Influence of the uniaxial stress $p_2$ and transverse fields $E_1$ and $E_3$ on the phase transitions and thermodynamic characteristics of GPI ferroelectric materials

2021 ◽  
Vol 8 (3) ◽  
pp. 454-464
Author(s):  
R. R. Levitskii ◽  
◽  
I. R. Zachek ◽  
A. S. Vdovych ◽  
O. B. Bilenka ◽  
...  
Keyword(s):  
Electric Fields ◽  
Thermodynamic Characteristics ◽  
Uniaxial Stress ◽  
Ferroelectric Materials ◽  
Simultaneous Action ◽  
Structural Elements ◽  
Cluster Approximation ◽  
Static Dielectric Permittivity ◽  
Piezoelectric Coupling ◽  
Transverse Fields

A modified GPI model that accounts for the piezoelectric coupling between the ordered structural elements and the strains $\varepsilon_j$ has been used for studing of effects arising in GPI ferroelectrics under the action of the uniaxial stress $p_{2}$ and electric fields $E_1$ and $E_3$. The polarization vectors and components of static dielectric permittivity are calcucated in the two-particle cluster approximation for mechanically clamped crystal, and piezoelectric and thermal parameters are also determined. The influence of the simultaneous action of the stress $p_{2}$ and fields $E_1$ and $E_3$ on the phase transition and physical characteristics of GPI crystal has been studied.

scholarly journals Influence of Longitudinal Electric Field on Thermodynamic Properties of NH3CH2COOH·H2PO3 Ferroelectric

2018 ◽  
Vol 63 (4) ◽  
pp. 350
Author(s):  
A. S. Vdovych ◽  
I. R. Zachek ◽  
R. R. Levitskii
Keyword(s):  
Electric Field ◽  
Dipole Moments ◽  
Quantitative Description ◽  
Thermodynamic Characteristics ◽  
Polarization Vector ◽  
Longitudinal Electric Field ◽  
Model Parameters ◽  
Cluster Approximation ◽  
Static Dielectric Permittivity ◽  
Piezoelectric Coupling

Using a modified model of ferroelectric glycine phosphite by considering the piezoelectric coupling with strains e1 within the two-particle cluster approximation, the expressions for the polarization vector, static dielectric permittivity tensor, piezoelectric coefficients, and elastic constants of the crystal in the presence of a longitudinal electric field E2 are calculated. An analysis of the influence of this field on thermodynamic characteristics of the crystal is carried out. The dependence of effective dipole moments on order parameters is taken into account. This allowed us to agree the effective dipole moments in the ferro- and paraelectricphases and to describe the smearing of phase transition under the influence of an electric field. The satisfactory quantitative description of the available experimental data for these characteristics has been obtained at the proper choice of the model parameters.

scholarly journals Longitudinal and Transverse Electrocaloric Effects in Glycinium Phosphite Ferroelectric

2021 ◽  
Vol 66 (5) ◽  
pp. 412
Author(s):  
A.S. Vdovych
Keyword(s):  
Electric Fields ◽  
Thermal Characteristics ◽  
Polarization Vector ◽  
Transverse Field ◽  
Shear Stresses ◽  
Cluster Approximation ◽  
Effective Dipole Moment ◽  
Transverse Electric Fields ◽  
Piezoelectric Coupling ◽  
Proton Ordering

A modified proton ordering model of glycinium phosphite ferroelectric, which involves the piezoelectric coupling of the proton and lattice subsystems, is used for the investigation of the electrocaloric effect. The model also accounts for the dependence of the effective dipole moment on a hydrogen bond on an order parameter, as well as a splitting of parameters of the interaction between pseudospins in the presence of shear stresses. In the two-particle cluster approximation, the influence of longitudinal and transverse electric fields on components of the polarization vector and the dielectric permittivity tensor, as well as on thermal characteristics of the crystal, is calculated. Longitudinal and transverse electrocaloric effects are studied. The calculated electrocaloric temperature change is quite small, about 1K; however, it can change its sign under the influence of a transverse field.

FERROELECTRICS IN ACOUSTOELECTRONICS

Akustika ◽  
2021 ◽  
pp. 217
Author(s):  
Tamara Patrusheva ◽  
Sergey Petrov ◽  
Ludmila Drozdova ◽  
Aleksandr Shashurin
Keyword(s):  
Dielectric Constant ◽  
Electric Fields ◽  
Piezoelectric Effect ◽  
Complex Oxide ◽  
Ferroelectric Materials ◽  
Oxide Materials ◽  
Ferroelectric Films ◽  
Synthesis Time ◽  
Resonance Effects ◽  
Materials Used

Аcoustoelectronics is one of the areas of acoustics, associated with the use of mechanical resonance effects and the piezoelectric effect, as well as the effect based on the interaction of electric fields with waves of acoustic stresses in a piezoelectric material. The main materials used in acoustoelectronics are ferroelectrics, which are mainly complex oxide materials. This article discusses the possibility of increasing the purity and homogeneity of ferroelectric materials, as well as softening the regimes of their synthesis using the solution extraction-pyrolytic method. It is shown that the synthesis temperatures of BaTiO3, SrTiO3, and Pb(Zr)TiO3 ferroelectric films are reduced to 550-600°C, and the synthesis time is down to 5-10 minutes. The dielectric constant and Curie temperature values correspond to the maximum characteristics for these materials. Thus, using the extraction-pyrolytic method we obtained suitable for use in acoustoelectronic technology ferroelectric films.

scholarly journals Dielectric Polarization and Electrorheological Response of Poly(ethylaniline)-Coated Reduced Graphene Oxide Nanoflakes with Different Reduction Degrees

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2528
Author(s):  
Yudong Wang ◽  
Min Yang ◽  
Honggang Chen ◽  
Xiaopeng Zhao ◽  
Jianbo Yin
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Electric Fields ◽  
Flow Instability ◽  
Interfacial Polarization ◽  
Simultaneous Action ◽  
Dielectric Polarization ◽  
Polarization Rate ◽  
Reduced Graphene ◽  
The Difference

We prepared poly(ethylaniline)-coated graphene oxide nanoflakes and then treated them with different concentrations of hydrazine solution to form dielectric composite nanoflakes having different reduction degrees of reduced graphene oxide core and insulating polyethylaniline shell (PEANI/rGO). The morphology of PEANI/rGO was observed by scanning electron microscopy, while the chemical structure was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectrometer. The influence of reduction degrees on the conductivity, dielectric polarization and electrorheological effect of PEANI/rGO in suspensions was investigated by dielectric spectroscopy and rheological test under electric fields. It shows that the PEANI/rGO has two interfacial polarization processes respectively due to rGO core and PEANI shell. As the number of hydrazine increases, the conductivity and polarization rate of rGO core increase. As a result, the difference between the polarization rate of rGO core and that of the PEANI shell gradually becomes large. This increased difference does not significantly decrease the yield stress but causes the flow instability of PEANI/GO suspensions under the simultaneous action of electric and shear fields.

Phase-Dield Simulation of Rhombohedral and Tetragonal Phases in Ferroelectric Single Crystals

Aerospace ◽  
2006 ◽  
Author(s):  
T. Liu ◽  
C. S. Lynch
Keyword(s):  
Free Energy ◽  
Phase Transformations ◽  
Single Crystals ◽  
Electric Fields ◽  
Tetragonal Phase ◽  
Ferroelectric Materials ◽  
Integration Scheme ◽  
Ferroelectric Crystal ◽  
Domain Structures ◽  
Tdgl Equation

Ferroelectric materials exhibit spontaneous polarization and domain structures below the Curie temperature. In this work the phase field approach has been used to simulate phase transformations and the formation of ferroelectric domain structures. The evolution of phases and domain structures was simulated in ferroelectric single crystals by solving the time dependent Ginzburg-Landau (TDGL) equation with polarization as the order parameter. In the TDGL equation the free energy of a ferroelectric crystal is written as a function of polarization and applied fields. Change of temperature as well as application of stress and electric fields leads to change of the free energy and evolution of phase states and domain structures. In this work the finite difference method was implemented for the spatial description of the polarization and the temporal evolution of polarization field was computed by solving the TDGL equation with an explicit time integration scheme. Cubic to tetragonal, cubic to rhombohedral and rhombohedral to tetragonal phase transformations were modeled, and the formation of domain structures was simulated. Field induced polarization switching and rhombohedral to tetragonal phase transition were simulated.

Multivalent Acceptor-Doped Germanium Lasers: a solid-state tunable source from 75 to 300 μm

1997 ◽  
Vol 484 ◽  
Author(s):  
D. R. Chamberlin ◽  
O. D. Dubon ◽  
E. Bründermann ◽  
E. E. Haller ◽  
L. A. Reichertzl ◽  
...  
Keyword(s):  
Electric Fields ◽  
Duty Cycle ◽  
Population Inversion ◽  
Continuous Wave ◽  
Laser Action ◽  
Far Infrared ◽  
Uniaxial Stress ◽  
Power Input ◽  
Infrared Light ◽  
Order Of Magnitude

AbstractWe report on the performance of far-infrared hole inversion lasers made from germanium doped with the multivalent acceptors beryllium and copper. Commonly used hole inversion lasers are made from Czochralski-grown Ga-doped Ge single crystals and show emission from 75 to 125 and 170 to 300 μm. The emission gap between 125 and 170 μm, originating from absorption of the far-infrared light due to internal hole transitions in the neutral Ga acceptor, is absent in the new Be and Cu-doped lasers. We also find a mechanism for inversion depopulation through neutral Ga which hinders lasing at low electric fields. This same mechanism is shown to cause population inversion in the Be-doped laser and allows lasing at lower fields. This reduces the power input into the germanium crystal and has allowed us to increase the duty cycle up to 2.5% which is one order of magnitude higher than the maximum duty cycle reported for Ga-doped Ge lasers. These new lasers may offer an opportunity for achieving continuous-wave operation.In addition we have performed preliminary studies on the effect of uniaxial stress on the lasing in these new materials. We demonstrate that small uniaxial stress increases laser action in Ge:Cu. We propose that this is due to an increased population inversion because under these conditions two separate mechanisms cause heavy holes to enter the light hole band.

Electromechanical Poling Treatment of Barium Titanate Single Crystals and their Piezoelectric Properties

2007 ◽  
Vol 350 ◽  
pp. 73-76
Author(s):  
Tomomitsu Muraishi ◽  
Keisuke Yokoh ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi ◽  
Satoshi Wada
Keyword(s):  
Phase Transition ◽  
Barium Titanate ◽  
Single Crystals ◽  
Electric Fields ◽  
Piezoelectric Properties ◽  
Uniaxial Stress ◽  
Notation System

The phase transition behaviors of the [111]c oriented barium titanate (BaTiO3) single crystals (the subscript c means the cubic notation system) were investigated as functions of temperature, uniaxial stress and electric fields. These results suggested that above Tc, combination between uniaxial stress and electric fields might be effective for a poling treatment of BaTiO3 single crystals. Thus, a new poling method for BaTiO3 single crystals was proposed using control of temperature, uniaxial stress and electric fields in this study.

In-situ observations of the behaviors of ferroelectric domains in BaTiO3 under applied electric fields with TEM

1992 ◽  
Vol 50 (1) ◽  
pp. 348-349
Author(s):  
Feng Tsai ◽  
Victoria Khiznichenko ◽  
J. M. Cowley
Keyword(s):  
Optical Microscopy ◽  
Electric Fields ◽  
Ferroelectric Materials ◽  
In Situ Tem ◽  
Bulk Crystals ◽  
Large Bulk ◽  
Ferroelectric Domains ◽  
In Situ Observations ◽  
New Interpretation

The previous studies on the behaviors of ferroelectric domains under applied electric fields were made by a number of researchers, e.g. Merz and Little on bulk BaTiO3 crystals with optical microscopy. It was suggested that under the applied electric field the new antiparallel domains nucleated and grew and 90° and 180° domains nucleated and grew sidewise. However, those results and conclusions were obtained from the experiments on large bulk crystals with optical microscopy of relatively lower magnification and resolution. TEM is a very powerful tool in the study of crystal structure and defects and may provide a new interpretation to the study of microdomains of hundred angstroms in thin ferroelectric films with a higher magnification and resolution and may be combined with electron diffraction. However, no reference has been found that an in-situ TEM study of the behaviors of ferroelectric materials under applied electric fields has ever been made.

scholarly journals Why Do Ferroelectrics Exhibit Negative Capacitance?

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3743 ◽  
Author(s):  
Michael Hoffmann ◽  
Prasanna Venkatesan Ravindran ◽  
Asif Islam Khan
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Landau Theory ◽  
Dipole Moments ◽  
Mean Field ◽  
Ferroelectric Materials ◽  
Negative Capacitance ◽  
Solid State Physics ◽  
Complex Interactions ◽  
S Curve

The Landau theory of phase transitions predicts the presence of a negative capacitance in ferroelectric materials based on a mean-field approach. While recent experimental results confirm this prediction, the microscopic origin of negative capacitance in ferroelectrics is often debated. This study provides a simple, physical explanation of the negative capacitance phenomenon—i.e., ‘S’-shaped polarization vs. electric field curve—without having to invoke the Landau phenomenology. The discussion is inspired by pedagogical models of ferroelectricity as often presented in classic text-books such as the Feynman lectures on Physics and the Introduction of Solid State Physics by Charles Kittel, which are routinely used to describe the quintessential ferroelectric phenomena such as the Curie-Weiss law and the emergence of spontaneous polarization below the Curie temperature. The model presented herein is overly simplified and ignores many of the complex interactions in real ferroelectrics; however, this model reveals an important insight: The polarization catastrophe phenomenon that is required to describe the onset of ferroelectricity naturally leads to the thermodynamic instability that is negative capacitance. Considering the interaction of electric dipoles and saturation of the dipole moments at large local electric fields we derive the full ‘S’-curve relating the ferroelectric polarization and the electric field, in qualitative agreement with Landau theory.

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