On revealing structural relaxation of ionic liquids by high-field dielectric techniques

Abstract

Using dielectric relaxation techniques at low and high electric fields, it is demonstrated how the conductivity and structural relaxation times can be obtained under identical sample conditions, e.g., for ionic liquids. This approach is useful for conductive materials for which low field dielectric loss spectra fail to display signatures of structural relaxation. The approach is based on field induced structural recovery in the regime of milliseconds, i.e., the process of fast physical aging in response to a small perturbation. For the case of viscous 1‑butyl‑3-methyl imidazolium tetrafluoroborate, this experiment reveals a decoupling quantified by structural relaxation being about nine times slower than conductivity relaxation.