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dc.contributor.authorBliem, Roland
dc.contributor.authorKim, Dongha
dc.contributor.authorWang, Jiayue
dc.contributor.authorCrumlin, Ethan J
dc.contributor.authorYildiz, Bilge
dc.date.accessioned2021-10-27T19:52:04Z
dc.date.available2021-10-27T19:52:04Z
dc.date.issued2021
dc.identifier.urihttps://hdl.handle.net/1721.1/133315
dc.description.abstractStable composition and catalytic activity of surfaces are among the key requirements for materials employed in energy storage and conversion devices, such as solid oxide fuel cells (SOFCs). Perovskite oxides that serve as cathode in SOFCs suffer from segregation of the aliovalent substitutional cations and the formation of an inert, non-conductive phase at the surface. Here, we demonstrate that the surface of the state-of-the-art SOFC cathode material La0.8Sr0.2MnO3 (LSM) is stabilized against the segregation of Sr at high temperature by submonolayer coverages of Hf. The Hf is vapor-deposited onto the LSM thin film surface by e-beam evaporation. Using in situ near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), we analyze the surface composition of LSM thin films. Half the LSM surface was kept as-prepared, and half was Hf-modified, for a direct comparison of untreated and Hf-treated regions on the same sample. The formation of a binary SrOx surface species is quantified as descriptor for surface degradation. The onset of Sr segregation is observed at 450 °C on the bare LSM, followed by a substantial advance at 550 °C. Hf-treated regions of the same LSM surface exhibit significantly less Sr surface segregation at 450-550 °C. We interpret this stabilization imparted by Hf to arise from the suppression of the electrostatic attraction of Sr2+ cations to surface oxygen vacancies. Doping the surface layer with Hf, that has a higher affinity to oxygen, reduces this attraction by decreasing the surface oxygen vacancy concentration. In doing so, the use of physical vapor deposition highlights the direct role of the metal species in this system and excludes artifacts that could be introduced via chemical routes. The present work demonstrates this stabilizing effect of Hf on the surface of LSM, broadening the relevance of our prior findings on surface metal doping of other perovskite oxides.
dc.language.isoen
dc.publisherAmerican Chemical Society (ACS)
dc.relation.isversionof10.1021/acs.jpcc.0c09707
dc.rightsCreative Commons Attribution 4.0 International license
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.sourceACS
dc.titleHf Deposition Stabilizes the Surface Chemistry of Perovskite Manganite Oxide
dc.typeArticle
dc.contributor.departmentMassachusetts Institute of Technology. Department of Materials Science and Engineering
dc.contributor.departmentMassachusetts Institute of Technology. Department of Nuclear Science and Engineering
dc.relation.journalJournal of Physical Chemistry C
dc.eprint.versionFinal published version
dc.type.urihttp://purl.org/eprint/type/JournalArticle
eprint.statushttp://purl.org/eprint/status/PeerReviewed
dc.date.updated2021-08-11T13:26:56Z
dspace.orderedauthorsBliem, R; Kim, D; Wang, J; Crumlin, EJ; Yildiz, B
dspace.date.submission2021-08-11T13:26:58Z
mit.journal.volume125
mit.journal.issue6
mit.licensePUBLISHER_CC
mit.metadata.statusAuthority Work and Publication Information Needed


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