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Title: Structural perturbations of epitaxial α-(Fe{sub 1−x}V{sub x}){sub 2}O{sub 3} thin films driven by excess oxygen near the surface

We examine the structure and composition of phase-pure epitaxial α-(Fe{sub 1−x}V{sub x}){sub 2}O{sub 3} thin films deposited on α-Al{sub 2}O{sub 3}(0001) substrates by oxygen-plasma-assisted molecular beam epitaxy for 0 ≤ x ≤ ∼0.5. The films crystallize in the corundum lattice, with vanadium substituting for iron throughout. Vanadium cations exhibit the expected 3+ charge state in the bulk, but exhibit higher valences nearer to the surface, most likely because of excess oxygen in interstitial sites near the surface. The extent of vanadium oxidation beyond the 3+ state is inversely proportional to x. The gradation of vanadium valence with depth has an impact on local bonding geometries, and could be highly significant in this material's efficiency as a photocatalyst.
Authors:
; ;  [1] ; ; ;  [2] ; ;  [3]
  1. Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
  2. Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)
  3. Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)
Publication Date:
OSTI Identifier:
22402808
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 23; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ALUMINIUM OXIDES; CATIONS; CHARGE STATES; CORUNDUM; IRON; MOLECULAR BEAM EPITAXY; OXYGEN; PERTURBATION THEORY; SUBSTRATES; SURFACES; THIN FILMS; VALENCE; VANADIUM