Piezoelectric Coefficient D33 Research Articles

Bonding Optimization Strategies for Flexibly Preparing Multi-Component Piezoelectric Crystals.

Flexible films with optimal piezoelectric performance and water-triggered dissolution behavior are fabricated using the co-dissolution-evaporation method by mixing trimethylchloromethyl ammonium chloride (TMCM-Cl), CdCl2, and polyethylene oxide (PEO, a water-soluble polymer). The resultant TMCM trichlorocadmium (TMCM-CdCl3) crystal/PEO film exhibited the highest piezoelectric coefficient (d33) compared to the films employing other polymers because PEO lacks electrophilic or nucleophilic side-chain groups and therefore exhibits relatively weaker and fewer bonding interactions with the crystal components. Furthermore, upon slightly increasing the amount of one precursor of TMCM-CdCl3 during co-dissolution, this component gained an advantage in the competition against PEO for bonding with the other precursor. This in turn improved the co-crystallization yield of TMCM-CdCl3 and further enhanced d33 to ≈71 pC/N, exceeding that of polyvinylidene fluoride (a commercial flexible piezoelectric) and most other molecular ferroelectric crystal-based flexible films. This study presents an important innovation and progress in the methodology and theory for maintaining a high piezoelectric performance during the preparation of flexible multi-component piezoelectric crystal films.

Exotic ferroelectricity in strained BaZrS3 chalcogenide perovskite for photovoltaics

Ferroelectricity in solar cells is credited with a multitude of benefits, including improved charge carrier separation and higher than band gap device voltages, however most ferroelectrics are wide-gap materials that generate very little photocurrent. Some halide perovskites are ferroelectric, but they suffer from degradation, despite their otherwise excellent performance. Recently, BaZrS3, a chalcogenide perovskite has received attention due to its optimal band gap, non-toxicity, and superior stability. The ground state of BaZrS3 is reportedly a GdFeO3-type distorted perovskite (space group Pnma). Here, using first-principle calculations, we show that the polar Pna21 is thermodynamically as stable as Pnma. This new phase is weakly ferroelectric, exhibiting a net polarization of 0.27 µC/cm2 and a d33 piezoelectric coefficient of only ~1 pm/V. Under strain, the interplay between out-of-plane and in-plane octahedral tilts amplifies spontaneous polarization, spin splitting, and large polaron radii. These exotic traits are comparable to those of the popular halide perovskites.

Fabrication, thermal, mechanical, and piezoelectric characterization of PLA/BT piezocomposites

Abstract The properties of polylactide (PLA) composites containing up to 40 vol% of barium titanate (BT) powder were investigated. PLA/BT composites were fabricated using twin-screw extrusion, which ensured uniform filler dispersion. The results demonstrated that increasing the BT content in PLA improved the thermal stability, stiffness, and degree of crystallinity of the composite. The piezoelectric coefficient d33 also increased with higher BT content and longer polarization times, reaching a maximum value of 35 pC/N for composites containing 40 vol% BT. Additionally, the studies revealed that the d33 coefficient is pressure dependent. Presented PLA/BT piezocomposites highlight the suitability of these materials for applications that require both biocompatibility and piezoelectric functionality, including regenerative medicine, energy harvesting, soft robotics, and electroactive biomedical devices.

Enhanced piezoelectricity of P(VDF-TrFE) by BN nanosheets doping and leading to high performance laminated magnetoelectric composites

With the development trend of miniaturization, lightweight and portability of electronic equipment, piezoelectric devices have been widely applied to transducers, sensors and energy harvesters. Piezoelectric polymers, like poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), possess the advantages of light weight, good flexibility, and simple preparation methods. However, P(VDF-TrFE) films is not entirely composed of piezoelectric phase (β phase), so increasing the content of β-phase is very important for the piezoelectric property of P(VDF-TrFE) films. Doping nanomaterials with unique properties has been proved to be a feasible way to increase the content of β-phase. In this paper, hexagonal boron nitride (h-BN) nanosheets, a kind of 2-dimensional van der Waals materials with wide bandgap, as filler were doping into poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) piezoelectric films by solution casting method. The composite films as designed, in which h-BN nanosheets were uniformly dispersed in P(VDF-TrFE), achieved higher contents of piezoelectric phase (β phase). Compared with pure P(VDF-TrFE) films, the optimal P(VDF-TrFE)/BN piezoelectric film achieved a much higher piezoelectric coefficient (d33) (∼42 pC/N), also leading to a higher piezoelectric voltage output than that of pure P(VDF-TrFE). By laminating the P(VDF-TrFE)/BN films as designed with FeSiB Metglas, high magnetoelectric voltage coefficients under zero and low DC magnetic bias were achieved. In summary, this paper presents a feasible and potential method for improving PVDF piezoelectricity, which has been successfully applied in high performance magnetoelectric devices.

Superior piezoelectric performance in holmium-substituted high-TC Bi5Ti3FeO15

High-temperature piezoelectric materials are essential for advanced sensor technologies, yet achieving both superior piezoelectric properties and a wide operating temperature range remains a persistent challenge. Bismuth titanate-ferrite (Bi5Ti3FeO15) is a promising candidate due to its notably high Curie temperature (TC) of approximately 761 °C. However, its low intrinsic piezoelectric response and limited poling efficiency, attributed to insufficient direct-current (dc) resistivity, have restricted its broader utilization. To address these issues, we explored compositional modifications by partially substituting A-site bismuth ions with holmium ions (Bi5-xHoxTi3FeO15, BTF-100xHo), aiming to enhance both piezoelectric performance and electrical resistivity. Comprehensive characterization was performed on the holmium-substituted ceramics, examining their crystal structure, microstructural attributes, and piezoelectric properties. Our findings reveal that the holmium-substituted Bi5Ti3FeO15 compositions exhibit significantly improved piezoelectric behavior in comparison to their unmodified counterparts. The optimized BTF-4Ho composition demonstrates a high piezoelectric coefficient (d33 = 23.1 pC/N) and an elevated TC of 795 °C. Moreover, the BTF-4Ho composition maintains stable electromechanical coupling across a wide temperature range, underscoring its potential for high-temperature sensor applications.

Next-generation hybrid nanogenerators using giant piezoelectric lead-free KNNS composites for sustainable self-powered electronics

This study presents a flexible hybrid nanogenerator that utilizes lead-free KNNS-BF-xBNZ materials integrated with polydimethylsiloxane (PDMS) to enhance energy harvesting performance. The findings demonstrate that by combining piezoelectric and triboelectric effects, the energy conversion efficiency of the nanogenerator is significantly improved, resulting in high output voltage and current, suitable for real-world applications. Specifically, the optimal composition of KNNS-BF-xBNZ ceramics, with x = 0.03 mol.%, yields superior piezoelectric, ferroelectric, and dielectric properties, with remnant polarization (Pr), spontaneous polarization (Ps), and piezoelectric coefficient (d33) values reaching 18.8 μmC/cm², 30.3 μmC/cm², and 358 pC/N, respectively. In the hybrid device, incorporating 15 wt% of KNNS-BF-3BNZ into PDMS resulted in the highest open-circuit voltage (VOC) of 107 V and short-circuit current (ISC) of 4.68 μA. The developed hybrid nanogenerator effectively charges capacitors for energy storage, powers LEDs, and drives small electronic devices, such as watches, showcasing its potential for practical energy harvesting applications. The findings suggest that the integration of KNNS-BF-3BNZ with PDMS provides an efficient and scalable pathway for fabricating high-performance nanogenerators, paving the way for advancements in self-powered devices and sustainable energy solutions.

Enhancement of piezoelectric properties and temperature stability of high-Curie temperature CaBi2Nb2O9 ceramics

Next-generation jet engines, metal forging processes, and non-destructive monitoring of nuclear power plants demand piezoelectric sensors with ultra-high operating temperature, exceptional sensitivity, and outstanding temperature stability. Bismuth calcium niobate (CaBi2Nb2O9, CBNO) is considered a candidate for high-temperature piezoelectric materials due to high-Curie temperature (TC) near 900 °C. However, pure CBNO shows a poor piezoelectric coefficient (d33) and low high-temperature resistivity (ρ). In this work, the piezoelectricity, ferroelectricity, and resistivity of CBNO ceramics were significantly improved by constructing pseudo-tetragonal boundary through the co-substitution of Li/Ce at A site and W/Mo at B site. Remarkably, Ca0.92(Li0.5Ce0.5)0.08Bi2Nb1.97(W2/3Mo1/3)0.03O9 (CLCBN-3WM) ceramic exhibits the best performance: ultra-high TC (∼ 922 °C), very high d33 (∼ 16.1 pC/N), a large remanent polarization (∼ 11.61 μC/cm2), and very good high-temperature insulation ρ (∼ 7.4 × 105 Ω·cm at 600 °C), as well as excellent thermal stability with its d33 value degeneration from 16.1 pC/N to 15.1 pC/N from room temperature to 800 °C (less than 7.0 %). These results indicate that CLCBN-3WM ceramics have significant potential for using in electromechanical transducers operating at high temperatures (600 °C or higher).

High mechanical quality factor and high piezoelectric coefficient achieved via acceptor-modified invisible boundary

High mechanical quality factor (Qm) and high piezoelectric coefficient (d33) are desired for high-power applications of piezoelectric ceramics. However, achieving them based on currently known mechanisms has proven challenging because of the tradeoff between Qm and d33. Here we report a surprising finding that this tradeoff can be overcome via acceptor-modified invisible-boundary (IB). High Qm ∼1096 and high d33 ∼337 pC/N were achieved and superior to those of both lead-free and commercial lead-based piezoceramics. The acceptor-modified IB was demonstrated in Fe-doped BaTi0.89Hf0.11O3 ceramics, where the acceptor doping in the IB composition increases Qm by ∼8.6 times and d33 by ∼1.5 times, being different from the acceptor doping effect in morphotropic/polymorphic phase boundary (MPB/PPB) compositions of increasing Qm but decreasing d33. We predict that our finding may also be made in other acceptor-modified IB systems and the obtained high-performance BaTiO3-based piezoceramic could provide an alternative to lead-based piezoceramics in underwater applications.

Fully biodegradable piezoelectric nanogenerator based on cellulose/PLLA electrospun fibers with high-performance for mechanical energy harvesting

Research efforts are intensifying to employ fully biodegradable piezoelectric nanogenerators (PENGs) as self-powered medical implanted devices and health monitoring products. Poly(L-lactic acid) (PLLA) shows significant promise for biological applications owing to its natural biodegradability, particularly when fabricated as nanofibrous structures via electrospinning. However, PLLA faces inherent limitations related to its relatively weak piezoelectric properties, specifically characterized by a low shear piezoelectric coefficient (d14), which is the familiar form. In this study, a fully biodegradable PLLA nanofiber incorporated with cellulose was applied as piezoelectric film by electrospinning approach. Cellulose/PLLA film exhibits remarkable enhancements in piezoelectric performance, showcasing a 1.6-fold increase in the longitudinal piezoelectric coefficient (d33∼64.2 pm/V) and a substantial boost of nearly 250 % in output voltage. Soil burial experiments conducted over a period of 120 days validate the film's superior biodegradability, with a degradation rate exceeding 93.6 %. Furthermore, the optimized cellulose/PLLA fiber-based PENG demonstrates a maximum open-circuit voltage of 10.3 V and robust mechanical stability, enduring 30,000 cycles without degradation. Notably, the cellulose/PLLA nanofiber-based piezoelectric sensor exhibits efficient detection capabilities, evidenced by distinct output signals in response to varying airflow pressures. Taking into account the advantages of facile fabrication and the utilization of readily available sustainable materials, the proposed cellulose/PLLA device presents a promising eco-conscious alternative for self-powered electronic skin and implantable medical applications.

Influence of Nd3+ ion on piezoelectric studies in lead barium niobate ferroelectric ceramics for device applications

Pb₁₋ₓ₋₃y/₂BaₓReᵧ³⁺Nb₂O₆ (PBN) ceramics, where x = 0.35 and y = 0.00, 0.02, 0.04, 0.06, and Re³⁺ = Nd³⁺, were successfully synthesized using the solid-state reaction method. X-ray diffraction (XRD) analysis confirmed the formation of a pure, single-phase tetragonal structure in both undoped and Nd³⁺-modified PBN ceramics. Rietveld refinement demonstrated a strong correlation between experimental and calculated profiles, with crystallite sizes ranging from 22.6 to 25.11 nm, indicating a gradual increase in size with increasing Nd³⁺ substitution. Grain size analysis showed values between 1.09 μm and 3.95 μm, with the microstructure becoming more refined as Nd³⁺ content increased. The maximum density of 5.95 g/cm³ was achieved at y = 0.06, reflecting optimal densification from Nd³⁺ modification. Dielectric studies revealed that the phase transition temperature (Tc) followed a consistent trend, with the undoped PBN-1 showing a Tc of 350 °C, and Nd³⁺-modified compositions exhibiting lower transition temperatures of 330 °C, 315 °C, and 283 °C as Nd³⁺ content increased. The dielectric constant (Kp) reached a peak value of 0.39 at the Curie temperature and broadened with increasing Nd³⁺ content, indicating enhanced temperature stability. Furthermore, the piezoelectric coefficient (d₃₃) improved significantly with Nd³⁺ doping, reaching a maximum of 178 pC/N for y = 0.06, signifying enhanced piezoelectric performance. These results demonstrate that Nd³⁺-modified PBN ceramics are promising candidates for high-performance piezoelectric applications, particularly in environments demanding high-temperature stability and superior piezoelectric properties.

Piezo-to-piezo (P2P) conversion: simultaneous β-phase crystallization and poling of ultrathin, transparent and freestanding homopolymer PVDF films via MHz-order nanoelectromechanical vibration.

An unconventional yet facile low-energy method for uniquely synthesizing neat poly(vinylidene fluoride) (PVDF) films for energy harvesting applications by utilizing nanoelectromechanical vibration through a 'piezo-to-piezo' (P2P) mechanism is reported. In this concept, the nanoelectromechanical energy from a piezoelectric substrate is directly coupled into another polarizable material (i.e., PVDF) during its crystallization to produce an optically transparent micron-thick film that not only exhibits strong piezoelectricity, but is also freestanding-properties ideal for its use for energy harvesting, but which are difficult to achieve through conventional synthesis routes. We show, particularly through in situ characterization, that the unprecedented acceleration associated with the nanoelectromechanical vibration in the form of surface reflected bulk waves (SRBWs) facilitates preferentially-oriented nucleation of the ferroelectric PVDF β-phase, while simultaneously aligning its dipoles to pole the material through the SRBW's intense native evanescent electric field . The resultant neat (additive-free) homopolymer film synthesized through this low voltage method, which requires only -orders-of-magnitude lower than energy-intensive conventional poling methods utilizing high kV electric potentials, is shown to possess a 76% higher macroscale piezoelectric charge coefficient d33, together with a similar improvement in its power generation output, when compared to gold-standard commercially-poled PVDF films of similar thicknesses.

Giant Piezoelectric Coefficient of Polyvinylidene Fluoride with Rationally Engineered Ultrafine Domains Achieved by Rapid Freezing Processing.

Domains play an essential role in determining the piezoelectric properties of polymers. The conventional method for achieving ultrafine piezoelectric domain structures for polymers is multiphase polymerization, which is not the primary choice for industrial-scale applications because of its complex synthesis and weak mechanical properties. In this study, it is demonstrated for the first time that a nanoscale domain design can be achieved in a commercially available polyvinylidene fluoride (PVDF) homopolymer through a simple fabrication method involving cyclic compression and rapid freezing. The domain-engineered PVDF exhibits largely enhanced piezoelectric output with a record-breaking piezoelectric coefficient (d33) of 191.4 picocoulombs per Newton (8.9 times higher than that of PVDF without engineered domain structure) and electromechanical coupling factor (k33) of 77.1%. Moreover, nanoscale domain-induced ferroelectric and dielectric evolutions are revealed. A smaller domain is found to be beneficial for domain switching. An in-depth understanding of the interplay between the domain structure and piezoelectric properties reveals a simple, low-cost method for fabricating high-performance polymeric piezoelectric.

Development of a novel Bi4Ti3O12/chitosan/rGO piezoelectric bio-composite for mechanical energy harvesting: Output energy optimization using response surface methodology modelling

This study focuses on the development of a novel 0–3 bio-piezoelectric composite utilizing bismuth titanate (Bi4Ti3O12) as the piezoelectric ceramic, chitosan as the polymer matrix, and graphene as a doping element. The primary objective of this study was to study the relationship between the mechanical, piezoelectric, and electrical properties within the developed 0–3 bio-piezoelectric composite. By systematically varying the weight percentages of bismuth titanate ceramic and graphene, our aim was to gain a comprehensive understanding of how these variations influence key properties such as young's modulus for flexibility, the piezoelectric coefficient d33, electrical conductivity, and voltage output. This exploration was driven by the recognition that these properties are interconnected and crucial for the performance of piezoelectric materials in practical applications. Response surface methodology (RSM) was specifically utilized to model the composite response, optimizing process variables through statistical and mathematical analyses. Through rigorous experimentation and modeling the optimal balance that maximizes conductivity, enhances piezoelectric performance, and ensures reliable voltage generation was determined. The optimum formula selected is the one prepared using a piezoelectric ceramic weight percentage of 35,07 %, and graphene weight percentage of 0.9 % for a harvested voltage equal to 12,05 V. The Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) Images of the optimized composite system revealed the uniform distribution of the fillers in the polymer matrix. The optimized composite design resulting from this systematic investigation holds significant promise for practical applications in energy harvesting and sensor technologies, aligning with the demands of Industry 4.0 and IoT technologies.

Machine learning-assisted design of CaBi2Nb2O9-based ceramics with high piezoelectricity and thermal stability

Calcium bismuth niobate CaBi2Nb2O9 (CBN)-based ceramics are promising candidates for high-temperature piezoelectric applications due to its high Curie temperature. However, the traditional trial-and-error method cannot realize fast design of high-temperature piezoceramics over a wide range of composition space. Based on small sample datasets, a machine learning model was proposed to accelerate the design of CBN-based ceramics with high piezoelectricity and thermal stability. Using the trained gradient boosting regression model, the piezoelectric coefficients are predicted for CBN-based ceramics with different compositions. Based on the machine learning prediction results, we prepared the co-doped Ca1-2x(NaCe)xBi2Nb2-x(W0.75Mn0.25)xO9 (CBNCWM-x) by solid phase reaction method. The results show that co-doping changes the lattice distortion, grain size and domain structures of CBN-based ceramics, realizing the enhanced piezoelectric properties. CBNCWM-0.03 ceramics exhibit an optimum piezoelectric coefficient (d33 ∼ 17.2 pC/N) that is quite close to the predicted result by machine learning model. Moreover, the CBNCWM-0.03 ceramics possess a Curie temperature of 913 °C and maintain 90.7 % of its original d33 value after annealing at 900 °C for 2 h, demonstrating excellent thermal stability. The present work not only provides an approach for the rapid discovery of CBN-based ceramics with high piezoelectricity but also obtains excellent thermally stable ceramics for high-temperature applications.

Co-doping Ce3+ and Mn4+ to induce pseudo tetragonal distortion in CaBi2Nb2O9 for improved piezoresponse

Calcium bismuth niobate (CBN), known for its high Curie temperature (TC), has been investigated as a potential material for vibration sensor due to its ability to operate at elevated temperatures. However, the inherent weakness in piezoresponse of CBN has limited its sensing performance. In this study, a pseudo-tetragonal distortion in CBN was successfully induced by incorporating Ce3+ ions into the (Bi2O2)2+ layers of CBN. This modification led to a change in the interaction between the perovskite and bismuth layers, resulting in enhanced piezoelectric and ferroelectric properties. Further enhancement was achieved by introducing Mn4+ ions into the Ce3+-doped CBN. The co-doped CaBi1.96Ce0.04Nb1.985Mn0.015O9 demonstrated a significantly improved piezoelectric coefficient (d33) of 15.9 pC/N, compared to 6.8 pC/N for pure CBN ceramics, and an increased remnant polarization (Pr) of 20.78 μC/cm2, compared to the 3.83 μC/cm2 of the pure material. This work not only deepens the understanding of bismuth-layer-structured ferroelectrics (BLSFs) but also presents a viable co-doping strategy to enhance the piezoresponse in CBN ceramics. This strategy could pave the way for the development of high-performance, high-temperature vibration sensors and potentially lead to the discovery of more novel BLSFs with superior performance.

Unlocking Electrostrain in Plastically Deformed Barium Titanate.

Achieving substantial electrostrain alongside a large effective piezoelectric strain coefficient (d33*) in piezoelectric materials remains a formidable challenge for advanced actuator applications. Here, a straightforward approach to enhance these properties by strategically designing the domain structure and controlling the domain switching through the introduction of arrays of ordered {100}<100> dislocations is proposed. This dislocation engineering yields an intrinsic lock-in steady-state electrostrain of 0.69% at a low field of 10kVcm-1 without external stress and an output strain energy density of 5.24Jcm-3 in single-crystal BaTiO3, outperforming the benchmark piezoceramics and relaxor ferroelectric single-crystals. Additionally, applying a compression stress of 6MPa fully unlocks electrostrains exceeding 1%, yielding a remarkable d33* value over 10000pmV-1 and achieving a record-high strain energy density of 11.67Jcm-3. Optical and transmission electron microscopy, paired with laboratory and synchrotron X-ray diffraction, is employed to rationalize the observed electrostrain. Phase-field simulations further elucidate the impact of charged dislocations on domain nucleation and domain switching. These findings present an effective and sustainable strategy for developing high-performance, lead-free piezoelectric materials without the need for additional chemical elements, offering immense potential for actuator technologies.

Broad Temperature Plateau for High Piezoelectric Coefficient by Embedding PNRs in Singe‐Phase KNN‐Based Ceramics

AbstractTo date, the enormous potential of lead‐free piezoceramics in ultrasonic transducers and micro‐actuators has driven extensive research and development. Although the piezoelectric coefficient (d33) of lead‐free ceramics is improved unprecedentedly, the breakthrough in comprehensive performance is still a key issue, one of which is the inverse relationship between d33 and Curie temperature (TC), and the other is the temperature stability of piezoelectricity. Here, based on the synergistic optimization of the chemical component modulation and texture technology, the high Curie temperature (≈365 °C), high piezoelectric properties (d33 ≈331 pC/N, d33* ≈561 pm V−1) and advanced piezoelectric temperature stability are realized by embedded PNRs in the conceived and prepared lead‐free single phase 0.96((K0.5Na0.5)(Nb0.98Ta0.02)O3)‐0.01(Bi(Ni0.67Nb0.33)O3)‐0.03(Bi0.5K0.5)HfO3 texture ceramics. The d33 changes by only 2.0% when the temperature is increased from 25 to 100 °C (≈10.0% to 200 °C), while the electrical strain (d33*) changes by only 4.2% when the temperature is increased from 25 to 175 °C (≈9.8% to 200 °C), which is comparable to the commercial lead‐based materials (i.e., PZT‐4). This work demonstrates significant progress in the comprehensive piezoelectric performance (especially the piezoelectric temperature stability) of lead‐free ceramics and inspires further attempts to achieve high‐temperature piezoelectric properties.

Achieving high piezoelectric performance in Pb(Mg1/3Nb2/3)O3–PbTiO3 ferroelectric single crystals through pulse poling technique

To maximize the piezoelectric performance of Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT) single crystals, a pulse poling (PP) method is proposed in this study. This study investigates the effects of pulse poling on the piezoelectric and dielectric properties of these PMN–PT single crystals and explores the polarization rotation mechanisms. Our findings indicate a significant improvement in the piezoelectric properties postpulse poling. The optimal PP conditions are identified as 30 pulse numbers at a pulsed electric field of 5 kV/cm. The dielectric constant ɛT33/ɛ0 and piezoelectric coefficient d33 of PMN–0.28PT post PP are 7000–7700 and 2200–2530 pC/N, respectively, representing increases of 49% and 66% compared with those of postdirect current poling (DCP). Additionally, the domain structures of the PMN–0.28PT single crystals after various DCP and PP treatments are examined and compared using piezoelectric force microscopy. The enhanced piezoelectric properties are attributed to the finer domain structures, as well as increased domain wall density achieved through PP. This research introduces a novel domain engineering approach to improve the electromechanical properties of relaxor ferroelectric single crystals.

On the measurement of piezoelectric d33 coefficient of soft thin films under weak mechanical loads: A rapid and affordable method

Thanks to their intrinsic flexibility, energy efficiency and high portability, soft piezoelectric thin films represent the most effective technological approach for wearable devices to monitor health conditions. In order to improve effectiveness and applicability, more and more innovative and high-performing soft piezoelectric materials are being developed and benchmarked through their piezoelectric d33 coefficient. However, most existing methods to measure the d33 were developed for ceramic or bulk materials and cannot be applied to soft materials because high force/pressure can deform and damage the material structure. This work introduces a simple, effective, and fast method to accurately measure the d33 of soft and thin piezoelectric films by applying weak sinusoidal forces to avoid any damage to the sample, and simultaneously measuring the charges produced by the direct piezoelectric effect. The approach is versatile as it can be used for different types of materials and sizes of the active area. This method represents an effective solution to speed up the process of material optimization, paving the way for the rapid development of novel wearable piezoelectric devices.

High Temperature-Insensitive Electrostrain Obtained in (K, Na)NbO3-Based Lead-Free Piezoceramics.

Over the last decades, notable progress is achieved in (K, Na)NbO3 (KNN)-based lead-free piezoceramics. However, more studies are conducted to increase its piezoelectric charge coefficient (d33). For actuator applications, piezoceramics need high electric-field induced strain under low electric fields while maintaining exceptional temperature stability across a wide temperature range. In this study, this work developes Li/Sb-codoped KNN (LKNNS) ceramics with high electrostrain by defect engineering and domain engineering. A remarkable strain of 0.43%, along with a giant d33* value of 2177 pm V-1, is attained in the LKNNS ceramic at 20 kV cm-1. The ceramic exhibits a minimal performance decrease of less than 15% over a temperature range from room temperature to 150 °C. The exceptional strain is attributed to the presence of A-site vacancy-oxygen vacancy ( ) defect dipoles and the increase in nano-domains. The hierarchical domain configuration and defect dipoles impede the switched domains from reverting to their original state as temperature increases, furthermore, the elongated dipole moments of caused by rising temperatures compensate for strain reduction results in exceptional temperature stability. This study provides a model for designing piezoelectric materials with exceptional overall performance under low electric fields and across a wide temperature range.