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Oxygen Storage Property and Chemical Stability of SrFe1–xTixO3−δ with Robust Perovskite Structure

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journal contribution
posted on 11.08.2017, 00:00 by Akito Demizu, Kosuke Beppu, Saburo Hosokawa, Kazuo Kato, Hiroyuki Asakura, Kentaro Teramura, Tsunehiro Tanaka
The compounds of SrFe1–xTixO3−δ with a robust perovskite structure are synthesized by Ti substitution for Fe sites in SrFeO3−δ, and they display improved oxygen storage properties and chemical stability in a CO2 atmosphere. The oxygen storage rate of SrFe0.8Ti0.2O3−δ is over 5 times faster than that of SrFeO3−δ. Further, in the presence of CO2, SrFe1–xTixO3−δ with x ≥ 0.2 maintains its oxygen storage property, whereas, for x ≤ 0.1, the oxygen release rate drastically deteriorates due to the formation of SrCO3. The perovskite structures (space group I4/mmm) of SrFe1–xTixO3−δ (x ≥ 0.2) are preserved even after reduction treatment under a H2 atmosphere at 773 K. In contrast, the material with x ≤ 0.1 undergoes a phase transformation from perovskite (I4/mmm) to brownmillerite structures (Ima2), and the latter easily reacts with CO2 to form a large amount of SrCO3 on the surface. Thus, the robust perovskite structure maintains its original framework despite the reduction treatment, resulting in improved oxygen storage rate as well as the CO2 resistance.