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AKE: Arbeitskreis Energie

AKE 5: Mobilität

AKE 5.2: Talk

Monday, March 14, 2011, 17:15–17:30, MENSA Dül

First-principle study and modeling of pressure dependent ionic diffusion in YSZ — •Julian Hirschfeld and Hans Lustfeld — Peter Grünberg Institut & Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, 52425 Jülich, Germany

Yttria Stabilized Zirconia (YSZ) is the state of the art electrolyte for Solid State Fuel Cells (SOFC). YSZ has a low thermal expansion coefficient and good ionic conductivity at a high operation temperature (800^∘C). Since this temperature also dictates the operating point of the SOFC, it has to be reduced to achieve an economic operation of a SOFC. The temperature dependence of the ionic conductivity is given by an Arrhenius expression [1]. Due to the inverse exponential dependence on the activation energy, it is crucial to gain a better knowledge about the dependence of this quantity on external parameters. It is possible to obtain the activation energy of individual ionic jump processes directly from ab-initio calculations [2]. This can increase the fundamental understanding of the physics behind and can lead to predictions of new systems.

In our work we use Density Functional Theory (DFT) ab-initio calculations to investigate the ionic energy barrier dependence on structural deformations. To obtain the activation energies, we calculate the energy barrier of the ionic movement in the framework of the Nudged Elastic Band (NEB) method. To gain a deeper insight into the physical meaning, we compare these results with those of a simple model.
M. Kilo et al., Phys. Chem. Chem. Phys. 5, 2219-2224 (2003)
Pornprasertsuk et al., J. Appl. Phys. 98, 103513 (2005)