Influence of Zr/Sn Ratio Electric Properties of PLZST Ceramic

2013 ◽  
Vol 547 ◽  
pp. 101-105 ◽  
Author(s):  
Jin Fei Wang ◽  
Tong Qing Yang ◽  
K. Wei ◽  
G. Li ◽  
Yong Xiang Li
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Dielectric Loss ◽  
Electric Field ◽  
Perovskite Structure ◽  
Ferroelectric Phase ◽  
Hysteresis Loops ◽  
Ferroelectric Ceramics ◽  
Antiferroelectric Phase ◽  
Lower Temperature

(Pb0.97La0.02)(Zr0.92-xSnxTi0.08)O3 (PLZST) ferroelectric ceramics with x=0.40, 0.25, 0.15, respectively, were investigated. It was found that these ceramics with different Zr:Sn ratios were perovskite structure. With increasing of Zr:Sn ratio, the phase-transition electric-field of antiferroelectric to ferroelectric phase increased. when x>0.15,All the samples have double hysteresis loops with antiferroelectric phase characteristics. Yet, when the electric field was removed at lower temperature of -5oC and -20oC, for x=0.25 and 0.40, the electric field induced FE phase can remain metastable FE state. But for x=0.15, the induced FE phase recover to AFE phase even at -20oC. Yet, electric field induced FE phase exist as metastable FE phase. TFE-AFE of the samples was -5oC, -20oC, when x=0.40, x=0.25, respectively. With increasing of Zr:Sn ratio, TFE-AFE increaseddecreased, Tc was hardly changed, but the dielectric constant increased from ~2500 to ~6000, the peak changed sharply, dielectric loss increased continuously with increasing of Zr:Sn ratio.

scholarly journals Molecular–Statistical Theory for the Description of Re-Entrant Ferroelectric Phase

Crystals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 583
Author(s):  
Alexander V. Emelyanenko
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
Dielectric Response ◽  
Temperature Scale ◽  
Statistical Approach ◽  
Ferroelectric Phase ◽  
Dipole Interaction ◽  
Normal Phase ◽  
Smectic Layer ◽  
Antiferroelectric Phase

The re-entrant ferroelectric phase (Sm- C re * ) is investigated in the framework of a molecular–statistical approach. It was found that anticlinic synpolar along the smectic layer normal phase can arise below the antiferroelectric phase (Sm- C A * ) in the temperature scale, and we suggest this phase to be Sm- C re * . We have shown that in the vicinity of Sm- C A * –Sm- C re * phase transition temperature, a very small electric field can cause a transition into the bidomain synclinic phase, where the helical pitch is unwound and the tilt planes have contributions either along or against the electric field. The helical rotation, elasticity and deformation of the Sm- C * , Sm- C A * and Sm- C re * structures without electric field or in the presence of electric field, as well as the dielectric response, are investigated. It is shown that Sm- C re * can arise solely due to the dipole–dipole interaction, and thus, in contrast to the conventional (improper) ferroelectric Sm- C * , appears to be the proper ferroelectric phase.

A polycrystal hysteresis model for ferroelectric ceramics

2006 ◽  
Vol 462 (2069) ◽  
pp. 1573-1592 ◽  
Author(s):  
Y Su ◽  
G.J Weng
Keyword(s):  
Electric Field ◽  
Hysteresis Loop ◽  
Ferroelectric Properties ◽  
Electric Displacement ◽  
Hysteresis Loops ◽  
Ferroelectric Ceramics ◽  
Domain Growth ◽  
Thermodynamic Approach ◽  
Hysteresis Model ◽  
Self Consistent

Most key elements of ferroelectric properties are defined through the hysteresis loops. For a ferroelectric ceramic, its loop is contributed collectively by its constituent grains, each having its own hysteresis loop when the ceramic polycrystal is under a cyclic electric field. In this paper, we propose a polycrystal hysteresis model so that the hysteresis loop of a ceramic can be calculated from the loops of its constituent grains. In this model a micromechanics-based thermodynamic approach is developed to determine the hysteresis behaviour of the constituent grains, and a self-consistent scheme is introduced to translate these behaviours to the polycrystal level. This theory differs from the classical phenomenological ones in that it is a micromechanics-based thermodynamic approach and it can provide the evolution of new domain concentration among the constituent grains. It also differs from some recent micromechanics studies in its secant form of self-consistent formulation and in its application of irreversible thermodynamics to derive the kinetic equation of domain growth. To put this two-level micromechanics theory in perspective, it is applied to a ceramic PLZT 8/65/35, to calculate its hysteresis loop between the electric displacement and the electric field ( D versus E ), and the butterfly-shaped longitudinal strain versus the electric field relation ( ϵ versus E ). The calculated results are found to be in good quantitative agreement with the test data. The corresponding evolution of new domain concentration c 1 and the individual hysteresis loops of several selected grains—along with those of the overall polycrystal—are also illustrated.

scholarly journals Поведение керамических твердых растворов 33PbYb-=SUB=-1/2-=/SUB=-Nb-=SUB=-1/2-=/SUB=-O-=SUB=-3-=/SUB=--22PbZrO-=SUB=-3-=/SUB=--45PbTiO-=SUB=-3-=/SUB=- в электрическом поле

2020 ◽  
Vol 46 (6) ◽  
pp. 31
Author(s):  
Л.С. Камзина ◽  
G. Li
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Electric Field ◽  
Electric Fields ◽  
Dielectric Parameters ◽  
Morphotropic Phase Transition ◽  
Temperature Dependences ◽  
Pseudocubic Phase

The temperature dependences of the dielectric parameters were studied, as well as the changes in the dielectric constant with time in ceramic 33PbYb1 / 2Nb1 / 2O3-22PbZrO3-45 PbTiO3 samples in electric fields (0 <E <8 kV / cm). It is shown that in the phase existing below the temperature of the morphotropic phase transition, in addition to the rhombohedral and tetragonal phases, a small fraction of the relaxor pseudocubic phase is present. It was found that, unlike other relaxors, the dielectric constant practically does not change with time when an electric field is applied in the phase below the temperature of the morphotropic phase transition. Possible reasons for this behavior are discussed.

Micro Mechanism of BaTiO3 Ferroelectric Phase Transition Described by Electron Cloud Model

2012 ◽  
Vol 479-481 ◽  
pp. 619-622
Author(s):  
Chao Fang ◽  
Liang Yan Chen
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Equilibrium Position ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Cloud Model ◽  
Electron Cloud ◽  
Oxygen Ions ◽  
Expansion Effect ◽  
Coulomb Attraction

In this paper the micro mechanism of BaTiO3 ferroelectric phase transition is studied based on the thermodynamic model using electron cloud model, and further the Curie - Weiss law is explained. The results indicate that the contraction of the electron cloud, as the temperature decreased through Curie temperature, causes oxygen ions shift the equilibrium position, and the Coulomb attraction makes Ti ion shift the equilibrium position causing phase transition; With temperature rising, the ion displacement polarization decreases owing to the electron cloud expansion effect, and the variation of dielectric constant with temperature follows the Curie - Weiss law.

Use of an External Electric Field to Convert the Paraelectric Phase to the Ferroelectric Phase in Ultra-thin Copolymer Films of P(VDF-TrFE)

2000 ◽  
Vol 655 ◽  
Author(s):  
Matt Poulsen ◽  
S. Adenwalla ◽  
Stephen Ducharme ◽  
V.M. Fridkin ◽  
S.P. Palto ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electric Field ◽  
External Electric Field ◽  
Ferroelectric Phase ◽  
Paraelectric Phase ◽  
Continuous Process ◽  
Structural Phase ◽  
X Ray Diffraction ◽  
Layer Spacing ◽  
X Ray

AbstractX-ray diffraction was used to probe the structural changes associated with the conversion of the paraelectric phase to the ferroelectric phase that results from the application of a large external electric field. The samples under study are ultrathin (150 to 250 Å) Langmuir-Blodgett films of the copolymer vinylidene fluoride (70%) with trifluoroethylene (30%) deposited on aluminum-coated silicon. Theta-2theta X-ray diffraction was used to measure the change in inter-layer spacing perpendicular to the film surface. Upon heating at zero external electric field, the crystalline films undergo a structural phase transition, at 100± 5°C, from the all-trans ferroelectric phase to the trans-gauche paraelectric phase. [1,2] Above the phase transition temperature, the non-polar paraelectric phase can be converted back to the polar ferroelectric phase, in a smooth continuous process, using a large external electric field (∼1 GV/m). For example, at 100° C the ferroelectric phase first appears above 0.2 GV/m and increases steadily in proportion while the paraelectric phase decreases until complete conversion to the ferroelectric phase is achieved at approximately 0.6 GV/m.

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