scholarly journals Dielectric Properties and Switching Processes of Barium Titanate–Barium Zirconate Ferroelectric Superlattices

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1436 ◽  
Author(s):  
Alexander Sidorkin ◽  
Lolita Nesterenko ◽  
Yaovi Gagou ◽  
Pierre Saint-Gregoire ◽  
Eugeniy Vorotnikov ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Barium Titanate ◽  
Dielectric Permittivity ◽  
Bias Field ◽  
Barium Zirconate ◽  
Temperature Hysteresis ◽  
Field Frequency ◽  
Entire Study ◽  
Heating And Cooling ◽  
Electric Field Frequency

This article is devoted to the investigation of the dielectric and repolarization properties of barium zirconate and barium titanate BaZrO3/BaTiO3 superlattices with a period of 13.322 nm on a monocrystal magnesium oxide (MgO) substrate. Synthesized superlattices demonstrated a ferroelectric phase transition at a temperature of approximately 393 °C, which is far higher than the Curie temperature of BaTiO3 thin films and bulk samples. The dielectric permittivity of the superlattice reached more than 104 at maximum. As the electric field frequency increased, the dielectric constant of the studied superlattice decreased over the entire study temperature range, but position of the maximum dielectric constant remained the same with changing frequency. The temperature dependence of the inverse dielectric permittivity 1/ε(T) for the studied samples shows that, in the investigated superlattice, both Curie–Weiss law and the law of “two” were followed. Additionally, the ε(T) dependences showed practically no temperature hysteresis with heating and cooling. Samples of synthesized superlattices had a relatively small internal bias field, which was directed from the superlattice towards the substrate.

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].

Anomalous Broad Dielectric Dispersion of 0.4PZN-0.3PSN-0.3PZN Relaxor Ceramics at Lower Temperatures

2006 ◽  
Vol 514-516 ◽  
pp. 216-220
Author(s):  
Juras Banys ◽  
Jan Macutkevic ◽  
Algirdas Brilingas ◽  
Vytautas Samulionis ◽  
K. Bormanis ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Bias Field ◽  
Dielectric Dispersion ◽  
Dielectric Losses ◽  
Low Frequencies ◽  
External Bias ◽  
Very High ◽  
Maximum Permittivity

Dielectric properties of 0.4PbZn1/3Nb2/3O3-0.3PbSc1/2Nb1/2O3-0.3PbMg1/3Nb2/3O3- (0.4PZN- 0.3PSN-0.3PMN) ceramics are presented for 200 < T < 500 K and 20 Hz < ν < 1 MHz. Dielectric constant is very high (more 14000) in the vicinity of the peak. Anomalous broad dielectric relaxation have been observed near the temperature of the maximum permittivity, Tm (at 1 kHz). External bias field considerably lowers the value of dielectric losses at low frequencies due to decrease of polar nano regions contribution to the dielectric permittivity.

scholarly journals Improved electromechanical properties of brominated butyl rubber filled with modified barium titanate

RSC Advances ◽  
2017 ◽  
Vol 7 (59) ◽  
pp. 37148-37157 ◽  
Author(s):  
Mengnan Ruan ◽  
Dan Yang ◽  
Wenli Guo ◽  
Shuo Huang ◽  
Yibo Wu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Dielectric Constant ◽  
Barium Titanate ◽  
High Dielectric Constant ◽  
Dielectric Elastomer ◽  
Butyl Rubber ◽  
Electromechanical Properties ◽  
Brominated Butyl Rubber ◽  
High Dielectric

Barium titanate (BT) particles, BT-KH570 particles, and polar plasticizer tri-n-butyl phosphate (TBP) were added into BIIR matrix to form a dielectric elastomer composite, which had a high dielectric constant, good mechanical properties, and large actuated strain.

scholarly journals Estimation of S-parameters and dielectric permittivity of quartz ceramics samples in millimeter waveband

Doklady BGUIR ◽  
2021 ◽  
Vol 19 (7) ◽  
pp. 65-71
Author(s):  
N. A. Pevneva ◽  
D. A. Kondrashov ◽  
A. L. Gurskii ◽  
A. V. Gusinsky
Keyword(s):  
Dielectric Constant ◽  
Dielectric Permittivity ◽  
Ceramic Materials ◽  
Reflection And Transmission Coefficients ◽  
Frequency Range ◽  
Reflection And Transmission ◽  
Transmission Coefficients ◽  
Higher Order Modes ◽  
S Parameters ◽  
The Fourier Transform

A modified Nicholson – Ross – Weir method was used to determine complex parameters and dielectric permittivity of ceramic materials in the range 78.33–118.1 GHz. The measuring equipment is a meter of complex reflection and transmission coefficients, a waveguide measuring canal with a special measuring cell, consisting of two irregular waveguides and a waveguide chamber between them, which provides insignificant influence of higher-order modes. The dependences of the amplitude and phase of the reflection and transmission coefficients on frequency were obtained experimentally for fluoroplastic and three ceramic samples in the frequency range 78.33–118.1 GHz. The obtained S-parameters are processed according to an algorithm that includes their averaging based on the Fourier transform in order to obtain the values of the dielectric permittivity. Fluoroplastic was used as a reference material with a known dielectric constant. The dielectric constant of fluoroplastic has a stable value of 2.1 in the above mentioned frequency range. The dielectric constant of sample No. 1 varies from 3.6 to 2.5 at the boundaries of the range, sample No. 2 – from 3.7 to 2.1, sample No. 3 – from 2.9 to 1.5. The experimental data are in satisfactory agreement with the literature data for other frequencies taking into account the limits set by the measurement uncertainty.

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.

Preparation and Dielectric Property of Al2O3 Surface Coating Modified BaTiO3/Polyimide Composite Film

2014 ◽  
Vol 908 ◽  
pp. 63-66
Author(s):  
Ya Jun Wang ◽  
Xiao Juan Wu ◽  
Chang Gen Feng
Keyword(s):  
Dielectric Constant ◽  
Barium Titanate ◽  
Composite Film ◽  
Breakdown Strength ◽  
In Situ Polymerization ◽  
Chemical Properties ◽  
Dielectric Strength ◽  
Xrd Analysis ◽  
Nanocomposite Films ◽  
The Matrix

Polyimide (PI) was chosen as the matrix of the composite, barium titanate/polyimide (BT/PI) nanocomposite films were prepared by in situ polymerization. In order to improve the dispersion and the physical-chemical properties of BT surface, barium titanate was modified by Al2O3coating and modified BT/PI nanocomposite films were prepared. The prepared modified BT was characterized by X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM), and the dielectric properties of the composites were characterized in detail. It was shown that surface modification with Al2O3is the chemical process and there were new substances forming. When BT was modified by 10 wt% Al2O3, the dielectric constant of the composite film was 18.96 (103Hz), the loss tangent 0.005, breakdown strength 70 MV·m-1, energy storage density 0.41 J·cm-3. The dielectric constant of BT modified by Al2O3is decreased while the dielectric strength of the modified BT/PI composite film is increased.

Preparation of Potassium Niobate–Barium Titanate Ceramics Using Well-Dispersed Nanoparticles and their Dielectric Properties

2011 ◽  
Vol 485 ◽  
pp. 39-42 ◽  
Author(s):  
Kenta Yamashita ◽  
Shigehito Shimizu ◽  
Ichiro Fujii ◽  
Kouichi Nakashima ◽  
Nobuhiro Kumada ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Barium Titanate ◽  
Potassium Niobate ◽  
Conventional Sintering ◽  
Titanate Ceramics ◽  
Sintering Method

ANbO3– BaTiO3(A=K, Na, or K0.5Na0.5) system ceramics were prepared using a conventional sintering method, and their dielectric properties were investigated. It was found that the dielectric constant of KNbO3-BaTiO3and (K0.5Na0.5) NbO3- BaTiO3system ceramics did not strongly depend on temperature between 20 and 400 °C, making them useful for capacitor application.

Quantitative phase transformation behavior in TiNi shape memory alloy thin films

2004 ◽  
Vol 19 (10) ◽  
pp. 2822-2833 ◽  
Author(s):  
Bo-Kuai Lai ◽  
H. Kahn ◽  
S.M. Phillips ◽  
Z. Akase ◽  
A.H. Heuer
Keyword(s):  
Thin Films ◽  
Shape Memory Alloy ◽  
Residual Stresses ◽  
Shape Memory ◽  
Microelectromechanical Systems ◽  
Rietveld Analysis ◽  
Phase Fraction ◽  
Temperature Hysteresis ◽  
Noticeable Effect ◽  
Heating And Cooling

Phase transformations in near-equiatomic TiNi shape memory alloy thin films were studied, and the phase fraction evolutions were quantitatively correlated to the stress and resistivity of the films. TiNi thin films with compositions of 50.1, 51.1, and 51.7 at.% Ti all exhibited transformation temperatures between 65 and 100 °C, low residual stresses at room temperature (RT), and high recoverable stresses, thus making them suitable for microactuators in microelectromechanical systems. Low residual stresses at RT, less than 50 MPa, can be obtained even when only a small quantity of martensite, less than 30%, is present. Phase fraction evolution during complete thermal cycles (heating and cooling) was studied using elevated temperature x-ray diffraction, combined with quantitative Rietveld analysis. R-phase always appeared in these near-equiatomic TiNi thin films during cooling but did not have a noticeable effect on the stress–temperature hysteresis curves, which mainly depend on the phase fraction evolution of martensite. On the other hand, the occurrence of R-phase determined the variation of film resistivity. Martensite, austenite, and R-phase coexisting within a single grain were observed using transmission electron microscopy.

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