We examine the structure and composition of phase-pure epitaxial a-(Fe1-xVx)2O3 thin films deposited on a-Al2O3(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 may have an impact on local bonding geometries, and could be highly significant in this material’s efficiency as a photocatalyst.
Revised: May 23, 2019 |
Published: December 21, 2014
Citation
Chamberlin S.E., T.C. Kaspar, M.E. Bowden, V. Shutthanandan, B.C. Kabius, S.M. Heald, and D. Keavney, et al. 2014.Structural perturbations of epitaxial a-(Fe1-xVx)2O3 thin films driven by excess oxygen near the surface.Journal of Applied Physics 116, no. 23:Article No. 233702.PNNL-SA-105900.doi:10.1063/1.4903839