Hydrostatic Piezoelectric Response Research Articles

Orientation effects and links between hydrostatic parameters in piezo-active 2–0–2 composites

The paper reports results on the large hydrostatic parameters of novel three-component 2–2-type composites based on [011]-poled relaxor-ferroelectric single crystals. The role of the rotation of the main crystallographic axes X and Y in forming the considerable hydrostatic piezoelectric response is studied. The composite consists of the single-crystal and 0–3 corundum ceramic/polyethylene layers that are regularly arranged along the non-polar axis. 0.72Pb(Mg1/3Nb2/3)O3–0.28PbTiO3 and 0.93Pb(Zn1/3Nb2/3)O3–0.07PbTiO3 single crystals poled along [011] of the perovskite unit cell are considered as main piezoelectric components of the composites with 2–0–2 connectivity. Links between the hydrostatic parameters (piezoelectric coefficients and squared figure of merit and electromechanical coupling factor ) are analysed by taking into account specifics of the microgeometry and elastic anisotropy of the 0–3 layer. Due to the large values of the aforementioned hydrostatic parameters, the studied 2–0–2 composites are of interest for hydroacoustic and piezoelectric energy-harvesting applications.

Piezoelectric Performance and Hydrostatic Parameters of Novel 2–2-Type Composites

This paper provides a detailed study of the structure-piezoelectric property relationships and the hydrostatic response of 2-2-Type composites based on relaxor-ferroelectric 0.72 Pb (Mg1/3Nb2/3)O3-0.28PbTiO3 single crystal (SC) material. Type I layers in the composite system are represented by a single-domain [111]-poled SC. Changes in the orientation of the crystallographic axes in the Type I layer are undertaken to determine the maximum values of the hydrostatic piezoelectric coefficients dh∗ , gh∗ , and eh∗ , and squared figure of merit dh∗ gh∗ of the composite. The Type II layers are a 0-3 composite whereby inclusions of modified PbTiO3 ceramic are distributed in a polymer matrix. A new effect is described for the first time due to the impact of anisotropic elastic properties of the Type II layers on the hydrostatic piezoelectric response that is coupled with the polarization orientation effect in the Type I layers. Large hydrostatic parameters gh∗ ≈ 300 -400 mV · m/N, eh∗ ≈ 40 -45 C/ [Formula: see text], and dh∗ gh∗ ∼10-11 Pa -1 are achieved in the composite based on the 0.72 Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 SC. Examples of the large piezoelectric anisotropy ( |d33∗ /d3f∗ | ≥ 5 or | g33∗ /g3f∗ | ≥ 5 ) are discussed. The hydrostatic parameters of this novel compositesystem are compared to those of conventional 2-2 piezocomposites.

Remarkable hydrostatic piezoelectric response of novel 2–0–2 composites

ABSTRACTThis is the first study of the significant influence of the 0–3 ceramic / polymer layer on the hydrostatic piezoelectric parameters of novel 2–0–2 relaxor-ferroelectric single crystal / ferroelectric ceramic / polymer composites. Examples of the performance of two 2–0–2 composites based on domain-engineered single crystals are analysed by taking into account the elastic anisotropy of the 0–3 ceramic/polymer layers with changes in the volume fraction of ceramic inclusions and their aspect ratio. The unique feature of the hydrostatic properties of the studied 2–0–2 composites consists in their large values of piezoelectric coefficients $d*h$ ≈ 1 nC/N and $e*h$ ≈ 20 C/m2, squared figure of merit $d*h$$g*h$∼ 10−10 Pa−1, and electromechanical coupling factor $k*h$ ≈ 0.7.

Anisotropy of electromechanical properties and hydrostatic response of advanced 2–2‐type composites

AbstractThe paper reports results on the high performance of novel piezo‐active composites based on relaxor‐ferroelectric single crystals (SCs) of xPb(In0.5Nb0.5)O3–yPb(Mg1/3Nb2/3)O3–(1 − x − y)PbTiO3. We present a comparative analysis of the electromechanical properties of 2–2‐type composites based on single‐domain SCs from symmetry classes 3m and mm2. The parallel connection of the layers, the presence of an auxetic polymer component and the appropriate orientation of the main crystallographic axes of the single‐crystal layers lead to the development of large piezoelectric anisotropy and considerable hydrostatic piezoelectric response in comparison to the single‐crystal component. Effective piezoelectric coefficients $d_{3j}^{*} $ and electromechanical coupling factors $k_{3j}^{*} $ of the composites obey the conditions $d_{33}^{*} $/|$d_{31}^{*} $| ≥ 10, $d_{33}^{*} $/|$d_{32}^{*} $| ≥ 10, $k_{33}^{*} $/|$k_{31}^{*} $| ≥ 10, and $k_{33}^{*} $/|$k_{32}^{*} $| ≥ 10 at $k_{33}^{*} $ ≈ 0.6. Hydrostatic piezoelectric coefficients $d_{{\rm h}}^{*} $ ≈ 470 pC/N and $g_{{\rm h}}^{*} $ ∼ (102–103) mV m/N are one to two orders‐of‐magnitude larger than those of the single‐crystal component, which make it attractive for various piezotechnical applications. The role of the elastic properties of the components is discussed in connection with the large hydrostatic parameters.

Features of the hydrostatic piezoelectric response of a novel 2–2–0 composite based on single-domain 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 crystal

The 2–2–0 single-domain 0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 crystal/porous polyurethane composite is studied in which the orientation of the spontaneous polarisation vector Ps of crystal, its volume fraction and the volume fraction and shape of pores in polymer are varied to attain maxima (minima) of effective hydrostatic piezoelectric coefficients dh∗ and gh∗, squared figure of merit dh∗gh∗ and electromechanical coupling factor kh∗. This paper describes an effect of the Ps orientation and the shape of pores on the hydrostatic piezoelectric response of this composite. Advantages caused by large values of dh∗, gh∗, dh∗gh∗, and kh∗ of the studied composite are discussed.

Polarization orientation effect and combination of electromechanical properties in advanced0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3 single crystal/polymer composites with 2–2 connectivity

A comparative study on the effective piezoelectric properties and hydrostaticpiezoelectric response is first carried out for advanced 2–2 composites based onsingle crystals of relaxor-ferroelectric solid solutions. Different orientationsof domains and different poling directions of components are taken intoconsideration in the analysis of the effective longitudinal piezoelectric coefficientsd33*,e33*,g33* and hydrostaticpiezoelectric coefficients dh*, eh* and gh*. The important role of the polarization orientation effect and the effectof combination of the electromechanical properties in attaining the largeeffective parameters is shown for the parallel-connected 2–2 single-domain0.67Pb(Mg1/3Nb2/3)O3–0.33PbTiO3/polyvinylidene fluoride composite. In particular, near extremum points of the effectiveparameters, this composite is characterized by the piezoelectric coefficientsg33*≈500 mV m N−1,|dh*|≈400 pC N−1,|eh*|≈40 C m−2,and gh*≈400 mV m N−1. Three piezo-sums are first found to describe major contributions of the piezoelectric coefficientsdij*,eij* andgij* todh*,eh* andgh*, respectively, in the vicinity of absolute maxima (minima) of the aforementionedhydrostatic parameters. Advantages concerned with the presence of the single crystal(either single-domain or polydomain) in the studied 2–2 composites are discussed inconnection with their piezoelectric activity, sensitivity and hydrostatic response.

Orientation effects in 2-2 piezocomposites based on (1−x)Pb(A1/3Nb2/3)O3−xPbTiO3 single crystals (A=Mg or Zn)

Volume fraction and orientation dependences of piezoelectric coefficients and hydrostatic piezoelectric response of 2-2 parallel-connected composites with two piezoactive components are analyzed. These composites comprise relaxor-ferroelectric (1−x)Pb(A1/3Nb2/3)O3−xPbTiO3 single crystals (A=Mg or Zn) and polyvinylidene fluoride, and different variants of poling directions of these layers are considered. It is shown how the orientation of the main crystallographic axes and the anisotropy of the electromechanical properties of the single crystal influence maxima of effective piezoelectric coefficients and other parameters of the composites. Advantages of the piezocomposites based on the [011] poled single crystals are discussed.

Characteristics of 1–3-type ferroelectric ceramic/auxetic polymer composites

This paper presents modelling and simulation results on 1–3 piezoactive composites comprising a range of ferroelectric ceramics, which are assumed to have variable properties and an auxetic polymer (i.e. a material with a negative Poisson ratio) that improves the hydrostatic piezoelectric response of the composite. Dependences of the effective piezoelectric coefficients and related parameters of the 1–3 composites on the degree of poling, mobility of the 90° domain walls within ceramic grains, on the volume fraction of the ceramic component and on the Poisson ratio of the polymer component have been calculated and analysed. The role of the piezoelectric anisotropy and domain-orientation processes in improving and optimising the effective parameters, piezoelectric activity and sensitivity of 1–3 ferroelectric ceramic/auxetic composites is discussed.

The influence of the external stress on the electromechanical response of electrostrictive 0.9Pb(Mg1/3Nb2/3)O3−0.1PbTiO3 in the dc electrical field-biased state

The influence of uniaxial compressive stress, T3, applied parallel to the electrical field, on the electromechanical parameters of 0.9Pb(Mg1/3Nb2/3)O3−0.1PbTiO3 ceramics in the dc electrical field-biased state and at temperatures near the dielectric constant maximum Tm was investigated. It was found that T3 reduces both the dielectric constant and polarization level, which results in a reduction of the piezoelectric coefficient with stress. However, the compliance of the material does not show much change with stress. As a consequence, the coupling factor k33 is also reduced with stress. On the other hand, the existence of the local micropolar region in the material causes anomalous changes in the aforementioned properties when the material is subjected to a high electric field, which induces a macropolar state. The transformation of this macropolar state back to a micropolar state under stress involves a large volume strain and results in an enhancement of the hydrostatic piezoelectric response.

A high sensitivity hydrostatic piezoelectric transducer based on transverse piezoelectric mode honeycomb ceramic composites

A new piezoelectric composite transducer based on the ceramic honeycomb structure is introduced. The transducer is operated in the transverse piezoelectric (TP) d/sub 31/ mode. The ceramic honeycomb configuration enables one to fabricate a TP honeycomb transducer by either embedding a honeycomb ceramic skeleton into a soft polymer matrix to form a composite or by blocking the openings of the honeycomb cells with thin layers of epoxy to form an end-capped honeycomb structure. With the unique honeycomb configuration and TP operation mode, the piezoelectric d/sub 33/ response of the ceramic is nearly eliminated and the piezoelectric responses from the three orthogonal directions add together when the transducer is subjected to a hydrostatic pressure. As a result, the transducer exhibits exceptionally high hydrostatic piezoelectric response.

A new transverse piezoelectric mode 2-2 piezocomposite for underwater transducer applications

In this paper, we present a new type of 2-2 piezoelectric ceramic-polymer composite operated at the transverse piezoelectric mode (TP). The new TP mode piezocomposite has exceptionally high hydrostatic piezoelectric response, high reliability, and can be made at low cost. Based on the isostrain approximation, an analytical model is developed to analyze and optimize the effective piezoelectric and the effective elastic properties of the composite. Several composites with the new structure were fabricated and tested. The calculated and experimental results show good agreement. It is shown that a TP 2-2 composite made of PZT plates in a soft polymer matrix with elastically unidirectional face plates yields an effective hydrostatic piezoelectric coefficient d/sub h/ of 6000 (pC/N) and a hydrostatic figure of merit d/sub h/g/sub h/ higher than 30000 (10/sup -15/ m/sup 2//N). >

Effects of face plates and edge strips on hydrostatic piezoelectric response of 1-3 composites

Abstract Piezoceramic-polymer composites with 1–3 connectivity provide higher hydrostatic figure of merit dhgh , and low density, which make them attractive for underwater applications. By incorporating rigid face plates on the composite electrode surfaces, the transverse piezoelectric response can be reduced effectively and dh increased significantly. When edge strips are put on the lateral dimensions, the hydrostatic response of the composite may be further improved, depending on the ratio of the sample thickness to the sample lateral dimensions and the elastic properties of the edge strips. In this work the effects of the rigid face plates and the edge strips on the piezoelectric response of 1–3 composites with different lateral dimensions were investigated. All the experimental features can be well accounted for by using the shear-coupling model developed recently by us and the isostrain model. Based on these results the relationship between the dh of the face plated 1–3 composite and the elastic prop...

(Pb, Bi)(Ti, Fe, Mn)O3/Polymer 0-3 composites for hydrophone applications

The hydrostatic piezoelectric response of composite materials incorporating (Pb1-xBix)(Ti1-xFex)O3 ceramic fillers from the highly anisotropic tetragonal region of the solid solution system in the vicinity of the morphotropic phase boundary were measured and compared. The considerable difficulty in poling and, hence, the diminished piezoelectric response encountered as the composition of the filler is shifted closer to the phase boundary was determined to be largely due to the high conductivity of the BiFeO3-rich compositions. The ceramic was modified with Mn in an attempt to lower its conductivity. Composites incorporating the Mn-doped filler poled more rapidly and easily than the undoped material and ultimately achieved a hydrostatic figure of merit, dhgh, 40% better than that observed for the undoped samples. Among the samples investigated, the highest hydrostatic figures of merit were exhibited by samples containing the doped and undoped x = 0.5 fillers. The hydrostatic response remains stable over a ...

Acoustic and Elastic Properties of PZT Ceramics with Anisotropic Pores

It has been shown that anisotropic porosity in PZT reduces the d31/d33, ratio, raising the hydrostatic piezoelectric response of PZT significantly. In the present work, this behavior is related to Poisson's ratio by applying the Gibbs thermodynamic energy function, literature data for dense PZT ceramics and for materials with hexagonal crystal symmetry, and experimental results for PZT with anisotropic porosity. Acoustic as well as mechanical tests of PZT ceramics with anisotropic pores demonstrate the elastic anisotropies that cause the reduction in Poisson's ratio. The dependence of d31/d33 on Poisson's ratio is also detailed. In addition, a close relation between d31/d33 and the longitudinal acoustic velocity is demonstrated. Flexural strength tests indicate that anisotropic pores provide dhn‐enhanced PZT ceramics with significantly greater strength than isotropic pores.

Piezoelectric response in trifluoroethylene copolymers of vinylidene fluoride

The copolymer system of polyvinylidene fluoride-trifluoroethylene, P(VDF-TrFe), has been shown to exhibit a Curie temperature Tc that is dependent upon the monomer ratio. Below this temperature the copolymer is in a ferroelectric phase similar to the stretched homopolymer, Polyvinylidene fluoride, PVDF. The piezoelectric response of this copolymer system for oriented, well-poled samples is very similar to and in some cases better than PVDF. Again the piezoelectric response may also depend upon the monomer ratio. However, when the copolymer with a monomer ratio of 3/1 for VDF/TrFE is poled above Tc and subsequently annealed it has an exceptionally high percentage crystallinity and an electromechanical coupling coefficient of 0.3. These values are for undrawn samples and can be used to predict a hydrostatic piezoelectric response approximately two to three times better than PVDF. These concepts and possible new data will be presented.