On the theory of the nonlinear effect in polar liquids

1978 ◽  
Vol 56 (2) ◽  
pp. 216-225 ◽  
Author(s):  
Constantino Grosse ◽  
Pedro Brito
Keyword(s):  
Dipole Moment ◽  
Nonlinear Effect ◽  
Spherical Cavity ◽  
Applied Field ◽  
Polar Liquids ◽  
Nonlinear Dielectric ◽  
Average Value ◽  
Molecular Moment ◽  
Dipolar Potential ◽  
Weak Fields

It is shown that in order to relate the permittivity ε = ε0[1–λE2] of a nonlinear dielectric with molecular parameters using Onsager's formalism, the condition to be used is that the average value of the dipolar potential outside the cavity and with an applied field must vanish. Consequently, the potential for a rigid dipole in a spherical cavity filled up with a continuum ε∞ and surrounded by a nonlinear dielectric immersed in a strong applied field are calculated both inside and outside. The average value of the external dipole moment is deduced from the torque exerted by the field outside the cavity on the sources of the applied field.The expression thus obtained for the parameter λ leads to values that are always positive and slightly smaller than those corresponding to earlier studies. The expression deduced for the permittivity in weak fields ε0 introduces a correction to Onsager's equation consisting of a factor multiplying the square of the molecular moment. In contradiction with recent results by other authors, this factor is always less than 1 and its value is of the order of 0.9.

scholarly journals Implications of Dipole Moment Secular Variation from 50,000–10,000 Years for the Radiocarbon Record

Radiocarbon ◽  
1992 ◽  
Vol 34 (2) ◽  
pp. 189-198 ◽  
Author(s):  
R. S. Sternberg ◽  
P. E. Damon
Keyword(s):  
Dipole Moment ◽  
Production Function ◽  
Secular Variation ◽  
Good Match ◽  
Average Value ◽  
The Past ◽  
Dc Gain ◽  
Ramp Function ◽  
Holocene Record ◽  
Linear Ramp

Sparse paleointensity data from 10–50 ka suggest that the average dipole moment (DM) was 50–75% of the average of 8.67 μ 1022 A m2 for the past 5 Ma, and 8.75 μ 1022 for the past 12 ka. A linear ramp function, increasing the DM from 4 to 8.75 μ 1022 A m2 between 50–10 ka BP, generates a total 14C inventory of 126 dpm/cme2, agreeing very well with an inventory assay of 128 dpm/cme2, which includes 14C in sediments. With the Lingenfelter and Ramaty (1970) production function and a model DC gain of about 100, this DM function would give a Δ14C of 500‰ at 20 ka BP, consistent with the Barbados coral record, and also gives a good match to the Holocene record. A Laschamp geomagnetic event at about 45 ka BP, with a DM of 25% of its average value and lasting 5 ka, would only increase the present inventory by 0.3–1.2 dpm/cme2, and would probably have only a small effect on Δ14C at 20 ka BP, but could produce a short-lived 14C spike of over 500‰.

Nonlinear dielectric response of polar liquids

2015 ◽  
Vol 142 (24) ◽  
pp. 244502 ◽  
Author(s):  
Dmitry V. Matyushov
Keyword(s):  
Dielectric Response ◽  
Polar Liquids ◽  
Nonlinear Dielectric

Nonlinear dielectric and magnetic relaxation after a sudden change of applied field

2001 ◽  
Vol 115 (10) ◽  
pp. 4444-4449 ◽  
Author(s):  
B. U. Felderhof ◽  
R. B. Jones
Keyword(s):  
Magnetic Relaxation ◽  
Applied Field ◽  
Sudden Change ◽  
Nonlinear Dielectric

scholarly journals Dielectric properties and switching processes of ferroelectric superlattices

2021 ◽  
Vol 5 (2) ◽  
Author(s):  
A.S. Sidorkin ◽  
L.P. Nesterenko ◽  
Y. Gagou ◽  
P. Saint-Gregoire ◽  
A.Yu. Pakhomov ◽  
...  
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Domain Walls ◽  
Bias Field ◽  
Average Value ◽  
Flexoelectric Effect ◽  
Precise Analysis ◽  
Internal Bias ◽  
Two Stages ◽  
Weak Fields

We review dielectric properties of BaZrO3/BaTiO3 (BZ/BT) superlattices deposited on a single-crystal MgO substrate, and having a period of 13.32 nm. These superlattices have specific properties distinguishing them from BZ or BT bulk materials, and from thin films, with a ferroelectric phase transition around 393-395 °?, significantly higher than in bulk samples and thin films of BT, and appearing of second order. The polarization switching occurs in two stages and the precise analysis of experimental data demonstrates that the motion of the domain walls causes the switching processes. We conclude that the mobility of the domain walls decreases on heating. The presence of an internal bias field has been demonstrated and shown to be directed from the superlattice to the substrate, in agreement with an analysis based on the flexoelectric effect. The switching current has been shown to vary in weak fields as 1/E? with the exponent ? much smaller than in thin ferroelectric films. The appearance of the power index ?, which is significantly different from unity, may be due to a decrease in the average value of the switched polarization due to the boundaries between layers of different materials.

scholarly journals First-principles experimental demonstration of ferroelectricity in a thermotropic nematic liquid crystal: Polar domains and striking electro-optics

2020 ◽  
pp. 202002290 ◽  
Author(s):  
Xi Chen ◽  
Eva Korblova ◽  
Dengpan Dong ◽  
Xiaoyu Wei ◽  
Renfan Shao ◽  
...  
Keyword(s):  
Applied Field ◽  
Nematic Phase ◽  
Mean Field ◽  
Electric Polarization ◽  
Dynamics Simulation ◽  
Glassy Material ◽  
Average Value ◽  
Polarization Density ◽  
Polar Orientation ◽  
Lower Temperature

We report the experimental determination of the structure and response to applied electric field of the lower-temperature nematic phase of the previously reported calamitic compound 4-[(4-nitrophenoxy)carbonyl]phenyl2,4-dimethoxybenzoate (RM734). We exploit its electro-optics to visualize the appearance, in the absence of applied field, of a permanent electric polarization density, manifested as a spontaneously broken symmetry in distinct domains of opposite polar orientation. Polarization reversal is mediated by field-induced domain wall movement, making this phase ferroelectric, a 3D uniaxial nematic having a spontaneous, reorientable polarization locally parallel to the director. This polarization density saturates at a low temperature value of ∼6 µC/cm2, the largest ever measured for a fluid or glassy material. This polarization is comparable to that of solid state ferroelectrics and is close to the average value obtained by assuming perfect, polar alignment of molecular dipoles in the nematic. We find a host of spectacular optical and hydrodynamic effects driven by ultralow applied field (E ∼ 1 V/cm), produced by the coupling of the large polarization to nematic birefringence and flow. Electrostatic self-interaction of the polarization charge renders the transition from the nematic phase mean field-like and weakly first order and controls the director field structure of the ferroelectric phase. Atomistic molecular dynamics simulation reveals short-range polar molecular interactions that favor ferroelectric ordering, including a tendency for head-to-tail association into polar, chain-like assemblies having polar lateral correlations. These results indicate a significant potential for transformative, new nematic physics, chemistry, and applications based on the enhanced understanding, development, and exploitation of molecular electrostatic interaction.

The distribution of fluctuations of the total dipole moment in polar liquids

1993 ◽  
Vol 80 (2) ◽  
pp. 225-231 ◽  
Author(s):  
P.G. Kusalik
Keyword(s):  
Dipole Moment ◽  
Total Dipole Moment ◽  
Polar Liquids

Nonlinear Dielectric Relaxation of Mn Doped Polycrystalline (Ba,Sr)TiO3 Thin Films Over the Temperature Range of 4.2 - 473 K

1998 ◽  
Vol 541 ◽  
Author(s):  
J.D. Baniecki ◽  
R.B. Laibowitz ◽  
T.M. Shaw ◽  
P.R. Duncombe ◽  
D.E Kotecki ◽  
...  
Keyword(s):  
Thin Films ◽  
Dielectric Relaxation ◽  
Applied Field ◽  
Equivalent Circuit Model ◽  
Nonlinear Dielectric ◽  
Nonlinear Relaxation ◽  
Temperature Range ◽  
Reciprocal Temperature ◽  
Mn Doped ◽  
Relaxation Component

AbstractWe have investigated the dielectric relaxation currents of Mn doped polycrystalline Ba0.7Sr0.3TiO3 (BSTO) thin films as a function of applied electric field and temperature (4.2 - 473 K). The dielectric relaxation currents followed a power law time dependence, J(t) = Jot-n, over the entire temperature range. Plots of log(Jo) vs. reciprocal temperature were not linear and showed slopes approaching values of 0.35 eV at high temperatures which rapidly decreased to 0.25 meV at lower temperatures. The relaxation currents were found to be nonlinear with applied field. The observed nonlinearity of the field dependence of the relaxation currents can be understood in terms of the nonlinear relaxation component of the total capacitance. An equivalent circuit model for a paraelectric BSTO thin film capacitor is presented and possible polarization mechanisms are briefly discussed.

Nonlinear Dielectric Relaxation Spectra Calculated with a Free Rotation Model of the Dipole Moment

1992 ◽  
Vol 31 (Part 1, No. 10) ◽  
pp. 3387-3391 ◽  
Author(s):  
Yasuyuki Kimura ◽  
Reinosuke Hayakawa
Keyword(s):  
Dipole Moment ◽  
Dielectric Relaxation ◽  
Free Rotation ◽  
Relaxation Spectra ◽  
Nonlinear Dielectric ◽  
Rotation Model
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