DIELECTRIC SPECTROSCOPY OF SLIGHTLY SALINE SANDS
P.P. Bobrov, T.A. Belyaeva, E.S. Kroshka, O.V. Rodionova
Omsk State Pedagogical University, Naberezhnaya Tukhachevskogo 14, Omsk, 644099, Russia
Keywords: Complex dielectric permittivity, conductivity, saline sands, dielectric-relaxation processes
Abstract
We present results of experimental measurements of the complex dielectric permittivity (CDP) of sand and powdered quartz granules with mass-averaged particle sizes of 5 to 250 μm, saturated with distilled water and NaCl solutions with a conductivity of up to 0.77 S/m. The CDP spectra were measured in the frequency range from 1 kHz to 8.5 GHz. The spectra at frequencies above 1 GHz were simulated using a refractive three-component mixture model. In the frequency range from 10 kHz to 1 GHz, the CDP spectra were simulated by three relaxation processes, using the Debye and Cole-Cole formulas. It is shown that the conductivity of the sample at a frequency of ~5 kHz is not proportional to the conductivity of the saturating solution. The intensities of two low-frequency processes are more intimately correlated with the conductivity of the sample than with the volume fraction of the solution. The relaxation times of the low-frequency and high-frequency processes are statistically correlated with the average particle size, and the relaxation time of the low-frequency process is additionally correlated with the specific surface area of the particles. We estimated the conductivity of the saturating solution at which the correlation is the strongest.
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