Berlin 2015 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 68: Glasses and Glass Transition (joint session CPP/ DF/ DY)
DY 68.2: Talk
Friday, March 20, 2015, 09:45–10:00, C 243
Broadband dielectric spectroscopy of ionic liquids — •Pit Sippel1, Michael Aumüller1, Stephan Krohns1,2, Peter Lunkenheimer1, and Alois Loidl1,2 — 1Experimental Physics V, University of Augsburg, Germany — 2Institute for Materials Resource Management, University of Augsburg, Germany
Due to their high potential for applications, e.g., in energy-storage devices such as supercapacitors or batteries, during recent years ionic liquids have come into the focus of research [1]. Ionic liquids are composed of organic cations and weakly coordinating anions.
An essential method for the study of ionic transport is dielectric spectroscopy. Our results on a large variety of ionic liquids cover a broad frequency and temperature range. This allows obtaining valuable information on phenomena like dc charge transport, the glass transition, electrode polarization, and relaxation. We analyze the dielectric spectra using an equivalent-circuit approach [2]. Amongst others, this enables the deduction of the relaxation times of the involved dynamic processes. We conclude that the main reorientational relaxation process of these ionic liquids, the α relaxation, is closely linked to the dc-conductivity. This provides insight into the underlying conductivity mechanisms and, thus, the mobility of the ionic charge carriers. Moreover, a number of secondary relaxation processes is found, including hints at the presence of a Johari-Goldstein relaxation process [3].
M. Armand et al., Nat. Mat. 8, 621 (2009).
[2] S. Emmert et al., Eur. Phy. J. B 83, 157 (2011).
[3] G.P. Johari and M. Goldstein, J. Chem. Phys. 53, 2372 (1970).