AVS 51st International Symposium
    Nanometer-scale Science and Technology Thursday Sessions
       Session NS1-ThA

Paper NS1-ThA8
Probing Ion Transport at the Nanoscale: Time-Domain Electrostatic Force Spectroscopy on Glassy Electrolytes

Thursday, November 18, 2004, 4:20 pm, Room 213C

Session: Nanoscale Imaging
Presenter: A. Schirmeisen, University of Muenster, Germany
Authors: A. Schirmeisen, University of Muenster, Germany
A. Taskiran, University of Muenster, Germany
H. Fuchs, University of Muenster, Germany
B. Roling, University of Muenster, Germany
S. Murugavel, University of Muenster, Germany
H. Bracht, University of Muenster, Germany
F. Natrup, University of Muenster, Germany
Correspondent: Click to Email
Ion conducting solid materials play an important role as electrolytes in energy conversion systems, such as batteries and fuel cells, and also in electrochemical sensors. Of particular interest are so-called fast ion conductors with conductivities that are comparable to liquid electrolytes. Currently, a lot of research work is being done in order to find new materials with improved conductivities. For instance, nanostructured materials become more and more technologically relevant. An important prerequisite for further progress in this field is a better understanding of the ion transport mechanisms on microscopic length scales. Up to now, the experimental techniques used for probing the ion transport are mainly macroscopic in nature, e.g. conductivity spectroscopy, tracer diffusion measurements and NMR relaxation techniques. The macroscopic averaging over the motions of all ions in a sample leads to a loss of information making it desirable to develop techniques that are capable of probing the ion transport on nanoscopic length scales. In this contribution, we demonstrate that electrical atomic force microscopy (AFM) techniques yield information about the dynamics of mobile ions in small subvolumes of a sample. In dynamic mode AFM, a voltage is applied between the tip and the sample, at typical tip-sample distances of about 10 nm. In this case, the voltage drop in the sample occurs mainly in a nanoscopic subvolume below the surface. Ionic motions in this subvolume influence the electrostatic forces acting between tip and sample. We record the time dependent evolution of the forces at sample temperatures from 100 K to 600 K, which allows us to extract the activation energy of the ion conduction process. The comparison of macroscopic with our nanoscopic measurements on different solid electrolytes shows that time-domain electrical AFM is capable of probing the ion dynamics and transport in nanoscopic subvolumes of the samples.