Effects of the Crystal Host Structure on the Oxygen Desorption Behavior in Perovskite-Type AeFe_0.9In_0.1O_3−δ (Ae = Sr and Ba)

Abstract

The relationship between the oxygen desorption properties and changes in the electronic state of Fe ions and the local atomic structures of the Fe–O polyhedra in perovskite-type AeFe0.9In0.1O3−δ (Ae = Sr (SFI010) and Ba (BFI010)) upon varying the A-site ions was investigated. Thermogravimetry showed that oxygen was released from both materials above 440 °C in air, suggesting charge compensation via the reduction of Fe ions. Changes in the Fe valences were greater for SFI010 than BFI010. On heating both samples in air, Fe K-edge X-ray absorption spectroscopy (XAS) spectra continuously changed, arising from the change in the symmetry of the local atomic structures of the Fe–O polyhedra. The influence of the reduction of the Fe ions on the XAS spectra was considered to be a charge compensation for oxygen desorption above 440 °C. With increasing temperature, the local atomic structure of the Fe ions in SFI010 changed whereas that of BFI010 barely changed, although the crystal structures of both were retained during oxygen desorption. High structural tolerance for large changes in the local structure and lower Fe valence at high temperatures were observed in SFI010 and allowed for high oxygen desorption. Therefore, the electronic state at high temperatures and the retention of the crystal structure are important factors for preparing superior oxygen storage materials.