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Impedance spectroscopy of mixed conductors: modelling and experiments J. Jamnik

Impedance spectroscopy of mixed conductors: modelling and experiments J. Jamnik National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia Max-Planck Institut für Festkörperforschung, Heisenbergstr. 1, Stuttgart, Germany. Polycrystalline mixed conductors with blocking grain boundaries

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Impedance spectroscopy of mixed conductors: modelling and experiments J. Jamnik

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  1. Impedance spectroscopy of mixed conductors: modelling and experiments J. Jamnik National Institute of Chemistry, Hajdrihova 19, Ljubljana, Slovenia Max-Planck Institut für Festkörperforschung, Heisenbergstr. 1, Stuttgart, Germany

  2. Polycrystalline mixed conductors with blocking grain boundaries Electrochemical parameters of interest:Parameters of no interest? Grains Grain boundaries Electrodes Energy dissipation Energy storage Different parametrisation possible, for example:

  3. Impedance spectroscopy: theory • Local description generalised equivalent circuits derived from • Nernst-Planck-Poisson equations • (J. Jamnik & J. Maier, PCCP 3, 1668 (2001)) . • Assumptions: • continuum model • 2-mobile charge carriers • internal reactions in local equilibrium • Microstructure Brick layer model

  4. Introductory remarks An important strength of IS is that the electrode effects appear separated from the bulk and grain boundary response!?? Pure ionic or electronic conductors Mixed conductors: Single crystals first Completely blocking or completely reversible electrodes Ideal selectively blocking electrodes

  5. Electrode effects in single crystals: Résumé electrode effects in single crystals  grain boundary effects in polycrystals but J. Jamnik, SSI 157, 19, 2003

  6. Experiment: bicrystal • 13 grain boundary: • strongly blocking for ions • weakly blocking for holes J. Jamnik, X. Guo, J. Maier, APL, in press.

  7. Consistency test:

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