Berlin 2024 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

O: Fachverband Oberflächenphysik

O 67: Poster: Oxide, Insulator and Semiconductor Surfaces

O 67.6: Poster

Mittwoch, 20. März 2024, 18:00–20:00, Poster C

Polaron formation on BaTiO₃ surfaces induced by oxygen vacancies — •Andreas Ziegler and Bernd Meyer — Interdisciplinary Center for Molecular Materials and Computer Chemistry Center, FAU Erlangen-Nürnberg, Germany

BaTiO₃ is widely used as substrate and recently found interest in catalysis for oxidative coupling reactions. For these applications it is important to understand its surface properties in an oxygen-deficient state. While the localization of electrons due to oxygen vacancies has been studied intensely for bulk BaTiO₃, excess electrons on the surfaces of BaTiO₃ have not been elucidated yet.

We applied spin-polarized density functional theory (DFT) with an on-site Hubbard+U correction to determine the behavior of defect electrons created by oxygen vacancies on the Ba- and Ti-terminated BaTiO₃(001) surface. By applying atomic distortions before geometry optimization we achieved different localization/delocalization pattern of the two defect electrons. We find that localization of both electrons is energetically always more favorable than solutions with delocalized electrons. On the Ba-terminated surface, in the lowest-energy configuration, one electron is localized within the oxygen vacancy on the surface and the other on a Ti ion in the subsurface layer. This is in contrast to the bulk, where both defect electrons preferentially localize on neighboring Ti sites. On the Ti-terminated surface, strong surface relaxations occur, hindering an electron to localize in the vacancy and allowing localization only on two specific Ti sites.

Keywords: barium titanate surfaces; surface polarons; DFT+U calculations