Piezoelectric Strain Coefficient D33 Research Articles

Development of high-performance piezoelectric composites for concrete construction through carbonation of calcium and magnesium-based binder

The use of cementitious piezoelectric composite enables structure monitoring of concrete construction, while its piezoelectric and mechanical performance are relatively low. This paper developed a novel high-performance piezoelectric composite through carbonation of calcium and magnesium-based binder (including Ca(OH)2 and Mg(OH)2). The influence of PZT volume, forming regime, and polarization condition on compressive strength and piezoelectric strain coefficient (d33) of the two piezoelectric composites was investigated. Results showed that the use of PZT volume from 20 % to 80 % led to a 6-fold and 3-fold greater d33 value for Ca(OH)2 and Mg(OH)2 piezoelectric composites, respectively. While, such change in PZT volume reduced the compressive strength by 50 % and 55 % for the two piezoelectric composites. This is due to the significantly increased porosity and decreased carbonation degree as indicated by microstructural analysis. The use of a higher forming pressure from 25 to 100 MPa resulted in 60 % and 105 % increases in d33 values for the two piezoelectric composites. Such improvements in compressive strength were 120 % and 135 %, respectively. The d33 values were increased by 45 % and 60 % with the polarization voltage increasing from 1.5 to 3.5 kV/mm for the two piezoelectric composites. Such increases in d33 were 64 % and 94 % when polarization duration extended from 5 to 25 min. This study determined the optimal preparation regime of the two piezoelectric composites that can ensure the best overall performance considering the trade-off among piezoelectric, mechanical, and microstructural properties of the composites. The results of this paper can facilitate the application of novel and high-performance of piezoelectric sensor in smart concrete structures.

Impact of Ca2+ and Zr4+ substitution on mechanical energy harvesting response of lead-free BaTiO3 piezoceramics with thermally stable storage density and efficiency

The Ba1-xCaxZryTi1-yO3 (BCZT; x = 0.18, y = 0.08; x = 0.15, y = 0.10; x = 0.12, y = 0.12; x = 0.09, y = 0.14; both x and y are in mol. %) piezoceramics were prepared by solid-state reaction method and investigated their energy storage and harvesting responses. The composition x = 0.15, y = 0.10 ( i.e. BCZT-2) reveals the morphotropic phase boundary (MPB) near room temperature with enhanced piezoelectric properties such as piezoelectric charge coefficient (d33) ~ 380 pC/N, piezoelectric strain coefficient (d33*) ~ 583.71pm/V, piezoelectric voltage coefficient (g33) ~ 14.09 ×10-3Vm/N, figure of merits (d33×g33) ~ 5.35 ×10-12m2/N and the electromechanical coupling coefficient (kp) ~ 0.291. The harvested peak-to-peak open circuit AC voltage is 30V and the calculated current is in the range of 0.02 to 0.14mA with varied load resistance and the maximum obtained power density is 13.38 μW/mm3 for BCZT-2 ceramics. The DC output signal of BCZT-2 ceramics successfully lit up the 'FCLNT' panel consisting of 53 red LEDs. At room temperature, BCZT ceramics have a recoverable energy storage density (Wrec) and storage efficiency (η) in the range between 506.46 - 257.49 mJ/cm3 and 50.53 – 64.93% respectively. The composition x = 0.12, y = 0.12 (i.e. BCZT-3) revealed the highest energy storage efficiency (η) ~ 64.93% at room temperature. Nonetheless, the temperature-dependent (till its Curie temperature) maximum obtained Wrec of all BCZT ceramics is found in the range between 238.41 to 446.49 mJ/cm3 with an η of 66.98% to 79.67%. Thus, compositionally tuned BCZT ceramics exhibit considerable piezoelectric properties, including energy storage and harvesting capabilities.

High-field complex parameters characterization of PMN-PT single crystal/epoxy 1–3 composites (φ = 0.4) under a high AC electric field with a varied intensity

It is essential to characterize the high-field properties of piezoelectric composites for their applications in ultrasonic transducers. This study involved the development of an experimental characterization system of piezoelectric impedance spectra and mechanical quality factors under high-field conditions to analyze the properties of PMN-PT piezoelectric single-crystal composites. The impedance spectra and mechanical quality factors of a [001]c-poled 0.69PMN-0.31PT single crystal/epoxy 1–3 composite disk with filling ratio φ = 0.4 under thickness resonance mode were tested at different driving voltages ranging from 1 to 120 Vpp to explore the influence of AC electric field on the material properties. By utilizing a theoretical approach, an evaluation was conducted on the variations in the material properties such as stiffness, permittivity, piezoelectric coefficient, and electromechanical coupling factor, along with respective loss factors. Our results suggest that as the AC electric field increases, the elastic modulus c33D and the mechanical quality factor Qm decrease, while the piezoelectric strain coefficient d33 and the electromechanical coupling factor kt increase. However, the dielectric coefficient ε33X does not show an obvious change in this field range. Furthermore, the elastic loss factor tanϕ, the dielectric loss factor tanδ33′, the piezoelectric loss factor tanθ33′, and the electromechanical coupling loss factor tanχt all increase, indicating that the loss of the piezoelectric composite becomes more evident as the AC electric field grows.

The structural evolution and electric field-induced strain performance of Bi0.5(Na0.41K0.09)TiO3–Ba(Fe0.5Sb0.5)O3 lead-free piezoelectric ceramics

In recent years, lead-free Bi0.5Na0.5TiO3 (BNT) based piezoelectric ceramics with excellent strain properties have gained widespread recognition for their application in high-precision displacement actuators. The (1-x)(0.82Bi0.5Na0.5TiO3-0.18K0.5Bi0.5TiO3)-xBa(Fe0.5Sb0.5)O3 ceramics were fabricated through the die-pressing method in this work. The effect of BFS introduction on the dielectric, ferroelectric and microstructure characteristics of BNKT ceramics was systematically investigated. Among these compositions, the BNKT-0.015BFS ceramics exhibited a piezoelectric strain coefficient (d33*) of 658 pm/V at an electric field of 55 kV/cm, while achieving a strain response of 0.51 % at 85 kV/cm. The observed improvement in strain performance can be attributed to the evolution from non-ergodic relaxor state to ergodic relaxor state caused by BFS substitution. Furthermore, transmission electron microscopy (TEM) explicitly confirmed coexistence of rhombohedral and tetragonal phase and revealed the morphology of nanosized domains. This study adds to a deeper comprehension of the characteristics of strain response enhancement in BNT-based ceramics, opening up avenues for designing novel lead-free piezoelectric ceramics with outstanding electromechanical performance.

Defect dipole stretching enables ultrahigh electrostrain.

Piezoelectric actuators have been extensively utilized as micro-displacement devices because of their advantages of large output displacement, high sensitivity, and immunity to electromagnetic interference. Here, we propose a straightforward approach to design <110>-oriented defect dipoles by introducing A-site vacancies and oxygen vacancies in (K0.48Na0.52)0.99NbO2.995 ceramics. As a result, we achieve ultrahigh electrostrains of 0.7% at 20 kV cm-1 (with an effective piezoelectric strain coefficient d33* = 3500 pm V-1), outperforming the performance of existing piezoelectric ceramics at the same driving field. The exceptional electrostrain is primarily attributed to the large stretching of defect dipoles when subjected to an applied electric field, a phenomenon that has been experimentally confirmed. Moreover, the strong interaction between these defect dipoles and <110> spontaneous polarizations plays a critical role in minimizing hysteresis and ensuring excellent fatigue resistance. Our findings present a practical and effective strategy for developing high-performance piezoelectric materials tailored for advanced actuator applications.

Ultra-high strain in Bi0.5(Na0.41K0.09)TiO3 Pb-free piezoelectric ceramics modified by Sr(Hf0.5Sb0.4)O3

The lead-free piezoelectric ceramics used in piezoelectric actuators have attracted extensive attention owing to their substantial electric-field-induced strain. In this study, The (1-x)Bi0.5(Na0.41K0.09)TiO3-xSr(Hf0.5Sb0.4)O3 (BNKT-xSHS) piezoelectric ceramics were synthesized using the conventional solid-state reaction method. The impact of SHS substitution on the microstructure and electrical properties was systematically explored. Among them, the BNKT-0.015SHS sample, featuring ergodic relaxor states, demonstrates a high piezoelectric strain coefficient (d33*) of 785 p.m./V under a low electric field of 50 kV/cm(Strain = 0.392 %). It exhibits a repeatable strain value of 0.47 % under an 80 kV/cm electric field(d33* = 590 p.m./V). Moreover, the strain values remain around 0.4 % between room temperature and 100 °C, with variations within 90 %. The heightened repeatable strain response is considered to be linked to the electric field-induced reversible phase transition occurring within the ergodic relaxor state. The higher strain temperature stability is ascribed to the coexistence of quadrilateral polar nanoregions and rhombic polydomain nanoregions. This study provides an effective example for achieving significant strain responses, presenting a feasible candidate material for applications in piezoelectric actuators.

Disclosing the dependencies of ferroelectric and piezoelectric performances on crystalline states of P(VDF‐TrFE) films by molecular dynamics simulations

AbstractWe present a molecular dynamics simulation method including x‐ray diffractometer pattern calculation, mean square displacement (MSD), and nonbonding energy distribution (NED) to disclose the dependencies of condensed structure on its crystalline process of the poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) films. For comparison, the P(VDF‐TrFE) solution is casted into the films, and followed that different thermal processes are performed to fabricate the crystalline states of the films. Simulation and experimental results have good consistency, indicating that high temperature annealing can effectively promote all‐trans β phase in the crystal region of P(VDF‐TrFE). As such, P(VDF‐TrFE) 80/20 mol% annealing at 140°C shows a higher MSD (~27.5 Å2) and a faster reducing rate of NED than that of other films, contributing to a large maximum polarization (Ps) of ~15.5 μC cm−2, high a remnant polarization (Pr) of ~11.8 μC cm−2, and an attractive piezoelectric strain coefficient (d33) of −27.1 pC N−1 under 200 MV m−1, respectively, and providing a reference for the applications of P(VDF‐TrFE) in flexible sensors, actuators, transducers, and so forth.

Low‐temperature sintering Sm‐doped PMN–PZ–PT multilayer ceramic actuator with high strain and temperature stability

AbstractMultilayer ceramic actuators find extensive utility in applications requiring precise displacement control or force output, due to their advantages of high precision control, rapid response, low driving voltage, low power consumption, and so on. For practical applications, there is a need for high‐performance multilayer ceramic actuators (MLAs) that combine cost‐effectiveness, efficiency, and temperature stability. In this work, 1.5 mol%Sm‐doped 0.25 Pb(Mg1/3Nb2/3)O3–0.36PbZrO3–0.39PbTiO3 piezoelectric ceramics with PbO–CuO as sintering aid were fabricated. The addition of PbO–CuO significantly reduced the sintering temperature by 300°C, while having minimal impact on the piezoelectric properties. The optimized sintering condition, achieved at a low sintering temperature of 950°C with the introduction of a tiny 0.4 wt% sintering aid, yields impressive piezoelectric strain coefficient d33* = 690 pm/V. This substantiates the viability of employing low‐cost Ag/Pd (90/10) as inner electrode, which can be co‐fired with ceramic layer to fabricate MLA. This innovation enables a remarkable displacement of 1 µm at a low driving voltage of 200 V across a 9‐layers piezoelectric actuator, accompanied by high‐temperature stability, exhibiting &lt;20% variation over the temperature range of 30–250°C. These results underscore a great potential for high‐performance piezoelectric actuators over a broad temperature range.

Tunable d33/d33* for MPB (Ba0.85Ca0.15) (Zr0.1Ti0.9)O3 lead-free piezoceramic by crystallographic texturing approach

The morphotropic phase boundary (MPB) Ba0.85Ca0.15Zr0.10Ti0.90O3 composition is successfully transferred into <001>-textured ceramic having Lotgering factor f-74 % (abbreviated as BCZT-T74) using high aspect ratio BaTiO3-template particles via templated grain growth (TGG) method. The microstructural aspects reveal the distinctive grain growth formation for non-textured (BCZT-NT) and textured (BCZT-T74) ceramics; confirming the proper grain growth formation for textured ceramics. The polarization behavior was tested at 1 Hz, 5 Hz, and 10 Hz electric field frequencies by applying a voltage bias of 1000 V; the BCZT-NT ceramics show more variation in remnant polarization (Pr) as well as maximum polarization (Pmax) peak position while BCZT-T74 ceramics exhibit nearly steady values. The frequency-dependent variation in Pr (i.e. ΔPr) for non-textured and textured BCZT ceramics is ±11.08 % and ±3.25 % respectively in the frequency range 1Hz–10Hz at an applied voltage bias of 1000 V. The bipolar strain-electric field (S-E) butterfly loop evidences the typical piezoelectric nature; for both non-textured and textured BCZT ceramics having the effective piezoelectric strain coefficient d33* of 576 pm/V and 657 pm/V respectively. The BCZT-NT and BCZT-T74 ceramics revealed the average positive strain % values of 0.063 % and 0.1123 % and negative strain % values of 0.003985 % and 0.02281 % respectively at the applied voltage 1000 V functioning at 1Hz. The enhancement in negative strain% for BCZT-T74 ceramics is > 5.70 times higher than BCZT-NT ceramics. The variation in positive strain (i.e. ΔS+ve) and variation in negative strain (i.e. ΔS-ve) for non-textured ceramics is ±11.74 % and ±67.34 %, however, for textured ceramics is only ±3.33 % and ±5.00 % respectively. The BCZT-NT and BCZT-T74 ceramics exhibit the piezoelectric charge coefficient (d33) of 370 pC/N and 520 pC/N (1.4 times that of BCZT-NT ceramics) respectively. The electrostrictive coefficient (Q33) of BCZT-T74 ceramics is 0.039 m4/C2, which is > 2 times higher than BCZT-NT ceramics as well as commercially used toxic PZT-5H ceramics. Therefore, less variation in a strain, as well as polarization nature with varying frequencies and enhancement in piezo properties, suggests the present textured MPB BCZT-T74 ceramics is a promising candidate for piezoelectric devices functioning at the wide range of applied electric field frequencies.

Investigations on electric properties and domain structures of Nd-doped 0.70Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 relaxor ferroelectric ceramics with high piezoelectric properties

Although rare earth neodymium (Nd) doping is common in Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) single crystals, it is rarely reported in PMN–PT ceramics. To explore the effect of Nd doping on PMN–PT ceramics, PMN–30PT:xNd3+ (x = 0%, 1%, 2%, and 3%) relaxor ferroelectric ceramics were fabricated using a solid-state method via two-step sintering. An enhanced piezoelectric charge coefficient (d33) of ~870 pC/N and a high piezoelectric strain coefficient (d33⁎) of ~1025 pm/V were achieved for x = 2%. Through Rayleigh analysis of polarization–electric field (P–E) hysteresis loops under small electric fields, it was found that the dielectric property was mainly influenced by the intrinsic contribution (local lattice distortion). Furthermore, by investigating domain configurations, high piezoelectric properties were found to be associated with the domain size reduction and local structural heterogeneity. The results indicate that the PMN–30PT:xNd3+ ceramics is a promising material for electronic devices, and that rare earth Nd doping is an efficient strategy for improving the electronic performance of Pb-based relaxor ferroelectrics.

Achieving ultrahigh electromechanical properties with high TC in PNN-PZT textured ceramics

<001> textured Pb(Ni1/3Nb2/3)O3-PbZrO3-PbTiO3 (PNN-PZT) ceramics were prepared by templated grain growth (TGG) technique using 0.36PNN-xPZ-(0.64-x)PT (x = 0.23, 0.25 and 0.27) powder matrix. Optimum template content was derived to achieve the best electromechanical properties of textured ceramics. The piezoelectric coefficient d33 = 1165 pC/N, Curie temperature TC = 197 °C, longitudinal mode electromechanical coupling factor k33 = 0.86 and a very large effective piezoelectric strain coefficient d33* = 2041 pm/V were simultaneously achieved at the morphotropic phase boundary (MPB) composition (x = 0.25) with 3 vol.% BaTiO3 (BT) templates. Domain structures of textured ceramics were analyzed in detail to reveal the origin of these high piezoelectric and electromechanical properties.

A (Ba0.94Ca0.06)(Ti0.95Zr0.05)O3 ceramic sheet doping to improve the inverse piezoelectric effect of the poly (vinylidene fluoride‐trifluoroethylene)‐based composite film

AbstractA lead‐free tetragonal‐phase (Ba0.94Ca0.06)(Ti0.95Zr0.05)O3 (BCTZ) micro sheet is prepared by molten‐salt growth method, which exhibits a polarizing behavior of relaxor ferroelectricity and possesses a high dielectric constant (εr) of ~2400. Subsequently, the BCTZ sheet is evenly doped into ferroelectric copolymer P(VDF‐TrFE)55/45 mol% with different mass fractions, and the flexible BCTZ/P(VDF‐TrFE) composite films are prepared using a conventional solution casting process. εr of BCTZ/P(VDF‐TrFE) increases with the mass content of BCTZ, and reaches 23.8 in 20 wt% BCTZ sample. Meanwhile, at a high electrical field of 30 MV/m, the strain and electric field of BCTZ/P(VDF‐TrFE) are in the opposite direction, indicating a negative value of piezoelectric strain coefficient (d33) caused by inverse piezoelectric effect. In addition, d33 of different BCTZ/P(VDF‐TrFE) films are fitted using a strain‐electrical field curve, which firstly increases and then decreases with increases in BCTZ content. As such, a high d33 of −47.3 pC/N is obtained in BCTZ/P(VDF‐TrFE)15/85 wt% film. Thus, this research concerning the inverse piezoelectric effect may provide a reference for designing a piezoelectric composite using in transducers and actuators.

Realization of high performance PZN-PT single crystal based piezoelectric flexural mode hydrophone for underwater sensor applications

In this article, attempts are made to grow large size PZN-PT single crystals using high temperature solution growth method by implementing novel bottom cooling technique. The grown crystals are oriented and poled along 〈001〉 direction and obtained larger piezoelectric strain coefficient (d33 > 2000 pm V−1) suitable for development of underwater acoustic sensor requirements. Flexural mode hydrophone is realized using the oriented PZN-PT single crystal discs. Finite element modeling is employed to examine the design of the flexural mode hydrophone and an equivalent circuit model is also applied to study its acoustic characteristic at two extreme boundary conditions like simply supported and clamped edge condition. The underwater acoustic response of the PZN-PT single crystal based flexural mode hydrophone is evaluated over the frequency range (100 Hz to 12 kHz) and its responses are compared with the FEM and equivalent circuit model results. The predicted results from FEM and equivalent circuit model are found to be in good agreement with the experimental results. The receiving sensitivity of the PZN-PT single crystal-based hydrophone is 12 dB higher than the PZT 5A based hydrophone in the frequency range of 2 kHz to 6 kHz. The fabricated PZN-PT single crystal-based hydrophone offers better performance than the conventional piezo ceramic based flexural hydrophone.

Design, fabrication, nonlinear analysis, and experimental validation for an active sandwich beam in strong electric field and thermal environment

In the present work, an efficient one-dimensional finite element (1D-FE) framework considering layerwise mechanics with full electro-mechanical coupling has been developed for the laminated smart sandwich beams submitted to active damping. Nonlinear constitutive relations of piezo-thermo-elasticity at large electric field with temperature-dependent material properties have been considered. The efficient layerwise theory (ELWT) considers the normal deformation of the piezoelectric sensing/actuating patches/layers due to the more significant value of piezoelectric strain coefficient d33. The electric potential variation across the thickness of the PZT sensor/actuator has been assumed quadratic. The state space format of the dynamical system has been constructed based on a reduced order model in modal space. The feedback linearization approach has been applied to the nonlinear system of equations to design an equivalent linear optimal control strategy. An experimental facility has been developed to test the accuracy of the present nonlinear FE model. This facility consists of a thermal chamber with a heating system, air gun, actuation & sensing units with band-pass filters, a smart sandwich beam equipped with PZT-SP5H patches, a data acquisition system, and a computer with LabVIEW software. Open- and closed-loop responses from the present 1D-FE model have been compared with those obtained through experimentation at different temperatures. It has been observed that the current nonlinear FE model correctly captures the dynamic behavior of the vibrating smart sandwich beam at different operating temperatures and strong electric field. The study shows a strong dependence of the PZT materials on thermal chamber temperature and actuation field. New results for a smart sandwich beam are also presented to study the performance of PZT-SP5H patches as sensors/actuators for nonlinear active shape and vibration control in a thermal environment. The effect of piezoelectric actuator/sensor thickness, patch size, position, and applied mechanical load on the active shape and vibration control has been discussed.

Enhancement of Piezoelectricity by Novel Poling Method of the Rare‐Earth Modified BiFeO3–BaTiO3 Lead‐Free Ceramics

AbstractIn piezoceramics, the Curie temperature (TC) and piezoelectric coefficient (d33) are often inversely proportional, so it is very difficult to optimize high piezoelectricity and TC simultaneously. In addition, the high and temperature‐insensitive piezoelectric strain coefficient (d33*) with small hysteresis is also a longstanding obstacle in the development of lead‐free ceramics. In this work, a facile approach of donor doping strategy is adopted to replace Ba2+ with Yb3+, Y3+, Sm3+, and Nd3+ as a result, a high TC of 450 °C and outstanding d33 of 422–436 pC N−1 is achieved by a novel magnetic poling method. Thermally‐stable and outstanding piezoelectric strain performance (d33* ≈ 520–550 pm V−1 and ΔST ≈ 10%) with small strain hysteresis (H &lt; 20%) results are highly encourageable in lead‐free ceramics. The main factors contributing to high piezoelectricity are the morphotropic phase boundary, suppression of defect charges by donor doping, thermal quenching, mesoscale nanodomain size, and novel poling method. The excellent piezoelectric performance and high TC of this work are superior to those of state‐of‐the‐art piezoceramics. The synergistic approaches of compositional design strategy and novel poling process in this work are highly beneficial for temperature‐insensitive piezoelectric sensor and actuator applications.

Dielectric and piezoelectric properties of cement-containing piezoelectric composites: Experiments and modeling

In this work, porous honeycomb lead zirconate titanate (PZT) ceramics with one dimensional ordered pore channels were fabricated by the ionotropic gelation of sodium alginate/PZT suspension with SrCl2 solution, then the piezoelectric cement/PZT paste with different mass fraction of PZT component were cast into the porous ceramics to produce cement-containing piezoelectric composites. The influences of PZT mass fraction of piezoelectric cement/PZT paste on the microscopic morphology were studied. The relative permittivity (εr) and longitudinal piezoelectric strain coefficient (d33) of piezoelectric composites were measured and predicted by experiments and modified “unit cell” model respectively, while both results displayed consistency. The composites presented typical electromechanical coupling behavior for the direct and inverse piezoelectric effect of PZT component, when the PZT mass fraction increased to 50 wt%, the cement-containing piezoelectric composites acquired the greatest thickness electromechanical coupling coefficient (Kt) value of 55.69% and acoustic impedance (Z) value of 10.00 MRayls, making it an appropriate candidate material in the structure health monitoring system.

Theoretical investigations of Sc2C based functionalized MXenes for applications in nanoelectromechanical systems

The piezoelectricity of functionalized MXenes is of increasingly interest in theoretical and experimental research due to many advantages, such as narrowing the electromechanical coupling size, enhancing the piezoelectric coefficients and producing the out-of-plane piezoelectricity. In this work, employing the first-principle calculations, the piezoelectricity together with related electronic and elastic properties of six functionalized MXenes Sc2CTT′ monolayers where T and T′ are functional groups were comprehensively investigated. All of them are mechanically stable and more flexible than graphene, indicating their potential use in flexible devices. Furthermore, the semiconducting nature and broken inversion symmetry endow them with piezoelectricity for nanoelectromechanical facilities. In terms of the in-plane piezoelectricity, Sc2CFCl possesses the biggest d22 and Sc2COHH has the biggest d15. Sc2CHCl and Sc2CFCl monolayers have stronger out-of-plane piezoelectricity when the strain is applied along the x axis due to their larger absolute value of d31 than other monolayers. In addition, with relative to MoSTe which has relatively good out-of-plane piezoelectricity, Sc2COHF and Sc2CHCl monolayers possess comparable out-of-plane piezoelectric strain coefficient d33, which is favorable for their applications in out-of-plane piezoelectric sensing. Excitingly, the value of d33 (35.64 pm/V) for Sc2COHH monolayer is surprisingly over three times of that for MoSTe. It is expected that the studied Sc2CTT’ monolayers with commendable piezoelectric properties can be utilized in certain nanoelectromechanical systems, such as the blood-pressure meter, bionic skin of robots and energy harvesting equipments.

Achieving ultrahigh electrostrain with giant piezoelectric strain coefficient in (Bi0.5Na0.5)TiO3-based ceramics via integrating NER/ER boundary and defect engineering

Ferroelectric ceramics with high electrostrain have been widely applied in actuators and sensors for their rapid response and precision. However, the current bottleneck is the inability to obtain superior electrostrain values along with high piezoelectric strain coefficient (d33*), limiting the practical applications. Herein, we report a remarkable enhancement of electrostrain values and d33* simultaneously in (Bi0.5Na0.5)0.93Ba0.07Ti1-x(Nb0.5Ga0.5)xO3 (BNBT-xNG, 0 ≤ x ≤ 0.06) ceramics with the integration of nonergodic/ergodic relaxor (NER/ER) boundary and defect engineering at room temperature. This strategy by combining NER/ER boundary and defect engineering allow for highly asymmetric strain-electric field (S-E) loops with an ultrahigh and temperature-insensitive electrostrain of 0.73% as well as giant piezoelectric strain coefficient of 913 pm/V simultaneously. The electrostrain value is greater than most of the reported lead-free ceramics and even exceeds those of conventional lead-based materials. This work suggests an effective method for developing new lead-free ceramics to achieve high piezoelectric response.

Ferroelastic Zr2P2XY (X/Y = I, Br, Cl or F; X [formula omitted] Y) monolayers with tunable in-plane electronic anisotropy and remarkable out-of-plane piezoelectricity

Two-dimensional materials with ferroelasticity, directional control of electronic behaviors and strong piezoelectricity are highly desirable for developing advanced multifunctional nanodevices. Here, we report the new tetragonal Zr2P2XY (X/Y = I, Br, Cl or F; X ≠ Y) monolayers with intrinsic ferroelasticity and remarkable piezoelectricity, based on first-principles calculation. These novel monolayers with semiconductor properties are dynamically, thermally and mechanically stable. The promising anisotropic properties of both mechanics and electron can be perpendicularly controlled based on the intrinsic ferroelasticity. Moderate switching barriers and reversible ferroelastic strains demonstrate their excellent ferroelastic performances along in-plane direction. Additionally, the inhomogeneous charge distribution caused by mirror asymmetry endows these monolayers with strong out-of-plane piezoelectricity. The remarkable piezoelectric strain coefficient d33 = 129.705 pm/V found in Zr2P2BrCl monolayer is two orders of magnitude higher than that of MoSTe multilayer. The Zr2P2BrCl monolayer has such excellent ferroelasticity, controllable anisotropic electronic properties along in-plane directions, and strong piezoelectricity along out-of-plane direction. It provides a unique platform for memory devices, robot bionic skin, or multipurpose nanodevices that require the special electronic and piezoelectric properties along different directions at same time.

Large electric-field induced strain in new ternary lead-free piezoelectric solid solution Na0.5Bi0.5TiO3-BaTiO3-Sr (Ta0.5Al0.5) O3

Ternary lead-free piezoelectric ceramics Na0.5Bi0.5TiO3-BaTiO3-Sr(Ta0.5Al0.5)O3 were synthesized via conventional solid-phase synthesis. All samples exhibited pure perovskite structure, indicating that Sr(Ta0.5Al0.5)O3 can be solidified into the Na0.5Bi0.5TiO3-BaTiO3 perovskite structure. The remanent polarization Pr and coercive field EC of the undoped Na0.5Bi0.5TiO3-BaTiO3 ceramic were Pr∼35.23µC/cm2 and EC∼42.46 kV/cm, respectively. The introduction of Sr(Ta0.5Al0.5)O3 sharply affected the ferroelectric properties of the substrate Na0.5Bi0.5TiO3-BaTiO3 ceramics. Increase in the content of Sr(Ta0.5Al0.5)O3 induces transition of this ternary system from a ferroelectric phase to an antiferroelectric-like phase, accompanied by double hysteresis loops in the 0.003SAT, 0.005SAT, and 0.01SAT components. The high dielectric constant ε′∼4300 was obtained for the 0.005SAT composition. The 0.015SAT composition yielded the maximum bipolar electric-field strain S (%) ∼0.53 % and high-field piezoelectric strain coefficient d33*∼ 996 pm/V. This result shows that a ternary Na0.5Bi0.5TiO3-BaTiO3-Sr(Ta0.5Al0.5)O3 solid solution is a promising alternative to lead-based piezoelectric materials in the field of high-performance actuators.