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MM: Fachverband Metall- und Materialphysik
MM 3: Transport - Atoms and Ions I
MM 3.4: Vortrag
Montag, 16. März 2020, 11:00–11:15, IFW A
Atomistic modeling of grain boundaries and their effects on oxygen vacancies in SrTiO3 — •Cong Tao1,2, Daniel Mutter1, Daniel F. Urban1, and Christian Elsässer1,3 — 1Fraunhofer IWM, Wöhlerstraße 11, 79108 Freiburg, Germany — 2IAM-CMS, Karlsruhe Institute of Technology, Straße am Forum 7, 76131 Karlsruhe, Germany — 3Freiburger Materialforschungszentrum FMF, Stefan-Meier-Str. 21, 79104 Freiburg, Germany
Point defects, especially oxygen vacancies, are involved in the accelerated grain growth behavior observed in strontium titanate (STO) perovskites in applied electric fields. The underlying mechanisms for the redistribution of oxygen vacancies along and across grain boundaries (GB) are not yet fully understood. In order to advance the understanding at the atomic scale, we employ classical atomistic simulations to investigate structures and properties of both the symmetric and asymmetric tilt GBs in SrTiO3. To locate the energetically favored sites for oxygen vacancies, their formation energies are calculated and analyzed with respect to local electrostatic potentials in atomistic supercell models. The simulation results indicate that oxygen vacancies preferentially form in the vicinity of the GBs. In addition to formation energies, the paths for oxygen vacancies migrating from all possible sites to their nearest neighbor sites are identified and systematically analyzed. The landscapes of oxygen vacancy formation energies and migration barriers are critically discussed with respect to experimental observations, in order to elucidate the specific role of GBs in trapping oxygen vacancies in SrTiO3 from both theoretical and practical viewpoints.