Hydrostatic Piezoelectric Coefficient Research Articles

Polarisation Orientation Effects and Hydrostatic Parameters in Novel 2–2 Composites Basedon PMN–xPT Single Crystals

Polarisation orientation effects in piezo-active composites based on relaxor-ferroelectric single crystals of (1–x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 open up new possibilities to vary the effective electromechanical properties and related parameters. In the present paper the hydrostatic performance of 2–2 parallel-connected single crystal / auxetic polymer composites is studied for x = 0.28 – 0.33 and two poling directions of the single-crystal component, [001] (4mm symmetry) and [011] (mm2 symmetry) in the perovskite unit cell. The effect of the orientation of the main crystallographic axes in the single-crystal component on the hydrostatic piezoelectric coefficients d*h, eh* and squared figure of merit d*hgh* is analysed for three rotation modes in single crystals and at various anisotropy of their piezoelectric and elastic properties. The role of the auxetic polymer component is emphasised in the context of the large hydrostatic parameters and anisotropy of squared figures of merit d*3jg3j* (j = 1, 2 and 3). The largest maximum values of d*h and e*h (1990 pC/N and 42.5 C/m2, respectively) are achieved in the composite based on [011]-poled 0.71Pb(Mg1/3Nb2/3)O3–0.29PbTiO3.

Influence of Electric Field, Temperature and Pressure on Hydrostatic Piezoelectric Coefficient of x(Bi0.5Na0.5)TiO3–y(Bi0.5K0.5)TiO3–pBaTiO Lead-Free Ferroelectric Ceramics

Hysteretic loop measurements of hydrostatic piezoelectric coefficient as a function of temperature and pressure for the lead-free ferroelectric ceramic 0.79(Bi0.5Na0.5)TiO3 – 0.14(Bi0.5K0.5)TiO3 – 0.07BaTiO3 (BNBK79), were realized. Curves of dh – E relation were obtained under applied electric field along polar axis up to temperature of 170°C and pressures in the range from 10 MPa up to 55 MPa. In addition, the temperature dependence of hydrostatic piezoelectric coefficient dh at zero field was studied.

Piezoelectric Properties of a Pioneering 3‐1 Type PZT/Epoxy Composites Based on Freeze‐Casting Processing

Lead zirconate titanate (PbZr1 − xTixO3, PZT)/epoxy composites with one‐ dimensional epoxy in PZT matrix (called 3‐1 type piezocomposites) have been fabricated by tert‐butyl alcohol (TBA)‐based directional freeze casting of PZT matrix and afterward infiltration of epoxy. The composites with PZT volume fraction ranging from 0.36 to 0.69 were obtained by adjusting initial solid loading in freeze‐casting slurry. The effect of poling voltage on piezoelectric properties of the composites was studied for various volume fraction of PZT phase. With the increasing of PZT volume fraction, relative permittivity (εr) increased linearly and piezoelectric coefficient (d33 and d31) increased step by step. The resultant composites with 0.57 PZT volume fraction possessed the highest hydrostatic piezoelectric strain coefficient (dh) value (184 pC/N), voltage coefficient (gh) value (13.6 × 10−3 V/m Pa), and hydrostatic figure of merit (HFOM) value (2168 × 10−15 Pa−1).

Role of Domain Orientations in Forming the Hydrostatic Performance of Novel 2–2 Single Crystal/Polymer Composites

This paper reports results of a detailed study of the effects of the crystallographic orientation on the performance of the 2–2 parallel-connected composites based on relaxor-ferroelectric single crystals of 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3. These single crystals are poled along one of the following directions in the perovskite unit cell: [111] (single-domain state), [001] and [011] (polydomain states). The effect of the orientation of the main crystallographic axes in the single-crystal component on the hydrostatic piezoelectric coefficients d* h , e* h and g* h , squared hydrostatic figure of merit d* h g* h and hydrostatic electromechanical coupling factor k* h of the composites is studied for three cases of the poling direction of 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3. Maximum values of the hydrostatic parameters in the 2–2 0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3 / polyvinylidene fluoride composites are d* h = 372 pC / N, g* h = 284 mV.m/N, d* h g* h = 33.8.10−12 Pa−1, and k* h = 0.361 (in the presence of the [011]-poled single crystal), and e* h = 45.1 C/m2 (in the presence of the [111]-poled single crystal). The inequality k*33/|k*3j | ≥ 5 (j = 1 and 2) is valid for the composite based on the [111]-poled single crystal under specific conditions. The composites exhibit remarkable properties, and the elastic and piezoelectric anisotropy of the single-crystal component (either [111]- or [011]-poled) plays an important role in achieving the large hydrostatic parameters.

THE HYDROSTATIC PIEZOELECTRICITY OF RELAXOR-PbTiO3 FERROELECTRIC CERAMICS AND CRYSTALS

The hydrostatic piezoelectricity of Pb ( Mg 1/3 Nb 2/3)–x PbTiO 3 (PMN–xPT) ceramics and PMN–0.32PT and Pb(Mg1/3Nb2/3)–Pb(In1/2Nb1/2)–PbTiO3 (PMN–PIN–PT) crystals were investigated through a quasi-static method. The results showed that pressure-induced depolarization occurred in PMN–xPT ceramics when pressure was above about 50 MPa, while there was no obvious pressure-induced depolarization for PMN–0.32PT and PMN–PIN–PT crystals in the whole pressure range (0~530 MPa). The hydrostatic piezoelectric coefficient d h of PMN–0.32PT and PMN–PIN–PT crystals was nearly independent of pressure. The d h of mono-domain orthorhombic and tetragonal phase crystals is slightly larger, on the order of 100 pC/N. In addition, the relationship between the hydrostatic piezoelectric coefficient d h and the longitudinal and transverse piezoelectric coefficients d33 and d31 for different crystal systems was summarized.

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.

Novel High-Sensitivity Composites Based on Ferroelectric Ceramics

The structure of a high-sensitivity 1–3-type composite is studied. The effect of the anisotropy of elastic moduli of the 0–3 matrix on piezoelectric sensitivity, hydrostatic piezoelectric coefficient and anisotropy of electromechanical coupling factors is analysed. Effective parameters are predicted and analysed for the 1–0–3 composite based on modified lead titanate ceramic. The large values of piezoelectric coefficients g*33 ≈ 400 mV.m/N and g* h ≈ 200 mV.m/N and the considerable anisotropy of electromechanical coupling factors (k*33/k*31 ≈ –15, k* t /k* p ≈ –9) of the studied composite are discussed.

Anisotropy Factors and Hydrostatic Parameters of 1–3-Type Piezo-Active Composites with Auxetic Polymer Matrices

Results on electromechanical properties and their anisotropy in 1–3-type composites with auxetic polyethylene matrices (Poisson's ratios from –0.83 to –0.20) are reported. The role of elastic properties of the auxetic component in forming a large piezoelectric anisotropy and hydrostatic piezoelectric coefficients d* h ≈ (1000–1500) pC/N and g* h ≈ (500– 600) mV.m/N, figures of merit, and electromechanical coupling factors is studied. Condition d*33/d*31→±∞ is valid at the volume fraction of ceramic 0.22≤ m*≤ 0.33, and m* correlates with the ratio c11/|c12| of elastic moduli of polymer. The effect of the aspect ratio of the elliptic cross section of rods on the volume-fraction dependence of d*3j , the piezoelectric anisotropy, and hydrostatic response is analysed.

Properties Evaluation of Piezoelectric Materials in Application of Cochlear Implant

Piezoelectric materials for their particular acoustic-electric transition characteristics could be used to cochlear implant. A series experiments both in vitro and vivo were described in this paper so as to understand the function of different parameters for acoustic-electric transition in the hydrostatic environment of inner ear. The vitro experiment indicated that the voltages produced by piezoelectric materials were mainly concerned with the hydrostatic piezoelectric voltage coefficient gh. The vivo experiment substantiated the feasibility of piezoelectric cochlear again and further analysis showed that factor of merit could be a better parameter to evaluate the properties of piezoelectric materials in application of cochlear implant.

Interrelations Between Microstructure and Piezoelectric Sensitivity in Novel 0–3–0 Composites Based on 0.67Pb(Mg1/3Nb2/3)O3 − 0.33PbTiO3 Single Crystal

This paper reports results on effective piezoelectric properties of advanced composites based on polydomain relaxor-ferroelectric single crystals of 0.67Pb(Mg1/3Nb2/3)O3 − 0.33PbTiO3. Two variants of the single crystal/porous polymer composite with 0–3–0 connectivity are proposed to study the role of microstructural factors in forming high piezoelectric sensitivity. The effective properties of the related 0–3 single crystal/polymer composite are predicted and considered to show ways of increasing the piezoelectric anisotropy and sensitivity. Examples of the volume-fraction and aspect-ratio dependences of the effective piezoelectric coefficients d 3j *, g 3j *, the hydrostatic piezoelectric coefficient gh *, and squared figures of merit d 33* g 33* and dh * gh * of composites are analysed to show in which ranges high piezoelectric sensitivity is attained. The presence of single-crystal polydomain inclusions in the porous 3–0 matrix promotes the large effective parameters (g 33* ∼ 103 mV · m/N, gh * ∼ 103 mV · m/N, d 33* g 33* ∼ 10−10 Pa−1, and dh * gh * ∼ 10−10 Pa−1), and the obvious high-performance advantage of the 0–3–0 composites is discussed taking into account features of their microstructure.

Hydrostatic Piezoelectric Coefficients of the 2–2 Composite Based on [011]-poled 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 Single Crystal

The effect of the polarisation orientation of [011]-poled polydomain PMN-0.29PT single crystal on the hydrostatic piezoelectric coefficients and of a parallel-connected 2–2 composite has been analysed. Orientation and volume-fraction dependences of the piezoelectric coefficients of the 2–2 PMN-0.29PT/polymer composite have been studied to determine extreme points of and in three cases of rotations of the main crystallographic axes of the PMN-0.29PT single crystal. The largest values of the hydrostatic piezoelectric coefficients = 444 pC/N and = 33.1 C/m2 are of interest for hydroacoustic applications. Important contributions from the piezoelectric coefficients and into and , respectively, have been determined near the extreme points of the hydrostatic parameters.

Dielectric properties of [001]-oriented Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystal under hydrostatic pressure

The dielectric properties of [001]-oriented 0.76Pb(Mg1/3Nb2/3)O3–0.24PbTiO3 (PMN–PT24) crystal were investigated as a function of frequency and temperature under hydrostatic pressure. The dependence of remnant polarization of the PMN–PT24 crystal on pressure was also measured. The results showed that both the temperature of the maximum dielectric permittivity T m and the depoling temperature T d of the PMN–PT24 crystal shifted to lower temperature, and the relaxor property became stronger with increasing hydrostatic pressure. The remnant polarization (P r) of the PMN–PT24 crystal decreased linearly with increasing pressure. Consequently, the hydrostatic piezoelectric coefficient, d h, was calculated.

Electromechanical Coupling in the Novel 2–2 Parallel-Connected PMN–0.33PT Single-Domain Crystal/Polymer Composite

This paper considers effective electromechanical properties of the relaxor-ferroelectric crystal/polymer composite with 2–2 connectivity. A single-domain 0.67Pb(Mg1/3Nb2/3)O3—0.33PbTiO3 crystal/polymer composite is proposed in which the polarisation vectors of components are tailored to optimise the electromechanical coupling factors k*3j and k* h . A strong correlation between the hydrostatic electromechanical coupling factor k* h and the hydrostatic piezoelectric coefficient d* h is observed near min k* h and max k* h . Examples of the condition k* 31 =k* 32 are also considered. The specific advantages and potential of the 2–2 composite in terms of its considerable d* h and k* h values are discussed in connection with the studied orientation effect.

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.

Prediction of relationships between hydrostatic coefficients and processing parameters of porous PZT ceramics by radial basis function

Abstract The high hydrostatic coefficients of porous piezoelectric materials provide the reduced acoustic impedance for the effective coupling with water medium as well as biological tissues. The hydrostatic strain coefficient (dh), voltage coefficients (gh) and longitudinal piezoelectric coefficient (d33) of porous piezoelectric materials has a strong dependence on processing parameters such as porosity parameter, polymer percentage, density and poling voltage. In this work, a nonparametric regression has been carried out to figure out the nonlinear relationships between the hydrostatic coefficients and its processing parameters. The nonparametric regression has been carried out by artificial neural network. The Network architecture utilized is radial basis function (RBF) which is combined with Fuzzy Clustering Method (FCM) to identify the hidden node numbers and widths. The porosity parameter was calculated from scanning electron micrographs of the porous piezoelectric materials using conventional image processing techniques. The results of the artificial neural network were evaluated against experimental data.

Auxetic behavior under electrical loads in an induced ferroelectric phase

The longitudinal and transverse strains were measured as a function of applied electric fields in a bulk ceramic sample of Pb0.99Nb0.02[(Zr0.57Sn0.43)0.94Ti0.06]0.98O3 at room temperature. Instead of a transverse contraction, a transverse expansion was observed in the electric-field-induced ferroelectric phase after the antiferroelectric-to-ferroelectric phase transition. Therefore, an auxetic behavior was established in monolithic ferroelectric polycrystalline ceramics under electrical loads. The behavior is characterized by a negative strain ratio that is analogous to the Poisson’s ratio. The transverse expansion leads to a large hydrostatic piezoelectric coefficient dh, which suggests new applications of antiferroelectric ceramics in piezoelectric devices.

The Influence of DC Electric Field on Piezoelectric Coefficients of PZT Ceramics

The paper deals with the non-linear properties of the piezoelectric ceramics Pb(Zr x Ti 1 − x )O 3 (PZT) at room temperature. The influence of DC electric field on the material parameters, such as piezoelectric coefficients d 31 and d 33 of PZT ceramics, was studied using the resonance method. The dependence of the resonance and antiresonance frequencies of PZT resonators on DC electric field was measured. Hydrostatic piezoelectric coefficients d h , calculated from d 33 and d 31 piezoelectric coefficients, were compared with d h coefficients, that were measured directly by dynamic hydrostatic method. Electric field limits for application on PZT ceramics were determined. A remarkable influence of the DC electric field on d 31 and d 33 piezoelectric coefficients values was exhibited for soft PZT ceramics (APC 850 and APC 856).

Piezoelectric Properties of PZT‐Based Ceramic with Highly Aligned Pores

Porous lead zirconate titanate–lead zinc niobate (PZT–PZN) piezoelectric ceramics with a high degree of pore alignment were fabricated using directional freeze casting of a ceramic/camphene slurry. Well‐aligned pores were formed as the replica of the camphene dendrites that grew in a preferential orientation, while a high porosity of 90% was achieved by employing a low initial solid loading of 5 vol%. As the orientation angle of the pores to the poling direction was decreased, the hydrostatic piezoelectric properties, such as hydrostatic piezoelectric strain coefficient (dh), the hydrostatic piezoelectric voltage coefficient (gh), and the hydrostatic figure of merit, increased significantly. The sample containing pores aligned parallel to the poling direction showed an extremely high HFOM of 161019 × 10−15 Pa−1, which was ∼1300 times higher than that (124 × 10−15 Pa−1) of the dense sample, owing to the presence of aligned pores.

Non-Linear Hysteresis Properties of PZT Ceramics

The paper deals with the dynamic measurement of the hydrostatic piezoelectric coefficients of Pb(Zr x Ti1 − x )O 3 (PZT) piezoelectric ceramics. The non-linear phenomena as the influence of a DC electric field on the hydrostatic voltage coefficient g h of a PZT sample was studied at various temperatures. Values of the coercive field were determined and compared with ones obtained from polarization vs. electric filed P(E) hysteresis loop measurements. Using the LVDT sensor, the deformation vs. electric field S(E) hysteresis loop, measured in the wide temperature range, was provided too. A noticeable influence of the temperature on coercive field values was exhibited both for hard and soft PZT ceramics (APC 841 and APC 856).

Pressure Dependence of Cymbal Transducers

The hydrostatic pressure limit that a receiver can withstand without failure is of major importance in underwater sonar systems. In this paper, the hydrostatic pressure tolerance and sensitivity of cymbal receivers were investigated. The failure mode in cymbal transducers under hydrostatic pressure is described. Effects of cavity geometry and material selection on hydrostatic piezoelectric coefficients and pressure limits were evaluated using both experimental data and finite-element analysis (FEA). It was found that cavity depth has a very strong effect on the stability of underwater sensitivity and pressure tolerance of these devices. Cymbals made with soft piezoelectric transducers (PZTs) possess higher figures of merit and better pressure tolerance than those made with hard PZTs. Alternatively, the cymbal sensitivity and pressure tolerance can be improved by changing the cap material.