Oxygen storage capacity and thermal stability of brownmillerite-type Ca2(Al1-xGax)MnO5+δ oxides
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Understanding the oxygen uptake/release mechanism in oxygen storage materials is of great importance in the design of energy-related materials and their corresponding applications. In this work, the effects of Ga doping amount on the oxygen storage capacity and thermal stability of Ca2(Al1-xGax)MnO5+δ (0 ≤ x ≤ 1) with a brownmillerite-type structure were investigated. Ca2AlMnO5+δ can reversibly store/release a large amount of excess oxygen (∼3.0 wt%) at low temperature (between 300 and 600 °C) under oxidative atmospheres. With the increasing Ga doping amount in Ca2(Al1-xGax)MnO5+δ, these materials uptake less oxygen at higher temperature which can be attributed to the difficulty in the oxidation of tetrahedral GaO4 blocks into octahedral GaO6 blocks under 1 atm O2. However, with the increasing of Ga-substitution amount, these Ca2(Al1-xGax)MnO5+δ (0 ≤ x < 1) can start to uptake oxygen at lower temperatures during the cooling process under flowing O2 due to the distorted structure. The results demonstrated that Ca2(Al1-xGax)MnO5+δ (0 ≤ x < 1) can reversibly store/release large amounts of oxygen via just controlling the surrounding temperature and/or oxygen partial pressure but without using reductive gases, which would enable them great potentials in many applications.
Huang , X , Ni , C & Irvine , J T S 2019 , ' Oxygen storage capacity and thermal stability of brownmillerite-type Ca 2 (Al 1-x Ga x )MnO 5+δ oxides ' , Journal of Alloys and Compounds , vol. 810 , 151865 . https://doi.org/10.1016/j.jallcom.2019.151865
Journal of Alloys and Compounds
Copyright © 2019 Elsevier B.V. All rights reserved. This work has been made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1016/j.jallcom.2019.151865
DescriptionThe authors gratefully thank the National Natural Science Foundation of China (No. 51802015), and the Engineering and Physical Sciences Research Council platform grant (EP/I022570/1 and EP/I022570/2) for financial support.
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