Electronic and Structural Properties of Single-crystal Jahn-Teller Active Co 1+x Mn 2-x O 4 Thin Films.

Autor: Blanchet MD; Physics, Auburn University, 380 Duncan Drive, Leach Science Center, Auburn, Alabama, 36849-5412, UNITED STATES., Heath JJ; Physics, Auburn University, 380 Duncan Drive, Leach Science Center, Auburn, Alabama, 36849-5412, UNITED STATES., Kaspar TC; Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, MSIN K8-87, Richland, Washington, 99352, UNITED STATES., Matthews BE; Energy and Environment Directorate, Pacific Northwest National Laboratory, PO Box 999, Richland, Washington, 99354, UNITED STATES., Spurgeon SR; Energy and Environment Directorate, Pacific Northwest National Laboratory, MSIN K8-87, Richland, Washington, 99352, UNITED STATES., Bowden M; Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, PO-Box 999, Richland, Washington, 99352, UNITED STATES., Heald SM; Argonne National Laboratory Advanced Photon Source, 9700 S. Cass Avenue, Lemont, Illinois, 60439, UNITED STATES., Isaacs-Smith T; Auburn University, 380 Duncan Drive, Leach Science Center, Auburn, Alabama, 36849, UNITED STATES., Kuroda MA; Auburn University, 380 Duncan Drive, Leach Science Center, Auburn, AL 36849-5319 , UNITED STATES., Comes R; Physics, Auburn University, 380 Duncan Drive, Leach Science Center, Auburn, Alabama, 36849-5412, UNITED STATES.
Jazyk: angličtina
Zdroj: Journal of physics. Condensed matter : an Institute of Physics journal [J Phys Condens Matter] 2020 Dec 21. Date of Electronic Publication: 2020 Dec 21.
DOI: 10.1088/1361-648X/abd573
Abstrakt: Recent investigations on spinel CoMn 2 O 4 have shown its potential for applications in water splitting and fuel cell technologies as it exhibits strong catalytic behavior through oxygen reduction reactivity. To further understand this material, we report for the first time the synthesis of single-crystalline Co 1+x Mn 2-x O 4 thin films using molecular beam epitaxy. By varying sample composition, we establish links between cation stoichiometry and material properties using in-situ x-ray photoelectron spectroscopy, x-ray diffraction, scanning transmission electron microscopy, x-ray absorption spectroscopy, and spectroscopic ellipsometry. Our results indicate that excess Co ions occupy tetrahedral interstitial sites at lower excess Co stoichiometries, and become substitutional for octahedrally-coordinated Mn at higher Co levels. We compare these results with density functional theory models of stoichiometric CoMn 2 O 4 to understand how the Jahn-Teller distortion and hybridization in Mn-O bonds impact the ability to hole dope the material with excess Co. The findings provide important insights into CoMn 2 O 4 and related spinel oxides that are promising candidates for inexpensive oxygen reduction reaction catalysts.
(© 2020 IOP Publishing Ltd.)
Databáze: MEDLINE
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