The growth of vanadium oxide on alumina and titania single crystal surfaces

Evaporation of vanadium metal onto alumina or titania surfaces at room temperature in an oxygen ambient results in the growth of V2O3 overlayers. The results of several complementary methods, including STM, indicate that the oxide grows in clusters 20-30 Angstrom in diameter, eventually covering the surface with a granular thin film at a coverage in excess of one monolayer of vanadium atoms. The similarity of the distribution of vanadium metal and the vanadium oxide on the surfaces observed by STM on a thin, crystalline alumina film suggests that the oxide is formed after the metal nucleates into small clusters. No surface reduction of cations occurs on either the TiO2(110) or Al2O3(0001) surface when the vanadium oxide is formed. On the alumina, the vanadium oxide film appears to be conducting at room temperature, as would be expected for V2O3 formation.