Topic

# Dielectric loss

About: Dielectric loss is a(n) research topic. Over the lifetime, 20296 publication(s) have been published within this topic receiving 349254 citation(s).

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TL;DR: In this article, the empirical dielectric decay function γ(t)= exp −(t/τ 0)β was transformed analytically to give the frequency dependent complex dielectrics constant if β is chosen to be 0.50 in the range log(ωτ0) > −0.5.

Abstract: The empirical dielectric decay function γ(t)= exp –(t/τ0)β may be transformed analytically to give the frequency dependent complex dielectric constant if β is chosen to be 0.50. The resulting dielectric constant and dielectric loss curves are non-symmetrical about the logarithm of the frequency of maximum loss, and are intermediate between the Cole-Cole and Davidson-Cole empirical relations. Using a short extrapolation procedure, good agreement is obtained between the empirical representation and the experimental curves for the α relaxation in polyethyl acrylate. It is suggested that the present representation would have a general application to the α relaxations in other polymers. The Hamon approximation, with a small applied correction, is valid for the present function with β= 0.50 in the range log(ωτ0) > –0.5, but cannot be used at lower frequencies.

3,504 citations

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TL;DR: In this article, a novel technique for the measurement of dielectric and magnetic properties of a homogeneous isotropic medium in the range of approximately 3 to 100 kmc is described.

Abstract: A novel technique for the measurement of dielectric and magnetic properties of a homogeneous isotropic medium in the range of approximately 3 to 100 kmc is described. An accuracy of /l.chemc/ 1 per cent is possible in the determination of permittivity or permeability in those cases where the loss tangent is sulliciently small. The measuring structure is a resonator made up of a right circular cyndrical dielectric rod placed between two parallel conducting plates. For measurement of permittivity two or more resonant TE/sub onl/ mode frequencies are determined whereas for the measurement of permeability two or more resonant TM/sub onl/ mode frequencies are determined. The dielectric or magnetic properties are computed from the resonance frequencies, structure dimensions, and unloaded Q. Since the loss tangent is inversely proportional to the unloaded Q of the structure, the precision to which Q is measured determines the accuracy of the loss tangent.

2,464 citations

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TL;DR: In this article, the dielectric properties of isostructural compounds of the type A 2/3 Cu 3 Ti 4 O 12 (A =trivalent rare earth or Bi) have been presented.

Abstract: High dielectric constants have been found in oxides of the type A Cu 3 Ti 4 O 12 . The most exceptional behavior is exhibited by CaCu 3 Ti 4 O 12 , which shows a dielectric constant at 1 kHz of about 12,000 that is nearly constant from room temperature to 300°C. The cubic structure of these materials is related to that of perovskite (CaTiO 3 ), but the TiO 6 octahedra are tilted to produce a square planar environment for Cu 2+ . The CaCu 3 Ti 4 O 12 structure down to 35 K has been examined by neutron powder diffraction. The structure remains cubic and centric. Most compositions of the type A 2/3 Cu 3 Ti 4 O 12 ( A =trivalent rare earth or Bi) show dielectric constants above 1000. The dielectric properties of isostructural compounds of the type A Cu 3 Ti 3 FeO 12 are also presented.

1,691 citations

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TL;DR: In this paper, the wave-number-dependent dielectric function is derived for various models of a semiconductor and expressions for the wave number-dependent Dielectric functions are derived for different models of semiconductors.

Abstract: Expressions for the wave-number-dependent dielectric function are derived for various models of a semiconductor The calculation is carried out for the diagonal part of the dielectric function at zero frequency It is found that calculations based on plane wave models (such as the free electron model) give poor results for small values of the wave number due to neglect of both Bragg reflections and Umklapp processes We use instead an isotropic version of the nearly free electron model in which dielectric function depends on only one parameter ${E}_{g}$ representing an average energy gap that can be determined from optical data It is noted that for small wave numbers Umklapp processes give the major contribution to the dielectricfunction, where-as for large wave numbers normal processes dominate The dielectric function is evaluated numerically for a value of ${E}_{g}$ appropriate to Si

1,548 citations

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30 Jun 1988TL;DR: A broad coverage of the theory and practice of industrial microwave heating can be found in this paper, where the authors present a broad survey of the literature on microwave heating and its applications.

Abstract: This book offers a broad coverage of the theory and practice of industrial microwave heating.

1,469 citations