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Piezoelectric materials with shunt circuits have aroused much research interest due to flexible parameter adjustment. However, shunted piezoelectric elements are difficult to respond to the dynamic changes in the whole system due to the absence of autonomous control ability, which constrains their practical applications. Here, we propose a digital metalayer to control the wave energy transmission across different materials in real time. This digital metalayer comprises a stack of multiple piezoelectric lead zirconate titanate (PZT) disks connected with shunt capacitance circuits (SCCs). The external digital control system adjusts the effective acoustic impedance of the PZT disks through digital potentiometers and microprogrammed control unit, thereby enabling digital manipulation of wave transmission. Utilization of optimized SCCs further enhances adjustment accuracy, supporting both negative and positive capacitance values. The experiments demonstrate that this digital metalayer exhibits remarkable performance in controlling wave transmission. Moreover, the distinct variations in transmitted amplitudes, precisely controlled by the digital metalayer, are harnessed as binary signals for information transmission. An image of letters is encoded into a series of amplitude-modulated waves by the digital metalayer and clearly transmitted. The proposed digital metalayer shows great promise for applications in intelligent impedance matching and the real-time modulation systems. [ABSTRACT FROM AUTHOR]

Solar-driven semiconductor photocatalysts are highly appealing in applications of environmental remediation and energy conversion. However, photocatalytic reactions, particularly oxygen evolution reaction (OER), are often constrained by the swift recombination of electron–hole pairs, thereby resulting in low reaction efficiency. Although it is effective to separate charge carriers by constructing heterojunctions to form built-in electric field, the lattice mismatch and inefficient interlayer charge transfer of heterojunctions in the photocatalysts limit their further development. Here, we propose a new strategy by constructing an internal electric field for OER through an individual piezoelectric two-dimensional material. The results indicate that the piezoelectric effect regulates the electronic structure, reduces bandgap, improves light absorption efficiency, and that the displacement of positive and negative charge centers is the key factor in the enhanced OER. This research indicates the feasibility of combining piezoelectric properties of two-dimensional materials with OER (1.19 eV), providing new insights and guidance for applying the piezoelectric effect in the OER and opening up a way to promote efficient separation of charge carriers. [ABSTRACT FROM AUTHOR]

Investigation and implementation of Active Willis Metamaterials (AWM) have been done exclusively, in all the available literature, by approaches that do not rely on any solid control theory basis. When coupled with piezoelectric control elements, the available approaches have not included, from the first principles, the exact form of the constitutive relationship of the piezoelectric materials. Furthermore, in all these approaches, stability analysis, robustness, ability to accommodate uncertainty or parameter changes, or consideration of disturbance rejection has not been addressed at all. More importantly, the available formulations have always mixed the flow and effort variables of the AWM, resulting in a form that is totally incompatible for the use in generating, investigating, or even designing any appropriate sensing or control applications of the material. In this paper, the piezoelectric-based AWM is modeled, from the first principles, to develop a constitutive coupling form that enables its use in actuation, sensing, and as an integrated controller that can be analyzed, designed, and optimized using the classical, optimal, and robust control system theories. Lagrange dynamics formulation is used to generate the equations governing the Willis coupling, the piezoelectric coupling, as well as the active robust controller. With this developed controlled-based structure of the AWM, the inherent and powerful capabilities of the AWM that lie in its ability to robustly control the material properties themselves such as the compliance (or stiffness) and specific volume (or density) are demonstrated in great detail via several numerical examples. Controlling these properties enables the AWM to be used in numerous important and imaginative applications such as cloaking, beam shifting, beam focusing, as well as many other applications that are limited only by our imagination. [ABSTRACT FROM AUTHOR]

The increasing demands of device applications in harsh environments have led to higher expectations for temperature and pressure resistance in high-temperature piezoelectric materials. In order to understand the performance characteristics of BiScO3-PbTiO3 (BS-PT) high-temperature piezoelectric materials in practical device applications, this study focuses on analyzing the dielectric, piezoelectric, and ferroelectric properties of BS-64PT ceramics under uniaxial stress up to 150 MPa, as well as its electromechanical performance under a hydrostatic pressure of up to 400 MPa. As the uniaxial pressure increases, both the bias-field and large-signal piezoelectric coefficients exhibit a pattern of initially increasing and subsequently decreasing. Furthermore, the bias-field piezoelectric coefficient exceeds 450 pC/N and the large-signal piezoelectric coefficient surpasses 630 pC/N under uniaxial pressures below 100 MPa. This highlights their exceptional resistance to depolarization caused by uniaxial stress. To obtain more precise piezoelectric properties for BS-64PT ceramics in the 31 and 33 modes under hydrostatic pressure, the admittance fitting method was utilized. This method takes into account the significant losses at higher pressures. Within the pressure range of 0–400 MPa, the values of d33 and d31 for BS-64PT ceramics exhibited a minor change of 7.6% and 8%, respectively. These findings indicate that BS-64PT ceramics exhibit more stable piezoelectric properties under both uniaxial and hydrostatic pressures when compared to the majority of Pb-based perovskite-structured materials. The exceptional stability of piezoelectric properties in BS-PT ceramics can be primarily attributed to their elevated anisotropy energy or coercivity field compared to other perovskite-structured Pb(Mg1/3Nb2/3)O3 (PMN) / Pb(Zr,Ti)O3 (PZT)-based ceramics reported. [ABSTRACT FROM AUTHOR]

In this paper, a new Stroh formalism for gradient electro-mechanics is derived for the first time, which is both mathematically concise and numerically powerful, applicable to generally coupled anisotropic material systems. Based on this new formalism, the complicated Lamb wave in flexoelectric and piezoelectric plates is investigated. The dispersion equation is obtained by solving the eigenvalue problem along with the unconditionally stable dual-variable and position method. From the obtained dispersion equation, the dispersion curves and mode shapes of the Lamb wave are calculated by the 1D form of the multidimensional moduli ratio convergence method. Two important and interesting features are observed from our analysis: One is the difference in the mode shape symmetry between the piezoelectric and flexoelectric cases, and the other is the size-dependent property of the flexoelectric effect as observed by nondimensionalization. These features are further illustrated by comparing the dispersion curves and wave-mode shapes among the three different material models (purely piezoelectric, purely flexoelectric, and flexoelectric and piezoelectric coupled). The newly derived Stroh formalism offers a robust, concise, and unified approach for dealing with strain gradient electro-mechanic materials with crystal systems of general anisotropy. The present work also explains the physical mechanism of symmetry breaking observed, as induced by flexoelectric coupling in piezoelectric materials. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) piezoelectric nanomaterials have widely been studied recently due to their promise for various applications in technology. Investigation of vertical piezoelectricity will contribute to a deeper understanding of the intrinsic mechanism of piezoelectric effects in the 2D structures. In this paper, we report a first-principle study for the structural, electronic, piezoelectric, and transport properties of new-designed Janus WSi Z 3 H (Z = N, P, and As) monolayers. The structural stability of WSi Z 3 H is theoretically confirmed based on the energetic, phonon dispersion, and also elastic analyses. At the ground state, while WSiN 3 H is an indirect semiconductor, both WSiP 3 H and WSiAs 3 H are predicted to be direct semiconductors with smaller bandgaps. When the spin-orbit coupling effects are taken into account, a large valley spin splitting is observed at the K point of WSi Z 3 H materials. Interestingly, a giant Rashba spin splitting is found in WSiP 3 H and WSiAs 3 H with Rashba constant α R up to 770.91 meV Å. Additionally, our first-principles study indicates that Janus WSi Z 3 H monolayers are piezoelectric semiconductors with high out-of-plane piezoelectric coefficient | d 31 | , up to 0.15 pm/V, due to the broken mirror symmetry. Besides, with high electron mobilities and also possessing direct band gaps, WSiP 3 H and WSiAs 3 H monolayers are favorable for applications in optoelectronics. [ABSTRACT FROM AUTHOR]

Piezoresponse Force Microscopy (PFM) is capable of detecting strains in piezoelectric materials down to the picometer range. Driven by diverse application areas, numerous weaker electromechanical materials have emerged. The smaller signals associated with them have uncovered ubiquitous crosstalk challenges that limit the accuracy of measurements and that can even mask them entirely. Previously, using an interferometric displacement sensor (IDS), we demonstrated the existence of a special spot position immediately above the tip of the cantilever, where the signal due to body-electrostatic (BES) forces is nullified. Placing the IDS detection spot at this location allows sensitive and BES artifact-free electromechanical measurements. We denote this position as x I D S / L = 1 , where x I D S is the spot position along the cantilever and L is the distance between the base and tip. Recently, a similar approach has been proposed for BES nullification for the more commonly used optical beam deflection (OBD) technique, with a different null position at x O B D / L ≈ 0.6 . In the present study, a large number of automated, sub-resonance spot position dependent measurements were conducted on periodically poled lithium niobate. In this work, both IDS and OBD responses were measured simultaneously, allowing direct comparisons of the two approaches. In these extensive measurements, for the IDS, we routinely observed x I D S / L ≈ 1 . In contrast, the OBD null position ranged over a significant fraction of the cantilever length. Worryingly, the magnitudes of the amplitudes measured at the respective null positions were typically different, often by as much as 100%. Theoretically, we explain these results by invoking the presence of both BES and in-plane forces electromechanical forces acting on the tip using an Euler–Bernoulli cantilever beam model. Notably, the IDS measurements support the electromechanical response of lithium niobate predicted with a rigorous electro-elastic model of a sharp PFM tip in the strong indentation contact limit [ d e f f ≈ 12 pm / V , Kalinin et al., Phys. Rev. B 70, 184101 (2004)]. [ABSTRACT FROM AUTHOR]

Low‐intensity pulsed ultrasound (LIPUS) and electrical stimulation (ES) are effective methods that promote neural repair. However, ES usually requires electrode implantation and a power supply, which are an inconvenience to future applications. Meanwhile, it is difficult to combine ultrasound and ES through traditional methods. Herein, a nanopatch consisting of an oriented barium titanate (BTO)‐incorporated polycaprolactone (PCL) nanofiber membrane for electricity generation and a layer of graphene oxide (GO)‐doped gelatin methacryloyl (GelMA) for neural interaction is developed. This band‐aid‐like BTO@PCL/GO@GelMA nanopatch has an excellent piezoelectric performance. In vitro, the nanopatches significantly promote axonal growth under LIPUS treatment. In a rat model of erectile dysfunction caused by peripheral nerve injury, the nanopatch is easily attached to a damaged nerve similar to a band‐aid. With the assistance of ultrasound, some mechanical energy is converted into electricity by the nanopatch, and synergistic neural stimulation of ultrasound and electricity is achieved. In this way, the nanopatch significantly promoted corpus cavernosum nerve repair, resulting in the improvement of tissue structure and erectile function as well as increased conception rate in female rats. In conclusion, the nanopatch offers a synergistic ultrasound‐ES for nerve repair easily and represents a novel strategy for peripheral nerve repair. [ABSTRACT FROM AUTHOR]

Piezoelectric ceramics with high electro strain are widely used in actuators, sensors, and so on. Here, this work investigates the electro strain of representative piezoelectric materials, and analyzes the influence of electrode type on the electro strain of PZT41 with significant strain anomalies. It is found that the occurrence of abnormally significant strain is not affected by the electrode but caused by intrinsic defects. Therefore, the ceramic samples with and without defects tailoring in Na 0.5 Bi 0.5 TiO 3 (NBT) based and PbZr 0.52 Ti 0.48 O 3 (PZT) based systems were prepared by the solid-state reaction method, and the results show that abnormally ultrahigh electro strains occur in excessively thin samples with diploes due to defects tailoring. Through displacement configuration experiments and comprehensive analysis of polarization switching processes, it is found that the occurrence of asymmetric abnormal significant strains is caused by reversible bending deformation in excessively thin samples. This work provides new support for the emergence of ultrahigh electro strain in piezoelectric ceramics. [ABSTRACT FROM AUTHOR]

This review article presents insights into acoustic interactions with semiconductors, exploring a continuum from electron dynamics to exciton behavior while highlighting recent developments in organic material systems. Various aspects of acoustic interactions, encompassing the manipulation of electrons and their transport mechanisms for applications in the fields of acoustoelectric and acousto-optics, explored by studying surface acoustic wave (SAW) devices integrated with inorganic and organic semiconductors, are presented here. SAWs are guided waves propagating along a piezoelectric material surface, inducing acoustic strain and piezoelectric fields within a semiconductor upon contact. These fields create a dragging force, transferring energy and momentum into the semiconductor, which manipulate and transport charge carriers, thereby generating an acoustoelectric current. Furthermore, SAW can influence exciton dynamics via type-II as well as type-I band-edge modulations, leading to alterations in their spatial distribution, causing transport of electron–hole pairs as distinct charge carrier packets and as bound pairs, respectively, along the SAW path. This paper explores advancements in these phenomena, shedding light on innovative applications and, especially, novel insights into the dynamic interplay between acoustics and organic semiconductor physics. The review concludes by outlining challenges and prospects in the field of SAW and semiconductor interactions, providing a roadmap for future research endeavors. [ABSTRACT FROM AUTHOR]

This work describes the development and characterization of tetragonal barium titanate nanoparticles (BTO NPs) and their surface functionalization with dopamine dodecylamine (DDA), a lipophilic organic ligand. The so‐obtained lipophilic NPs (BTO‐DDA) are then formulated at low loadings (< 5 wt.%) into liquid photocurable resins for vat photopolymerization (VP) and 3D printed into solid objects. The printed composites are mechanically characterized in order to assess the effect of the nanomaterial on the mechanical properties of the 3D printed polymer, revealing no significant variations in the mechanical properties (tensile or flexural) of the nanocomposites compared to the original polymer matrix. In light of these results, the printed nanocomposites are studied in terms of their capacity to generate a separation of charge by the piezoelectric effect, typical of the BTO crystal structure. This study reveals that BTO‐loaded nanocomposites display outstanding piezoelectric coefficients as high as 50 pC/N when BTO‐DDA is formulated at 3.0 wt.%, only slightly less than one‐third of the piezoelectric coefficient previously reported for bulk BTO, while preserving the mechanical properties of the polymer matrix. [ABSTRACT FROM AUTHOR]

Highlights To address the need for efficient, flexible, and wearable power sources for portable electronics, a high performance triboelectric nanogenerator (TENG) was proposed by incorporating vertically‐aligned barium titanate (BaTiO3)/antimony tin oxide (ATO) nanofibers in polydimethylsiloxane (PDMS) negative triboelectric layer, where BaTiO3 served as piezoelectric material, and ATO served as conductive filler. Silver‐coated conductive fabric was used as electrode to ensure integrability and wearability. By strategically coupling the triboelectric effect of PDMS, the piezoelectric effect of BaTiO3 nanofibers, and the charge transfer effect of ATO nanofibers, the TENG exhibited the optimum output voltage and current of approximately 119 V and 28 μA, and power density of 11.74 μW/cm2, respectively. This device demonstrates its potential applications in energy supply by effectively illuminating 174 commercial green LEDs and charging capacitors for powering electronics. Additionally, the successful integration of the TENG into a smart fencing jacket highlights its utility in practical applications. TENGs with vertically‐aligned BaTiO3/ATO composite nanofibers was constructed. The output performance of TENGs were enhanced by coupling triboelectric and piezoelectric effects. Conductive ATO nanofibers were incorporated to enhance charge transfer for performance enhancement. A smart fencing jacket with scoring system was developed using the wearable TENG. [ABSTRACT FROM AUTHOR]

Organic and metal-free molecules with piezoelectric and ferroelectric properties have gained wide interest for their applications in the domain of mechanical energy harvesting due to their desirable properties such as light weight, thermal stability, mechanical flexibility, feasibility to achieve high Curie temperatures, and ease of synthesis. However, the understanding and design of these materials for piezoelectric energy harvesting applications is still in its early stages. This review paper presents a comprehensive overview of the fundamental characterization of piezoelectricity for a range of organic ferro- and piezoelectric materials and their composites. It also discusses the limitations of traditional piezoelectric materials and highlights the advantages of organic materials in this area in the introduction part. In addition, the paper provides a detailed description of peptide-based and other biomolecular piezoelectric materials as a bio-friendly alternative to current materials. This perspective aims to guide researchers in designing functional organic materials and composites for practical mechanical energy harvesting applications and to highlight current limitations and future perspectives in this emerging area of research. [ABSTRACT FROM AUTHOR]

Studies on the piezoelectric materials capable of efficiently outputting high electrostrains at low electric fields are driven by the demand for precise actuation in a wide range of applications. Large electrostrains of piezoceramics in operation require high driving fields, which limits their practical application due to undesirable nonlinearities and high energy consumption. Herein, a strategy is developed to enhance the electrostrains of piezoceramics while maintaining low hysteresis by incorporating lead magnesium niobate relaxors into lead zirconate titanium at the morphotropic phase boundary. An ultrahigh inverse piezoelectric coefficient d 33 * of 1380 pm/V with a reduced hysteresis of 11.5% is achieved under a low electric field of 1 kV/mm, outperforming the major lead-based piezoelectric materials. In situ synchrotron X-ray diffraction and domain wall dynamics characterization with sub-microsecond temporal resolution reveal that the outstanding performances originate from facilitated domain wall movement, which in turn is due to reduced lattice distortion and miniaturized domain structures. These findings not only address the pending challenges of effective actuation under reduced driving conditions but also lay the foundation for a more systematic approach to exploring the origin of large electrostrains. The authors develop an application-oriented low-field actuating piezoceramic via relaxor substitution. Their in situ synchrotron XRD analysis along with domain wall dynamics characterization reveals the mechanisms of outstanding performance. [ABSTRACT FROM AUTHOR]

Bismuth layer‐structured ferroelectrics (BLSF) show great potential as piezoelectric materials for high‐temperature applications. In this study, c‐axis/[001]‐textured CaBi4Ti4O15 (CBT) ceramic was synthesized through templated grain growth (TGG) method. A high Lotgering factor (f) of 96% was achieved in textured CBT ceramic using 20 wt% CBT homogeneous template. The piezoelectric coefficient d33 has significantly increased from 7.8 pC/N for random ceramic to 24.3 pC/N for textured ceramic (poled perpendicular to the c‐axis/[001] texture direction), representing an impressive 300% enhancement while maintaining an ultra‐high Curie temperature (TC) of 788°C. In addition, a low dielectric loss (tanδ = 0.4%) and relatively high resistivity (ρ = 1.1 × 1012 Ω·cm) were achieved simultaneously at room temperature. The significant enhancement of d33 in textured CBT ceramic origins from its strong piezoelectric anisotropy. The large d33,T⊥ is due to the nature of polarization switching in CBT (the spontaneous polarization PS of CBT is along a‐axis direction, and the switching of PS is restricted within the a–b plane). Furthermore, the variation of d33,T⊥ remained below 10% across the temperature range of 25–700°C, highlighting the excellent thermal stability of the textured CBT ceramics. These findings suggest that textured CBT ceramic is a promising piezoelectric material for high‐temperature sensor applications. [ABSTRACT FROM AUTHOR]

The operation of iontronic capacitive sensors typically requires an external alternating current (AC) power source, resulting in additional energy consumption and AC‐frequency‐related sensing performance. Here, a class of self‐powered iontronic capacitive sensing units (SICSUs) is proposed based on a dynamic electric double layer (EDL), with a significant charge sensitivity of up to 24270 pC N−1, surpassing most piezoelectric materials by nearly 10 times. The effects of various design parameters and loading conditions on the sensing performance of the SICSUs are systematically investigated. The EDL at the hydrogel‐electrode interface is characterized in situ, revealing the underlying mechanism for high sensitivity and linearity. The capability of SICSUs in detecting diverse human‐related mechanical loads is demonstrated. Furthermore, a robotic hand equipped with a SICSU‐based artificial algesia sensor is fabricated to mimic the withdrawal reflex behavior of a human hand when its skin detects noxious stimuli caused by sharp objects. [ABSTRACT FROM AUTHOR]

Using piezoelectric bionanomaterials to promote the generation of reactive oxygen species (ROS) is being increasingly recognized in ultrasound (US)‐triggered tumor treatments. The mechanism underlying this innovative treatment involves US irradiation, which activates the built‐in electric field (BIEF) and induces energy‐band bending in piezoelectric materials (PEMs). In this study, Sr0.5Ba0.5Nb2O6 (SBN) nanorods (NRs) are synthesized using a molten salt method. Subsequently, oxygen‐vacancy (OV)‐rich SBN/Sr2Nb2O7 (SBN/SNO) heterojunction nanocomposites (NCs) are fabricated via H2 annealing of the SBN NRs. The engineering strategy focused on enhancing ROS generation, thereby augmenting the piezoelectric catalytic activity of the NCs. This configuration ensures that the BIEF and heterojunction‐induced field act synergistically to provide a sustained driving force for the separation of electron‐hole (e−‐h+) pairs. Importantly, the OVs on the surfaces of the H2‐annealed SBN NRs create electron‐rich sites, which substantially enhance their piezocatalytic capabilities. In vitro and in vivo analyses of hepatocellular carcinoma (HCC) models demonstrate the significant cytotoxic and tumor‐inhibitory capabilities of this rich OV‐mediated sonopiezoelectric therapy (SPT) and illustrate its potential as a promising therapeutic approach against cancer. [ABSTRACT FROM AUTHOR]

In this study, an Integrated Electronics Piezoelectric (IEPE)-type accelerometer based on an environmentally friendly lead-free piezoceramic was fabricated, and its field applicability was verified using a cooling pump owned by the Korea Atomic Energy Research Institute (KAERI). As an environmentally friendly piezoelectric material, 0.96(K,Na)NbO3-0.03(Bi,Na,K,Li)ZrO3-0.01BiScO3 (0.96KNN-0.03BNKLZ-0.01BS) piezoceramic with an optimized piezoelectric charge constant (d33) was introduced. It was manufactured in a ring shape using a solid-state reaction method for application to a compression mode accelerometer. The fabricated ceramic ring has a high piezoelectric constant d33 of ~373 pC/N and a Curie temperature TC of ~330 °C. It was found that the electrical and physical characteristics of the 0.96KNN-0.03BNKLZ-0.01BS piezoceramic were comparable to those of a Pb(Zr,Ti)O3 (PZT) ring ceramic. As a result of a vibration test of the IEPE accelerometer fabricated using the lead-free piezoelectric ceramic, the resonant frequency fr = 20.0 kHz and voltage sensitivity Sv = 101.1 mV/g were confirmed. The fabricated IEPE accelerometer sensor showed an excellent performance equivalent to or superior to that of a commercial IEPE accelerometer sensor based on PZT for general industrial use. A field test was carried out to verify the applicability of the fabricated sensor in an actual industrial environment. The test was conducted by simultaneously installing the developed sensor and a commercial PZT-based sensor in the ball bearing housing location of a centrifugal pump. The centrifugal pump was operated at 1180 RPM, and the generated vibration signals were collected and analyzed. The test results confirmed that the developed eco-friendly lead-free sensor has comparable vibration measurement capability to that of commercial PZT-based sensors. [ABSTRACT FROM AUTHOR]

Bone repair and regeneration require physiological cues, including mechanical, electrical, and biochemical activity. Many biomaterials have been investigated as bioactive scaffolds with excellent electrical properties. Amongst biomaterials, piezoelectric materials (PMs) are gaining attention in biomedicine, power harvesting, biomedical devices, and structural health monitoring. PMs have unique properties, such as the ability to affect physiological movements and deliver electrical stimuli to damaged bone or cells without an external power source. The crucial bone property is its piezoelectricity. Bones can generate electrical charges and potential in response to mechanical stimuli, as they influence bone growth and regeneration. Piezoelectric materials respond to human microenvironment stimuli and are an important factor in bone regeneration and repair. This manuscript is an overview of the fundamentals of the materials generating the piezoelectric effect and their influence on bone repair and regeneration. This paper focuses on the state of the art of piezoelectric materials, such as polymers, ceramics, and composites, and their application in bone tissue engineering. We present important information from the point of view of bone tissue engineering. We highlight promising upcoming approaches and new generations of piezoelectric materials. [ABSTRACT FROM AUTHOR]

To improve the efficiency of topology optimization for piezoelectric energy harvesters (PEHs), this paper proposes a discrete level set method enhanced by conformal mapping. By mapping the PEH onto a 2D regular domain, the original 3D topology optimization problem is simplified as a 2D problem by using a scalar function. Then re-meshing and barycentric interpolation theory are used to simplify the solution of the driving equation and resolve the issue of inconsistent discretization between the level set function and the finite element model. Moreover, based on the proposed method, the finite element expression of the piezoelectric shell element is derived, taking into account the piezoelectric material coupling effect and polarization direction. This leads to an accurate numerical solution for the optimization process. Resultantly, numerical examples demonstrate that proposed method enables the optimization using a simple discretization, while effectively preserving surface characteristics of PEHs. Hence, this method offers a new approach for the structural optimization of PEHs. [ABSTRACT FROM AUTHOR]

Achieving precisely defined and stable component binding is of great interest for composite materials and batteries, but very challenging owing to the lack of effective strategies to manipulate the binder itself. Here, a concept of single‐particle binding (SPB) strategy is proposed based on a polymer‐sol binder to conquer the above challenge. To do that, a polymer‐sol binder is first prepared by dispersing commercial poly(vinylidene fluoride) (PVDF) powder into a mixture of its solvent and non‐solvent with a rational weight ratio of 8:2. Then, by manipulating this PVDF‐sol microfluid, PVDF particles are uniformly and singly introduced onto the surface of other components, such as graphene oxide nanosheets and battery separators. Results further show that the temperature‐induced sol–gel transition of the microfluid finally generates single‐particle fusion and strong component binding with commercial separators (31.6 N m−1). Meanwhile, a surface‐swelling model is proposed to understand its binding mechanism. Finally, this unique SPB strategy has been employed to fabricate nacre‐like nanocomposites with advanced self‐polarized piezoelectricity (23.0 mV N−1), and component‐integrated batteries with robust separator/electrode interphases. This SPB strategy with the PVDF‐sol binder may inspire significant studies on polymer sol, microfluidics, nanocomposites, battery interfaces and beyond. [ABSTRACT FROM AUTHOR]

Prevention of aseptic loosening, the main reason for secondary surgery of bone implants, is of great crucial clinical importance. As a promising bioactive material to promote bone regeneration, the piezoelectric materials for preventing aseptic loosening has not been reported. Here, a surface coating is presented for implants based on piezoelectric poly(L‐lactic acid) (PLLA). The coating ingeniously utilizes zoledronic acid (ZA), a drug used to treat osteoporosis, as a nucleating agent to enhance the piezoelectricity of PLLA. The coating can not only provide a continuous porous piezoelectric environment to stimulate osteogenic differentiation without intervention, but also effectively inhibit the osteolytic activity of osteoclasts through the slow release of ZA, achieving long‐term effectiveness with a single implantation. The rat femur cavity implantation experiment suggests that, the PLLA/ZA coating can rapidly initiate osseointegration of the implant and effectively mitigate the risk of aseptic loosening, even in the presence of metal submicroscopic particles that induce aseptic loosening. This strategy of piezo‐enhanced PLLA drug‐loaded coating may provide a new idea for the surface modification of bone implants. [ABSTRACT FROM AUTHOR]

A basic solution to the problem of three collinear equal cracks in a transversely isotropic piezoelectric material plate is obtained under the influence of electromechanical forces. Stroh formalism and complex variable methods are used to derive the mathematical expressions for SIF (stress intensity factor), COD (crack opening displacement), and COP (crack opening potential). The length of the saturation zones is investigated at each crack tip under the influence of quadratically varying electric displacement. Furthermore, a numerical study is carried out to discuss the effect of quadratically varying electrical potential on the saturation zone, COD, and COP. The results obtained numerically are reported graphically. [ABSTRACT FROM AUTHOR]

Broadband vibration attenuation is a challenging task in engineering since it is difficult to achieve low-frequency and broadband vibration control simultaneously. To solve this problem, this paper designs a piezoelectric meta-beam with unidirectional electric circuits, exhibiting promising broadband attenuation capabilities. An analytical model in a closed form for achieving the solution of unidirectional vibration transmission of the designed meta-beam is developed based on the state-space transfer function method. The method can analyze the forward and backward vibration transmission of the piezoelectric meta-beam in a unified manner, providing reliable dynamics solutions of the beam. The analytical results indicate that the meta-beam effectively reduces the unidirectional vibration across a broad low-frequency range, which is also verified by the solutions obtained from finite element analyses. The designed meta-beam and the proposed analytical method facilitate a comprehensive investigation into the distinctive unidirectional transmission behavior and superb broadband vibration attenuation performance. [ABSTRACT FROM AUTHOR]

At present, rigid-flexible coupling systems have been used in various engineering fields extensively, due to task demands, the systems have become complex increasingly, and thus, it is crucial to study the dynamic problems and active control of rigid-flexible coupling systems. Piezoelectric materials with electromechanical coupling phenomenon have great applications in active control of rigid-flexible coupling systems. In the current study, the active control of rigid-flexible coupling rectangular thin plate is investigated based on piezoelectric effect. The dynamic model of rigid-flexible coupling piezoelectric rectangular thin plate is established first using the Hamilton's principle, and its discrete form is obtained using the superposition method. The dynamic equations of the system are numerically solved using the Newmark-β method. The active control of the rigid-flexible coupling system has been carried out. Case studies show that, for rigid-flexible coupling rectangular thin plate, the rigid motion will drive the vibration of flexible thin plate, and the vibration of the flexible thin plate can cause rigid body motion. The piezoelectric patch can achieve active control of rigid body motion and flexible plate vibration simultaneously. The active control effect is related to the distribution position and thickness of the piezoelectric patch, as well as the excitation voltage. The closer the piezoelectric patch is to the edges of the rectangular thin plate, the better the active control effect on the rigid body motion. The closer the piezoelectric patch is to the center of the rectangular thin plate, the better the active control effect on the flexible plate vibration. Furthermore, the thicker the piezoelectric patch, the greater the excitation voltage, and the better the active control effect. The conclusion of the current work has direct and important engineering applications. [ABSTRACT FROM AUTHOR]

In this work, the sound transmission loss (STL) of a simply supported doubly curved shallow aluminum shell covered by two layers of piezoelectric material, PZT-5H is presented. The study takes into account the presence of uncertain ambient temperature which is shown to significantly affect piezoelectric control of sound transmission. To derive the equations of motion, the assumed mode method combined with the first-order shear deformation theory and Hamilton's principles are employed. The modeling process incorporates the ambient temperature and thoroughly investigates its effects on STL, vibrational displacement, and piezoelectric voltage in terms of thermal strain, piezoelectric constants, and the pyroelectric coefficient uncertainties. Results show that uncertainty in environmental temperature significantly affects STL uncertainty up to 10% and vibrational displacement of the shell to the 15 times of its lowest value. The piezoelectric voltage also fluctuates with the variation in the temperature in a maximum range of 0.12–5.2 Volt. Further, the piezoelectric sensing voltage which accounts for the piezoelectric sensor thickness is observed to be highly sensitive to the temperature uncertainty with a maximum range of 0.65–7.6 Volt, causing depolarization and hysteresis nonlinearity. Thus, environmental temperature variation is considered as one of the main uncertain aspects for robust sound transmission controller. The proposed study provides an insightful investigation for robust piezoelectric control of STL in the presence of thermal uncertainty. [ABSTRACT FROM AUTHOR]

High-performance piezoelectric materials are essential for diverse electromechanical devices, from actuators to sensors and transducers. Here, we synthesized Ce 2 O 3 -doped Pb(Mg 1/3 Nb 2/3)O 3 -0.29PbTiO 3 (x Ce-PMNT29) solid solutions via conventional solid-state methods. In the x = 2.5 % modified composition, we achieved a notable electrostrain-hysteresis trade-off, enhancing electrostrain (0.2 %), equivalent piezoelectric coefficient d 33 * (1701 pm V–1 at 3 kV cm–1), and reducing strain hysteresis to 8.1 %. Additionally , direct high-temperature piezoelectric characterizations revealed real-time variations in piezoelectric coefficient (d 33) and the actual depolarization temperature, with d 33 reaching 859 pC N−1 at 53 °C and planar electromechanical coupling coefficient (k p) exceeding 70 % within 30−85 °C. Leveraging x-ray diffraction (XRD) and piezoelectric force microscopy (PFM), we elucidated synergistic effects between complex nanodomains and local structural heterogeneity, enhancing piezoelectric activity. This study presents a promising approach for improving electromechanical performance and electrostrain in ferroelectrics, with significant potential for practical piezoelectric applications. [ABSTRACT FROM AUTHOR]

Lead-free piezoelectric ceramics with large strain response and good temperature stability are highly required for actuator applications. However, the search for lead-free ceramics with both enhanced strain and reduced thermal-dependent behavior is a great challenge. In this work, by employing templated grain growth technique and elaborately modulate the phase structure, large unipolar strain of 0.30 %, low strain hysteresis H s ∼ 12 %, along with small strain variation 11.8 % between 20 and 100 °C are achieved in (001) C -oriented (Ba 0.95 Ca 0.05)(Sn 0.04 Ti 0.96)O 3 ceramics, being the optimal level of BaTiO 3 family. It is revealed the ceramics exhibit a coexistence of orthorhombic and tetragonal phases. The inherent piezoelectric anisotropy of orthorhombic phase, the reversible a → c domain switch, along with the refined non-180° domain structures contribute to the remarkable electrostrain characteristic. This study proposed a promising strategy to develop high performance piezoelectric materials for actuator applications. [ABSTRACT FROM AUTHOR]

Piezoelectric materials capable of generating an inherent electric field under strain, exhibit promising applications in in-situ piezocatalysis and enhanced photocatalytic activities. SrTiO 3 (STO) is a photocatalytic material, but it faces challenges such as low efficiency in photogenerated carrier separation and transfer, as well as limited reduction and oxidation reactions. To address these issues, this study utilized the piezoelectric properties of tetragonal BaTiO 3 (BTO) nanoparticles and the photocatalytic properties of STO to prepare BaTiO 3 /SrTiO 3 composite materials for piezoelectric assisted photocatalytic degradation of dyes. Disperse BTO nanoparticles with different mass ratios in STO spinning solution to produce a suspension, which is electrospun to form BTO-STO-1:x. The optimal degradation performance and catalytic activity of BTO-STO-1:x were determined through testing to identify the best composite material. It provides a robust foundation for underpinning the coupling mechanism between the enhancement of piezoelectricity and photocatalytic effect, offering an efficient pathway for advancing the field of piezoelectric assisted photocatalysis. [ABSTRACT FROM AUTHOR]

If a crystal undergoes mechanical stress, then an electrical potential is developed across its sides; this phenomenon is called piezoelectricity, or the piezoelectric effect. Piezoelectric materials include quartz, zinc oxide (ZnO), lead zirconate titanate (PZT4), and Rochelle salt. There are numerous uses for piezoelectricity in signal and electrical transducers. In this work, transitional and creep stresses are evaluated in a thin disc made up of piezoelectric transversely isotropic solids subjected to rotation. The mathematical expressions of stress components are computed for the rotating disc by using Seth's transition theory considering the rotation effect in circular disc. The electric displacement relations and various stress components are computed using Hooke's Law. A non-homogeneous differential equation is obtained by using mathematical relations and the equilibrium equation. The theoretical solution of the differential equation is obtained under specified boundary conditions. Creep stresses are studied for the considered material. The obtained results are shown graphically, analyzed numerically, and concluded with a discussion of the results for transversely isotropic piezoelectric materials such as BaTiO3 and PZT-4, among others. On the basis of all the numerical discussions and graphs, it is concluded that discs composed of transversely isotropic piezoelectric (PZT4 and BaTiO3) materials are more stable than discs composed of transversely isotropic (magnesium and beryl). [ABSTRACT FROM AUTHOR]

Here, we successfully synthesized a pair of enantiomeric molecular piezoelectric materials by H/F substitution strategy. These compounds show a large piezoelectric coefficient d33 value of 25 pC N−1 measured by the quasi-static method. A simple energy harvesting device was fabricated based on this crystal, showing great potential in piezoelectric mechanical energy harvesters. [ABSTRACT FROM AUTHOR]

Fluoropolymers and metal halide perovskites (MHPs), as two classes of important piezoelectric materials, suffer from active phases through a facile process and brittleness led poor manufacturability, respectively. Here, TMCM‐CdCl3/PVDF nanocomposites (TMCM = trimethylchloromethyl ammonium, PVDF = polyvinylidene fluoride) are synthesized to overcome the above shortcomings. The abundant hydrogen (H) and chlorine (Cl) sites in TMCM‐CdCl3 can interlock with H and fluorine (F) atoms within PVDF via C─H···Cl and C─H···F interactions. This programming effect augments the dipole alignment and consequently promotes the formation of polar phases within PVDF. The devices made by these nanocomposites exhibit high energy harvesting properties surpassing established MHP/PVDF analogues, and prominent performance in sensing delicate human motions. Moreover, the devices show exceptional capabilities for detecting underwater ultrasound waves. The signal intensity is ≈4 times that of commercial PVDF film devices, and the frequency distortion is only a quarter of that observed in commercial ceramic transducers. This study opens up new possibilities for developing high‐performance piezoelectric nanocomposites and the creation of advanced electromechanical devices. [ABSTRACT FROM AUTHOR]

Chiral hybrid metal halides have emerged as a promising class of piezoelectric materials owing to their ease of synthesis, low acoustic impedance, and solution processibility. However, many known chiral halides crystalize in structures with only shear piezoelectricity which is less facile to be utilized compared with the longitudinal piezoelectricity, largely preventing their practical utility. In addressing this problem, chiral lead‐free S‐MPBiCl5 and R‐MPBiCl5 (MP = 2‐methylpiperazinium) with shear piezoelectricity are synthesized and the thin films orientating along the polarization direction are fabricated. These orientated films, characterized by numerous grains and compact grain boundaries, can effectively facilitate the grain boundary sliding to convert normal stress into shear stress, thus facilely activating the shear piezoelectricity. The resulting devices can accurately identify the position and type of ultrasound sources without the need for a complex acoustic impedance matching layer. Moreover, these devices can successfully sense delicate variations in momentum caused by table tennis balls. The findings open up a new pathway to utilize shear piezoelectricity that is normally considered unuseful of metal halides and other molecular piezoelectrics. [ABSTRACT FROM AUTHOR]

Sr2Nb2O7 (SNO) ceramics are promising high‐temperature piezoelectric materials due to their high Curie temperature (TC), good thermal stability, and high electrical resistivity. However, SNO presents low piezoelectric activity (d33 < 1 pC/N). Here, we successfully obtain textured SNO ceramics with an orientation factor of 0.86 by microstructure regulation. Saturated polarization‐electric loop was obtained in textured ceramic with remanent polarization Pr∼3.56 µC/cm2 and coercive field EC∼53.4 kV/cm. The piezoelectric coefficient d33 of the textured SNO ceramics is increased to 3.2 pC/N, with a high TC of 1342°C, while the low‐textured SNO ceramics exhibit no effective d33. Meanwhile, the piezoelectric coefficient d33 of textured SNO ceramics maintains consistency even at 1300°C, showing excellent thermal stability. The underlying mechanism driving this improvement is elucidated, emphasizing the facilitated domain‐wall motion enabled by the engineered microstructure. Furthermore, textured SNO ceramics exhibit high resistivity of 1.33 × 106 Ω⋅cm at 800°C. This study presents a simple and feasible microstructure engineering approach to enhance the piezoelectric properties of layer‐structured materials, offering valuable insights into the design and development of ceramics for diverse applications. [ABSTRACT FROM AUTHOR]

In this paper, distributed strain nucleus is presented to compute the modes I/II stress intensity factors (SIFs) and electric displacement intensity factors (EDIFs) for multiple unequal cracks placed between a functionally graded piezoelectric materials (FGPMs) and a piezoelectric half-plane. Employing the Fourier transform, the governing electro-elastic equations are solved in terms of the Burgers vectors b x , b y and b ϕ. These equations converted into a system of singular integral equations with Cauchy type then are solved numerically with the help of collocation methods. Crack problems can be solved by establishing the stress and displacement fields in the crack's absence and distributing strain nuclei along the line of the crack. The distributed strain nucleus is a powerful method to calculate accurate solutions to plane crack problems. In fact, the technique is excellent for solutions of complex crack patterns and it is suitable to analyze multiple cracks. Hence this technique allows considering multiple cracks with arbitrary lengths and positions at the interface. The validation of results has been checked by available analytical, finite element and experimental papers. The primary objective of this paper is to study the interacting effects among multiple unequal interface cracks, the non-homogeneity parameter, geometry and material properties and loading parameters on the field intensity factors. Numerical results show that the normalized modes I/II SIFs and EDIFs decreasing with increasing stiffness and thickness of coating. [ABSTRACT FROM AUTHOR]

Piezoelectric ultrasonic energy harvesters (PUEHs) have recently attracted increasing attention. For minimizing the energy losses during energy transfer, it is crucial for core piezoelectric materials to maintain high piezoelectric coefficient (d 33), mechanical quality factor (Q m), and piezoelectric voltage coefficient (g 33). Herein, a simple way of hardening strategy improves the piezoelectric properties of KNN-based ceramics, combined with optimizing grain growth. The enhanced d 33 (∼340 pC/N), high Q m (∼211) and T C (∼305 °C) are obtained simultaneously in this system, accompanied by superior d 33 × g 33 =8770×10−15 m2/N. Through variable temperature resonance test, the polarization rotation diversity caused by phase structure difference is found to closely related to the temperature stability of Q m value. A prototype of PUEH device was further designed and fabricated, with adjustable ultrasound-induced output voltage up to 8.2 V. Our work exhibits an effective way to improve performance of PUEHs by optimizing piezoelectric materials, which is helpful for further developing PUEHs. [ABSTRACT FROM AUTHOR]

AbstractThe distribution of discrete piezoelectric patches critically influences the vibration control performance of beams. However, few studies have comprehensively addressed this issue for piezoelectric beams under different boundary conditions, especially when both traditional and optimal control strategies are considered. This paper investigates the optimal placement of piezoelectric actuator/sensor pairs for beams with cantilever, simply supported, and clamped boundary conditions, using a genetic algorithm (GA) based on the principle of minimum retained energy. The performance of active vibration control laws, including classical methods such as direct proportional feedback, constant gain negative velocity feedback, and model-based linear quadratic regulator (LQR) control, is thoroughly investigated. [ABSTRACT FROM AUTHOR]

The dynamic electromechanical coupling behavior of composite materials is highly dependent on external excitation frequency. While degradable biomolecular materials typically exhibit lower piezoelectric coefficients compared to ceramics, neglecting their frequency‐dependent performance in the design of piezoelectric devices further leads to less efficient utilization of their piezoelectric properties. This oversight greatly hinders the practical application of these materials. To address this, a novel fractional derivation (FD) theory‐assisted model is introduced to reversely design the glycine‐polyvinyl alcohol (PVA) thin films for versatile enhanced bio‐applications. An electromechanical coupling model incorporating FD theory is developed to learn the relationships between FD parameters, film dimensions, and dynamic electromechanical properties. This model accurately predicts the electromechanical performance of the films across a wide frequency range, validated by both finite element simulations and experimental results. This therefore allows to establish key design principles for piezoelectric thin film in bioenergy harvesting and sensing, by tailoring thin film parameters to enhance the piezoelectric performance at specific stimuli frequencies. Demonstrations of glycine‐PVA film devices guided by this model reveal excellent performance in ultrasonic energy harvesting and carotid artery bio‐signal sensing. This study provides a robust theoretical framework for designing and optimizing biodegradable piezoelectric materials for various practical applications. [ABSTRACT FROM AUTHOR]

The ability of piezoelectric materials to convert mechanical energy into electric energy and vice versa has made them desirable in the wide range of applications that oscillate from medicine to the energetics industry. Their implementation in optical communication is often connected with the modulation or other manipulations of the light signals. In this article, the recent advancements in the field of piezoelectrics‐based devices and their promising benefits in optical communication are explored. The application of piezoelectrics‐based devices in optical communication allows dynamic control, modulation, and manipulation of optical signals that lead to a more reliable transmission. It turns out that a combination of artificial‐intelligence‐based algorithms with piezoelectrics can enhance the performance of these devices, including optimization of piezoelectric modulation, adaptive signal processing, control of optical components, and increase the level of energy efficiency. It can enhance signal quality, mitigate interference, and reduce noise‐connected issues. Moreover, this technological fusion can increase the security of optical communication systems. Finally, the potential future research lines are determined. [ABSTRACT FROM AUTHOR]

Hierarchical Bi2Fe4O9/BiOI S-scheme nanoflower heterostructures are prepared by hydrothermal method, which exhibit exceptional photo-piezoelectric catalytic performance. The tight binding between the sheets ensures the efficient electron transport, and provides a large interface area and adequate reaction sites for photo-piezoelectric catalytic reactions. At the same time, because the water flow in the water body produces hydraulic shear force on the material, the material produces piezoelectric effect. Bi2Fe4O9/BiOI exhibit a remarkable degradation efficiency of 99.4% for tetracycline and a hydrogen production rate of 4089.36 µmol h−1 g−1. The observed behavior can be explained by the combined influence of the formation of S-scheme structure and the process of photo-piezoelectric catalysis, confirmed by in-situ XPS, transient/steady-state fluorescence and piezoelectric response force test. The excellent stability of the material suggests its possible use in the sectors of energy and environment. This work introduces novel concepts for the future advancement of photo-piezoelectric synergistic catalysis. [ABSTRACT FROM AUTHOR]

The macroscopic properties of piezoelectric materials can be profoundly influenced by stress. In this research, thermodynamic potential parameters of K0.4Na0.6NbO3 (KNN) single crystals have been experimentally quantified to assess the effects of stress. Leveraging the Landau thermodynamic potential theory, it has been identified that the application of biaxial tensile stress causes a significant elevation in both the piezoelectric property and phase transition temperature in KNN crystals. This transition remarkably extends their working range and improves the material's applicated potential. The coherence between these computational outcomes and experimental data—from the strategic growth of KNN single crystals with internal stress—underscores the reliability of our findings (dielectric constant from 213 to 1274, TO-T from 180 to 234 °C). Additionally, theoretical calculation predicts a potential enhancement in the piezoelectric capabilities of KNN single crystals. This study provides valuable insights for the growth of high-quality piezoelectric crystals and further promotes the application of lead-free piezoelectric materials. [ABSTRACT FROM AUTHOR]

Owing to the architected void-filled low-density configurations, metamaterials are prone to defects during the complex manufacturing process, or damages under operational conditions. Recently mechanical cloaking has been proposed to shield the effect of such disorders in terms of homogenized mechanical responses. The major drawback in these studies are that the damage location should be known a priori, and the cloak is designed around that damaged zone before manufacturing. Such postulation does not allow unsupervised damage resilience during the manufacturing and service life of metamaterials by active reconfiguration of the stress field depending on the random and unpredictable evolution of damage. Here, we propose a radically different approach by introducing piezoelectric lattices where the effect of random appearance of any single or multiple disorders and damages with complex shapes, sizes and distributions can be shielded through active multi-physically controlled cloaks by voltage-dependent modulation of the stress fields within the cloaking region. Notably, this can be achieved without breaking periodicity and any additional material in the cloaking region unlike earlier studies concerning mechanical cloaks. The proposed active class of elastic metamaterials will bring a step-change in the on-demand mechanical performance of critically important structural components and unsupervised damage resilience for enhanced durability and sustainability. This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 1)'. [ABSTRACT FROM AUTHOR]

Flexoelectric effect possesses potential applications in electromechanical conversion, and the flexoelectric coefficient of ferroelectrics is greatly larger than that of ordinary dielectrics. Among the ferroelectrics, BaTiO 3 (BT) ceramics are lead-free materials, also receive a high flexoelectric response. However, it is still inferior to the piezoelectric response of lead-based piezoelectric materials. Herein, we inhomogeneously added x wt. % ZrO 2 into BT ceramics (x wt. % ZrO 2 /BT ceramics, and x = 0.05, 0.5, 1, 2) to enhance the flexoelectric response of BaTiO 3 -based ceramics. The largest effective flexoelectric coefficients (μ ρ) of ∼800 μC/m at room temperature (RT) and ∼1500 μC/m near Curie temperature (T C ∼ 127 °C) were obtained in 0.5 wt % ZrO 2 /BT ceramics, which is ∼6.7 times and ∼3.9 times larger than that of the as-prepared BT ceramics at RT and near T C (∼131.7 °C here) respectively. Although T C of the 0.5 wt % ZrO 2 /BT ceramics decreases compared with that of BT ceramics, its higher μ ρ than that of the as-prepared BT ceramics maintains a wide temperature range, extending to 160 °C. The enhancement of the μ ρ of the 0.5 wt % ZrO 2 /BT ceramics is largely attributed to the compositional heterogeneity between grain boundaries gathered with irregular paraelectric and orthorhombic Ba(Zr, Ti)O 3 , and grains which are tetragonal BaTiO 3. The compositional heterogeneity is easily shaped into a strain gradient (namely a flexoelectric polarization), which plays a promoting effect on the flexoelectric coefficients. [ABSTRACT FROM AUTHOR]

A novel synergistic strategy was used to improve the piezoelectric characteristics of high-temperature piezoelectric ceramics. This work combined three commonly used strategies, constructing the Morphotropic Phase Boundary to reduce energy barriers, changing domain structures impacting macroscopic piezoelectric properties, and adjusting BO 6 octahedral distortions reflecting microstructural changes, thus effectively regulating the piezoelectric behaviors of BiFeO 3 -based ceramics. As a result, the 0.67BiFeO 3 -0.32BaTiO 3 -0.01BiAlO 3 component, exhibiting the maximum distortion of the BO 6 octahedron and the coexistence of macrodomains and nanodomains, achieved the optimal piezoelectric characteristics (d 33 = 225 ± 10 pC N−1, T C = 450 °C). Additionally, the ceramic maintained its high piezoelectric properties even at temperatures as high as 280 °C (346 pC N−1). This study presents a novel collaborative design strategy that combines phase structure, domain structure, and BO 6 octahedral distortion, significantly enhancing the development potential of lead-free high-temperature piezoelectric materials in the future. [ABSTRACT FROM AUTHOR]

The piezoelectric and electromechanical coupling coefficients in conjunction with their temperature stability are the crucial figure-of-merits of piezoelectric materials, due to these properties determine their response sensitivity and operating temperature range, respectively for practical applications. In this work, Sb, (Bi 0.5 Na 0.5)ZrO 3 , and (Bi 0.5 K 0.5)HfO 3 were used to regulate phase transition of KNN-based ceramics, and resultant large piezoelectric constants d 33 ∼ 430 ± 10 pC/N, unipolar strain S uni ∼ 0.18 % at 40 kV/cm, and a high planar electromechanical coupling factor k p ∼ 55 % were observed in the composition with rhombohedral-orthorhombic-tetragonal (R-O-T) multiphase coexistence. Ex-situ electric field XRD measurement and TEM observation indicate the outstanding piezoelectric properties are originated from the electric field-induced phase transition, nanodomains and polar nanoregions, which lower polarization anisotropy and facilitate polarization rotation between different crystallographic symmetries. In addition, the piezoelectric properties of the samples with R-O-T phases coexistence show superior temperature stability and fatigue resistance after 106 bipolar electric cycles. The present study not only helps to understand the structural origin of high piezoresponse, but also lays a foundation for the applications of KNN-based ceramics. [ABSTRACT FROM AUTHOR]

The van der Waals interaction enables atomically thin layers of exfoliated 2D materials to be interfaced in heterostructures with relaxed epitaxy conditions, however, the ability to exfoliate and freely stack layers without any strain or structural modification is by no means ubiquitous. In this work, the piezoelectricity of the exfoliated van der Waals piezoelectric α‐In2Se3 is utilized to modify the magnetic properties of exfoliated Fe3GeTe2, a van der Waals ferromagnet, resulting in increased domain wall density, reductions in the transition temperature ranging from 5 to 20 K, and an increase in the magnetic coercivity. Structural modifications at the atomic level are corroborated by a comparison to a graphite/α‐In2Se3 heterostructure, for which a decrease in the Tuinstra‐Koenig ratio is found. Magnetostrictive ferromagnetic domains are also observed, which may contribute to the enhanced magnetic coercivity. Density functional theory calculations and atomistic spin dynamic simulations show that the Fe3GeTe2 layer is compressively strained by 0.4%, reducing the exchange stiffness and magnetic anisotropy. The incorporation of α‐In2Se3 may be a general strategy to electrostatically strain interfaces within the paradigm of hexagonal boron nitride‐encapsulated heterostructures, for which the atomic flatness is both an intrinsic property and paramount requirement for 2D van der Waals heterojunctions. [ABSTRACT FROM AUTHOR]

Ferroelectrics are essential in memory devices for multi-bit storage and high-density integration. Ferroelectricity mainly exists in compounds but rare in single-element materials due to their lack of spontaneous polarization in the latter. However, we report a room-temperature ferroelectricity in quasi-one-dimensional Te nanowires. Piezoelectric characteristics, ferroelectric loops and domain reversals are clearly observed. We attribute the ferroelectricity to the ion displacement created by the interlayer interaction between lone-pair electrons. Ferroelectric polarization can induce a strong field effect on the transport along the Te chain, giving rise to a self-gated ferroelectric field-effect transistor. By utilizing ferroelectric Te nanowire as channel, the device exhibits high mobility (~220 cm2·V−1·s−1), continuous-variable resistive states can be observed with long-term retention (>105 s), fast speed (<20 ns) and high-density storage (>1.92 TB/cm2). Our work provides opportunities for single-element ferroelectrics and advances practical applications such as ultrahigh-density data storage and computing-in-memory devices. Authors find room-temperature ferroelectricity in single element Te nanowires, highlighting that reducing dimensions to 1D in low-dimensional piezoelectric materials with chain structures is an effective strategy to induce ferroelectricity absent in their 2D form. [ABSTRACT FROM AUTHOR]

The study reviews the current progress in the sol-gel method for the synthesis of ferroelectric powders, thin films, and rods in the lead zirconate-titanate system. In addition, it examines methods for obtaining controlled particle morphology, primarily rod-like. The synthetic approaches in the sol-gel process and heat treatment conditions for obtaining lead zirconate-titanate ceramics of pre-defined morphology are the primary focus of the present review. [ABSTRACT FROM AUTHOR]

The progress of next-generation electromechanical devices is substantially reliant upon achieving high electromechanical coupling performance in piezoelectric materials. Here, a local stress regulation strategy is introduced to significantly enhance the overall electromechanical response of lead-free piezoceramics. A remarkable large piezoelectric coefficient (d33) of ∼800 pC N−1 and longitudinal electromechanical coupling factor (k33) of 88% are obtained in (K,Na)NbO3 (KNN)-based textured piezoceramics. From both experimental examinations and theoretical simulation, including phase-field analyses, it is found that the improved piezoelectric performance primarily stems from the stress-induced elastic field aligned with the preferred crystallographic orientation, which constrains the domain size, resulting in nanoscale short-range ordered domain structures. Such structures facilitate the flexible rotation of electric dipoles within coexisting phases due to flattened free energy distribution, thereby leading to the exceptionally large piezoelectric response. This understanding provides valuable guidance for the design of novel lead-free piezoceramics with excellent piezoelectric performance. [ABSTRACT FROM AUTHOR]