Effect Of Domain Switching Research Articles

Domain switching effect on fracture of piezoelectric solids

Rational design of smart sensors and actuators that consist of piezoelectric solids requires a thorough understanding of the constitutive behavior of this material under mechanical and electrical loading. Domain switching is the cause of significant nonlinearity in the constitutive behavior of piezoelectric solids, which may be enhanced in the presence of cracks. In this paper, the response of piezoelectric solids is formulated by coupling thermal, electrical, and mechanical effects. The corresponding finite element equations are derived and applied in the solution of the piezoelectric center crack problems. The effects of domain switching are evaluated on the near tip stress intensity factors.

An analysis of the effect of domain switching on fracture behavior of piezoelectricsolids

Understanding the effect of an electric field on fracture behavior of piezoelectricmaterials is an important step towards a rational design of smart sensors andactuators. Domain switching has been observed to be the cause of significantnonlinearity in the response of piezoelectric materials subjected to mechanical andelectrical loads. While linear piezoelectricity is incapable of explaining the resultsof the experiments conducted on cracked piezoelectric specimens, a nonlinearanalysis considering domain switching is found to be necessary to describe some ofthe key observations of these experiments. In this paper, the response ofpiezoelectric solid is formulated by coupling thermal, electrical, and mechanicaleffects. The corresponding finite-element equations are derived and applied in thesolution of the piezoelectric centre crack problem, with different polingdirections, subjected to various mechanical and electrical loads. The effects ofdomain switching are evaluated on the near-tip stresses and the stressintensity factors. It is observed that a negative electric field increasesthe peak stress intensity factor while a positive electric field reduces it.

A micromechanics method to study the effect of domain switching on fracture behavior of polycrystalline ferroelectric ceramics

The effect of domain switching on anisotropic fracture behavior of polycrystalline ferroelectric ceramics was revealed on the basis of the micromechanics method. Firstly, the electroelastic field inside and outside an inclusion in an infinite ferroelectric ceramics is carried out by the way of Eshelby-Mori-Tanaka's theory and a statistical model, which accounts for the influence of domain switching. Further, the crack extension force (energyrelease rate) Gext for a penny-shape crack inside an effective polycrystalline ferroelectric ceramics is derived to estimate the averaged effect of domain switching on the fracture behavior of polycrystalline ferroelectric ceramics. The simulations of the crack extension force for a crack in a BaTiO3 ceramics are shown that the effect of domain switching must be taken into consideration while analyzing the fracture behavior of polycrystalline ferroelectric ceramics. These results also demonstrate that the influence of the applied electric field on the crack propagation is more profound at smaller mechanical loading and the applied electric field may enhance the crack extension in a sense, which are consistent with the experimental results.

Fully coupled non‐linear analysis of piezoelectric solids involving domain switching

AbstractDomain switching is the cause of significant non‐linearity in the response of piezoelectric materials to mechanical and electrical effects. In this paper, the response of piezoelectric solids is formulated by coupling thermal, electrical, and mechanical effects. The constitutive equations are non‐linear. Moreover, due to the domain switching phenomenon, the resulting governing equations become highly non‐linear. The corresponding non‐linear finite element equations are derived and solved by using an incremental technique. The developed formulation is first verified against a number of benchmark problems for which a closed‐form solution exists. Next, a cantilever beam made of PZT‐4 is studied to evaluate the effect of domain switching on the overall force–displacement response of the beam. A number of interesting observations are made with respect to the extent of non‐linearity and its progressive spread as the load on the beam increases. Copyright © 2002 John Wiley & Sons, Ltd.

A statistical model prediction of effective electroelastic properties of polycrystalline ferroelectric ceramics with randomly oriented defects

In terms of the microstructure characteristics of polycrystalline ferroelectric ceramics, a statistical micromechanics model is employed to predict the effective electroelastic properties of polycrystalline ferroelectric ceramics with randomly oriented defects, such as voids and microcracks, by the method of Eshelby’s equivalent inclusion theory and Mori–Tanaka’s mean field concept. The model incorporates the effects of crystallographic domain switching under external mechanical or electric field and the randomly oriented defects on the macroscopic behaviors of the polycrystalline ferroelectric ceramics. The analytical predictions of BaTiO 3 polycrystalline ceramics are shown that the defects can enhance the effective piezoelectric properties but reduce the elastic properties, which are consistent with the experimental results.

Nonlinear fracture analysis of piezoelectric ceramics by finite element method

In this paper, a simple nonlinear constitutive model for piezoelectric ceramics is devised. The model is implemented in a research finite element code and used to study the effect of domain switching and electric nonlinearity on the cracking behavior. J-integrals are computed along contours close to and well away from the crack tip. For linear materials, the computed J-integrals are essentially path independent. With the material nonlinearity considered, the integrals computed at the crack tip vicinity is higher than the ones computed well away from the crack tip. Using the former as the fracture criterion, it is found that crack propagation can be promoted by the electric field.

A statistical model for predicting effective electroelastic properties of polycrystalline ferroelectric ceramics with aligned defects

This work is focused on the analysis of the effects of domain switching and defects on the effective electroelastic properties of polycrystalline ferroelectric ceramics. On the basis of experimental results and the classical nucleation theory, a statistical micromechanics model is developed in order to describe the microstructural evolution of polycrystalline ferroelectric ceramics. Further, the methods of Eshelby’s equivalent inclusion and Mori–Tanaka’s mean field theory are used to predict the effective electroelastic properties of polycrystalline ferroelectric ceramics with aligned defects, taking the effects of the shapes of individual crystal and defect into consideration. Some numerical results for BaTiO 3 polycrystalline ceramics with aligned defects are carried out in order to illustrate the effects of the domain switching and defects on the effective electroelastic properties of polycrystalline ferroelectric ceramics. It has been shown that the simulations are in good agreement with the experimental results.

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.

Effects of Domain-Switching and Site-Directed Mutagenesis on the Properties and Functions of the VP7 Proteins of Two Orbiviruses

Based on the crystal structure of the VP7 major core protein of bluetongue virus serotype 10 (BTV-10) and that of the top domain of the VP7 protein of African horsesickness virus serotype 4 (AHSV-4), chimeras and site-directed mutants of the proteins were constructed and the products analyzed with respect to their properties and functions. Chimeras with the central upper domain of BTV-10 VP7 replaced by that of AHSV-4 VP7 (construct BAB) formed trimers, as did the converse construct (ABA). Further, both proteins exhibited the expected conformational epitopes of the constituent sequences. Using BAB VP7 it was demonstrated that residues of the upper domain of AHSV-4 VP7 contribute to the observed insolubility of the protein. By contrast, ABA VP7 protein was as soluble as wild-type BTV-10 VP7. Replacement of selected amino acid residues in the top domain (e.g., A167 by R; F209 by T) improved the solubility of BAB VP7. Since the trimeric BAB and ABA VP7 proteins did not form core-like particles (CLPs) when coexpressed with BTV VP3, it was concluded that trimerization of chimeric VP7 is not sufficient for CLP formation. When the N-terminal region of the ABA protein (aa 1–120) was replaced by the respective sequences of BTV VP7 (construct BBA), the protein aggregated and did not form CLPs with coexpressed BTV VP3, most likely due to disruption of the required contacts between the N- and C-terminal regions of the bottom domain, leading to incorrect folding of the chimera.

Effect of illumination on switching process in PbTiO3crystals

Abstract The effect of photoassisted domain switching depending on irradiating light was found in PbTiO3 crystals.

The possibilities of ferroelectric liquid crystals for video displays

Abstract— Different approaches were used to examine the possibility of using surface‐stabilized ferroelectric liquid‐crystals (SSFLCs) in video displays. The advantages of such displays lie in the viewing‐angle independence and the high switching speed. The large number of gray levels needed for video can, in principle, be obtained by digital or analog techniques. From simulation experiments on a high‐resolution CRT, it is estimated that for video, for the case of equidistant luminance levels, 128 levels for each primary colour are needed. Discrete gradation by means of bi‐level subpixels (spatial dither) is simulated for projection and direct‐view displays. Efficient subpixelation (minimum number of extra connections) results in perceptual artefacts when the three primary colours (RGB) are projected onto each other, as in a projection system. In the case of a direct‐view display with mosaic colour filter, the layout of this mosaic turns out to be more important than subpixelation. Analog gradation methods are based on in‐pixel domain switching effect. They require accurate control of the multidomain structures. Active‐matrix addressing for the SSFLC strongly enhances the reproducibility of the multidomain gray levels via the charge‐control process. This is demonstrated on test displays. Passive‐matrix addressing takes advantage of the bistability and switching speed of the SSFLC effect. One approach to control the multidomain gray levels in passive‐matrix addressing is the “texture method,” which is based on a distribution of the threshold voltage for switching within each pixel. The mechanism, the addressing scheme, the obtainable contrast in the different textures, the applicability of various FLC mixtures, and the resulting temperature sensitivity are discussed. The performance of test displays, operating at video rate, is evaluated. Several issues, such as temperature sensitivity, texture stability, and hysteresis in the transmission‐voltage curve have to be further improved.

Interferometer for the determination of strains due to domain switching in ferroelectrics

A thermally stable double beam laser interferometer for the measurement of mechanical strains due to domain switching in ferroelectric materials is described. Sample sizes vary from 0.25 mm to 5 mm in thickness, and maximum strains produce from 1 to 50 fringes in the data. A quadrature detection scheme provides the resolution which is required to interpolate accurately the fringe record and determine the direction of surface mechanical displacement. Specific sample mounting techniques are also developed in order to attain well-defined loading conditions. Two sample holders, one for mounting very thin discs and the other for 5 mm cubes, are described. They induce minimal mechanical loadings on the samples. Typical data exhibiting the effects of domain switching due to an applied electric field are shown for the hot-pressed ceramic PZT 65/35.

Direct observation of ferroelasticity in Pb 3(PO 4) 2  Pb 3(VO 4) 2

Ferroelasticity has been established in the room temperature phase of Pb 3(P xV 1-xO 4) 2, (x ≥ 0.8). The coercitive stress and the spontaneous strain have been determined and found to be 1.6 bars and ca. 3.5 · 10 −4 respectively. The effect of domain switching on double refraction and Raman spectra is clearly brought out.

Domain switching effects in epitaxial films of ferroelectric bismuth titanate

Domain switching effects in epitaxial films of ferroelectric bismuth titanate