Interpreting the real part of the dielectric permittivity contributed by mobile ions in ionically conducting materials

Electrical conductivity relaxation experimental data of ionically conductin g glasses, crystals, and melts are most often discussed in the context of e ither the real part of the complex conductivity, Re[sigma*(omega)], the ima ginary part of the complex permittivity Im[epsilon*(omega)], or the complex electric modulus M*(omega). In contrast, the real part of the complex perm ittivity, Re[epsilon*(omega)], and the contribution of mobile ions to it ar e seldom considered. One reason for the lack of attention to Re[epsilon*(om ega)] is the complication caused by a large additional capacitive contribut ion to Re[epsilon*(w)] from electrode surface polarization, making the task of separating the two contributions difficult. However, there are still ma ny ionic conducting materials in which the electrode polarization effects c an be isolated and the contribution from mobile ions, epsilon(ion)'(omega), determined. The frequency dispersions of epsilon(ion)'(omega) in several s uch ionic conductors are used to examine the different interpretations of t he mechanism of ion conductivity.