Berlin 2005 – wissenschaftliches Programm

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DF: Dielektrische Festkörper

DF 3: FV-internes Symposium „Polare Polymere und Ferroelektrete“

DF 3.6: Vortrag

Samstag, 5. März 2005, 11:00–11:20, TU C130

Time-domain electrostatic force spectroscopy (EFS) on Solid Electrolytes using an AFM — •Ahmet Taskiran, Andre Schirmeisen, Harald Fuchs, Bernhard Roling, Sevi Murugavel, Hartmut Bracht, and Frank Natrup — Physikalisches Institut and CeNTech, University of Muenster, Wilhelm-Klemm-Str.10, 48149 Münster, Germany

Ion conducting solid materials are widely used as solid electrolytes in batteries, etc. An important prerequisite for further progress in this field is a better understanding of ion transport mechanisms on nanoscopic length scales. We are using an AFM for EFS to measure the ionic conductivity in nanoscale volumes of homogeneous and heterogeneous solid electrolytes. The AFM is operated in the non-contact mode under ultra-high-vacuum conditions. After a change of the tip voltage the relaxation of the electrostatic force between tip and sample is measured as a function of time. The measurements are carried out at different temperatures ranging from 200 K to 675 K and at different places on the sample. The relaxation times at different temperatures can be fitted with an Arrhenius function. From the Arrhenius plot we obtain the activation energy of the ion hopping processes in the sample. In our work we focus on nanostructured solid electrolytes, where dramatic changes in the ion conductivity are caused by incorporated nanocrystallites. We find that the activation energies for the ions in the nanocrystallites and in the glass regions are different, in agreement with macroscopic results. Our measurements show that EFS is capable of probing the ion dynamics and transport in nanoscopic subvolumes of the samples.