Regensburg 2025 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 37: Brownian Motion and Anomalous Diffusion

DY 37.5: Talk

Thursday, March 20, 2025, 16:00–16:15, H43

Modeling charge attachment induced ion transport in glasses — •Quinn Emilia Fischer and Philipp Maass — Department of Physics, Universität Osnabrück, Germany

In charge attachment induced ion transport (CAIT), material foreign mobile ions can replace native mobile ions near the surface of a glass below the glass transition temperature. Insight into the ion dynamics during CAIT experiments is provided by measurements of near-surface concentration profiles.

We discuss the modeling of concentration profiles by coupling the Poisson equation to kinetic equations of linear irreversible thermodynamics. Solving the kinetic equations requires knowledge on the dependance of both the Onsager coefficients and chemical potentials of the mobile ions on the ion concentrations.

We show how chemical potentials can be derived for a model, where mobile ions occupy sites in a disordered energy landscape, and how Fermi energies are generalized to a system of multiple ion types. We further explain the determination of Onsager coefficients by modeling thermally activated hopping motion in the energy landscape and the relation between the coefficients and ion mobilities.

The dependence of both the Onsager coefficients and the chemical potentials on mobile ion concentration is sensitive to the form of the energy landscape. It is argued that this sensitivity needs to be taken into account in a consistent theoretical modeling of CAIT experiments, which requires solutions of the coupled Poisson and kinetic equations to reproduce measured concentration profiles.

Keywords: glasses; ionic transport; disordered energy landscape; theoretical modeling