Charge transport and mass transport in imidazolium-based ionic liquids

Abstract

The mechanism of charge transport in the imidazolium-based ionic liquid 1,3-dimethylimidazolium dimethylphosphate is analyzed by combining broadband dielectric spectroscopy (BDS) and pulsed field gradient nuclear magnetic resonance (PFG NMR). The dielectric spectra are dominated-on the low-frequency side-by electrode polarization effects while, for higher frequencies, charge transport in a disordered matrix is the underlying physical mechanism. Using the Einstein and Einstein-Smoluchowski equations enables one to determine-in excellent agreement with direct measurements by PFG NMR-the diffusion coefficient of the charge carriers. By that, it becomes possible to extract from the dielectric spectra separately the number density and the mobilities of the charge carriers and the type of their thermal activation. It is shown that the observed Vogel-Fulcher-Tammann (VFT) dependence of the dc conductivity can be traced back to a similar temperature dependence of the mobility while for the number density an Arrhenius-type thermal activation is found. Extrapolating the latter to room temperature indicates that nearly all charge carriers are participating in the conduction process.

Electrical and thermal properties of nylon 6/calcium carbonate composites

“…,in which, the exponent s lies between 0 and 1, ν s characterizes the onset of dc conductivity, which is related to ν e by the Barton-Nakajima-Namikawa relation, 29 σ o ≈ 1/τ e (τ e = 2πν e ). Figure 11 shows a linear relation of the dc conductivity as a function of high temperatures (120-220…”

“…27 It is instructive to present the dielectric spectra in terms of both complex conductivity, σ * , (σ * = σ + iσ ) and permittivity, ε * , (ε * = ε − iε ) functions since they emphasize different aspects of the dielectric processes under study. 28,29 The equivalence of complex functions can be given as σ…”

Multiple Mechanisms for Electron Transfer at Metal/Self‐Assembled Monolayer/Room‐Temperature Ionic Liquid Junctions: Dynamical Arrest versus Frictional Control and Non‐Adiabaticity

“…The response functions were found to be biphasic, consisting of a sub-picosecond component (100 fs to 200 ps) of modest amplitude (10 to 20 %), and a dominant slower component extended down to tens and, presumably, hundreds of nanoseconds. In addition, the broadband dielectric spectroscopic experiments [36,37] detected ultraslow, extremely large-scale (highly cooperative) structural fluctuations in RTILs, which presumably occur in the electrode-adjusting interfacial layer (the diffusive Stern zone, see below).…”

“…[21,22,[25][26][27][28][29] In addition, as demonstrated previously, [25] alkanethiol SAMs (including thin SAMs, which are considered to be the most inconvenient type because of a higher probability of defect formation) immersed into [ that have exceptional physical properties. [30][31][32][33][34][35][36][37] A broad distribution of relaxational characteristics, involving both the fast and slow degrees of freedom of the solvent, should be mentioned. The results of recent experimental (dielectric and solvation spectroscopy, NMR spectroscopy, Kerr relaxations, etc.)…”

Ionic Liquids Gelation with Polymeric Materials: The Ion Jelly Approach

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