Relaxation Phenomena in Dilute Charged Solutions

Abstract

The study of transport phenomena in conductive media of different dimensions often involves impedance diagnostics. The desire to exclude the influence of contact phenomena accompanying dc measurements on the current–voltage characteristic is a general reason for the application of complicated ac measurements instead of the quite methodologically simple dc regime. Relaxation phenomena in electrolytes with electrohydrodynamics linear in the density of the dopant n_d have been analyzed in detail in this work. It has been shown that the well-known Debye–Hückel–Onsager theory of the electrolyte conductivity cannot ensure the linearity of electrohydrodynamics of dilute solutions in the density n_d. Its linear alternative based on the theory of transport in finely dispersed two-phase systems called Maxwell formalism has been proposed. It has been shown that this allows one to interpret the observed relaxation time in the form \({{\tau }_{c}} \simeq RC\), where R is the resistance of the bulk portion of a cell with an electrolyte in terms of the Maxwell formalism and C is the electrolytic capacitance of the metal–electrolyte transition regions appearing on its control electrodes. Examples of the successful use of RC-matched ac diagnostics have been discussed.