Dielectric properties of BaTiO3–BaZrO3 ceramics under a high electric field

2002 ◽  
Vol 17 (4) ◽  
pp. 755-759 ◽  
Author(s):  
T. Tsurumi ◽  
Y. Yamamoto ◽  
H. Kakemoto ◽  
S. Wada ◽  
H. Chazono ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Field Dependence ◽  
Electric Fields ◽  
Broad Maximum ◽  
Ac Electric Fields ◽  
Ceramic Disk ◽  
Ac Field ◽  
Ac Fields ◽  
Temperature Side

Multilayered ceramic capacitors (MLCCs) with BaTiO3–BaZrO3 (BTZ) dielectric layers were fabricated, and the dielectric permittivity of the BTZ layers with different thicknesses in MLCCs was measured. The dielectric permittivity of the BTZ ceramic disk was also measured under various ac electric fields. The variation in the dielectric behaviors with the thickness of BTZ layers in MLCCs was explained by the ac-field dependence of dielectric permittivity observed in the BTZ ceramic disk. The ac-field dependence of dielectric permittivity of BTZ was markedly observed below the temperature of a broad maximum in the dielectric permittivity versus temperature (є versus T) curve. It was found that the temperature of the broad maximum shifted to the low-temperature side and the peak shape became asymmetric with increasing ac field. These changes in the dielectric properties under high ac fields were explained by a model of relaxors with the concept of the formation of polar microregions (PMRs) and the freezing of fluctuating ipoles in PMRs.

Vesicle dynamics in uniform electric fields: squaring and breathing

Soft Matter ◽  
2015 ◽  
Vol 11 (24) ◽  
pp. 4840-4846 ◽  
Author(s):  
Lane C. McConnell ◽  
Petia M. Vlahovska ◽  
Michael J. Miksis
Keyword(s):  
Electric Fields ◽  
Ac Electric Fields ◽  
Vesicle Dynamics ◽  
Ac Field ◽  
Prolate Ellipsoidal ◽  
Dynamic Transitions

We computationally investigate the dynamics of a vesicle exposed to uniform DC or AC electric fields. Our simulations capture the “squaring” phenomenon, in which vesicles deform into rectangular profiles with corner-like regions of high curvature, as vesicles undergo dynamic transitions between oblate and prolate ellipsoidal shapes. In AC field, this occurs periodically resembling “breathing”.

scholarly journals Долговечность полимеров в переменном электрическом поле

2020 ◽  
Vol 90 (2) ◽  
pp. 251
Author(s):  
В.А. Закревский ◽  
В.А. Пахотин ◽  
Н.Т. Сударь
Keyword(s):  
Free Radicals ◽  
Excited States ◽  
Electric Fields ◽  
Charge Accumulation ◽  
Nonradiative Relaxation ◽  
Polymer Dielectric ◽  
Ac Electric Fields ◽  
Ac Field ◽  
The Difference ◽  
Electron Excited States

An explanation of the difference in the electrical properties of polymers in the DC and AC electric fields is proposed. Energy release during recombination of electrons and holes injected into a polymer dielectric is considered as a factor accelerating the processes of electric aging of these dielectrics in an AC field. It is shown that nonradiative relaxation of electron excited states causes breaks of bonds in macromolecules and formation of free radicals. Due to the lower ionization energy of free radicals (compared to the original molecules), the rate of charge accumulation in the polymer dielectric increases, which leads to a decrease in its durability in an AC field compared to the durability of polymers in a DC field.

Gentle Dielectrophoretic Focusing of Yeast Cells in Curved Microchannels

2009 ◽  
Author(s):  
Christopher Church ◽  
Gaoyan Wang ◽  
Junjie Zhu ◽  
Tzuen-Rong Jeremy Tzeng ◽  
Xiangchun Xuan
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cell Concentration ◽  
Yeast Cells ◽  
Field Frequency ◽  
Electric Field Magnitude ◽  
Ac Electric Fields ◽  
Microfluidic Flow ◽  
Dc Electric Field ◽  
Ac Field

Focusing cells into a tight stream is usually a necessary step prior to counting, detecting and sorting them in, for example, microfluidic flow cytometers. We present herein a simple and gentle cell focusing technique in physiological solutions through a serpentine microchannel using DC-biased AC electric fields. This electrokinetic focusing eliminates sheath flows and in-channel microelectrodes. It results from the cross-stream dielectrophoretic motion of cells induced by the intrinsic channel curvatures. The effects of electric field magnitude, AC to DC electric field ratio, AC field frequency, and cell concentration on the focusing performance of yeast cells will be studied.

MOTION OF CHARGED PARTICLES IN DC-AC ELECTRIC FIELDS

1993 ◽  
Vol 07 (25) ◽  
pp. 4215-4226 ◽  
Author(s):  
XIAN-GENG ZHAO ◽  
XIN-WEI ZHANG ◽  
SHI-GANG CHEN ◽  
WAN-XIANG ZHANG
Keyword(s):  
Long Range ◽  
Electric Fields ◽  
Charged Particles ◽  
Real Space ◽  
Dynamic Localization ◽  
Dimensional Lattice ◽  
One Dimensional ◽  
Ac Electric Fields ◽  
Ac Fields ◽  
Theoretical Analyses

The motion of charged particles on a one-dimensional lattice under the influence of dc-ac electric fields is investigated. Analytic probability propagators in real space have been obtained, taking into account of the long-range intersite interactions. It is found that the effect of dynamic localization and delocalization arises mainly from the coupling of dc fields and ac fields. Various situations for the occurrence of localization and delocalization have been discussed in detail. The theoretical analyses show that such phenomena of dynamic localization and delocalization should be observable.

Fabrication of ZrO 2 /rGO nanocomposites by flash sintering under AC electric fields

2021 ◽  
Author(s):  
Xinghua Su ◽  
Mengying Fu ◽  
Gai An ◽  
Zhihua Jiao ◽  
Qiang Tian ◽  
...  
Keyword(s):  
Electric Fields ◽  
Ac Electric Fields ◽  
Flash Sintering

scholarly journals Sintering, Microstructure, and Dielectric Properties of Copper Borates for High Frequency LTCC Applications

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4017
Author(s):  
Dorota Szwagierczak ◽  
Beata Synkiewicz-Musialska ◽  
Jan Kulawik ◽  
Norbert Pałka
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
High Frequency ◽  
Ceramic Materials ◽  
Sintering Behavior ◽  
Terahertz Time Domain Spectroscopy ◽  
Very High Frequency ◽  
X Ray ◽  
Low Dielectric ◽  
Very High

New ceramic materials based on two copper borates, CuB2O4 and Cu3B2O6, were prepared via solid state synthesis and sintering, and characterized as promising candidates for low dielectric permittivity substrates for very high frequency circuits. The sintering behavior, composition, microstructure, and dielectric properties of the ceramics were investigated using a heating microscope, X-ray diffractometry, scanning electron microscopy, energy dispersive spectroscopy, and terahertz time domain spectroscopy. The studies revealed a low dielectric permittivity of 5.1–6.7 and low dielectric loss in the frequency range 0.14–0.7 THz. The copper borate-based materials, owing to a low sintering temperature of 900–960 °C, are suitable for LTCC (low temperature cofired ceramics) applications.

AC Electrokinetics for Biosensors

2004 ◽  
Author(s):  
M. Sigurdson ◽  
C. Meinhart ◽  
D. Wang
Keyword(s):  
Electric Fields ◽  
Dna Hybridization ◽  
Fluid Motion ◽  
Diffusive Transport ◽  
Analyte Concentration ◽  
Ac Electrokinetics ◽  
Ac Electric Fields ◽  
Binding Rate ◽  
Electrothermal Flow ◽  
Biosensor Device

We develop here tools for speeding up binding in a biosensor device through augmenting diffusive transport, applicable to immunoassays as well as DNA hybridization, and to a variety of formats, from microfluidic to microarray. AC electric fields generate the fluid motion through the well documented but unexploited phenomenon, Electrothermal Flow, where the circulating flow redirects or stirs the fluid, providing more binding opportunities between suspended and wall-immobilized molecules. Numerical simulations predict a factor of up to 8 increase in binding rate for an immunoassay under reasonable conditions. Preliminary experiments show qualitatively higher binding after 15 minutes. In certain applications, dielectrophoretic capture of passing molecules, when combined with electrothermal flow, can increase local analyte concentration and further enhance binding.

scholarly journals Spinning Janus doublets driven in uniform ac electric fields

2014 ◽  
Vol 89 (1) ◽  
Author(s):  
Alicia Boymelgreen ◽  
Gilad Yossifon ◽  
Sinwook Park ◽  
Touvia Miloh
Keyword(s):  
Electric Fields ◽  
Ac Electric Fields

scholarly journals Polytetrafluoroethylene Films in Rigid Polyurethane Foams’ Dielectric Permittivity Measurements with a One-Side Access Capacitive Sensor

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1173
Author(s):  
Ilze Beverte ◽  
Ugis Cabulis ◽  
Sergejs Gaidukovs
Keyword(s):  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Low Frequency ◽  
Capacitive Sensor ◽  
Polyurethane Foams ◽  
Active Area ◽  
Ptfe Film ◽  
Practical Applications ◽  
Permittivity Measurements ◽  
The Impact

As a non-metallic composite material, widely applied in industry, rigid polyurethane (PUR) foams require knowledge of their dielectric properties. In experimental determination of PUR foams’ dielectric properties protection of one-side capacitive sensor’s active area from adverse effects caused by the PUR foams’ test objects has to be ensured. In the given study, the impact of polytetrafluoroethylene (PTFE) films, thickness 0.20 mm and 0.04 mm, in covering or simulated coating the active area of one-side access capacitive sensor’ electrodes on the experimentally determined true dielectric permittivity spectra of rigid PUR foams is estimated. Penetration depth of the low frequency excitation field into PTFE and PUR foams is determined experimentally. Experiments are made in order to evaluate the difference between measurements on single PUR foams’ samples and on complex samples “PUR foams + PTFE film” with two calibration modes. A modification factor and a small modification criterion are defined and values of modifications are estimated in numerical calculations. Conclusions about possible practical applications of PTFE films in dielectric permittivity measurements of rigid PUR foams with one-side access capacitive sensor are made.

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