Dielectric relaxation of neodymium chloride in water and in methanol

Abstract An open-ended coaxial probe was used to study the dielectric relaxation of neodymium chloride (NdCl3) in water and in methanol at room temperature over the frequency range 0.2–40.0 GHz. An equivalent circuit model based on the antenna model was used to obtain the dielectric spectra with the effective removal of spurious effects. This extends the use of the open-ended coaxial probe technique for highly conductive substances. The structural and thermodynamic parameters obtained from the dielectric spectra of aqueous NdCl3 solutions suggest that solvent-separated ion pairs and solvent-shared ion pairs dominate the low-frequency behavior at low concentrations. In methanol, solvent-shared ion pair relaxation modes were detected. No contact pair relaxation was observed in either solvent. Under all conditions, Nd3+ was strongly solvated, as reflected by its high effective hydration number. The estimated association constant of NdCl3 in water at infinite dilution was within the literature values and was lower than that observed in methanol.