Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 83: Surface Chemistry and Growth
O 83.11: Vortrag
Donnerstag, 19. März 2015, 13:00–13:15, MA 144
Monitoring the formation of quasicrystalline barium titanate on Pt(111) using XPS and NEXAFS — •Alireza Bayat1, Stefan Förster1, Rene Hammer1, Eva-Maria Zollner1, Wolf Widdra1,4, Reinhard Denecke2, Silvano Lizzit3, Paolo Lacovig3, and Karl-Michael Schindler1 — 1Institut für Physik, Martin-Luther-Universität, Halle-Wittenberg, D-06120 Halle, Germany — 2Wilhelm-Ostwald-Institut, Universität Leipzig, D-04103 Leipzig, Germany — 3Elettra-Sincrotrone Trieste S.C.p.A. I-34149 Basovizza, Trieste, Italy — 4Max-Planck-Institut für Mikrostrukturphysik, D-06120 Halle, Germany
The discovery of a 2D quasicrystalline BaTiO3-derived (BTO) layer on Pt(111) opened a new field in fundamental physics as well as applications [1]. Using high-resolution XPS and NEXAFS, we have determined chemical states and coordination environments of all elements in the layer. In addition, the reversible transformation between BTO(111) islands and the quasicrystalline layer has been monitored using fast-XPS. The XPS spectra show that the islands contain titanium only as Ti4+ and are fully oxidized. The quasicrystalline layer contains Ti3+ and Ti4+ in approximately equal amounts and their formations from Ti in the islands happen simultaneously. The chemical shifts indicate that the coordinations of both Ti species in the quasicrystalline layer are different from bulk. NEXAFS spectra at Ti L- and O K-edges in normal and grazing incidences confirm an anisotropy in the quasicrystalline layer, presumably arising from a planar or near planar coordination of Ti. [1] S. Förster et al., Nature, 502 (2013) 215-218