A self-consistent polycrystal model for the spontaneous polarization of ferroelectric ceramics

2006 ◽  
Vol 462 (2070) ◽  
pp. 1763-1789 ◽  
Author(s):  
Y Su ◽  
G.J Weng
Keyword(s):  
Curie Temperature ◽  
Electric Field ◽  
Spontaneous Polarization ◽  
Mixture Theory ◽  
Temperature Shift ◽  
Dielectric Constants ◽  
Ferroelectric Ceramics ◽  
Consistent Model ◽  
Self Consistent ◽  
Polycrystalline Ceramic

Motivated by the observation that the spontaneous polarization process of a ferroelectric polycrystal under the influence of a superimposed stress and/or electric field involves heterogeneous evolution of the ferroelectric phase among its constituent grains, a self-consistent electromechanical model is developed to determine the effective behaviour of the polycrystalline ceramic from such a heterogeneous electromechanical state. We start out from consideration of a micromechanics-based thermodynamic process to establish the kinetic equation of the crystallite and use it to evaluate the evolution of its ferroelectric domain. Then together with the Curie–Weiss law for the dielectric constants of the tetragonal phase, a dual-phase mixture theory is adopted to determine the change of its electromechanical moduli as temperature cools down below its Curie point. The overall property of the polycrystal is subsequently calculated by the self-consistent model through orientational average over its constituent grains. This two-level micromechanics model is applied to examine the shift of Curie temperature and evolution of the effective electromechanical moduli of a BaTiO 3 ceramic under cooling. The calculated results show that its Curie temperature decreases with increasing hydrostatic pressure, but increases with a superimposed axial compression or a biased electric field. The predicted temperature shift and change of the dielectric constants are found to be consistent with experimental observations.

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.

Temperature Dependence of Electric Field Induced Strain in PLZT 9/65/35 Ceramics

2016 ◽  
Vol 675-676 ◽  
pp. 643-646 ◽  
Author(s):  
Siripong Somwan ◽  
Narit Funsueb ◽  
Apichart Limpichaipanit ◽  
Athipong Ngamjarurojana
Keyword(s):  
Mechanical Properties ◽  
Solid Solution ◽  
Electric Field ◽  
Temperature Dependence ◽  
Spontaneous Polarization ◽  
Solution Method ◽  
Michelson Interferometer ◽  
Ferroelectric Materials ◽  
Ferroelectric Ceramics ◽  
Electric Field Induced Strain

In this study, leadbased ferroelectric ceramics Pb0.91La0.09Zr0.65Ti0.35O3 PLZT (9/65/35) were fabricated by solid solution method. The electrical and mechanical properties were measured by modified Michelson interferometer and Sawyer-Tower circuit to investigate electric field induced strain and polarization (s-P-E) of PLZT (9/65/35) at 30-70 °C. The induced strain and polarization were changed when the temperature was increased indicating the change of spontaneous polarization inside the ferroelectric materials.

Dielectric Properties of (Bi1/2Na1/2)TiO3-SrTiO3 Ferroelectric Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 49-50
Author(s):  
Chao Liu ◽  
Yuan Fang Qu ◽  
Feng Long Han ◽  
Yuan Liang Li ◽  
Xiao Yan Li
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Curie Temperature ◽  
Ferroelectric Properties ◽  
Dielectric Constants ◽  
Ferroelectric Ceramics

Ferroelectric properties of (Bi1/2Na1/2) TiO3-SrTiO3 were studied. The dielectric properties were measured at 1KHz. It was found that the dielectric constants are improved with the increase of additive amount of BNT. If the amount continues increasing, the properties become worse, the optimum dielectric constant of the samples can reach 4300. When the proportion of (Bi1/2Na1/2)TiO3: SrTiO3 is 65:35, with the increase of additive amount of MnCO3, the Curie temperature descends obviously. The dielectric constant increased at beginning and dropped sharply when the amount of MnCO3 exceeds 1.1wt%.

Strain Evolution of Highly Asymmetric Polycrystalline Ferroelectric Ceramics via a Self-Consistent Model and In Situ X-Ray Diffraction

2012 ◽  
Vol 95 (12) ◽  
pp. 3947-3954 ◽  
Author(s):  
Goknur Tutuncu ◽  
Maziar Motahari ◽  
Joel Bernier ◽  
Mesut Varlioglu ◽  
Jacob L. Jones ◽  
...  
Keyword(s):  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Strain Evolution ◽  
Consistent Model ◽  
Self Consistent

Tunability of the dielectric constant of Ba0.1Sr0.9TiO3 ceramics in the paraelectric state

1995 ◽  
Vol 10 (6) ◽  
pp. 1411-1417 ◽  
Author(s):  
Abdelkader Outzourhit ◽  
John U. Trefny ◽  
Tomoko Kito ◽  
Baki Yarar
Keyword(s):  
Dielectric Constant ◽  
Solid State ◽  
Electric Field ◽  
Solid State Reaction ◽  
Paraelectric Phase ◽  
Solid State Reaction Method ◽  
Dielectric Constants ◽  
Ferroelectric Ceramics ◽  
Reaction Method ◽  
Paraelectric State

Ba1−xSrxTiO3 (x = 0.9) ferroelectric ceramics were prepared successfully using a new wet technique and their structure and dielectric properties compared with those synthesized by the solid-state reaction method. The voltage dependence of the dielectric constant in the paraelectric phase was examined. It was found that the dielectric constants of these materials, prepared by both methods, exhibit large changes with applied voltage in the paraelectric phase. Tunability (the percentage change of the dielectric constant from its zero-bias value in the presence of a de-biasing electric field) was observed to exceed 30% at only 1.7 kV/cm at 77 K in the samples prepared by the solid-state reaction method. The tunability was found to decrease dramatically as the operating temperatures increased above the Curie point. These observations are interpreted in light of an existing phenomenological theory. The dependence of the dielectric constant in the paraelectric state upon a de-biasing electric field is also demonstrated as a potential method for the characterization of dielectric nonuniformities in ferroelectric ceramics.

Correlations Between the Bipolar- and Unipolar-Electric Field Induced Strain in Pb(Mg1/3Nb2/3)O3-PbTiO3 Ceramics

1994 ◽  
Vol 360 ◽  
Author(s):  
Jae-Hwan Park ◽  
Byung-Kook Kim ◽  
Soon Ja Park
Keyword(s):  
Electric Field ◽  
Spontaneous Polarization ◽  
Relaxor Ferroelectric ◽  
Ferroelectric Ceramics ◽  
Polarization Direction ◽  
Temperature Range ◽  
Residual Strains ◽  
Pbtio3 Ceramics ◽  
Electric Field Induced Strain ◽  
Relaxor Ferroelectric Ceramics

AbstractCorrelations between the strains induced by a unipolar-electric field and the strains induced by a bipolar-electric field were investigated for Pb(Mg1/3Nb2/3)O3 (PMN) and 0.9{Pb(Mg1/3Nb2/3)O3}-0.1PbTiO3 (0.9PMN- 0.1PT) relaxor ferroelectric ceramics in the temperature range of −50°C ∼ 150°C. The magnitudes of the unipolarly induced-strains are almost the same as the differences between the bipolarly induced-strains and the residual strains, which were attributed to the absence of change of spontaneous polarization direction when the unipolar-electric field is applied.

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