Anomalous low frequency dispersion and dielectric relaxation in the layered intercalated compounds Cd0.75PS3A0.5(H2O) [A=K, Cs]

1998 ◽  
Vol 108 (3) ◽  
pp. 1206-1215 ◽  
Author(s):  
P. Jeevanandam ◽  
S. Vasudevan
Keyword(s):  
Dielectric Relaxation ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Intercalated Compounds

On the relationship between matric potential and dielectric properties of organic free soils: a sensitivity study

2009 ◽  
Vol 46 (10) ◽  
pp. 1202-1215 ◽  
Author(s):  
Norman Wagner ◽  
Alexander Scheuermann
Keyword(s):  
Dielectric Relaxation ◽  
Low Frequency ◽  
Bound Water ◽  
Frequency Dispersion ◽  
Strong Relationship ◽  
Sensitivity Study ◽  
Relative Dielectric Permittivity ◽  
Relaxation Processes ◽  
Matric Potential ◽  
Relaxation Effects

High-frequency electromagnetic determination of moisture in porous media, (e.g., soil) is based on the strong relationship between volumetric water content and relative dielectric permittivity. In particular, in fine-grained soils the movement of water is influenced by different surface-bonding forces due to interface processes. The interface effects lead to a number of dielectric relaxation processes (free- and bound-water phase, Maxwell–Wagner effect, counterion relaxation effects). These relaxation processes are the reason for the strong frequency dependence of the electromagnetic material properties below 1 GHz. The matric potential is a measure of the bonding forces on water in the soil. Based on a thermodynamic relationship between soil matric potential and dielectric relaxation behaviour of water in different binding states, a broadband dielectric relaxation model was developed that considers low-frequency dispersion up to 1 MHz as well as losses due to direct-current conductivity. The sensitivity of the model on soil suction was systematically analyzed based on a pedotransfer function (PTF) for soil textures ranging from pure sand up to pure clay. The results are compared with known empirical and semiempirical calibration functions, as well as theoretical mixing models.

Low Frequency Dispersion of a Molecular Crystal

1977 ◽  
Vol 32 (5) ◽  
pp. 515-516
Author(s):  
B. Hinopoulos ◽  
P. U. Sakellaridis
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Molecular Crystal ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Lattice Defects ◽  
Dielectric Behaviour ◽  
Crystalline Sample ◽  
Dielectric Relaxation Process

Abstract The dielectric behaviour of solid 1,4-Butandiol has been studied. A region of low frequency dispersion has been ob­ served. In a crystalline sample treated to have more lattice faults, the losses were increased. The effect is attributed to a dielectric relaxation process existing in connection with the lattice defects.

Dielectric Relaxation Studies of Silver Nanoparticles dispersed Liquid Crystal

2015 ◽  
Vol 8 (3) ◽  
pp. 2176-2188 ◽  
Author(s):  
Keisham Nanao Singh
Keyword(s):  
Activation Energy ◽  
Silver Nanoparticles ◽  
Liquid Crystal ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Relaxation Times ◽  
Low Frequency ◽  
Bulk Liquid ◽  
Molecular Rearrangement ◽  
Relaxation Studies

This article reports on the Dielectric Relaxation Studies of two Liquid Crystalline compounds - 7O.4 and 7O.6 - doped with dodecanethiol capped Silver Nanoparticles. The liquid crystal molecules are aligned homeotropically using CTAB. The low frequency relaxation process occurring above 1 MHz is fitted to Cole-Cole formula using the software Dielectric Spectra fit. The effect of the Silver Nanoparticles on the molecular dipole dynamics are discussed in terms of the fitted relaxation times, Cole-Cole distribution parameter and activation energy. The study indicate a local molecular rearrangement of the liquid crystal molecules without affecting the order of the bulk liquid crystal molecules but these local molecules surrounding the Silver Nanoparticles do not contribute to the relaxation process in the studied frequency range. The observed effect on activation energy suggests a change in interaction between the nanoparticles/liquid crystal molecules.

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

Volume low-frequency dispersion in a semi-insulating system

1988 ◽  
Vol 23 (2) ◽  
pp. 209-213 ◽  
Author(s):  
A.K. Jonscher ◽  
L. Levesque
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion

Dielectric Relaxation at Ultra Low Frequency

2003 ◽  
Vol 294 (1) ◽  
pp. 3-11
Author(s):  
E. R. Neagu ◽  
J. N. Marat-Mendes ◽  
C. J. Dias
Keyword(s):  
Dielectric Relaxation ◽  
Low Frequency

Low-frequency dielectric relaxation of hematite and silica sols

Langmuir ◽  
1993 ◽  
Vol 9 (7) ◽  
pp. 1625-1633 ◽  
Author(s):  
Johan Kijlstra ◽  
Herman P. van Leeuwen ◽  
Johannes Lyklema
Keyword(s):  
Dielectric Relaxation ◽  
Low Frequency ◽  
Silica Sols

Theory of the ferroelectric Mott-Hubbard phase in organic conductors

2002 ◽  
Vol 12 (9) ◽  
pp. 149-152
Author(s):  
S. Brazovskii
Keyword(s):  
Activation Energy ◽  
Phase Transitions ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Organic Conductors ◽  
The State ◽  
Charge Disproportionation ◽  
Subsequent Phase

Recently the ferroelectric FE anomaly (Nad, Monceau, et al.) followed by the charge disproportionation CD (Brown, et al) have been discovered in ($TMTTF)_2X$ compounds. A theory of the combined Mott-Hubbard state describes both effects by interference of the build-in nonequivalence of bonds and the spontaneous one of sites. The state gives rise to three types of solitons: $\pi -$ solitons (holons) are observed via the activation energy A in conductivity G; noninteger $\alpha -$ solitons provide the frequency dispersion of the FE response; combined spin-charge solitons determine $G(T)$ below subsequent phase transitions. The optical edge lies well below the conductivity gap 2A; the critical FE mode coexists with a combined electron-phonon resonance and a phonon antiresonance. The CD and the FE can exists hiddenly even in the Se subfamily giving rise to the unexplained yet low frequency optical peak, the enhanced pseudogap and traces of phonons activation.

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