scholarly journals Theoretical Study of Ferroelectric Triglycine Sulphate (TGS) Crystal in External Electric Fields

2013 ◽  
Vol 11 ◽  
pp. 54-65 ◽  
Author(s):  
Trilok Chandra Upadhyay ◽  
Ashish Nautiyal
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Temperature Dependent ◽  
Triglycine Sulphate ◽  
Acoustical Properties ◽  
Coupled Mode ◽  
Electric Field Dependence ◽  
Crystal Electric Field ◽  
Double Time ◽  
Good Agreement

A modified two sub-lattice pseudospin-lattice coupled mode model of Mitsui et al [Phys. Rev., 111 (1958) 1259] by adding third, fourth order phonon anharmonic interaction and external electric field terms has been applied to ferroelectric triglycine sulphate crystal. Electric field dependence of ferroelectric, dielectric and acoustical properties has been studied. With the help of double time temperature dependent Green’s function method, expressions for shift, width, soft mode frequency, dielectric constant, loss tangent and acoustic attenuation have been derived. Numerically calculations have been made and results have been compared with experimental data reported by Bye et al [Ferroelectrics 4 (1974) 243] and Shreekumar et al [Ferroelectrics 160 (1994) 23] for TGS crystal and a good agreement has been observed.

scholarly journals CHANGES IN FERROELECTRIC PROPERTIES OF MASD ALUM ALONG WITH TEMPERATURE BY USING PLCM MODEL

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Anubhuti Mamgain ◽  
Trilok Chandra Upadhyay
Keyword(s):  
Ferroelectric Properties ◽  
Function Technique ◽  
Temperature Dependent ◽  
Spin Lattice ◽  
Coupled Mode ◽  
Dielectric Constant And Loss ◽  
Double Time ◽  
Anharmonic Interactions ◽  
Theoretical Results ◽  
Good Agreement

With addition of third-and fourth-order phonon anharmonic interactions, and extra spin-lattice interaction term into pseudospin-lattice coupled mode (PLCM) model, MASD alum has been studied. Employing double time temperature dependent Green′s function technique expressions for shift and width of response function, normal mode frequency, dielectric constant and loss stangent have been derived for MASD alum. Numerical calculation has been done. Theoretical results have been compared with experimental results of Pepinsky et al. [16]. A good agreement has been found.

scholarly journals CHANGES IN FERROELECTRIC PROPERTIES OF MASD ALUM ALONG WITH TEMPERATURE BY USING PLCM MODEL

2019 ◽  
Vol 14 (2) ◽  
Author(s):  
Anubhuti Mamgain ◽  
Trilok Chandra Upadhyay
Keyword(s):  
Ferroelectric Properties ◽  
Function Technique ◽  
Temperature Dependent ◽  
Spin Lattice ◽  
Coupled Mode ◽  
Dielectric Constant And Loss ◽  
Double Time ◽  
Anharmonic Interactions ◽  
Theoretical Results ◽  
Good Agreement

With addition of third-and fourth-order phonon anharmonic interactions, and extra spin-lattice interaction term into pseudospin-lattice coupled mode (PLCM) model, MASD alum has been studied. Employing double time temperature dependent Green′s function technique expressions for shift and width of response function, normal mode frequency, dielectric constant and loss stangent have been derived for MASD alum. Numerical calculation has been done. Theoretical results have been compared with experimental results of Pepinsky et al. [16]. A good agreement has been found.

Electric Field Dependence of Curie Temperature in Ferroelectric Crystals

1973 ◽  
Vol 51 (17) ◽  
pp. 1874-1881 ◽  
Author(s):  
B. S. Semwal ◽  
P. K. Sharma
Keyword(s):  
Curie Temperature ◽  
Electric Field ◽  
Field Dependence ◽  
Paraelectric Phase ◽  
Scattering Data ◽  
Function Technique ◽  
Temperature Dependent ◽  
Ferroelectric Crystal ◽  
Electric Field Dependence ◽  
Double Time

The electric field dependence of the Curie temperature of a ferroelectric crystal in its paraelectric phase is investigated from the Silverman–Joseph Hamiltonian augmented with fourth-order phonon coordinates using the temperature dependent double-time Green's function technique. It is shown that the Curie temperature shifts to a lower value by the application of an electric field. This result agrees with the recent Raman scattering data of Worlock and Fleury for SrTiO3.

On the Interaction of Positrons with Argon

1972 ◽  
Vol 50 (8) ◽  
pp. 821-825 ◽  
Author(s):  
Peter W. Hewson ◽  
Garth Jones ◽  
Erich W. Vogt
Keyword(s):  
Electric Field ◽  
Positron Annihilation ◽  
Field Dependence ◽  
Local Density ◽  
Polarization Potential ◽  
Annihilation Rate ◽  
Temperature Dependent ◽  
Electric Field Dependence ◽  
Enhancement Factors ◽  
Good Agreement

A semi-phenomenological model of the interaction of positrons with atoms is outlined, and some model properties—enhancement factors, effective mass, and effective charge—are calculated using a local density approximation. These properties are used with a one parameter polarization potential to predict the electric field dependence and the temperature dependence of the positron annihilation rate in argon gas. Comparison of these predictions with experimental data shows good agreement for the electric field dependence, but the predicted temperature dependent effect is less than published experimental results. The model is also applied to helium, with unsatisfactory results, and a prediction of the electric field dependence of the positron annihilation rate in krypton is made.

The Electric Field Measuring by Phase Selective Photoreflectance

1996 ◽  
Vol 421 ◽  
Author(s):  
J. S. Hwang ◽  
W. Y. Chou ◽  
S. L. Tyan ◽  
Y. C. Wang ◽  
H. Shen
Keyword(s):  
Electric Field ◽  
Theoretical Calculation ◽  
Buffer Layer ◽  
Electric Fields ◽  
Phase Angle ◽  
Substrate Interface ◽  
Field Measuring ◽  
Lock In ◽  
Good Agreement ◽  
Reference Phase

AbstractThe built-in electric fields in a MBE grown δ-doped GaAs homojunction have been investigated by the techniques of photoreflectance and phase suppression. Two Franz-Keldysh oscillation features originating from two different fields in the structure superimpose with each other in the photoreflectance spectrum. By properly selecting the reference phase of the lock-in amplifier, one of the features can be suppressed, thus enabling us to determine the electric fields from two different regions. We have demonstrated that only two PR spectra, in-phase and outphase components, are needed to find the phase angle which suppresses one of the features. The electric field in the top layer is 3.5 ± 0.2 × 105 V/cm, which is in good agreement with theoretical calculation. The electric field in the buffer layer is 1.2 ± 0.1 × 104 V/cm, which suggests the existence of interface states at the buffer/substrate interface.

ELECTRIC FIELD INFLUENCE ON TRAVELING WAVE PROPAGATION AND STATIONARY PATTERN FORMATION

1995 ◽  
Vol 05 (03) ◽  
pp. 797-807 ◽  
Author(s):  
J. MOSQUERA ◽  
M. GÓMEZ-GESTEIRA ◽  
V. PÉREZ-MUÑUZURI ◽  
A.P. MUÑUZURI ◽  
V. PÉREZ-VILLAR
Keyword(s):  
Wave Propagation ◽  
Pattern Formation ◽  
Electric Field ◽  
Electric Fields ◽  
Traveling Wave ◽  
Traveling Fronts ◽  
Spatial Terms ◽  
Oregonator Model ◽  
Field Influence ◽  
Good Agreement

The electric field influence on pattern formation and traveling wave propagation is investigated in the framework of the Oregonator model. When an electric field is applied to a system that can suffer spatial instabilities, Turing and Turing-like patterns (traveling fronts that become stationary patterns when reaching a zero-flux boundary) are observed. On the other hand, when an electric field is applied to a system that cannot become unstable by spatial terms and where wavefronts are propagating in the absence of electric fields, the velocity of these wavefronts is modified and can even be reversed. This is in good agreement with previous experimental results.

Dynamic Electromechanical Response of Multilayered Piezoelectric Composites From Room to Cryogenic Temperatures for Fuel Injector Applications

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Yasuhide Shindo ◽  
Takayoshi Sasakura ◽  
Fumio Narita
Keyword(s):  
Domain Wall ◽  
Electric Field ◽  
Electric Fields ◽  
Wall Motion ◽  
Domain Wall Motion ◽  
Cryogenic Temperatures ◽  
Fuel Injector ◽  
Temperature Dependent ◽  
Piezoelectric Composites ◽  
Ac Electric Fields

This paper studies the dynamic electromechanical response of multilayered piezoelectric composites under ac electric fields from room to cryogenic temperatures for fuel injector applications. A shift in the morphotropic phase boundary (MPB) between the tetragonal and rhombohedral/monoclinic phases with decreasing temperature was determined using a thermodynamic model, and the temperature dependent piezoelectric coefficients were obtained. Temperature dependent coercive electric field was also predicted based on the domain wall energy. A phenomenological model of domain wall motion was then used in a finite element computation, and the nonlinear electromechanical fields of the multilayered piezoelectric composites from room to cryogenic temperatures, due to the domain wall motion and shift in the MPB, were calculated. In addition, experimental results on the ac electric field induced strain were presented to validate the predictions.

Calculations of Some Transport Coefficients in Simple Semiconductors at Low Temperatures and High Electric Fields

1971 ◽  
Vol 49 (7) ◽  
pp. 876-880 ◽  
Author(s):  
Jyoti Kamal ◽  
Satish Sharma
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Low Temperatures ◽  
Transport Coefficients ◽  
Drift Mobility ◽  
Temperature Dependent ◽  
Hall Constant ◽  
The Difference ◽  
High Electric Fields ◽  
Model Semiconductor

In this paper the authors have calculated Hall mobility, drift mobility, and Hall constant for a non-degenerate simple model semiconductor at low temperatures for an arbitrary electric field strength. Following Paranjape the modified distribution of phonons has been taken into account. The difference between the calculations of transport coefficients made by taking into account the modified phonon distribution and by not taking it into account is quite appreciable at high electric field. Calculations also show that for Ne = 1016/cm3 the mobility of electrons remains temperature dependent.

High Field Limitation of Poole-Frenkel Emission Caused by Tunneling

1999 ◽  
Vol 560 ◽  
Author(s):  
S. D. Ganichev ◽  
E. Ziemann ◽  
W. Prettl ◽  
A. A. Istratov ◽  
E. R. Weber
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Field Dependence ◽  
Electric Fields ◽  
High Field ◽  
Emission Rate ◽  
Electric Field Dependence ◽  
Straight Line ◽  
Frenkel Emission ◽  
Assisted Tunneling

ABSTRACTThe electric field dependence of emission of carriers from deep impurities in semiconductors has been investigated applying static and terahertz electric fields. It is shown that at high electric field strengths carrier emission is dominated by phonon assisted tunneling which may easily be recognized by plotting the emission rate as a function of the square of the electric field strength in a log-lin plot giving a straight line. For charged impurities the transition from phonon assisted tunneling to Poole-Frenkel effect at low fields can be traced back.

scholarly journals Ionization and Attachment Coefficients in C4F7N Gas Measured by the Steady-State Townsend Method

2019 ◽  
Vol 9 (18) ◽  
pp. 3686 ◽  
Author(s):  
Zhaoyu Qin ◽  
Yunxiang Long ◽  
Zhenyu Shen ◽  
Cheng Chen ◽  
Liping Guo ◽  
...  
Keyword(s):  
Steady State ◽  
Electric Field ◽  
Electric Fields ◽  
Room Temperature ◽  
Ionization Coefficient ◽  
Ionization Coefficients ◽  
Insulation Performance ◽  
Attachment Coefficient ◽  
Good Agreement ◽  
Effective Ionization

The normalized Townsend first ionization coefficient α/N and normalized attachment coefficient η/N in pure C4F7N were measured by using the steady-state Townsend (SST) method for a range of reduced electric fields E/N from 750 to 1150 Td at room temperature (20 °C). Meanwhile, the effective ionization coefficients are obtained. All SST experimental results show good agreement with pulsed Townsend (PT) experiment results. Comparisons of the critical electric fields of C4F7N with SF6 and other alternative gases such as c-C4F8 and CF3I indicate that C4F7N has a better insulation performance with a much higher normalized critical electric field at 959.19 Td.

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