Orientation-dependent electrochemical reduction and proton evolution in the oxygen-deficient perovskite SrFeO<sub>2.5+y </sub>
Yosuke Isoda, Daisuke Kan, T. Majima, Yuichi Shimakawa
Abstract
Abstract Electrochemical reactions with insertions of ions in solids depend on crystallographic orientations. We investigated electrochemical responses of (100), (110) and (111)-oriented oxygen-deficient perovskite SrFeO 2.5+ y epitaxial films in electric-field-effect transistor structures with the proton-conducting electrolyte Nafion as a gate insulator. We found that only (100)-oriented SrFeO 2.5+ y films exhibit changes associated with gate-voltage-induced electrochemical reductions. Furthermore, elastic recoil detection analysis shows that electrochemically reduced (100) films can accommodate protons, forming the proton-containing oxide H 0.11 SrFeO 2.5+ y . Our results show that oxygen vacancies form preferentially along the {100} axes and ion diffusion in electrochemical reactions occurs dominantly along the {100} directions in SrFeO 2.5+ y .