Domain Clamping Research Articles

Mechanical and electrical properties of Na0.55K0.45NbO3 + 0.2% MnO/Al2O3 composites for energy harvesting applications

To increase the power output of piezoelectric energy harvesters, there are several options that have been the focus in a number of scientific studies. This work explores a new concept, by using ceramic/ceramic composites (Na0.55K0.45NbO3 + 0.2% MnO/Al2O3) for energy harvesting applications. The idea of increasing the elastic properties to maintain a sufficient power output is used. Mechanical and electrical properties of these composites with varying Al2O3 content have been evaluated to determine the energy harvesting properties. Here, the measured power densities exceeded the predicted values with a decrease from 0.11 μW mm−3 at 0 vol% to approximately 0.09 μW mm−3 between 5 and 15 vol%. Observations on the dielectric, piezoelectric and elastic properties revealed a residual stress inside the piezoelectric matrix. Whereas residual stress had a negative effect on the piezoelectric properties due to domain clamping and direct measurements of the energy harvesting properties showed a positive enhancement.

Stress, temperature and electric field effects in the lead-free (Ba,Ca)(Ti,Zr)O3 piezoelectric system

The large signal strain response as a function of uniaxial compressive stress, electric field and temperature is investigated for compositions across the morphotropic phase boundary in the (Ba,Ca)(Ti,Zr)O3 ferroelectric system. The largest piezoelectric coefficient in terms of unipolar strain divided by the maximum applied field, Su/Emax, is 1540pmV−1, which clearly exceeds the piezoelectric response of most lead zirconate titanate materials. The extraordinarily large piezoelectric properties occur in the vicinity of the morphotropic phase boundary region on the rhombohedral side of the phase diagram. In this material, an electric threshold field is observed that is required to overcome the stress-induced domain clamping and obtain a measurable strain response. Moreover, the study reveals that careful selection of composition, stress and field amplitude allow for large signal piezoelectric coefficients of over 740pmV−1 in the temperature range of 25–75°C. The extraordinarily large unipolar strain response can be assigned to an electric field-controlled regime, in which the unipolar compressive stress induces non-180° domain switching perpendicular to the applied electric field. During electrical loading, the electric field can realign these domains back into the parallel direction, maximizing non-180° domain switching and enhancing unipolar strain.

Poling Field Dependence of Ferroelectric Properties in Alkali Bismuth Titanate Lead-Free Ceramics

The DC poling field dependence of ferroelectric properties was investigated to evaluate the mechanism of domain alignment in lead-free ceramics of the forms of (1-x)(Na0.5Bi0.5)TiO3–x(K0.5Bi0.5)TiO3 (x=0.08–0.28), 0.79(Na0.5Bi0.5)TiO3–0.20(K0.5Bi0.5)TiO3–0.01Bi(Fe0.5Ti0.5)O3 and (1-x)(Na0.5Bi0.5)TiO3–xBaTiO3 (x=0.03–0.11). From the DC poling field (E) dependence of ferroelectric properties, asymmetrical shapes in piezoelectric constants vs ±E caused by nonuniform mobility of domain alignment in the application of positive and negative poling fields were observed in the small amount substitution by (K0.5Bi0.5)TiO3 (x≦0.11) and BaTiO3 (x≦0.03). On the other hand, symmetrical shapes in piezoelectric constants vs ±E were observed in higher piezoelectricity with lower frequency constant accompanied with typical domain clamping. The effects to improve ferroelectric properties by Bi(Fe0.5Ti0.5)O3 and by BaTiO3 substitutions for (Na0.5Bi0.5)TiO3 were also proved by the measurement of P–E hysteresis loops.

Evaluation of Ferroelectric Domain Behaviors Using Acoustic Emission Method

Two kinds of acoustic emission (AE) signals are used to evaluate the ferroelectric domain behaviors in tetragonal lead zirconate titanate (PZT) ceramics: AE related to the ferroelectric domain and vibro acoustic emission (vibro-AE) caused by sample vibration. The signal level of vibro-AE caused by the sample vibration is suppressed using an external resistor, and the vibro-AE and AE related to the ferroelectric domain are observed simultaneously. It is shown that the vibro-AE measured as an AE signal Vrms reflects the piezoelectricity of the sample. The Kaiser effect in terms of electrical loading is found to be valid for ferroelectric PZT ceramics. From the vibro-AE measurement, it is shown that domain clamping occurs at critical fields at which the vibro-AE signal vanishes. It is also shown that domain-related AE takes place above the coercive field Ec and after domain clamping occurs. From these obtained AE activities, conflicts among ferroelectric domains in the sequence of domain reorientation from the clamped state to the aligned domain state and the resulting stress relaxations are considered to be the origin of AE.

Oxygen-vacancy-induced90°-domain clamping in ferroelectricBi4Ti3O12single crystals

We have investigated domain clamping in ferroelectric single crystals of ${\text{Bi}}_{4}{\text{Ti}}_{3}{\text{O}}_{12}$ (BiT) and $({\text{Bi}}_{3.6}{\text{La}}_{0.4}){\text{Ti}}_{3}{\text{O}}_{12}$ (BLT) using polarization measurements along the $a(b)$ axis and piezoresponse force microscopy (PFM). PFM observations reveal that $90\ifmmode^\circ\else\textdegree\fi{}$ domains are clamped during polarization switching. The crystals of BiT with less oxygen vacancies and BLT exhibited a low volume fraction of the clamped $90\ifmmode^\circ\else\textdegree\fi{}$ domains. Polarization measurements demonstrate that the clamping of $90\ifmmode^\circ\else\textdegree\fi{}$ domains decreases the remanent polarization in BiT crystals. These experimental results and ab initio calculations show that an attractive interaction between $90\ifmmode^\circ\else\textdegree\fi{}$-domain walls and oxygen vacancies is the main origin of the clamping of $90\ifmmode^\circ\else\textdegree\fi{}$ domains.

層状構造強誘電体の欠陥構造と機能

Ferroelectric materials with layered structure have attracted a great deal of attention in technological and scientific points of view because of their high Curie temperature and large spontaneous polarization. The current status and problems of representative layered ferroelectric material, Bi4Ti3O12, are briefly reviewed. Piezoresponse force microscopy observations reveal that the clamping of 90° domain walls is the origin of poor polarization properties of Bi4Ti3O12 crystals. The origin of the domain clamping is suggested to be the strong interaction between oxygen vacancies and 90° domain walls. High-pressure-oxygen sintering is shown to be effective processing for obtaining high-quality Bi4Ti3O12-based devices with superior polarization properties.

Drift of charged defects in local fields as aging mechanism in ferroelectrics

Point defect migration is considered as a mechanism for aging in ferroelectrics. Numerical results are given for the coupled problems of point defect migration and electrostatic energy relaxation in a two-dimensional domain configuration. The peak values of the clamping pressure at domain walls are in the range of ${10}^{6}\phantom{\rule{0.3em}{0ex}}\mathrm{Pa}$, which corresponds to macroscopically observed coercive stresses in perovskite ferroelectrics. The effect is compared to mechanisms involving orientational reordering of defect dipoles in the bulk of domains. Domain clamping is significantly stronger in the drift mechanism than in the orientational picture for the same material parameters.

Poling Field Dependence of Ferroelectric Properties in Piezoelectric Ceramics and Single Crystal

Domain structures of ferroelectric materials were investigated by measuring the poling field dependence of dielectric and piezoelectric properties. Ferroelectric materials evaluated consist of as follows: soft and hard lead zirconate titanate (PZT) ceramics with tetragonal and rhombohedral phases, lead titanate (PT) ceramics, barium titanate (BT) ceramics and a relaxor based single crystal of Pb(Zn 1/3 Nb 2/3 ) 0.91 Ti 0.09 O 3 (PZNT). Changing the poling field (E) from 0 M +E M 0 M m E M 0 to +E, the electromechanical coupling factor (k p , k 33 ), dielectric constant ( l r ) and frequency constant (fc) were measured. The minimum k p , k 33 and l r were obtained at the same E because of the 180° domain clamping. Furthermore, the E due to the domain clamping corresponded to the coercive field (Ec) determined by the poling field dependences. At the Ec, maximum fc was confirmed in the cases of soft PZT (tetragonal and rhombohedral) and hard PZT (tetragonal) ceramics, BT ceramics and PZNT single crystal. It was thought that the materials became mechanically hard by the electrical attracting through the domain clamping ( N O ). In hard PZT (rhombohedral), PT and BT ceramics, the peak of l r and/or minimum fc were observed at an E, which corresponds to the threshold of 90°, 71° or 109° domain rotations.

Poling Field Dependence of Ferroelectric Properties in Barium Titanate Ceramics

The domain switching and rotation in barium titanate ceramics were evaluated by investigating the poling field dependence of the ferroelectric properties. The effect of domain clamping on the planar coupling factor and dielectric constant at the coercive field was confirmed in barium titanate ceramics as well as in the cases of soft and hard tetragonal lead zirconate titanate ceramics and lead titanate ceramics. The frequency constant peaks due to domain clamping were also observed in barium titanate ceramics. Furthermore, it is considered that domain rotations occurred at the fields required to obtain the maximum dielectric constant and the minimum frequency constant.

Poling Field Dependence of Crystal Orientation and Ferroelectric Properties in Lead Titanate Ceramics

Domain switching and rotation in lead titanate ceramics were evaluated by investigating the poling field dependence of the relative intensity of the X-ray diffraction (002) peak and the electrical properties. Although the lead titanate ceramic surface was highly oriented in the direction of the c-axis by the poling field, it was difficult to align the crystal orientation of the ceramic bulk because of the large anisotropy of the crystal structure. The effect of domain clamping on the planar coupling factor and dielectric constant at coercive fields was confirmed in lead titanate ceramics as well as in the case of soft and hard tetragonal lead zirconate titanate ceramics. The peaks of frequency constant due to domain clamping were not observed in lead titanate ceramics. Further, it was thought that domain rotations occurred at the fields required to obtain the minimum frequency constant.

Damage evolution in ferroelectric PZT induced by bipolar electric cycling

The fatigue behaviour of commercial bulk Lead Zirconate Titanate (PZT) induced by bipolar cycling was investigated. Polarisation and strain hysteresis loops as well as acoustic emissions (AE) were monitored. Higher cycling fields (2× E c ) yield stronger fatigue, higher AE energy values and lower threshold values for the onset of AE events at high cycle numbers. AE amplitudes and energies were found to be a measure for the degree of domain clamping. Cycling at 2 E c leads to an increasing asymmetry of the strain hysteresis, which is explained by an offset polarisation. Corrosion paths were observed by SEM, most numerously in the centre of a strongly fatigued sample. A damage scenario based on domain wall clamping due to the coalescence of point defects is presented.

Domain structure of ferroelectric ceramics

PZT ceramics were statically and dynamically evaluated to examine the relationship between domain structures and electrical properties. We investigated the domain structures of tetragonal, M.P.B. and rhombohedral PZT ceramics at various poling fields to measure the poling field dependence of the crystal orientations and electrical properties as a statical evaluation. Furthermore, responses to repeated voltage pulses applied to the ceramics were measured by a high voltage test system as a dynamical evaluation. Through these evaluations, we could clarify the domain behavior for the 90° (71° or 109°) domain rotation, switching and clamping of 180° domain, and transient phenomena on the domain orientation.

Domain switching and rotation in lead zirconate titanate ceramics by poling fields

Domain switching and rotation in soft lead zirconate titanate (PZT) ceramics were investigated in comparison with those in hard PZT ceramics by measuring the poling field dependence of the dielectric and piezoelectric properties. The minimum dielectric constant (fcp) and maximum frequency constant (fcp) were observed at the coercive fields, which correspond to the poling fields required to obtain the minimum planar coupling factor. These phenomena were due to the 180° domain clamping at these fields. The fields of 90° (71° or 109°) domain rotation were estimated using the relationships between the maximum fcp and minimum fcp. While minimum ϵt and maximum fcp due to domain clamping were observed in the compositions of tetragonal and rhombohedral soft PZT ceramics, domain rotations which caused maximum ϵt and minimum fcp were mainly observed in rhombohedral hard PZT ceramics. It was thought that the reason why domain rotations which caused maximum ϵt and minimum fcp were not obtained in soft PZT was the mechanical softness of the ceramics.

Effect of Domain Switching and Rotation on Dielectric and Piezoelectric Properties in Lead Zirconate Titanate Ceramics

Domain switching and rotation in soft lead zirconate titanate (PZT) ceramics were investigated in comparison with those in hard PZT ceramics by measuring the poling field dependence of the dielectric and piezoelectric properties. The minimum dielectric constant (εr) and maximum frequency constant (fcp) were observed at the coercive fields, which correspond to the poling fields required to obtain the minimum planar coupling factor. These phenomena were due to the 180° domain clamping at these fields. The fields of 90° (71° or 109°) domain rotation were estimated using the relationships between the maximum εr and minimum fcp. While minimum εr and maximum fcp due to domain clamping were observed in the compositions of tetragonal and rhombohedral soft PZT ceramics, domain rotations which caused maximum εr and minimum fcp were mainly observed in rhombohedral hard PZT ceramics. It was thought that the reason why domain rotations which caused maximum εr and minimum fcp were not obtained in soft PZT was the mechanical softness of the ceramics.

Pulse response measurement of transient phenomena on ferroelectric domains in PZT ceramics

Lead zirconate titanate ceramics were evaluated to examine the relationship between domain structures and ferroelectric properties. Responses to repeated voltage pulses applied to the ceramics were measured by a high voltage test system as a dynamical evaluation. Through the evaluation, it was clarified the domain behavior for the 90° (71° and 109°) domain rotation, 180° domain switching and clamping, and transient phenomena on the domain orientation.

Poling Field Dependence of Ferroelectric Properties and Crystal Orientation in Rhombohedral Lead Zirconate Titanate Ceramics

Rhombohedral lead zirconate titanate (PZT) ceramics were evaluated statically and dynamically to examine the relationship between domain structures and electrical properties. The poling field dependence of the electrical properties and crystal orientation was investigated as a statical evaluation. When the poling field was varied, maximum dielectric constant, minimum planar coupling factor, minimum frequency constant and minimum relative intensity of the X-ray diffraction (222) peak were obtained at the poling fields of ±0.5, ±1.0, ±0.5 and ±0.75 kV/mm, respectively. Since 180° domain switching was the dominant factor affecting the coupling factor, it was thought that the electrical domain clamping occurred at ±1.0 kV/mm. Furthermore, responses to repeated voltage pulses applied to the ceramics were measured by a high voltage test system as a dynamical evaluation. From these evaluations, we could clarify the domain behavior for the switching and clamping of 180° domain, 71° and 109° domain rotations and transient phenomena on the domain orientation.

DC field effects on dielectric, elastic and piezoelectric anisotropies of 0.37 Pb(Zn1/3Nb2/3)O3-xPbTiO3-(0.63-x)PbZrO3ceramics

Abstract The change of dielectric, elastic and piezoelectric properties with dc field in 0.37 Pb(Zn1/3Nb2/3)O3-xPbTiO3-(0.63-x)PbZrO3 ceramics was discussed from the view point of domain reorientation mechanism. In the rhombohedral phase region, dielectric and elastic properties were saturated at relatively low electric field compared with those in the tetragonal phase region and also the change of these properties were saturated at different electric fields. From the examination of X-ray diffraction patterns and the coercive field measurement, it is found that the change of dielectric and elastic properties in the tetragonal phase is affected with 180[ddot] domain clamping and 90[ddot] domain reorientation, respectively.

The Aging Characteristics in Perovskite-Type Ferroelectric Ceramics

The aging characteristics of the physical constants have been studied under various biasing and temperature conditions for the ceramics of BaTiO3 and Pb(Zr-Ti)O3 system. The change of the dielectric constant is assumed to be divided into two parts: one is the increase due to the 90°-back-rotation of domains in connection with the dielectric anisotropy and the other is the decrease mainly due to the 180°-back-reversal in relation to the domain clamping effect. The aging of the dielectric constant has been calculated under the above assumption using the measured values of electrostriction and polarization. The calculated values agree well with the observed ones both in BaTiO3 and Pb(Zr-Ti)O3 families ceramics, and the aging characteristics can be explained by the present treatment. The aging rate of the dielectric constant does not increase monotonically with temperature for unpoled Pb(Zr-Ti)O3 families ceramics, and suggests that in this case aging cannot be interpreted with a simple thermally activated process.

Domain Clamping Effect in Barium Titanate Single Crystals

We have found that the dielectric constant of good single crystals of barium titanate decreases as the average polarization is decreased by means of an electric field. This has been interpreted as being due to a domain clamping effect arising from the multidomain situation in the crystal that accompanies the reduction in polarization. These measurements give a value for the coefficient of coupling of 0.50 which is in agreement with Caspari and Merz's value of ${d}_{33}$ and our measurement of ${S}_{33}$.. The coupling coefficient has been studied as a function of temperature using this clamping effect.