Dielectric relaxation spectroscopy of electrolyte solutions: ZnCl2 in N-methyl-2-pyrrolidone, tetramethylurea and ethylacetate

The dielectric spectra of the title systems (with moderate to high salt concentrations) have been measured between MHz frequencies and 72 GHz at 20, 40 and 60 degrees C (EtAc only 20 degrees C). Apart from the conductivity contribution, there are two evidently discernible relaxation contributions. These are ascribed to unaffected solvent (at higher frequencies) and, on the other hand, to affected solvent and to ionic species (at lower frequencies). The nature of the latter and their relaxation mechanism are discussed by comparing the respective relaxation parameters with those of other liquid systems.