We examine the structure and composition of phase-pure epitaxial α-(Fe1-xVx)2O3 thin films deposited on α-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 has an impact on local bonding geometries, and could be highly significant in this material's efficiency as a photocatalyst.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)