"oxygen Sponge" Dynamics in Topotactic SrCo_{1- x}Fe_xO_3-δ

Topotactic transitions in complex oxides provide a pathway for the design of electronic, optical, and magnetic material properties. Here, we report on epitaxial perovskite (PV)- and brownmillerite (BM)-phase SrCo0.66Fe0.34O3-δ thin films that were grown on SrTiO3, LaAlO3, and DyScO3 single-crystal substrates by pulsed laser deposition. Temperature-dependent X-ray diffraction is used to investigate structural transitions and properties of the fabricated thin films and their associated "oxygen sponge"dynamics. We find that the topotactic phase transition between PV and BM phases in this material can be controlled in a wide temperature range between 200 and 325 °C and shows that it can be strongly tuned by the respective strain state and oxygen environment. Our findings reveal crucial insights for the control of topotactic transformations and are interesting for utilizing SrCo0.66Fe0.34O3-δ in redox devices and electrochromic applications.