Oxygen desorption properties of perovskite-type SrFe1−xCoxO3−δ: B-site mixing effect on the reduction properties of Fe and Co ions

• Published in: Journal of solid state chemistry Vol. 312
• Main Authors: Fujishiro, Fumito, Oshima, Natsumi, Sakuragi, Tokio, Oishi, Masatsugu
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.08.2022
• Subjects: B-site mixing effect; Oxygen storage materials; Perovskite-type oxides; Thermogravimetry; X-ray absorption spectroscopy; B-site mixing effect; Oxygen storage materials; X-ray absorption spectroscopy; Perovskite-type oxides; Thermogravimetry
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2022.123254

To understand the B-site mixing effect in perovskite-type SrFe1−xCoxO3−δ, we evaluated the relationship between the oxygen desorption properties and the reduction behavior of Fe and Co ions using thermogravimetry and in-situ X-ray absorption spectroscopy. The valence states of Fe and Co ions were estimated to be 3.56+ and 3.27+, respectively, which remained constant with changes in composition. Maximum oxygen desorption occurred at x ​= ​0.2 below 800 ​°C. As temperature was increased and oxygen was released, a relationship was observed between the valence and coordination number changes of each B-site ion; these changes were more pronounced for the Fe ions than for the Co ions. In SrFe1−xCoxO3−δ samples, oxygen adjacent to Fe ions was released more readily than oxygen adjacent to Co ions. This conclusion is supported by the electronic states of the two B-site ions. These results are important for the design of new oxygen storage materials. The B-site mixed cubic perovskite-type SrFe1−xCoxO3−δ (0.2 ​≤ ​x ​≤ ​0.8) showed the enhancement of oxygen desorption during heating under air, because of the decrease in the onset temperature by Co-doping. [Display omitted] •Oxygen desorption properties of B-site mixed perovskite-type SrFe1−xCoxO3−δ.•Fe and Co valences were estimated as constant values of 3.56+ and 3.27+, respectively.•Electronic state of Fe4+ in perovskite phase facilitated oxygen release adjacent to the Fe.