Abstract
MEASUREMENTS have been made at 9,200 Mc/s to determine the dependence of dielectric constant of powder samples' packing densities. The net polarization P produced in a substance in an electric field consists of the contributions of electronic, atomic and dipolar polarizations. It is related to the dielectric constant by Clausius–Masotti relation: where K = (ɛ − l)/(ɛ + 2), M the molecular weight, ɛ the dielectric constant and d the density. In a mixture of two dielectrics the net value of K can be determined by summing up the K/d ratio of the individual substances in proportion to the masses. A powder sample is a dielectric–air mixture. If the contribution of air is neglected, it is expected that K/d ratio for the powder at any packing density will be constant. The relation between dielectric constant of solid ɛ0 of density d0 to the dielectric constant of powder sample ɛ′ of density d is hence given by : Cumming1 had made measurements of the dielectric constant of snow of various densities. Snow is an ice–air mixture and hence it should follow relation (2). He has shown that his results from a density of 0.22 to 0.92 g/c.c. follow:
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References
Cumming, W. A., J. App. Phys., 23, 768 (1962).
Von Hippel, A., Dielectric Materials and Applications (John Wiley and Sons, 1954).
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SWARUP, P., ARORA, R. Dielectric Constant of Powders. Nature 201, 1018 (1964). https://doi.org/10.1038/2011018a0
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DOI: https://doi.org/10.1038/2011018a0
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