scholarly journals Coexistence of Flexo- and Ferro-Electric Effects in an Ordered Assembly of BaTiO3 Nanocubes

Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 188
Author(s):  
Kyuichi Yasui ◽  
Hiroki Itasaka ◽  
Ken-ichi Mimura ◽  
Kazumi Kato
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Frequency Dependence ◽  
Dielectric Response ◽  
The Other ◽  
Flexoelectric Effect ◽  
Alternating Electric Field ◽  
Ordered Assembly ◽  
Electric Effects ◽  
Theory And Experiments

It has been reported that the flexoelectric effect could be dominant in the nanoscale. The discrepancy between theory and experiments on the frequency dependence of the dielectric constant of an ordered assembly of BaTiO3 nanocubes is nearly resolved by assuming the coexistence of flexo- and ferro-electric effects. Although flexoelectric polarizations perpendicular to the applied alternating electric field contribute to the dielectric constant, those parallel to the electric field do not contribute because the magnitude of the flexoelectric polarization does not change due to the mismatch of strain at the interface of the nanocubes. On the other hand, some dielectric response is possible for the ferroelectric component of the polarization parallel to the electric field.

The Hertzian Spectrum of Rubber and Its Micellar Constitution

1946 ◽  
Vol 19 (4) ◽  
pp. 1085-1087
Author(s):  
Pierre Girard ◽  
Paul Abadie
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Wave Length ◽  
Structural Features ◽  
Loss Angle ◽  
First Case ◽  
Dipolar Molecules ◽  
Alternating Electric Field ◽  
Different Types ◽  
Absorption And Dispersion

Abstract The spectra which were studied lie within the region of hertzian frequencies, and can be represented either by dispersion curves showing the dielectric constant of the substance as a function of the frequency (or wave length λ), or by absorption curves showing the loss angle as a function of this frequency. These two types of curves represent the same phenomenon, i.e., orientation of the dipolar molecules in the alternating electric field, in accordance with the theory of Debye. The spectra and their interpretation depend chiefly on whether the molecules are crystalloid with relatively small and similar dimensions, or are colloidal, with large and unequal dimensions. In the first case, the spectra gives evidence chiefly on the form of the molecules and their structural features. Dilution in a nonpolar solvent shows for certain dipolar compounds, e.g., alcohol, considerable deformations, which differ according to the solvent. In the case of colloids, e.g., rubber, which has a permanent moment, the spectra and the meaning of these spectra are far different. In this case the spectra indicate that the absorption and dispersion values in the hertzian region are closely related to the micellar constitution, i.e., to the different types of micelles, to their size, and to the proportion of each type.

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.

Electrical Properties and Polarization Reversal in (Li,Na)NbO3 Lead-Free Piezoelectric Ceramics

2011 ◽  
Vol 485 ◽  
pp. 69-72 ◽  
Author(s):  
Takayuki Ohashi ◽  
Rintaro Aoyagi ◽  
Masaki Maeda ◽  
Makoto Iwata
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Frequency Dependence ◽  
Piezoelectric Ceramics ◽  
Polarization Switching ◽  
Coupling Factor ◽  
The Other ◽  
Lead Free ◽  
Polarization Reversal ◽  
Other Hand

In this study, the relationships between the electrical properties and polarization switching of lead-free (Li0.06Na0.94)NbO3 (LNN6) ceramics were investigated. The electrical properties of stoichiometric LNN6 did not change with polarization switching. On the other hand, the frequency dependence of the impedance of Na-deficient LNN decreased with polarization switching, and the coupling factor kp, the piezoelecric constant d33 and the dielectric constant ε33T/ε0 decreased with polarization switching. Moreover, the dielectric curve of Na-deficient LNN6 after 10 switchings showed peaks at approximately 330, 400 and 500 °C

The Influence of DC Bias on the Dielectric Response of Sr1-xCaxTiO3 Ceramics

2006 ◽  
Vol 514-516 ◽  
pp. 240-244
Author(s):  
Alexander Tkach ◽  
Branca Araújo ◽  
Paula M. Vilarinho
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Dielectric Response ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Average Grain Size ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Dc Bias ◽  
Microstructural Studies

The effect of the electric field on the dielectric response of the Sr1-xCaxTiO3 ceramic system was analysed and complemented by structural and microstructural studies. A monotonic decrease of the lattice parameter and an increase of the average grain size from 11 to 23 μm with increasing x were observed by X-ray diffraction and scanning electron microscopy analysis respectively. Samples with x = 0.003 and 0.01 reveal a monotonous increase of low-temperature dielectric constant, corresponding to an enhancement of the tunability and a reduction of the driving electric field at 10-30 K for x = 0.01. For Sr1-xCaxTiO3 ceramic samples with x = 0.04 and 0.10 the ferroelectric phase transition of around 20 K was observed together with the enhanced tunability of the dielectric constant at 30-85 K for x = 0.10.

Removal of Particles From the Surface of a Droplet

2008 ◽  
Author(s):  
N. Aubry ◽  
P. Singh ◽  
S. Nudurupati ◽  
M. Janjua
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Strong Electric Field ◽  
Dielectric Constants ◽  
The Other ◽  
Uniform Electric Field ◽  
Drop Deformation ◽  
Ambient Fluid ◽  
Dielectrophoretic Force ◽  
Different Types

We present a technique to concentrate particles on the surface of a drop, separate different types of particles, and remove them from the drop by subjecting the drop to a uniform electric field. The particles are moved under the action of the dielectrophoretic force which arises due to the non-uniformity of the electric field on the surface of the drop. Experiments show that depending on the dielectric constants of the fluids and the particles, particles aggregate either near the poles or near the equator of the drop. When particles aggregate near the poles and the dielectric constant of the drop is greater than that of the ambient fluid, the drop deformation is larger than that of a clean drop. In this case, under a sufficiently strong electric field the drop develops conical ends and particles concentrated at the poles eject out by a tip streaming mechanism, thus leaving the drop free of particles. On the other hand, when particles aggregate near the equator, it is shown that the drop can be broken into three major droplets, with the middle droplet carrying all particles and the two larger sized droplets on the sides being free of particles. The method also allows us to separate particles for which the sign of the Clausius-Mossotti factor is different, making particles of one type aggregate at the poles and of the second type aggregate at the equator. The former are removed from the drop by increasing the electric field strength, leaving only the latter inside the drop.

Micro Walking Machines Using Piezoelectric Actuators

1989 ◽  
Vol 1 (2) ◽  
pp. 124-127 ◽  
Author(s):  
Kenji Uchino ◽  
Keyword(s):  
Electric Field ◽  
Piezoelectric Actuators ◽  
Piezoelectric Ceramics ◽  
Ultrasonic Motor ◽  
The Other ◽  
Mechanical Resonance ◽  
Walking Machines ◽  
Alternating Electric Field ◽  
The Future ◽  
Made In

A large number of attempts have been made in recent years to apply piezoelectric ceramics to actuators for movable systems. In effect, piezoelectric ceramics have been placed under the category of precision positioners.i> In this paper, the future of micro travelling systems is reviewed mainly on the basis of studies conducted by the author et al. Piezoelectric/electrostrictive actuators can roughly be classified according to their driving principles into the following two types: one type is designed to utilize the displacement created rigidly under an electric field applied; the other type is designed to utilize the displacement created by an alternating electric field as a result of mechanical resonance. The elements of both types, called inchworm and ultrasonic motor respectively, differ considerably in driving principle, though they are very similar in appearance. In addition, a third type known as photostrictive actuator has been developed. This type is designed to be driven by irradiated light.

scholarly journals Influence of mechanical, thermal, and electrical perturbations on the dielectric behaviour of guest-encapsulated HKUST-1 crystals

2020 ◽  
Vol 8 (37) ◽  
pp. 12886-12892
Author(s):  
Arun Singh Babal ◽  
Jin-Chong Tan
Keyword(s):  
Electric Field ◽  
Mechanical Stress ◽  
Temperature Variation ◽  
Dielectric Response ◽  
Metal Organic Framework ◽  
Dielectric Behaviour ◽  
Alternating Electric Field ◽  
Metal Organic ◽  
Organic Framework

Dielectric response of a guest-encapsulated metal-organic framework (HKUST-1 MOF) can be tuned and regulated by imposing an alternating electric field, coupled with temperature variation and mechanical stress.

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