Oxygen migration pathways in layered LnBaCo2O6-δ (Ln = La-Y) perovskites
Abstract
Layered LnBaCo2O6-δ perovskites are important mixed ionic-electronic conductors, exhibiting outstanding catalytic properties for the oxygen evolution/reduction reaction. These phases exhibit considerable structural complexity, in particular, near room temperature, where a number of oxygen vacancy ordered superstructures are found. This study uses bond valence site energy calculations to demonstrate the key underlying structural features that favor facile ionic migration. BVSE calculations show that the 1D vacancy ordering for Ln = Sm–Tb could be beneficial at low temperatures as new pathways with reduced barriers emerge. By contrast, the 2D vacancy ordering for Ln = Dy and Y is not beneficial for ionic transport with the basic layered parent material having lower migration barriers. Overall, the key criterion for low migration barriers is an expanded ab plane, supported by Ba, coupled to a small Ln size. Hence, Ln = Y should be the best composition, but this is stymied by the low temperature 2D vacancy ordering and moderate temperature stability. The evolution of the oxygen cycling capability of these materials is also reported.
Citation
Hesse , F , da Silva , I & Bos , J-W G 2024 , ' Oxygen migration pathways in layered LnBaCo 2 O 6-δ (Ln = La-Y) perovskites ' , JACS Au , vol. 4 , no. 4 , pp. 1538-1549 . https://doi.org/10.1021/jacsau.4c00049
Publication
JACS Au
Status
Peer reviewed
ISSN
2691-3704Type
Journal article
Description
Funding: Engineering and Physical Sciences Research Council - EP/L016419/1.Collections
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