Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 39: Oxide and Insulator Surfaces: Structure, Epitaxy and Growth II
O 39.1: Vortrag
Dienstag, 21. März 2017, 14:00–14:15, WIL C107
NEXAFS and EXAFS structure determination within quasicrystalline barium titanate on Pt(111) — •Alireza Bayat1, Stefan Förster1, Eva-Maria Zollner1, Wolf Widdra1,2, Paula Huth3, Reinhard Denecke3, Angelika Chasse1, and Karl-Michael Schindler1 — 1Institut für Physik, Martin-Luther-Universität, Halle-Wittenberg, D-06120 Halle, Germany — 2Max-Planck-Institut für Mikrostrukturphysik, D-06120 Halle, Germany — 3Wilhelm-Ostwald-Institut, Universität Leipzig, D-04103 Leipzig, Germany
The discovery of an aperiodic barium titanate derived quasicrystalline film on a periodic platinum substrate opened a new field in science and technology [1]. The key point of understanding the physical properties and potential future applications is to determine its geometric structure. EXAFS modulations at the Ti K-edge of the BaTiO3-derived quasicrystal on Pt(111) were recorded and FEFF6 calculations were performed. With respect to the first layer Pt atoms the analysis reveals the Ti in a near 3-fold hollow position with distances in the range of 2.3 - 2.4 Å. The short distances indicate bonding between Ti and Pt and emphasize their relevance for understanding the structure. Furthermore, pre-edge features of the NEXAFS spectrum at the Ti K-edge indicate a coordination of Ti by less than 4 O. In line with this, the chemical shift of Ti 2p photoemission lines proves that Ti ions exist only in the 3+ oxidation state.
[1] S. Förster et al., Nature, 502 (2013) 215-218.