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.

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.

STABILISATION OF PARAELECTRIC PHASE BY STRONG CUBIC AND QUARTIC PHONON ANHARMONICITIES IN KDP CRYSTAL

1995 ◽  
Vol 09 (01) ◽  
pp. 45-55 ◽  
Author(s):  
T.C. UPADHYAY ◽  
N.S. PANWAR ◽  
B S. SEMWAL
Keyword(s):  
Soft Mode ◽  
Mode Frequency ◽  
Dielectric Susceptibility ◽  
Tangent Loss ◽  
Kdp Crystal ◽  
Coupled Mode ◽  
Para Phase ◽  
Real Value ◽  
Double Time ◽  
Anharmonic Interactions

Considering cubic and quartic phonon anharmonic interactions into the pseudospinphonon coupled mode model of Kobayashi6 expressions for shift, width, soft mode frequency and hence Curie temperature, dielectric susceptibility, Curie-Weiss constant and dielectric (tangent) loss have been evaluated for ferroelectric KDP. The method of retarded double-time thermal Green’s function and the treatment of Dyson’s equation have been used in the development. It is shown that cubic and quartic phonon anharmonic interactions render real value to the soft mode frequency in the para-phase. Results are in agreement with the experimental results of others.

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 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.

Dielectric Properties of β-SiAlON at High Temperature Using Perturbation Method

2008 ◽  
Vol 403 ◽  
pp. 121-123 ◽  
Author(s):  
Young Hoon Seong ◽  
Ha Neul Kim ◽  
Do Kyung Kim
Keyword(s):  
Dielectric Constant ◽  
High Temperature ◽  
Dielectric Properties ◽  
Perturbation Method ◽  
Hot Pressing ◽  
Room Temperature ◽  
Tangent Loss ◽  
Resonator Method

-SiAlON with various z-values (z = 0.5~4.0) were produced by hot pressing. The dielectric properties (dielectric constant and tangent loss) of -SiAlON were characterized by the post-resonator method at room temperature and by the perturbation method from room temperature to 1200 oC at 2.45 GHz, respectively. Effect of z-values and temperatures with -SiAlON were investigated.

Temperature Dependence of Soft Mode Frequency and Dielectric Constant in Ferroelectric PbHPO[sub 4] Crystal

2011 ◽  
Author(s):  
Trilok Chandra Upadhayay ◽  
Mayank Joshi ◽  
P. K. Bajpai ◽  
K. S. Ojha ◽  
K. N. Singh
Keyword(s):  
Dielectric Constant ◽  
Temperature Dependence ◽  
Soft Mode ◽  
Mode Frequency

Effect of P2O5 on Microstructure and Properties of Calcium Aluminoborosilicate Glasses

2013 ◽  
Vol 538 ◽  
pp. 258-261
Author(s):  
X.H. Zhang ◽  
Y.L. Yue ◽  
H.T. Wu
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Dielectric Constant ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Dielectric Properties ◽  
Alkaline Earth ◽  
Chemical Durability ◽  
Tangent Loss ◽  
Structure And Properties ◽  
Weight Losses

In alkaline earth aluminoborosilicate glasses containing P2O5, the changes of structure and properties caused by variations in the ratio P2O5/B2O3were investigated. The structure was investigated by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The dielectric constant and tangent loss were measured at 1 MHz. Chemical durability was evaluated by weight losses of glass samples after immersion in water. The results indicated that the fraction of four-coordinated boron atoms (N4), chemical durability and dielectric properties increased with increasing P2O5/B2O3replacements.

Dielectric Properties and Leakage Current Characteristics of Al2O3 Thin Films with Thickness Variation

2001 ◽  
Vol 666 ◽  
Author(s):  
Jae-Hoon Choi ◽  
Ji-Woong Kim ◽  
Tae-Sung Oh
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Dielectric Properties ◽  
Film Thickness ◽  
Leakage Current ◽  
Thickness Variation ◽  
Tangent Loss ◽  
Maximum Dielectric Constant ◽  
Current Densities ◽  
Current Characteristics

ABSTRACTDielectric properties and leakage current characteristics of the Al2O3 thin films, deposited by reactive sputtering at room temperature, have been investigated with variations of the O2 content in the sputtering gas and the film thickness. The Al2O3 films of 10-300 nm thickness were amorphous without depending on the O2 contents of 25-75% in the sputtering gas. Maximum dielectric constant was obtained for the Al2O3 film deposited with the sputtering gas of 50% O2 content. With reduction of the film thickness from 300 nm to 10 nm, dielectric constant decreased from 9.04 to 3.71 and tangent loss increased from 0.0035 to 0.0594, respectively. When the O2 content in the sputtering gas was higher than 50%, the Al2O3 films exhibited no shift of the flatband voltage in C-V curves. The leakage current density increased with increasing the film thickness, and the Al2O3 films thinner than 100 nm exhibited the leakage current densities lower than 10−6 A/cm up to 650 kV/cm.

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