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Title: Dielectric dispersion and microwave dielectric study of marbles in support of radar investigations
Authors: Sengwa, R J
Soni, A
Keywords: Geological materials
Dielectric constant
Cole-Cole plots
Relaxation time
Issue Date: Oct-2005
Publisher: CSIR
Series/Report no.: G01R27/26
Abstract: The dielectric permittivity <img src='/image/spc_char/italics_e.gif' border=0>' and loss <img src='/image/spc_char/italics_e.gif' border=0>'' of nine marble samples collected from open marble mines of Makarana, Rajsamand, Ambhaji and Kesariyaji of Rajasthan were studied in the frequency range 100 Hz-100 kHz and also at 10.1 GHz at room temperature. It is found that the <img src='/image/spc_char/italics_e.gif' border=0>' values of dry marbles decrease with increase in frequency in the range 100 Hz-100 kHz. All the studied marbles are governed by the Cole-Cole dielectric dispersion. The values of static dielectric constant <img src='/image/spc_char/italics_e.gif' border=0><sub>o</sub>, high frequency limiting dielectric constant <img src='/image/spc_char/italics_e.gif' border=0><sub>∞</sub>, dielectric relaxation strength <img src='/image/spc_char/delta.gif' border=0><img src='/image/spc_char/italics_e.gif' border=0>, distribution parameter <img src='/image/spc_char/alpha.gif' border=0>, and relaxation time for dipole rotation τ were determined from the complex Cole-Cole plots. All these samples have <img src='/image/spc_char/alpha.gif' border=0> values greater than 0.5 and their Δ<img src='/image/spc_char/italics_e.gif' border=0> values vary significantly. Further, wide variation in <i style="">ac</i> conductivity σ is also observed for different samples. The effect of sample bulk density and variation in the chemical composition on low frequency and microwave permittivity of the studied marbles have been recognized. The measured values of dielectric permittivity of these marbles were also compared and discussed with the earlier reported <img src='/image/spc_char/italics_e.gif' border=0>' values of marbles and limestones of other regions. The precise microwave dielectric measurements of marbles and recognization of their dependence on petrological and chemical composition are interesting and can be used in support of radar investigations of the Earth’s geology.
Description: 777-782
ISSN: 0975-1041 (Online); 0019-5596 (Print)
Appears in Collections:IJPAP Vol.43(10) [October 2005]

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