Frequency Dependence of Electrorheological (ER) Effect and Its Relationship to Dielectric and Electrical Properties in Ba1-xSrxTiO3 Suspensions

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1443-1448 ◽  
Author(s):  
Yasuhito Misono ◽  
Shoichi Furukawa ◽  
Hitomi Yosinaga ◽  
Junko Sugiyama ◽  
Keishi Negita
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Dielectric Permittivity ◽  
Field Strength ◽  
Electric Field ◽  
Frequency Dependence ◽  
Applied Electric Field ◽  
Electrode Polarization ◽  
Low Frequencies ◽  
High Frequencies

Varying the electric field strength (E), the ER effect, the dielectric permittivity, and the electrical conductivity were simultaneously measured on the Ba 0.75 Sr 0.25 TiO 3 suspension. It was found that at high E the ER effect increased with the frequency (f), while at low E it once decreased and then increased with increase in f. At high E, the dielectric permittivity at low frequencies was much larger than that at high frequencies, indicating that an electrode polarization was formed as a result of accumulations of ions, which were dissociated from the liquid at high E, near the electrodes. This electrode polarization was further confirmed in the time dependence of the electrical conductivity after the electric field was switched on. From these results it is suggested that the E-dependent frequency dependence of the ER effect may be due to the electrode polarization, which causes larger shielding of the applied electric field at lower f while smaller shielding at higher f.

THE FREQUENCY DEPENDENCE AND NON-LINEAR DIELECTRIC PROPERTY OF ER FLUID

1996 ◽  
Vol 10 (23n24) ◽  
pp. 3073-3080 ◽  
Author(s):  
KUNQUAN LU ◽  
WEIJIA WEN ◽  
CHENXI LI
Keyword(s):  
Dielectric Property ◽  
Field Strength ◽  
Electric Field ◽  
Frequency Dependence ◽  
Threshold Value ◽  
Shear Stresses ◽  
Linear Behavior ◽  
Non Linear ◽  
Er Fluids ◽  
Er Fluid

The frequency dependence of the shear stress in ac field and the non-linear dielectric property of ER fluid have been studied. We find that the shear stresses of some water-free ER fluids increase monotonously with the frequency and tend to reach saturated values at high frequency. The measurements on KNbO 3/silicone ER fluid show that the shear stresses under 103 Hz frequency a.c. field are several times or even an order larger than that under d.c. field for the same field strength. The studies of non-linear dielectric properties of ER fluids show that the permittivity of ER fluid increases linearly with increasing field strength when the electric field exceeds a threshold value E 1 and tends to a saturated constant beyond a high field strength E 2. Correspondingly the current density follows linear behavior no longer in the region between E 1 and E 2. A model based on the rearrangement of the particles under the electric field. which causes the variation of the dielectric property of the ER fluid, is proposed and the analysis is consistent with the measured results.

Parametric Study of Dielectrophoretic Interactive Motion of Particles

2015 ◽  
Author(s):  
Mohammad Robiul Hossan ◽  
Matthew J. Benton ◽  
Prashanta Dutta ◽  
Robert Dillon
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Electric Field ◽  
Free Particle ◽  
Immersed Boundary ◽  
Label Free ◽  
Navier Stokes Equation ◽  
Immersed Interface Method ◽  
Immersed Interface ◽  
Fluid Medium

Dielectrophoresis (DEP) has become one of the most popular mechanisms for label free particle manipulations and transport in microfluidics. The efficacy of this mechanism is greatly dependent on the understanding and control of DEP interactive motion among particles. In this study, we performed a systematic investigation to understand the effect of particles size and electrical properties on DC DEP interactions among particles using in-house hybrid immersed boundary – immersed interface numerical method. Immersed boundary method is employed to predict flow field and immersed interface method is used to simulate electric field. The numerical model utilizes Maxwell’s stress tensor to obtain DEP forces, while solving transient Navier-Stokes equation it determines the hydrodynamic interaction between each of the particles and the fluid containing them. By varying the number of particles as well as the particles’ size, electrical properties and initial orientations, a number of possibilities were considered. Results indicate that the particles with similar electrical conductivities attract each other and tend to align themselves parallel to the external electric field regardless of sizes. If electrical conductivity of particles is lower than that of the fluid medium then the particle-particle interactions is caused by the negative DEP. If electrical conductivity of particles is higher than that of the fluid medium then the interactive motions of particle is attributed to the positive DEP. On the other hand, electrically dissimilar particles still attract each other but tend to align perpendicular to the electric field. Both negative and positive DEP contributes in interactions between electrically dissimilar particles. Numerical simulation also shows that the identical sized particles move at the same speed during interaction. In contrast, smaller particles moves faster than the larger particle during the interactions. This study explains the effect of size and electrical properties on DEP interactive motions of particles and can be utilized to design microfluidic devices for DEP particle manipulations.

Electroviscoelastic Properties in ER Gel of Disperse System under DC Electric Field

2002 ◽  
Vol 16 (17n18) ◽  
pp. 2433-2439 ◽  
Author(s):  
R. HANAOKA ◽  
S. TAKATA ◽  
H. FUJITA ◽  
T. FUKAMI ◽  
K. SAKURAI ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Disperse System ◽  
Fine Particles ◽  
Silicone Oil ◽  
Dynamic Properties ◽  
Low Frequencies ◽  
Hydrosilylation Reaction ◽  
Microscopical Method ◽  
Dc Electric Field

The silicone oil-based electrorheological (ER) gel containing the non-aqueous fine particles was newly created in the present study. After these particles were dispersed at 30wt.% in the dimethylsilicone oil, the ER gel was produced by the hydrosilylation reaction in the mixture of the modified silicone oil. The reaction could considerably be promoted by heating at 90°C. The behavior of particles in the ER gel was observed by a microscopical method. When an electric field was applied to the ER gel, the gap between the electrodes was bridged by the chains of particles arranged in the direction of the electric field. The dynamic properties of the ER gel were also examined under the applied dc electric field up to 2kV/mm using the oscillating rheometer with the low frequencies of 1Hz or less. Consequently, it is shown that the electroviscoelastic effect of the gel can be controlled by the electric field strength.

A study of the frequency dependence of the dielectrophoretic effect in thermoset polymers

1997 ◽  
Vol 12 (9) ◽  
pp. 2345-2356 ◽  
Author(s):  
C. P. Bowen ◽  
T. R. Shrout ◽  
R. E. Newnham ◽  
C. A. Randall
Keyword(s):  
Electric Field ◽  
Frequency Dependence ◽  
Electrode Polarization ◽  
Dielectrophoretic Force ◽  
Low Field ◽  
Fibril Structure ◽  
Alternating Electric Field ◽  
Current Voltage ◽  
Spatial Redistribution ◽  
Thermoset Polymer

Ceramic-polymer composites with a 1–3 connectivity can be created via a novel process called dielectrophoretic assembly. The process involves an electric field which is applied to a suspension of ceramic particles in an uncured thermoset polymer matrix. Under appropriate conditions, the applied electric field acts to induce a spatial redistribution of the particles into a chained or fibril structure. It was shown previously that the electrorheological response and fibril microstructure are dependent on both the frequency and magnitude of the applied alternating electric field.3 This paper will show that the frequency dependence of the uncured thermoset polymer suspensions results from the complex electrical phenomena specific to each thermoset system. Specifically, it will be shown through low field dielectric measurements and high field current-voltage analysis that the dielectrophoretic effect can be limited by electrode polarization, ionic conductivity, and space charge relaxation. It is the frequency dependence of these limiting phenomena that gives rise to the observed frequency dependence in the dielectrophoretic force of attraction being utilized to drive particulate assembly.

Effect of Electric Field Strength on Texture Evolution of IF Steel Sheet during Annealing

2012 ◽  
Vol 706-709 ◽  
pp. 2617-2621
Author(s):  
Chang Shu He ◽  
Xiang Zhao ◽  
Wei Ping Tong ◽  
Liang Zuo
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Steel Sheet ◽  
Texture Evolution ◽  
If Steel ◽  
X Ray Diffraction ◽  
If Steel Sheet

Specimens cut from a cold-rolled IF steel sheet of 1 mm thickness were respectively annealed at 750°C for 20min under a range of DC electric fields (1kV/cm~4kV/cm). The Effect of electric field strength on recrystallization texture of IF steel sheet was studied by mean of X-ray diffraction ODF analysis. It was found that γ-fiber textures were notably enhanced as electric field strength increased. The strength of γ-fiber textures got their peak values as the applied electric field reached to 4kV/cm. The possible reason for such phenomena was discussed in the viewpoint of interaction between the applied electric field and the orientation-dependent stored-energy in deformed metals which is known as the driving force for recrystallization during annealing.

Bestimmung der elektrischen Leitfähigkeit von Helium aus integralen Lichtbogenmessungen

1969 ◽  
Vol 24 (9) ◽  
pp. 1427-1428 ◽  
Author(s):  
E. Fischer ◽  
J. Hackmann ◽  
J. Uhlenbusch
Keyword(s):  
Electrical Conductivity ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Arc Plasma ◽  
Gas Temperature ◽  
Free Plasma

Abstract In Ohmic heated plasmas the temperature of the electrons is always higher than the gas temperature. In this case the electrical conductivity can be assumed as a function of the gas temperature and the electric field strength. With this assumption comparing the characteristics of two arcs with different radii the electrical conductivity of an helium arc plasma (1 atm) is determined and reduced to the value for a field free plasma.

scholarly journals Conduction mechanism in (ZnO/PVC) polymer nanocomposite

2021 ◽  
Vol 2070 (1) ◽  
pp. 012007
Author(s):  
A Joy Singh
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Space Charge ◽  
Applied Electric Field ◽  
High Field ◽  
Conduction Mechanism ◽  
Polymer Nanocomposite ◽  
Zno Nanoparticle ◽  
Pure Sample ◽  
Transition Field

Abstract The electrical conductivity of ZnO nanoparticle doped PVC polymer of different concentrations and thickness has been investigated as a function if applied electric field and temperature. The LnJ versus E1/2 plot for the pure sample shows transition field but for highly doped sample, the plot shows curvature for both low and high field, i.e., there is no transition field. This nonlinearity of the plot is due to space charge built up in the sample. The value of β is calculated from the slope of LnJ versus E1/2 plot and compared with the theoretical value. The result shows the Poole-Frenkel mechanism of conduction is operative.

HIGH-VOLTAGE ELECTRIC CONDUCTIVITY OF RUBIDIUM DIHYDROPHOSPHATE AND ITS RELAXATION

2019 ◽  
Author(s):  
S.M. Gadzhiev ◽  
A.S. Gadzhiev
Keyword(s):  
Electrical Conductivity ◽  
Relaxation Time ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Relative Increase ◽  
Relaxation Processes ◽  
Electrolyte Conductivity ◽  
Increasing Temperature ◽  
Limiting Value

The dependence of electrical conductivity on the electric field strength and relaxation processes in the proton solid electrolyte RbH₂PO₄ are investigated. With increasing electric field strength, the electrolyte conductivity increases in an attempt to the limiting value. The relative increase in conductivity and relaxation time with increasing temperature increase and reaches 208% at 600 K. The relaxation time is of the order of 104 s.

New Fabrication (PVA-CMC -PbO) Nanocomposites Structural and Electrical Properties

2021 ◽  
Vol 19 (4) ◽  
pp. 38-46
Author(s):  
Manar S. Toman ◽  
Sameer Hassan Al-nesrawy
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Electrical Properties ◽  
Dielectric Loss ◽  
Electric Field ◽  
Lead Oxide ◽  
Optical Microscope ◽  
Structural And Electrical Properties ◽  
Oxide Concentration ◽  
Structural Aspects

This paper presents the work conducted on preparing (PbO PVA-PEG) nanocomposites through adding the different weight concentrations of lead oxide (0,1,3,5,7 wt%). The structural aspects such as optical microscope, FTIR and electrical features of nanocomposites (PVA-CMC/PbO) were examined. The resulting data shows that the dielectric constant decreased along with the decline of dielectric loss, whereas the frequency value rose while applying of an electric field. As for the electrical conductivity AC, the dielectric loss and dielectric constant of all samples rose along with the increase in lead oxide concentration.

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