Perovskite-Derived Layered Crystal Structure in SrCo0.26Fe0.74O3-δ Thin Films.

Oxygen coordination and vacancy ordering play an important role in dictating the functionality of complex oxides. In this work, an unconventional layering of oxygen ions in a mixed conductor SrCo_1-xFe_xO_3-δ (SCFO) thin film grown epitaxially on SrTiO₃ (STO) is reported. Scanning transmission electron microscopy (STEM) reveals alternating layers of oxygen deficiency along the growth direction, with the oxygen-rich layer correlated with the neighboring Co,Fe-site intensity, and contraction of the Sr–Sr distance. Density functional theory (DFT) calculations and STEM image simulations support the emergence of periodic (Co,Fe)O₆ and (Co,Fe)O₄/(Co,Fe)O₅ layers, an ordering that is also sensitive to the Co:Fe ratio. [ABSTRACT FROM AUTHOR]