Vanadium surface oxides on Pd(111): A structural analysis

Christof Klein, Georg Kresse, Svetlozar L. Surnev, Falko P. Netzer, Michael A. Schmid, Peter Varga

    Veröffentlichungen: Beitrag in FachzeitschriftArtikelPeer Reviewed

    Abstract

    Scanning tunneling microscopy studies of vanadium oxides grown on Pd(111) show interesting structures especially in the low-coverage region. Evaporation of V in an oxygen background at elevated sample temperature (250 °C) results in the formation of a nonperiodic honeycomb-like structure growing from the steps, which starts to transform into an ordered phase at a vanadium coverage of ?-0.2 ML (monolayer). At 0.31 ML the entire surface is covered by this well-ordered open (4 × 4) structure. Annealing this structure in H2 atmosphere transforms the phase into a V2O3 surface oxide with (2 × 2) periodicity, whose optimal coverage is reached at 0.5 ML vanadium. Models for both ordered structures have been suggested before on the basis of ab initio density-functional theory (DFT) calculations and molecular-dynamics simulations and these models are now unambiguously confirmed by quantitative low-energy electron-diffraction (LEED) analyses. In the (4 × 4) phase, the V atoms are surrounded by four oxygen atoms in an unusual tetrahedral coordination leading to a V5O14 stoichiometry. This tetrahedral coordination allows the oxide to adopt open loosely packed two-dimensional (2D) and 1D structures, which are stabilized by the surface-oxide interface energy. Furthermore, it is shown that state of the art DFT calculations can indeed predict complex structures exactly as well as that modern quantitative LEED is capable of dealing with very large unit cells.
    OriginalspracheEnglisch
    Aufsatznummer235416
    Seitenumfang10
    FachzeitschriftPhysical Review B
    Jahrgang68
    Ausgabenummer23
    DOIs
    PublikationsstatusVeröffentlicht - 2003

    ÖFOS 2012

    • 103009 Festkörperphysik
    • 103015 Kondensierte Materie
    • 103025 Quantenmechanik
    • 103036 Theoretische Physik

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