Ultrahigh Piezoelectric Response Research Articles

Significantly enhancing high-temperature piezoelectric response and Tdr of BF-BT-based ceramics through multi-component optimization strategy

Phase boundary-domain engineering modulation with diverse group elements and coexistence of multiphase and composite domain structures is a good pathway that can be realized to simultaneously improve the piezoelectric properties of BF-BT ceramics and their thermal stability. Here, we propose a multicomponent optimization strategy. We innovatively introduce the 0.8(Bi0.5Na0.5)TiO3-0.2(Bi0.5K0.5)TiO3 (BNT-20BKT) component to 0.69BF-0.31BT ceramic, to build a morphotropic phase boundary (MPB) for enhancing d33. Meanwhile, Bi(Zn0.5Ti0.5)O3 with high Curie temperature and high tetragonal degree was introduced with the expectation of obtaining higher thermal stability along with high piezoelectric properties. The 0.69BiFeO3-0.31BaTiO3-0.005[0.8(Bi0.5Na0.5)TiO3-0.2(Bi0.5K0.5)TiO3]-xBi(Zn0.5Ti0.5)O3 (referred to as BF31BT-0.005(BNT-20BKT)-xBZT, 0.00 ≤ x ≤ 0.025) ceramics were successfully prepared. For the first time, an ultra-high piezoelectric performance of 749.6 pC/N was achieved at a real-time depolarization temperature (Tdr) of 395.6 °C, reflecting the real-time piezoelectric properties and ultra-high temperature stability of the ceramic at high temperatures. A two-phase coexisting structure of R and PC phases was produced in BF31BT-0.005(BNT-20BKT)-0.025BZT ceramic. TEM results showed the formation of nanodomains and a large number of polar nanoregions (PNRs). By adjusting the appropriate R/PC phase ratio, oxygen octahedral distortion, and optimizing the local domain engineering, an effective strategy is provided for simultaneously achieving ultra-high temperature stability and ultra-high piezoelectric response.

Ultrahigh Piezoelectric Response Obtained by Artificially Generating a Large Internal Bias Field in BiFeO3–BaTiO3 Lead‐Free Ceramics

AbstractPiezoelectric actuators are vital devices that convert electrical signals into mechanical strain, offering rapid and precise responses. Lead‐based piezoceramics have traditionally been the preferred choice for commercial piezoelectric actuators, while the low Curie temperature and the rising environmental concerns hinder their applications at high temperatures. In this study, a novel strategy is proposed to achieve high piezoelectric responses in lead‐free 0.67Bi1.05FeO3–0.33BaTiO3 (67BF‐33BT) ceramics with high Curie temperature by artificially generating a large internal bias field through repeat poling and aging treatments. A comprehensive exploration of how this internal bias field responds to applied electric fields and temperature variations has been conducted. The results suggest that the internal bias field originates from two aspects, one arises from the free charges that compensate for the depolarization field, while the other is attributed to the highly oriented defect dipoles. As a result of this internal bias field, the ceramics exhibit asymmetric strain–electric field (S–E) behaviors, resulting in a high strain (ε = 0.21%) and an extremely high piezoelectric coefficient (d33* = 1033.70 pm V−1) when subjected to low electric field (20 kV cm−1), along with good temperature stability from room temperature (RT) to 100 °C.

Polarization extension yielding ultrahigh piezoelectric response in xPb(Nb2/3Ni1/3)O3-(1-x)Pb(Zr0.3Ti0.7)O3 ferroelectrics ceramics

The heightened piezoelectric performance observed in most explored perovskite systems is typically attributed to the electric-field-induced phase transition near the morphotropic phase boundary (MPB) or polymorphic phase boundary (PPB). This study, however, unveils a distinct piezoelectric enhancement mechanism in the xPb(Nb2/3Ni1/3)O3-(1–x)Pb(Zr0.3Ti0.7)O3 (PNN-PZT) system, diverging from the MPB/PPB-centered piezoelectric systems. Notably, the composition with x = 0.55, positioned close to the tetragonal-pseudocubic (T-PC) phase boundary, achieves an unprecedented piezoelectric coefficient (d33) of 1264 pC/N, while retaining a tetragonal local structure. Importantly, on a local scale, electric fields do not incite phase transitions, suggesting that the exceptional piezoelectric performance in PNN-PZT stems from polarization extension near the T-PC boundary. Distinct from other mechanisms, the relative permittivity significantly increases post-poling due to this particular enhancement process. The dielectric behavior in poled specimens does not exhibit a conspicuous change at the ferroelectric-relaxor transition temperature. However, both the relative permittivity and planar electromechanical coupling coefficient experience a sharp rise in the temperature range of −25 °C to 25 °C. This investigation underscores the pivotal role of designing compositionally-driven T-PC phase boundaries, presenting a promising avenue for enhancing piezoelectric properties in ferroelectric ceramics.

Effect of Sb-induced oxygen octahedral distortion on piezoelectric performance and thermal stability of Pb(In,Nb)O3-Pb(Hf,Ti)O3 ceramics

The combination of excellent thermal stability and outstanding electrical performance is of great significance for piezoelectric ceramics. Herein, we have prepared 0.11Pb(In0.5Nb0.5)O3-0.89Pb(Hf0.47Ti0.53)O3-Sb2O5 (PIN-PHT-xSb) ceramics by solid-phase method and investigated the effect of oxygen octahedral lattice distortion on microstructure and macroscopic electrical properties. The distortion index of oxygen octahedra is studied by Rietveld refinement, showing that optimal octahedral distortion can soften B-O repulsion, disrupt long-range ordered ferroelectric domains, and enhance local heterogeneities, significantly increasing piezoelectric properties. Moreover, outstanding thermal stability and ultrahigh piezoelectric response of PIN-PHT-1.2Sb ceramics are realized under the synergistic influence of octahedral distortion, excellent density, and large grain size. Compared with PIN-PHT ceramics, PIN-PHT-1.2Sb ceramics exhibit ultrahigh piezoelectric responses (d33 = 706 pC/N, kp = 0.68, εr = 3244), a high Curie temperature (TC) of 300 °C, excellent thermal stability, and anti-fatigue properties.

Self-powered multifunctional body motion detectors based on highly compressible and stretchable ferroelectrets with an air-filled parallel-tunnel structure

The new kind of ferroelectret electroactive polymers for flexible film sensors represent an attractive opportunity for self-powered wearable devices, which could offer sustainable and convenient health care services for people without the problem of energy supply. However, due to the mechanical heterogeneity, obtaining ferroelectrets with both a high longitudinal and transverse piezoelectric response is still a great challenge, which limits its multifunctional sensing application, especially in body motion tracking. Herein, we develop an air-filled parallel tunnel ferroelectret-based self-powered body motion detectors. Ascribed to the high mechanical compression and tensile properties of the specially designed parallel tunnel void structure and excellent charge storage stability of the fluorinated polyethylene propylene (FEP) electret film, these laminated films exhibit many fascinating merits, including ultrahigh longitudinal piezoelectric response (piezoelectric coefficient of 6200 pC/N, pressure sensitivity of 1950 pC/kPa), wide pressure detection range (0.03–62 kPa), remarkable transverse piezoelectric response (tensile sensitivity of 1600 pC/mm), long-term durability (1,08,0000 cycles), and superior friction force detection capability. This is the first work, to our knowledge, that ever use one kind of piezoelectric mechanism in a single ferroelectret-based sensor to achieve longitudinal stress, transverse stress, and tangential friction force sensing. Furthermore, on the basis of such sensors and machine learning algorithms, we designed an intelligent gesture recognition system for future human-machine interaction applications. Looking forward, our material design methodologies offer an approach to the self-powered flexible multifunctional sensor with great prosperity in household healthcare, smart mobile medical electronics, and humanoid robots.

Grain-Oriented Ferroelectric Ceramics with Single-Crystal-like Piezoelectric Properties and Low Texture Temperature

High-performance piezoelectrics are pivotal to various electronic applications including multilayer actuators, sensors, and energy harvesters. Despite the presence of high Lotgering factor F001, two key limitations to today's relaxor-PbTiO3 textured ceramics are low piezoelectric properties relative to single crystals and high texture temperature. In this work, Pb(Yb1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PYN-PMN-PT) textured ceramics with F001 ∼ 99% were synthesized at only 975 °C through liquid-phase-assisted templated grain growth, where of particular significance is that single-crystal properties, i.e., very large electrostrain Smax/Emax ∼ 1830 pm V-1, giant piezoelectric figure of merit d33 × g33 ∼ 61.3 × 10-12 m2 N-1, high electromechanical coupling k33 ∼ 0.90, and Curie temperature Tc ∼ 205 °C, were simultaneously achieved. Especially, the Smax/Emax and d33 × g33 values correspond to ∼180% enhancement as compared to the regularly 1200 °C-textured ceramics with F001 ∼ 96%, representing the highest values ever reported on piezoceramics. Phase-field simulation revealed that grain misorientation has a stronger influence on piezoelectricity than texture fraction. The ultrahigh piezoelectric response achieved here is mainly attributed to effective control of grain orientation features and domain miniaturization. This work provides important guidelines for developing novel ceramics with significantly enhanced functional properties and low synthesis temperature in the future and can also greatly expand application fields of piezoceramics to high-performance, miniaturized electronic devices with multilayer structures.

Factors contributing to the local polar-structural heterogeneity and ultrahigh piezoelectricity in Sm-modified Pb(Mg1/3Nb2/3)O3–PbTiO3

Recently, an ultrahigh piezoelectricity (longitudinal piezoelectric coefficient d33 ~ 1500 pC/N) was reported in polycrystalline specimens of Sm-modified relaxor ferroelectric system Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) (Li et al 2018 Nat. Mater. 17 349). Here, we examine the factors associated with this anomalous phenomenon by carrying out a comparative structural, dielectric, ferroelectric and impedance spectroscopy on Sm-free 0.71PMN-0.29PT (piezoelectric coefficient d33 ~ 380 pC/N) and its Sm modified counterpart (d33 ~ 1160 pC/N). We found that, apart from inducing a Cm → P4mm inter-ferroelectric instability, Sm modification stabilizes a considerable degree of oxygen vacancies, with Sm exhibiting valence fluctuation. Based on our results, we argue that these defect types are the important source for creating structural-polar heterogeneity on the local scale, the interaction of which with the long-range ferroelectric order makes the system exhibit an ultrahigh piezoelectric response.

Large flexoelectric response in PMN-PT ceramics through composition design

Flexoelectricity yields electric polarization through graded strains and exists in various kinds of solid dielectrics but usually with a weak coupling response. In this letter, several Bi-doped Pb(Mg2/3Nb1/3)O3-xPbTiO3 (PMN-xPT) ferroelectric ceramics were prepared and the interplay of their piezoelectricity and flexoelectricity was systematically investigated. The largest flexoelectric response (∼300 μC/m) was 30 times larger than that of pure PMN-PT and was observed in the Bi-doped PMN-32PT, where the after poling piezoelectric coefficients were also the largest (990 pC/N) among all the compositions. This suggests that the apparent flexoelectricity in ferroelectrics is highly related to the bulk piezoelectricity. Therefore, introducing a local structural heterogeneity is considered as a feasible approach to achieve an ultrahigh piezoelectric response while also providing an ultrahigh flexoelectricity.

Microscopic origin of the high piezoelectric response of Sm-doped BiFeO3 near the morphotropic phase boundary

Rare-earth element-doped BiFeO3 has an ultrahigh piezoelectric response near the morphotropic phase boundary (MPB), making it a promising substitute for toxic lead-based piezoelectric materials. As a ferroelectric–antiferroelectric MPB, its microscopic mechanism, especially the contribution of each phase to the piezoelectric performance, is still unclear. In this work, the origin of the giant piezoelectric response of Sm-doped BiFeO3 thin films was studied by combining nanoscale in situ electric field experiments and atomic-resolution electron microscopy. Two independent reversible phase transitions were found under an external electric field: a phase transition between the polar and nonpolar phases and a phase transition between the polar and antipolar phases. Calculations indicated that the enhancement of the piezoelectric response at the MPB originated from these two reversible phase transitions, which were realized via the nucleation of the nanoscale new phase and the motion of the phase boundary under the external electric field. The above results provide deeper insight into the mechanism of the electromechanical response near the ferroelectric–antiferroelectric MPB in rare-earth element-doped BiFeO3 thin films.

Giant electromechanical coupling of relaxor ferroelectrics controlled by polar nanoregion vibrations.

Relaxor-based ferroelectrics are prized for their giant electromechanical coupling and have revolutionized sensor and ultrasound applications. A long-standing challenge for piezoelectric materials has been to understand how these ultrahigh electromechanical responses occur when the polar atomic displacements underlying the response are partially broken into polar nanoregions (PNRs) in relaxor-based ferroelectrics. Given the complex inhomogeneous nanostructure of these materials, it has generally been assumed that this enhanced response must involve complicated interactions. By using neutron scattering measurements of lattice dynamics and local structure, we show that the vibrational modes of the PNRs enable giant coupling by softening the underlying macrodomain polarization rotations in relaxor-based ferroelectric PMN-xPT {(1 - x)[Pb(Mg1/3Nb2/3)O3] - xPbTiO3} (x = 30%). The mechanism involves the collective motion of the PNRs with transverse acoustic phonons and results in two hybrid modes, one softer and one stiffer than the bare acoustic phonon. The softer mode is the origin of macroscopic shear softening. Furthermore, a PNR mode and a component of the local structure align in an electric field; this further enhances shear softening, revealing a way to tune the ultrahigh piezoelectric response by engineering elastic shear softening.

Ferroelectric origin in one-dimensional undoped ZnO towards high electromechanical response

Ferroelectricity in ZnO is an unlikely physical phenomenon. Here, we show ferroelectricity in undoped [001] ZnO nanorods due to zinc vacancies. Generation of ferroelectricity in a ZnO nanorod effectively increases its piezoelectricity and turns the ZnO nanorod into an ultrahigh-piezoelectric material. Here using piezoelectric force microscopy (PFM), it is observed that increasing the frequency of the AC excitation electric field decreases the effective d33. Subsequently, the existence of a reversible permanent electric dipole is also found from the P–E hysteresis loop of the ZnO nanorods. Under a high resolution transmission electron microscope (HRTEM), we observe a zinc blende stacking in the wurtzite stacking of a single nanorod along the growth axis. The zinc blende nature of this defect is also supported by the X-ray diffraction (XRD) and Raman spectra. The presence of zinc vacancies in this basal stacking fault modulates p–d hybridization of the ZnO nanorod and produces a magnetic moment through the adjacent oxygen ions. This in turn induces a reversible electric dipole in the non-centrosymmetric nanostructure and is responsible for the ultrahigh-piezoelectric response in these undoped ZnO nanorods. We reveal that this defect engineered ZnO can be considered to be in the competitive class of ultrahigh-piezoelectric nanomaterials for energy harvesting and electromechanical device fabrication.

Unusual domain configurations and local piezoresponse in the [720]‐cut BaTiO3 single crystal

AbstractThe domain configurations and local piezoresponse property of the [720]‐cut BaTiO3 single crystal and [001]‐oriented BaTiO3 crystal were investigated by high‐resolution piezoresponse force microscopy. Large differences in their surface topography features, domain configurations and local piezoresponse were found between [720]‐cut and [001]‐oriented BaTiO3 crystals. The large surface bending angle due to ferroelastic domain walls leads to a high strain energy appearing in the [720]‐cut BaTiO3, further resulting in unique band‐like topographic features, needle domains for stress compensation and locally ultrahigh piezoelectric response as well. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Electromechanical properties of Pb(In1/2Nb1/2)O3–Pb(Mg1/3Nb2/3)O3–PbTiO3 single crystals

The Pb(In(1∕2)Nb(1∕2))O(3)-Pb(Mg(1∕3)Nb(2∕3))O(3)-PbTiO(3) (PIN-PMN-PT) crystals were studied as function of phase and orientation. The properties, including the Curie temperature T(C), ferroelectric-ferroelectric phase transition temperature T(R∕O-T), coercive field, and piezoelectric∕dielectric responses, were systematically investigated with respect to the composition of PIN-PMN-PT crystals. The Curie temperature T(C) was found to increase from 160 to 220 °C with ferroelectric-ferroelectric phase transition temperature T(R-T) and T(O-T) being in the range of 120-105 °C and105-50 °C, respectively. The piezoelectric activity of PIN-PMN-PT crystals was analyzed by Rayleigh approach. The ultrahigh piezoelectric response for domain engineered [001] (1600-2200 pC∕N) and [011] (830-1550 pC∕N) crystals was believed to be mainly from the intrinsic contribution, whereas the enhanced level of piezoelectric and dielectric losses at the compositions around morphotropic phase boundaries (MPBs) was attributed to the phase boundaries motion.

Composition and phase dependence of the intrinsic and extrinsic piezoelectric activity of domain engineered (1−x)Pb(Mg1/3Nb2/3)O3−xPbTiO3 crystals

The piezoelectric response of [001] poled domain engineered (1-x)Pb(Mg(13)Nb(23))O(3)-xPbTiO(3) (PMN-PT) crystals was investigated as a function of composition and phase using Rayleigh analysis. The results revealed that the intrinsic (reversible) contribution plays a dominant role in the high piezoelectric activity for PMN-PT crystals. The intrinsic piezoelectric response of the monoclinic (M(C)) PMN-xPT crystals, 0.31</=x</=0.35, exhibited peak values for compositions close to R-M(C) and M(C)-T phase boundaries, however, being less than 2000 pCN. In the rhombohedral phase region, x</=0.30, the intrinsic piezoelectric response was found to increase as the composition approached the rhombohedral-monoclinic (R-M(C)) phase boundary. The maximum piezoelectric response was observed in rhombohedral PMN-0.30PT crystals, being on the order of 2500 pCN. This ultrahigh piezoelectric response was determined to be related to the high shear piezoelectric activity of single domain state, corresponding to an ease in polarization rotation, for compositions close to a morphotropic phase boundary (MPB). The role of monoclinic phase is only to form a MPB with R phase, but not directly contribute to the ultrahigh piezoelectric activity in rhombohedral PMN-0.30PT crystals. The extrinsic contribution to piezoelectric activity was found to be less than 5% for the compositions away from R-M(C) and M(C)-T phase boundaries, due to a stable domain engineered structure. As the composition approached MPBs, the extrinsic contribution increased slightly (<10%), due to the enhanced motion of phase boundaries.

Polarization rotation and multiphase coexistence forPb(Mg1/3Nb2/3)O3-PbTiO3single crystals at the morphotropic phase boundary under electric loading

In situ observations of the domain evolution and the polarization rotation under bipolar cyclic and static electric fields are carried out for [001]-oriented $68\text{Pb}({\text{Mg}}_{1/3}{\text{Nb}}_{2/3}){\text{O}}_{3}\text{\ensuremath{-}}32{\text{PbTiO}}_{3}$ (PMN-32PT) single crystal which is located at the morphotropic phase boundary (MPB). The results demonstrate that after being poled in [001] direction, the original rhombohedral $(R)$ phase is transformed into a monoclinic ${M}_{C}$ phase with $Pm$ space group. When the single crystal is subjected to bipolar cyclic electric field, distinct domain-boundary structures are revealed which are unlikely to be detected in static electric loadings. The existence of $R$ phase is also detected during the polarization reversal. Under static electric field, polarization rotation from ${M}_{C}$ to $R$ occurs and, as the field increases, phase transition from ${M}_{C}$ to tetragonal $(T)$ phase takes place. In the vicinity of regions where ${M}_{C}\text{\ensuremath{-}}T$ phase transition takes place, polarization reversal of ${M}_{C}$ phase is observed, which is attributed to the local stress field from the strain compatibility between the transitioned area and the nontransitioned area. With the removal of the field, $T$ and ${M}_{C}$ phases retain while $R$ phase reverses to ${M}_{C}$ phase. The results demonstrate that the energy differences among ${M}_{C}$, $R$, and $T$ phases are rather slim. Accordingly, the multiphase coexistence and polarization rotation under both cyclic and static electric loadings might be responsible for the ultrahigh piezoelectric response of the [001]-oriented rhombohedral $\text{Pb}({\text{Mg}}_{1/3}{\text{Nb}}_{2/3}){\text{O}}_{3}{\text{-PbTiO}}_{3}$ single crystals near the MPB.

Phase instability induced by polar nanoregions in a relaxor ferroelectric system

Relaxor ferroelectrics are a special class of material that exhibit an enormous electromechanical response and are easily polarized with an external field. These properties make them attractive for applications as sensors and actuators. Local clusters of randomly oriented polarization, known as polar nanoregions (PNRs), are specific to relaxor ferroelectrics and play a key role in governing their dielectric properties. Here, we show through neutron inelastic scattering experiments that the PNRs can also significantly affect the structural properties of the relaxor ferroelectric Pb(Zn(1/3)Nb(2/3))O(3)-4.5%PbTiO(3) (PZN-4.5%PT). A strong interaction is found between the PNRs and the propagation of acoustic phonons. A comparison between acoustic phonons propagating along different directions reveals a large asymmetry in the lattice dynamics that is induced by the PNRs. We suggest that a phase instability induced by this PNR-phonon interaction may contribute to the ultrahigh piezoelectric response of this and related relaxor ferroelectric materials. Our results naturally explain the emergence of the various observed monoclinic phases in these systems.

Ultrahigh piezoelectric response along some special cleavage plane in BaTiO3 single-crystals

Ultrahigh piezoelectric response along easy cleavage plane in BaTiO3 singl e_crystal was found. An extremely high value of piezoelectric coefficient d 33 value over 2000 pC/N was obtained after being poled perpendicular to th is plane of BaTiO3 crystal, which is more than 20 times higher than those poled along spontaneous polarization direction 〈001〉 (d33〈001〉=87p C/N). A large strain of 06% was obtained at a very low electric field. The res ults may generate a wide range of lead_free materials for the piezoelectric tran sducer application.

Ultrahigh piezoelectric response perpendicular to special cleavage plane in BaTiO3 single crystals

We report on the ultrahigh piezoelectric response perpendicular to some special cleavage plane in BaTiO3 single crystals. An extremely high value of piezoelectric coefficient d33 value over 2000pC∕N was obtained after being poled perpendicular to special plane (270) in BaTiO3 crystal, which is more than 20 times higher than those poled along spontaneous polarization direction ⟨001⟩ (d33⟨001⟩=87pC∕N). A large strain of 0.6% was obtained at a very low electric field.

Electric-field-induced strain and piezoelectric properties of a high Curie temperature Pb(In 1/2Nb 1/2)O 3–PbTiO 3 single crystal

The temperature dependence of dielectric and piezoelectric properties, electric-field-induced strains of 0.66 Pb(In 1/2Nb 1/2)O 3–0.34 PbTiO 3 single crystals, which were grown directly from melt by using the modified Bridgman technique with the allomeric Pb(Mg 2/3Nb 1/3)O 3–PbTiO 3 seed crystals, were determined as a function of crystallographic orientation with respect to the prototypic (cubic) axes. Ultrahigh piezoelectric response ( d 33∼2000 pC/N, k 33∼94%) and strain levels up to 0.8%, comparable to rhombohedral (1− x)Pb(Mg 2/3Nb 1/3)O 3– xPbTiO 3 and (1− x)Pb(Zn 2/3Nb 1/3)O 3– xPbTiO 3 single crystals, were observed for the 〈0 0 1〉-oriented crystals. Strain levels up to 0.47% and piezoelectric constant d 33∼1600 pC/N could be achieved being related to an electric-field-induced rhombohedral–orthorhombic phase transition for the 〈1 1 0〉-oriented crystals. In addition, high electromechanical coefficients k 33 (∼88%) can be achieved even heating to 110 °C. High T C (∼200 °C), large electromechanical coefficients k 33 (∼94%) and low dielectric loss factor (∼1%), along with large strain make the crystals promising candidates for a wide range of electromechanical transducers.