Dresden 2014 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 44: Poster III: Focus session: Resistive switching by redox and phase change phenomena
DS 44.8: Poster
Donnerstag, 3. April 2014, 16:00–19:00, P1
Oxygen-vacancy behavior in strontium titanate — •Marcel Schie1, Roger A. De Souza2, and Rainer Waser1 — 1Institute of Materials in Electrical Engineering and Information Technology, RWTH Aachen University, 52074 Aachen — 2Institute of Physical Chemistry, RWTH Aachen University and JARA-FIT, 52056 Aachen
We investigate the effect of acceptor-type cation dopants on oxygen-vacancy migration in the perovskite oxide SrTiO3 by static lattice simulation techniques. We focus on two themes: cation dopants modifying the activation energies for vacancy migration, and cation dopants (Ni2+, Fe2+, Co2+, Mn2+ and Al3+) binding oxygen vacancies in binary associates. In both cases a variety of defect configurations exceeding the scope of nearest neighbor (NN) interaction is examined Our results predict that, regardless of the cation dopant, the binding energy of an oxygen vacancy to a dopant is negative at NN sites, but only converges to zero for NNNNN sites. In addition the simulations show that the migration energy of a vacancy is affected by an acceptor dopant cation over a length scale of several unit cells. The results are also used in an analytic three frequency model of ionic conductivity in SrTiO3 to show trends for different dopants and concentrations. For comparison, a simple defect-chemical model containing only dopant-vacancy association at nearest neighbor sites is employed to reconcile literature data. Within this model two major results that are apparently inconsistent with different migration enthalpies are combined.