Synthesis of La_0.6Sr_0.4FeO₃/La_0.6Sr_0.4CoO₃ mixed ion conducting superlattices by PLD

Artificial superlattices (SLs) of mixed conducting oxides, La_0.6Sr_0.4FeO₃ (LSFO) and La_0.6Sr_0.4CoO₃ (LSCO) have been synthesized on MgO(001) substrates by Pulsed Laser Deposition (PLD) to investigate the structural effect on their properties as oxide permeable ceramics. To obtain higher epitaxy and better crystallinity of the SL, oxygen partial pressure, substrate temperature, laser power and repetition rate of the laser have been tuned to optimize the PLD conditions. With the optimized conditions, Reflection High Energy Electron Diffraction (RHEED) oscillation was observed, indicating that the growth of the film is a layer-by-layer process. The thin films of LSFO and LSCO, and the SLs were grown exclusively in [001] direction of the fundamental perovskite structure, and the pole figures of those films clearly specify that they are epitaxially grown on the (001)MgO substrate. In-plane and out-of-plane lattice constants of LSFO and LSCO layers of the SL have been obtained from an XRD reciprocal space mapping. The in-plane lattice parameters come closer to each other at a smaller SL period, while the difference in their out-of-plane lattice parameters slightly changes. In this system, therefore, the SL with smaller period is more distorted. The electrical conductivity of the SL is slightly higher than the average value of LSFO and LSCO and is completely different from that of a La_0.6Sr_0.4Fe_0.5Co_0.5O₃ thin film.