Charge transport and dipolar relaxations in an alkali metal oligoether carboxylate ionic liquid
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Charge transport and dipolar relaxations in a sodium-based oligoether carboxylate ionic liquid are investigated in a wide frequency and temperature range by means of broadband dielectric spectroscopy (BDS). The dielectric spectra are described at lower temperatures in terms of dipolar relaxations whereas hopping conduction in a random spatially varying energy landscape is quantitatively shown to dominate the spectra at higher temperatures. Based on detailed analysis of the dielectric relaxation strength in its temperature dependence, the slower secondary relaxation process is attributed to molecular fluctuation of ion pairs (sodium and carboxylate ions) while the localized motion of the carboxylate anion gives rise to the faster process observed.
KeywordsIonic liquids Dielectric relaxation Charge transport Secondary relaxations
Financial support from the University of Tennessee-Knoxville through tenure-track faculty start-up funds is gratefully acknowledged. The author also thanks the German Research Foundation for the support under the DFG SPP 1191 Priority Program on Ionic Liquids. The experiments reported in the current article were performed in the laboratory of Prof. Friedrich Kremer at the University of Leipzig, and Prof. Richard Buchner (University of Regensburg) kindly provided the samples.
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