ELECTROPHYSICAL PROPERTIES OF POROUS SOLIDS: STRUCTURE, MODELLING AND EXPERIMENTAL DATA

The paper presents a review of the structure and electrophysical properties of liquid-impregnated porous media. Principal parameters are considered, which reflect the internal structure of the systems and are used to describe porous media in the literature. The main physical processes, which govern the electrophysical properties of these systems are interface polarization and intrinsic dielectric relaxation in the liquid, with the frequency of the first process being practically always lower than that of the second one. The consequence of this ratio of frequencies of relaxation processes is the basic difference in behavior of liquid-impregnated porous media in three frequency regions, below, inside and above the interface polarization region. Principal electrophysical properties of porous media are reviewed and experimental data is classified in three frequency ranges. Different methods of calculating complex permittivity of porous media are compared: composite approximation, Bergman-Milton theory, Grain Consolidation Model, local porosity theory, called volume averaging theory, etc. The advantages and drawbacks of each model in different frequency ranges are outlined.