Nanoscale physics

Role of interface effects in the formation of the electrical conductivity of electrolyte-based suspensions
Balika S. D, Sushko M.Ya.
Department of Theoretical Physics and Astronomy, Odesa I.I.Mechnikov National University. 2 Dvoryans’ka St., Odesa 65026, Ukraine. 
E-mail: svitlana.balika@onu.edu.ua

     The electrical conductivity σeff of a suspension can change significantly compared to that of the base liquid even at low volume concentrations c of the filler particles. Modern electrokinetic theories deal with systems of coupled differential equations for the flow field and related distributions of ions and electric field around a hard particle. The results obtained depend on many approximations that are reliable only for highly dilute suspensions and low surface potentials, when electromagnetic interaction between the structural units is weak. 
     We present a many-particle theory designed to investigate interface effects on σeff of concentrated suspensions. The theory is based upon the compact group approach [1] proposed for systems of solid dielectric particles and elaborated [2] for systems of conducting particles with a hard-core–penetrable-shell morphology. The system’s mesostructure is modeled in terms of the conductivity distribution, various processes in the system being taken into account through an inhomogeneous conductivity profile of the shell. This makes it possible to effectively describe the combined contribution to σeff from different factors, such as the surface potential, matrix molarity, structure of the interface layer, etc. 
    The theory reveals the existence of different scenarios for the behavior of σeff with c, depending on the structure and electrical parameters of the interface layer. The results obtained fit experimental data [3] for suspensions of transparent particles (ghosts) in the entire range of c up to 0.6.

1.	Sushko M. Ya. Dielectric permittivity of suspensions // JETP.-2007.-105. -P. 426-431.
2.	Sushko M. Ya., Semenov A. K. Rigorously solvable model for the electrical conductivity of dispersions of hard-core–penetrable-shell particles and its applications // Phys. Rev. E.-2019.-100.-P. 052601-1–14.
3.	Zukoski C. F. IV, Saville D. A. Electrokinetic properties of particles in concentrated suspensions // J. Colloid Interface Sci.-1987.-115.-P. 422-436.