Content area
The performance and durability of solid oxide fuel cells (SOFCs) are critically governed by the structural and chemical coherency of the hetero-interfaces between oxygen ion-conducting electrolytes and electronically conducting electrodes. In particular, realizing coherent and chemically stable interfaces between La₀.₈Sr₀.₂Ga₀.₈Mg₀.₂O₃−δ (LSGM), a fast oxygen-ion conductor, and (La₀.₆Sr₀.₄)₀.₉₅Co₀.₂Fe₀.₈O₃−δ (LSCF), a mixed ionic-electronic conductor, is critical for minimizing interfacial resistance and enabling high-efficiency energy conversion.
A major challenge in solid-state fuel cells arises from the potential interdiffusion of cations across electrolyte/electrode interfaces, which can lead to the formation of undesired secondary phases and degraded ionic/electronic transport properties. Therefore, precise interface engineering is essential to preserve the functional stability of both layers. Despite the technological importance, detailed experimental studies remain lacking, especially on the epitaxial growth and hetero-interface structure of LSGM and LSCF heterostructures using Pulsed Laser Deposition (PLD).
In this work, we systematically optimized PLD growth conditions for single-crystalline LSGM and LSCF thin films on SrTiO₃ (001) substrates, aiming to establish a coherent and well-defined hetero-interface suitable for fundamental studies of interfacial phenomena under the fuel cell operating condition. X-ray diffraction (XRD) analysis revealed that LSGM films grown at 800 °C and 150 mTorr of oxygen partial pressure exhibited a lattice parameter of 3.909 Å (±0.017) with a full-width-at-half-maximum (FWHM) of 0.169°, while LSCF films grown under optimized conditions showed a lattice parameter of 3.916 Å (±0.021) and an FWHM of 0.072°, indicating high crystallinity and epitaxial alignment. As a result, the successful fabrication of LSGM/LSCF heterostructure exhibited distinct XRD peaks from both layers, suggesting layered epitaxial growth without significant interdiffusion or secondary phase formation under the optimized conditions. This study provides a reproducible route for the coherent integration of LSGM electrolytes and LSCF electrodes via PLD, offering a model platform for exploring interfacial transport, defect chemistry, and long-term stability — essential aspects for the development of next-generation, high-performance SOFC devices.