Forschergruppe
Nonlinear response to probe vitrification

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P7 Roling, Universität Münster

Nonlinear ion transport in glass-forming ionic liquids: Higher harmonic ac currents and electrical creep

Summary
In this project, the nonlinear ion transport in glass-forming ionic liquids will be studied by (i) applying
high ac electric fields and analyzing higher harmonics in the resulting current response
and by (ii) carrying out electrical creep experiments under a constant bias field. Ionic liquids will
be chosen, for which the frequency dependence of the conductivity is governed by subdiffusive
translational movements of the ions, whereas rotational movements play a minor role. These
are in particular: (a) Monocationic and monoanionic liquids with small or zero permanent dipole
moments of the ions. (b) Dicationic ionic liquids, for which we expect a dynamic decoupling of
the small monovalent anions from the larger divalent cations upon supercooling. (c) Systems
with oligomeric cations, for which we have already observed a pronounced dynamic decoupling
of the monovalent anions from the oligomeric cations. The frequency/time dependence
as well as the temperature dependence of the nonlinear conductivity will be analysed in detail and compared to solid electrolytes. The interpretation of the nonllinear conductivity will be supported by molecular dynamics simulations.