.5, 0.7) layered perovskite cathodes for SOFC. Ceramics International. ISSN 0272-8842 (In Press)

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Abstract

In this study, the electrical properties of SmBa0.5Sr0.48(Co1-xFex)2.05O5+d (x= 0, 0.3, 0.5, 0.7) (SBSCF) were analyzed under different oxygen partial pressures to find suitable candidates for cathodes for solid oxide fuel cells. Characteristic for these cathode materials are layered perovskite structures with a B-site excess non-stoichiometric composition. The XRD analysis confirmed that all investigated SBSCF compositions with Co substitution exhibit a single-phase layered perovskite structure. Additionally, the XRD peaks exhibited shifts, separation, and merging depending on the Fe substitution amount. SBSCF showed a behavior of decreasing electrical conductivity with increasing Fe substitution. The change in electrical conductivity was observed as the atmosphere was repeatedly varied between air and nitrogen environments, leading to a variation between high and low oxygen partial pressure. SBSCF exhibited higher electrical conductivity in an air atmosphere compared to a nitrogen atmosphere. Moreover, as the Fe substitution amount increased, the difference in electrical conductivity between the oxygen and nitrogen atmospheres became more pronounced. By repeatedly alternating between oxygen and nitrogen atmospheres and analyzing the electrical conductivity, it was confirmed that the SBSCF cathodes in this experiment demonstrated that after a heating and cooling process in a nitrogen atmosphere, the electrical conductivity recovers above 300 °C in air atmosphere, regardless of the amount of Fe substitution. These results indicate that the SBSCF cathode exhibits reversible electrical conductivity behavior, meaning no or very little conductivity loss occurs under typical SOFC cathode conditions, even after changes in oxygen pressure and temperature. Consequently, the SBSCF oxide system demonstrates stable electrical conductivity properties.