EFFECTS OF PREPARATION PROCEDURE AND ELECTRIC FIELD FREQUENCY ON THE DIELECTRIC CONSTANTS AND ELECTRORHEOLOGY OF A ZEOLITE/SILICONE OIL SUSPENSION

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1191-1197 ◽  
Author(s):  
D. McNEISH ◽  
K. JUNG ◽  
C. M. BALIK ◽  
H. CONRAD
Keyword(s):  
Dielectric Constant ◽  
Shear Stress ◽  
Electric Field ◽  
Silicone Oil ◽  
Dielectric Constants ◽  
Preparation Procedure ◽  
Complex Dielectric Constant ◽  
Field Frequency ◽  
Electric Field Frequency ◽  
Single Heating

Determined were the effects of preparation procedure and electric field frequency f = dc to 105 Hz on the dielectric constants and ER response (shear rate [Formula: see text]) of a suspension in silicone oil of 23 wt.% zeolite particles originally containing 19 wt.% H 2 O . Heating the oil and the zeolite particles at 110°C both prior to, and following, mixing decreased the conductivity of the suspension more than simply heating the suspension following mixing. The double heating procedure reduced the complex dielectric constant [Formula: see text] of the particles and the complex mismatch parameter β*. The ER shear stress τ E was proportional to [Formula: see text] for the single heating and [Formula: see text] for the double heating, where [Formula: see text] is the complex dielectric constant of the silicone oil. The lower exponent corresponds to a higher water content and in turn higher conductivity of the suspension. Erratic ER response occurred for f =10 Hz in tests with [Formula: see text], but not in tests with [Formula: see text].

Synthesis, characterization and electrorheological properties of biodegradable chitosan/bentonite composites

Clay Minerals ◽  
2013 ◽  
Vol 48 (1) ◽  
pp. 129-141 ◽  
Author(s):  
M. Cabuk ◽  
M. Yavuz ◽  
H. I. Unal ◽  
O. Erol
Keyword(s):  
Particle Size ◽  
Shear Rate ◽  
Electric Field ◽  
Cetyltrimethylammonium Bromide ◽  
Particle Concentration ◽  
Silicone Oil ◽  
Creep Recovery ◽  
Field Frequency ◽  
Electric Field Frequency ◽  
Electrorheological Properties

AbstractBiodegradable chitosan/bentonite composites with three different compositions were synthesized by the intercalation method using cetyltrimethylammonium bromide as the cationic surfactant. The composites were characterized using conductivity, density, particle size measurements, FTIR, TGA, XRD and SEM methods. Colloidal stabilities of the suspensions prepared in silicone oil (SO) were observed to increase with decreasing density. The effects of dispersed particle concentration, shear rate, electric field strength, electric field frequency and temperature on the electrorheological (ER) activities of the suspensions were investigated. The electric field viscosities of the suspensions showed typical shear thinning non-Newtonian viscoelastic behaviour. Yield stresses of the suspensions were observed to change in proportion to the square of applied electric field (E). Further, according to creep and creep-recovery analysis, reversible viscoelastic deformations were observed in the suspensions under E ≠ 0 kV mm–1.

Modified Morris-Lecar neuron model: Effects of very low frequency electric fields and of magnetic fields on the local and network dynamics of an excitable media

2021 ◽  
Author(s):  
Karthikeyan Rajagopal ◽  
Irene Moroz ◽  
Balamurali Ramakrishnan ◽  
Anitha Karthikeyan ◽  
Prakash Duraisamy
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Electric Field ◽  
Neuron Model ◽  
Low Noise ◽  
Spiral Waves ◽  
Excitable Media ◽  
Field Frequency ◽  
Electric And Magnetic Fields ◽  
Electric Field Frequency

Abstract A Morris-Lecar neuron model is considered with Electric and Magnetic field effects where the electric field is a time varying sinusoid and magnetic field is simulated using an exponential flux memristor. We have shown that the exposure to electric and magnetic fields have significant effects on the neurons and have exhibited complex oscillations. The neurons exhibit a frequency-locked state for the periodic electric field and different ratios of frequency locked states with respect to the electric field frequency is also presented. To show the impact of the electric and magnetic fields on network of neurons, we have constructed different types of network and have shown the network wave propagation phenomenon. Interestingly the nodes exposed to both electric and magnetic fields exhibit more stable spiral waves compared to the nodes exhibited only to the magnetic fields. Also, when the number of layers are increased the range of electric field frequency for which the layers exhibit spiral waves also increase. Finally the noise effects on the field affected neuron network are discussed and multilayer networks supress spiral waves for a very low noise variance compared against the single layer network.

Pulsed Laser Deposition of BaxSr1−xTiO3 Films on MgO, LaAlO3 and SrTiO3 for Tunable Microwave Applications

1998 ◽  
Vol 541 ◽  
Author(s):  
Wontae Chang ◽  
James S. Horwitz ◽  
Won-Jeong Kim ◽  
Jeffrey M. Pond ◽  
Steven W. Kirchoefer ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Electric Field ◽  
Pulsed Laser Deposition ◽  
Pulsed Laser ◽  
Dielectric Constants ◽  
Laser Deposition ◽  
Film Stress ◽  
Donor Acceptor ◽  
Bst Films

AbstractSingle phase BaxSr1−xTiO3 (BST) films (∼0.5-7 μm thick) have been deposited onto single crystal substrates (MgO, LaAlO3, SrTiO3) by pulsed laser deposition. Silver interdigitated electrodes were deposited on top of the ferroelectric film. The room temperature capacitance and dielectric Q (1/tanδ) of the film have been measured as a function of electric field (≤80 kV/cm) at 1 - 20 GHz. The dielectric properties of the film are observed to strongly depend on substrate type and post-deposition processing. After annealing (≤1000° C), it was observed that the dielectric constant and % tuning decreased and the dielectric Q increased for films deposited onto MgO, and the opposite effect was observed for films deposited onto LaA1O3. Presumably, this change in dielectric properties is due to the changes in film stress. Very thin (∼50 Å) amorphous BST films were successfully used as a stress-relief layer for the subsequently deposited crystalline BST (∼5000 Å) films to maximize % tuning and dielectric Q. Films have been deposited from stoichiometric targets and targets that have excess Ba and Sr. The additional Ba and Sr has been added to the target to compensate for deficiencies in Ba and Sr observed in the deposited BST (x=0.5) films. Films deposited from compensated targets have higher dielectric constants than films deposited from stoichiometric targets. Donor/acceptor dopants have also been added to the BST target (Mn, W, Fe ≤4 mol.%) to further improve the dielectric properties. The relationship between the dielectric constant, the dielectric Q, the change in dielectric constant with electric field is discussed.

ER Properties of a Suspension of Polymer Graft Carbon Black Particles

1999 ◽  
Vol 13 (14n16) ◽  
pp. 1682-1688
Author(s):  
Masayoshi Konishi ◽  
Teruhisa Nagashima ◽  
Yoshinobu Asako
Keyword(s):  
Shear Stress ◽  
Carbon Black ◽  
Electric Field ◽  
Silicone Oil ◽  
Average Particle Size ◽  
Average Particle ◽  
Zero Field ◽  
Average Value ◽  
Time Period ◽  
Micron Size

We newly developed ER particles with sub-micron size. The particle was polymer graft carbon black (GCB1) composed of carbon black particles and a polymer. The average particle size of GCB1 was found to be 81 nm. An ER suspension (ER1) was obtained by mixing GCB1 (30 wt%) with silicone oil (70 wt%). The ER1 showed excellent dispersion stability. Further, GCB1 particles did not settle under centrifuging at 9000G. The zero-field viscosity was 80 mPa·s at 25°C. The kinetic friction coefficient of ER1 was 0.15, while that of the silicone oil used was 0.23. When the electric field of 3 kV/mm (AC 1000 Hz) at the temperature of 25°C and the shear rate of 700 s -1 was applied to ER1, the shear stress of 116Pa was induced. The induced shear stress did not change for a long period of time period. In the temperature range between 25 and 150°C the induced shear stress and the current density were almost constant at any electric field. When 3 kV/mm (AC 50Hz) at 25°C and 700s-1 was applied to ER1, the shear stress of 88Pa was induced but the deviation of the induced shear stress from the average value was pluses and minuses 3 Pa.

THE COMPLEX DIELECTRIC CONSTANT OF SOLUTIONS OF TRIMETHYLPENTANE AND NITROBENZENE NEAR THE CONSOLUTE TEMPERATURE

1961 ◽  
Vol 39 (3) ◽  
pp. 526-534 ◽  
Author(s):  
B. D. Ripley ◽  
R. McIntosh
Keyword(s):  
Dielectric Constant ◽  
Phase Separation ◽  
Standing Wave ◽  
Applied Field ◽  
Coaxial Line ◽  
Dielectric Constants ◽  
Complex Dielectric Constant ◽  
Experimental Procedure ◽  
Chemical Systems ◽  
Consolute Temperature

The complex dielectric constants of three compositions of trimethylpentane and nitrobenzene have been measured as a function of temperature for a range near the consolute temperature. The frequency employed was 3300 Mc/sec. The experimental procedure involved the study of the standing wave established in a coaxial line. The chemical systems showed maxima in both the real and imaginary parts of the complex dielectric constant at temperatures above those at which phase separation occurs. The finding of Semenchenko and Azimov is thus confirmed. A discussion of the validity of applying thermodynamic formulae to dielectrics showing loss is given and some qualitative remarks are offered concerning the change of the systems as they are cooled. These remarks are based upon the effect of the applied field upon the entropy of the solutions.

Effect of the electric field frequency on heat exchange in free convection

1984 ◽  
Vol 47 (3) ◽  
pp. 1023-1026
Author(s):  
Yu. K. Solomatnikov ◽  
A. G. Usmanov ◽  
D. M. Mikhailov
Keyword(s):  
Heat Exchange ◽  
Free Convection ◽  
Electric Field ◽  
Field Frequency ◽  
Electric Field Frequency

Investigation on dielectric properties of the polyetherketone nanocomposite with lead titanate ultrafines

2001 ◽  
Vol 79 (5) ◽  
pp. 847-855 ◽  
Author(s):  
W Shi ◽  
C Fang ◽  
S Guo ◽  
Q Ren ◽  
Q Pan ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Constants ◽  
Inorganic Nanoparticles ◽  
Complex Dielectric Constant ◽  
Nanocomposite Polymer ◽  
Local Field Theory ◽  
Constant Expression ◽  
Space Polarization ◽  
Good Agreement

The dielectric properties of polymer composites with inorganic nanoparticles were investigated. In the demonstration of the dielectric constant expression of the nanocomposite polymer, the dielectric contributions of the displacement polarization, the orientation polarization, and the space polarization in the nanocomposite polymer were all considered. In the demonstration, two dielectric relaxation models were used, that of Debye for inorganic nanoparticles and the Havriliak–Negami function model for polymers. Then the expression of the complex dielectric constant of the nanocomposite polymer was obtained by using Onsager's local field theory. Furthermore, the nanocomposite polymer thin films that consist of PbTiO3 nanoparticles and polyetherketone were prepared. The real parts of the dielectric constants were measured and calculated, respectively. It was found that our calculated results are in good agreement with our measured results. PACS Nos.: 77.20, 77.55, 81.20T

Sign in / Sign up

Export Citation Format

Share Document