Influence of oxygen ion enrichment on optical, mechanical, and electrical properties of LSCF perovskite nanocomposite

La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) is a mixed ionic electronic conductor with excellent surface catalytic activity for oxygen reduction. This work demonstrated that introduction of pure oxygen ion conductor to LSCF particles can significantly influence in-plane electronic conduction at the surface of LSCF-samarium-doped ceria (SDC) composite. The composite functional layer was prepared by mixing 50 wt% SDC particles with LSCF particles obtained from glycine-nitrate process. Homogeneous LSCF-SDC composite layer deposited by screen printing on an SDC substrate has been studied with and without LSCF current-collecting layer (CCL). The microstructural, optical, Raman, mechanical and electrical properties, and interfacial polarization resistance (Rp) of the prepared powders were evaluated. Results revealed that addition of oxygen ion conductor SDC exerted negligible effect on the phase structure and specific surface area but significantly influenced the band gap, oxygen vacancies, and electrical conductivity of LSCF. SDC addition significantly increased area specific resistance (ASR) of LSCF from 0.138 Ω cm2 to 0.481 Ω cm2 at 800 °C, thereby blocking the conduction path among LSCF particles. Rp value of LSCF-SDC composite can be improved by more than six times by enlarging the in-plane electronic conduction with thin CCL. Electrochemical measurement revealed that LSCF CCL reduced the Rp value, resulting in the lowest ASR of 0.087 Ω cm2 at 800 °C for the LSCF-SDC composite.