scholarly journals Study of Ferroelectric Properties of Hydrogen Bonded Rubidium Dihydrogen Arsenate (RdA) Crystal

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Pawan Singh ◽  
Trilok Chandra Upadhya ◽  
Muzaffar Iqbal Khan ◽  
Sidharth Kashyap
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Response Function ◽  
Ferroelectric Properties ◽  
Mode Frequency ◽  
Experimental Results ◽  
Ferroelectric Crystal ◽  
Coupled Mode ◽  
Theoretical Results ◽  
Hydrogen Bonded

A simple pseudospin lattice coupled mode model with addition of third and fourth-order phonon anharmonic interactions terms, direct spin-spin interactions terms and external electric field term has been considered for investigation of transition phenomena and dielectric properties of hydrogen bonded ferroelectric crystal Rubidium dihydrogen arsenate (RDA). A double-time thermal dependent Green’s function method has been used for derivation of response function. From response function shift, width and soft mode frequency have been derived for RDA crystal. Response function is also related to dielectric constant which has been obtained in present paper. By fitting model values of different parameters in obtained expressions, the temperature variations of normal mode frequency, dielectric constant, and loss tangent have been calculated numerically for RDA crystal. Our theoretical results are compared with experimental results. It is observed that our theoretical results agree with experimental results. Therefore, it can be concluded that the modified pseudo-spin lattice coupled mode model with the simplest approximation is quite suitable to explain the transition and dielectric properties of RDA crystal.

scholarly journals Theoretical Study of Dielectric Properties in Triglycine Sulphate Crystal

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Naveen Kohli ◽  
Trilok Chandra Upadhyay
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Soft Mode ◽  
Mode Frequency ◽  
Experimental Results ◽  
Tangent Loss ◽  
Spin Lattice ◽  
Coupled Mode ◽  
Interaction Terms ◽  
Crystal Model

Present paper investigate theoretically dielectric properties such as dielectric constant, soft mode frequency and tangent loss by considering two sub lattice pseudospin, spin-lattice coupled mode model (PLCM) and adding third and fourth-order anharmonic (phonon) and spin-lattice interaction terms and using thermal Green’s function (double time) method expression for dielectric constant, soft mode frequency, and tangent loss is derived for TGS crystal. Model value have been fitted in expression and their temperature dependence have been calculated for TGS crystal. Theoretical results have been correlated with experimental results of (Aravzhi et al 1997), which is approximate close to experimental results.

Study of ferroelectric lead monohydrogen phosphate type crystals

2017 ◽  
Vol 31 (32) ◽  
pp. 1750260 ◽  
Author(s):  
Aanchal Rawat ◽  
Trilok Chandra Upadhyay
Keyword(s):  
Experimental Data ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Loss Tangent ◽  
Function Method ◽  
Mode Frequency ◽  
Temperature Variations ◽  
Ferroelectric Transition ◽  
Coupled Mode ◽  
Dielectric Constant And Loss

In this paper, the ferroelectric transition and dielectric properties of the lead monohydrogen phosphate (PbHPO4) crystal are theoretically investigated. By using Green’s function method and modified two sublattice pseudospin–lattice coupled mode model, formulae for PbHPO4 type crystals are derived. Temperature variations of ferroelectric mode frequency, dielectric constant and loss tangent are calculated for the PbHPO4 crystal. Our results agree well with the experimental data.

scholarly journals Investigation of AC-Measurements of Epoxy/Ferrite Composites

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 492 ◽  
Author(s):  
Moustafa A. Darwish ◽  
Alex V. Trukhanov ◽  
Oleg S. Senatov ◽  
Alexander T. Morchenko ◽  
Samia A. Saafan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Frequency ◽  
Precipitation Method ◽  
Semiconductor Behavior ◽  
Ferrite Composites ◽  
Co Precipitation ◽  
Theoretical Results ◽  
Composite Samples

A pure ferrite and epoxy samples as well as the epoxy/ferrite composites with different 20 wt.%, 30 wt.%, 40 wt.%, and 50 wt.% weight ferrite contents have been prepared by the chemical co-precipitation method. AC-conductivity and dielectric properties such as the dielectric constant and dielectric loss of the prepared samples have been studied. The obtained results showed that the samples had a semiconductor behavior. The dielectric constant of the composites has been calculated theoretically using several models. For the composite sample that contains 20 wt.% of ferrites, these models give satisfactory compliance, while for the composite samples with a higher percentage of nanofillers, more than 30 wt.% theoretical results do not coincide with experimental data. The investigated polymer has very low conductivity, so this type of polymer can be useful for high-frequency applications, which can reduce the losses caused by eddy current. Thus, the prepared samples are promising materials for practical use as elements of microwave devices.

STRUCTURAL AND DIELECTRIC PROPERTIES OF Ba0.5Sr0.5TiO3 THIN FILMS GROWN ON LAO WITH HOMO-EPITAXIAL LAYER FOR TUNABLE APPLICATIONS

2004 ◽  
Vol 18 (15) ◽  
pp. 2153-2168 ◽  
Author(s):  
M. CHANDRA SEKHAR
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Interfacial Layer ◽  
Ferroelectric Properties ◽  
Buffer Layers ◽  
High Tunability ◽  
Low Leakage ◽  
Structural Growth ◽  
Bst Films ◽  
Dielectric Devices

The epitaxial, single phase (100) Ba 0.5 Sr 0.5 TiO 3 (BST) films with thin interfacial layer of BST (x=0.4) were deposited on LAO (100) substrates using Pulse Laser Deposition (PLD). These films were characterized in terms of their phase formation and structural growth characteristics using X-ray diffraction and Atomic Force Microscopy respectively. The dielectric properties are strongly affected by the substrate type, post deposition annealing time, and temperature. In order to verify all these properties, thin interfacial-buffer layers of BST (10, 20, 50 nm) were introduced to relieve the stress induced between the film and the substrate. The variations of dielectric constant and ferroelectric properties of as deposited films are discussed in detail. The high tunability, low dielectric loss and low leakage current of these films make them attractive candidates for fabricating tunable dielectric devices. The observed dielectric properties of the BST-films are attributed to homo-epitaxial interfacial layer, which is responsible for the increase in the dielectric constant and tunability.

scholarly journals Dielectric Properties of Deuterated Cesium Dihydrogen Phosphate Crystal

2021 ◽  
Vol 16 (2) ◽  
Author(s):  
Muzaffar Iqbal Khan ◽  
Trilok Chandra Upadhyay ◽  
Pawan Singh ◽  
Sidharth Kashyap
Keyword(s):  
Dielectric Properties ◽  
Function Theory ◽  
Mode Frequency ◽  
Physical Parameters ◽  
Dihydrogen Phosphate ◽  
Thermal Dependence ◽  
Normal Mode Frequency ◽  
Coupled Mode ◽  
Dielectric Constant And Loss ◽  
Model Hamiltonian

Modified two sublattice pseudospin lattice coupled-mode model Hamiltonian has been applied to study the dielectric properties of deuterated cesium dihydrogen phosphate crystal. With the help of model Hamiltonian and Green’s function theory, the theoretical expressions for normal mode frequency, dielectric constant and loss tangent are derived. By fitting the model values of different physical parameters, the thermal dependence of the above quantities has been calculated. Our theoretical obtained results are well compared with experimental data.

scholarly journals Mixing Formulae and Experimental Results for the Dielectric Constant of Snow

1985 ◽  
Vol 31 (108) ◽  
pp. 163-170 ◽  
Author(s):  
Ari Sihvola ◽  
Ebbe Nyfors ◽  
Martti Tiuri
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Liquid Water ◽  
Complex Permittivity ◽  
Experimental Results ◽  
Exponential Models ◽  
Dielectric Mixture ◽  
Excess Permittivity ◽  
Wet Snow ◽  
Mixture Theories

AbstractThis paper discusses dielectric properties of snow according to various dielectric models and compares them with experimental results. The complex permittivity of wet snow is assumed to consist of two parts, being the sum of the permittivity of dry snow (a mixture of ice and air) and the excess permittivity due to liquid water (resulting from the dielectric mixture of water and air). In particular the effect of liquid water is considered. Exponential models and structure-dependent models based on mixture theories by Taylor and Tinga and others are applied. It is shown that the assumption that water inclusions have the form of either randomly oriented discs or needles, or of spheres do, not get empirical confirmation but the inclusions are preferably prolate ellipsoids (ellipticity 0.16) or oblate ellipsoids (ellipticity 0.12), dry snow being a dielectric mixture of randomly oriented disc-shaped ice particles and air.

ELECTRICAL PROPERTIES OF HETEROLAYERED BaTiO3/(Bi1/2Na1/2)TiO3 THICK FILMS

2009 ◽  
Vol 23 (31n32) ◽  
pp. 3785-3791
Author(s):  
SUNG-PILL NAM ◽  
HYUN-JI NOH ◽  
SUNG-GAP LEE ◽  
SEON-GI BAE ◽  
YOUNG-HIE LEE
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Electrical Properties ◽  
Screen Printing ◽  
Remanent Polarization ◽  
Ferroelectric Properties ◽  
Thick Films ◽  
Rhombohedral Structure ◽  
Structural And Electrical Properties ◽  
Printing Techniques

The heterolayered BT/BNT thick films were fabricated by screen printing techniques on alumina substrates electrodes with Pt . Their structure and ferroelectric properties were investigated with the heterolayered tetragonal/rhombohedral structure composed of the BT and the BNT thick films. The structural and electrical properties of the heterolayered BT/BNT thick films were studied. The dielectric properties such as dielectric constant, loss and remanent polarization of the heterolayered BT/BNT thick films were superior to those of single composition BNT, and those values for the heterolayered BT/BNT thick films were 1455, 0.025 and 12.63 µC/cm2.

scholarly journals Enhanced dielectric and ferroelectric properties of surface hydroxylated Na0.5Bi0.5TiO3 (NBT)-poly(vinylidene fluoride) (PVDF) composites

2018 ◽  
Vol 08 (03) ◽  
pp. 1850017 ◽  
Author(s):  
Srikanta Moharana ◽  
Shraddhakara Sai ◽  
Ram Naresh Mahaling
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Dielectric Constant ◽  
Vinylidene Fluoride ◽  
Ferroelectric Properties ◽  
Material Surface ◽  
Hydroxyl Groups ◽  
Energy Storage Devices ◽  
Surface Hydroxylation ◽  
High Dielectric

The surface hydroxylation treatment has been carried out by using hydrogen peroxide (H2O2) to modify the surface of Na[Formula: see text]Bi[Formula: see text]TiO3 (NBT) particles in a ferroelectric polymer (PVDF) via solution casting technique. The FTIR study confirms the presence of hydroxyl groups on the surface of NBT. The FE-SEM analysis reveals that h-NBT particles are dispersed homogeneously within the polymer matrix. The surface hydroxylation treatment plays an important role in high dielectric constant and also reduced loss by conducting the material surface with [Formula: see text]OH functional groups. The prepared composite with 40[Formula: see text]wt.% of h-NBT showed enhanced dielectric constant ([Formula: see text]114), negligible loss (0.22) and high AC conductivity as compared to that of the unmodified NBT. Such significant enhancement in dielectric properties may be due to the strong interaction between h-NBT particles and PVDF matrix at the interface. The percolation theory is used to explain the dielectric properties of h-NBT-PVDF composite. Furthermore, the remnant polarization of the un-poled h-NBT-PVDF composites (2[Formula: see text]Pr–1.19[Formula: see text][Formula: see text]C/cm2 for 40[Formula: see text]wt.% of h-NBT) is also improved. The present findings give an idea of high dielectric constant and relatively low loss composite materials as a promising candidate for electronic and energy storage devices.

Effects of (Li, Ce) Co-Doping on Microstructure, Dielectric and Ferroelectric Properties of Strontium Niobate Ceramics

2014 ◽  
Vol 787 ◽  
pp. 236-241 ◽  
Author(s):  
Gang Chen ◽  
Jie Hao Wei ◽  
Xiao Dong Peng ◽  
Chun Lin Fu ◽  
Wei Cai
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Solid State ◽  
Remnant Polarization ◽  
Ferroelectric Properties ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Co Doping ◽  
Maximum Value ◽  
Coercive Electric Field

Sr2-x(Li2/3, Ce1/3)x Nb2O7 (x = 0, 0.05, 0.1, 0.2, 0.3, 0.5) (SLCN) ceramics were prepared by solid-state reaction method. The microstructure, dielectric and ferroelectric properties were investigated. The results show that all ceramics have high relative densities. Li+ and Ce4+ co-doping can promote the grains growing, and improve the dielectric and ferroelectric properties of strontium niobate ceramics. The dielectric constant decreases firstly, and then increases with the increasing of x in Sr2-x(Li2/3, Ce1/3)x Nb2O7, and the sample with x = 0.5 exhibits enhanced dielectric properties (εr ≈ 250, tanδ ≈ 0.02). The remnant polarization (Pr) and coercive electric field (Ec) of SLCN ceramics increase firstly, and then decrease with the increasing of Li+ and Ce4+ content, finally reach the maximum value of remnant polarization (Pr ≈ 0.058μC/cm2, Ec ≈ 6.87 kV/cm ) for x = 0.2.

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