Dielectric and electrical properties of polycrystalline rocks at various hydration levels

• Published in: IEEE transactions on dielectrics and electrical insulation Vol. 7; no. 4; pp. 493 - 497
• Main Authors: Kyritsis, A., Siakantari, M., Vassilikou-Dova, A., Pissis, P., Varotsos, P.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.08.2000; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Comparative analysis; Complex permittivity; Conductivity; Dielectric materials; Dielectric measurements; Dielectric properties; Dielectrics; Dispersion; Drying; Electrochemical impedance spectroscopy; Electrodes; Frequency measurement; Hydration; Moisture content; Permittivity measurement; Rocks; Thickness measurement; Water
• ISSN: 1070-9878; 1558-4135
• DOI: 10.1109/94.868067

The dielectric properties of low porosity natural polycrystalline rock material (marble) were investigated using broadband 10/sup -2/ to 10/sup 6/ Hz) dielectric relaxation spectroscopy at several hydration levels, from dry to fully hydrated samples, with the water content varying from 0 to 0.08% g water/g dry material. The measured dielectric response is characterized by large low frequency dispersions, which depend strongly on the water content. Upon varying the sample thickness, dielectric and water sorption measurements reveal that bulk rather than electrode/sample interface effects are responsible for the main part of the high values obtained for the complex permittivity /spl epsi/*. Comparative analysis of the experimental data within the complex permittivity /spl epsi/*, impedance Z* and modulus M*, allows a detailed investigation of the AC conductivity mechanisms existing in the rocks and of water content dependency. Concerning the rock-water interaction, a critical water content h/sub c/, (h/sub c//spl sim/0.04%, the water content for ambient humidity conditions) has been found.