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Defects and Oxide Ion Migration in the Solid Oxide Fuel Cell Cathode Material LaFeO3

Taylor, FH; Buckeridge, J; Catlow, CRA; (2016) Defects and Oxide Ion Migration in the Solid Oxide Fuel Cell Cathode Material LaFeO3. Chemistry of Materials , 28 (22) pp. 8210-8220. 10.1021/acs.chemmater.6b03048. Green open access

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Abstract

LaFeO3, a mixed ionic electronic conductor, is a promising cathode material for intermediate temperature solid oxide fuel cells (IT-SOFC). Key to understanding the electronic and ion conducting properties is the role of defects. In this study ab initio and static lattice methods have been employed to calculate formation energies of the full range of intrinsic defects—vacancies, interstitials, and antisite defects—under oxygen rich and oxygen poor conditions, to establish which, if any, are likely to occur and the effect these will have on the properties of the material. Under oxygen rich conditions, we find that the defect chemistry favors p-type conductivity, in excellent agreement with experiment, but contrary to previous studies, we find that cation vacancies play a crucial role. In oxygen poor conditions O2– vacancies dominate, leading to n-type conductivity. Finally, static lattice methods and density functional theory were used to calculate activation energies of oxide ion migration through this material. Three pathways were investigated between the two inequivalent oxygen sites, O1 and O2; O2–O2, O1–O2, and O1–O1, with O2–O2 giving the lowest activation energy of 0.58 eV, agreeing well with experimental results and previous computational studies.

Type: Article
Title: Defects and Oxide Ion Migration in the Solid Oxide Fuel Cell Cathode Material LaFeO3
Open access status: An open access version is available from UCL Discovery
DOI: 10.1021/acs.chemmater.6b03048
Publisher version: http://dx.doi.org/10.1021/acs.chemmater.6b03048
Language: English
Additional information: This is an open access article published under a Creative Commons Attribution (CC-BY) License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium, provided the author and source are cited (see http://pubs.acs.org/page/policy/authorchoice_ccby_termsofuse.html).
Keywords: Science & Technology, Physical Sciences, Technology, Chemistry, Physical, Materials Science, Multidisciplinary, Chemistry, Materials Science, Total-energy Calculations, Oxygen-surface Exchange, Wave Basis-set, Structural Stability, Polycrystalline Lafeo3, Electronic-properties, Schottky Defects, Perovskite, Coefficient, Diffraction
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry
URI: https://discovery.ucl.ac.uk/id/eprint/1542209
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