Electrochemical control and protonation of the strontium iron oxide SrFeOy by using proton-conducting electrolyte

To electrochemically control structural and transport properties of oxygen-deficient perovskite SrFeOy (2.5 & LE; y & LE; 3) (SFO) epitaxial films, we employed electric-field-effect transistor structures in which the proton-conducting solid electrolyte Nafion is used as a gate insulator. When a positive gate voltage (V-GS) is applied and protons are injected toward the film channel layer, the SFO films are electrochemically reduced, leading to increases in the channel resistance. On the other hand, when a negative V-GS is applied and protons are removed, the SFO films are oxidized, and as a result, the channel resistances decrease. In addition, we found that the electrochemically reduced SFO films accommodate protons, forming the proton-containing oxide HxSrFeO2.5 whose proton concentration is determined by elastic recoil detection analysis to be x & SIM; 0.11. Our results indicate the usefulness of the proton-conducting solid electrolyte for electrochemically controlling transition metal oxides and for exploring proton-containing oxides.

Automated summary

In this study, we used a proton-conducting solid electrolyte, Nafion, as the gate insulator to electrochemically control the structure and transport properties of SrFeOy films. Positive and negative gate voltages cause electrochemical reduction and oxidation of the films, respectively, leading to changes in the channel resistance. Additionally, we found that the electrochemically reduced SFO films can accommodate protons.