SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 61: Poster Session V: Oxide and insulator surfaces: Structure, epitaxy and growth I
O 61.9: Poster
Mittwoch, 3. März 2021, 10:30–12:30, P
Metal-supported two-dimensional ternary oxides: A case study of BaTiOx on Pd(111) — •Friederike Wührl, Sebastian Schenk, Oliver Krahn, Stefan Förster, and Wolf Widdra — Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany
The discovery of a quasicrystalline phase in ultrathin films of BaTiOx (BTO) on Pt(111) opened a new field of research on ternary oxides on metal substrates [1]. The dodecagonal oxide quasicrystal (OQC) shows up in a two-dimensional wetting layer, for which atomically-resolved scanning tunneling microscopy (STM) images show the Ti subgrid decorating the vertices of three tiling elements with equal edge lengths: square, triangle and rhombus [2]. To elucidate the role of the substrate on the formation of OQCs, we report here on a growth study of ultrathin BTO films on Pd(111). Upon annealing in UHV at 930 K to 1030 K, reduced BTO forms long-range ordered two-dimensional layers encapsulating the Pd substrate. In these wetting layers a series of structures has been identified by means of STM and LEED. Depending on the preparation conditions, the different structures follow triangle-rhombus, triangle-square or in case of the largest ones triangle-square-rhombus tilings. They can be classified according to their atom density per unit area. Although the largest unit cell, which covers an area of (2.6 x 6.4) nm2, host a complex triangle-square-rhombus tiling, an aperiodically ordered structure has not been detected on Pd(111).
[1] S. Förster et al., Nature 502, 215 (2013)
[2] S. Förster et al., Phys. Status Solidi B, 1900624 (2019)