Large Piezoelectricity Research Articles

Enhancing piezoelectric properties of BiScO3-PbTiO3 ceramics via- incorporation of Bi(Zn1/2Ti1/2)O3 with high spontaneous polarization

High-performance piezoelectric materials are the core elements for the fabrication piezoelectric transducers and actuators. In recent years, there has been an increasing demand for piezoelectric materials with both high operational temperature and large piezoelectricity. However, the conventional approach of soft doping to enhance the piezoelectric response often results in a reduction in Curie temperature. To address this issue, we incorporated Bi(Zn1/2Ti1/2)O3 with a large spontaneous polarization (Ps ∼ 100 µC/cm2) and high Curie temperature (Tc ∼ 1380 °C) into BiScO3-PbTiO3 ceramics to improve the piezoelectric response while maintaining high Tc. The newly developed 0.08Bi(Zn1/2Ti1/2)O3-0.335BiScO3-0.585PbTiO3 ceramic exhibits impressive properties including a high d33 value of 585 pC/N (increased by ∼ 33 % compared to the 0.36BiScO3-0.64PbTiO3 ceramics), an electromechanical coupling coefficient k33 of 0.75, a dielectric constant ε′ of 2380, a relatively high Tc of 421 °C. These remarkable improvements hold great promise for advancing high-temperature piezoelectric devices.

Large Piezoelectricity Induced by Internal Stress in (K,Na)NbO3 Single Crystals.

Achieving a high piezoelectric response and excellent stability is essential for practical applications of ferroelectric materials. Herein, large piezoelectricity of d33 = 167 pC/N and kt = 0.52 is found in a K0.7Na0.3NbO3 lead-free ferroelectric single crystal without poling, which is comparable to the artificially poled KNN crystals. The large piezoelectricity is maintained up to 196 °C, showing excellent thermal stability. It was demonstrated that the high piezoelectricity is associated with strong self-polarization in the crystals. The strong internal stress formed during crystal growth gives a preferred spontaneous polarization orientation, resulting in a net macro total polarization. In addition, the internal stress also pins domain wall motions and provides a "restoring force" for the domain switching. This work provides a strategy for designing and optimizing the piezoelectric performance of ferroelectric materials.

Electrically Induced Crystal Field Distortion in a Ferroelectric Perovskite Revealed by Electron Paramagnetic Resonance.

The magnetoelectric material has attracted multidisciplinary interest in the past decade for its potential to accommodate various functions. Especially, the external electric field can drive the quantum behaviors of such materials via the spin-electric coupling effect, with the advantages of high spatial resolution and low energy cost. In this work, the spin-electric coupling effect of Mn2+-doped ferroelectric organic-inorganic hybrid perovskite [(CH3)3NCH2Cl]CdCl3 with a large piezoelectric effect was investigated. The electric field manipulation efficiency for the allowed transitions was determined by the pulsed electron paramagnetic resonance. The orientation-included Hamiltonian of the spin-electric coupling effect was obtained via simulating the angle-dependent electric field modulated continuous-wave electron paramagnetic resonance. The results demonstrate that the applied electric field affects not only the principal values of the zero-field splitting tensor but also its principal axis directions. This work proposes and exemplifies a route to understand the spin-electric coupling effect originating from the crystal field imposed on a spin ion being modified by the applied electric field, which may guide the rational screening and designing of hybrid perovskite ferroelectrics that satisfy the efficiency requirement of electric field manipulation of spins in quantum information applications.

Large piezoelectricity in two-dimensional doped β-Ga2O3

2D piezoelectric materials that can realize the mutual conversion of mechanical and electrical energy play an important role in nanoelectromechanical devices. As a new generation of ultra-wide band gap semiconductor, the monoclinic β-Ga2O3 has received extensive attention and research. In this paper, the inversion center of 2D β-Ga2O3 was broken by a metal atom substitutional doping. The values of out-of-plane (in-plane) piezoelectric coefficient d31/d33 (d11) for Cu-doped and Al-doped β-Ga2O3 reach −4.04 (3.95) pm/V and −2.91 (0.37) pm/V, respectively. Although they are both two-dimensional structures, the results fall within the same order of magnitude as those of the commonly used bulk piezoelectric materials such as α-quartz (d11 = 2.3 pm/V), AlN (d33 = 5.1 pm/V), and GaN (d33 = 3.1 pm/V). Our research shows a great potential application of doped β-Ga2O3 in micro and nano-electromechanical devices such as sensitive sensors, smart wearables, and micro energy converters.

Piezoelectric characteristics of doped β-Ga2O3 monolayer: a first-principles study

Two-dimensional (2D) piezoelectric materials have been widely concerned because of their important applications in nano-piezoelectric generators. Finding two-dimensional materials with large piezoelectric effects is still a great challenge. In this work, the inversion center of the β-Ga2O3 monolayer was broken by substitutional doping. Not only the in-plane piezoelectric effect but also the uncommon out-of-plane piezoelectric effect is induced in the doped β-Ga2O3 monolayer. In addition, we analyzed the cause of the piezoelectric effects from their electronic properties. The values of out-of-plane (in-plane) piezoelectric coefficient for Cu-doped and Al-doped β-Ga2O3 reach −4.04 (3.95) pm/V and −2.91 (0.37) pm/V, respectively. The results are comparable with those of the commonly used bulk piezoelectric materials such as α-quartz (d11 = 2.3 pm V−1), AlN (d33 = 5.1 pm V−1), and GaN (d33 = 3.1 pm V−1), even though they are both two-dimensional structures. Our study shows a great potential application of doped β-Ga2O3 monolayer in micro and nano-electromechanical devices such as smart wearables, sensors, energy converters, and micro energy collectors.

Multiscale Structural Engineering Boosts Piezoelectricity in Na0.5Bi2.5Nb2O9-Based High-Temperature Piezoceramics.

High-temperature piezoelectric materials, which enable the accurate and reliable sensing of physical parameters to guarantee the functional operation of various systems under harsh conditions, are highly demanded. To this end, both large piezoelectricity and high Curie temperature are pivotal figures of merit (FOMs) for high-temperature piezoceramics. Unfortunately, despite intensive pursuits, it remains a formidable challenge to unravel the inverse correlation between these FOMs. Herein, a conceptual material paradigm of multiscale structural engineering was proposed to address this dilemma. The synergistic effects of phase structure reminiscent of a polymorphic phase boundary and refined domain morphology simultaneously contribute to a large piezoelectric coefficient d33 of 30.3 pC/N and a high Curie temperature TC of 740 °C in (LiCeNd) codoped Na0.5Bi2.5Nb2O9 (NBN-LCN) ceramics. More encouragingly, the system has exceptional thermal stability and is nonsusceptible to mechanical loading. This study not only demonstrates that the high-performance and robust NBN-LCN high-temperature piezoceramics hold great potential for implements under harsh conditions but also opens an avenue for integrating antagonistic properties for the enhancement of the collective performance in functional materials.

Special role of indium nitride in the properties of related compounds and quantum structures

This Review provides a thorough description of the experimental progress on the InN family and other relevant compounds. Although InN is of great interest, many of its properties are not well understood and are still puzzling researchers with a number of unexpected effects. These include a surprisingly small energy gap, sensitivity to applied pressure in terms of lattice stability, and poor miscibility with compounds with smaller lattice parameters, such as GaN and AlN. Special features of InN under pressure are highlighted, such as the effect of conduction band filling and the strong pressure dependence of the effective mass. Several negative and positive effects due to the presence of In have been observed. We highlight their implications for InN-based alloys and quantum structures, which are crucial materials in modern optoelectronics (light emitting diodes and laser diodes). These effects include In clustering, large piezoelectricity resulting in strong internal electric fields that reduce the optical gain in nitride heterostructures, and difficulties in growing high-In superlattices and other quantum structures. All of these effects pose challenges that need to be addressed. We show that theoretical explanations allow for the clarification of puzzling experimental observations. Discussed are (i) a reformulation of the rule describing the bandgap dependence on pressure in all III–V semiconductors; (ii) the very large bandgap curvatures in nitride alloys; and (iii) the discrepancies between theory and experiment in the optical emission from InN/GaN superlattices, leading to the conclusion that epitaxial growth of high In content InxGa1−xN (x > 0.3) quantum wells on GaN is not possible.

Ultra-broad temperature insensitive Pb(Zr, Ti)O3-based ceramics with large piezoelectricity

The rapid growth of new electromechanical applications has increased the demand for ferroelectric ceramics with excellent piezoelectric properties and a wide temperature operating range. However, achieving robust piezoelectricity and temperature stability simultaneously in lead zirconate titanate (Pb(Zr, Ti)O3) based piezoelectric ceramics poses a significant challenge. This study proposes a new material system of 0.98Pb0.84Ba0.16(Zr2/3Ti1/3)O3–0.02Pb(Sb1/2Nb1/2)O3 + x wt.%Sm2O3 (PBZT-PSN-xSm) to address this challenge. Remarkably, the ceramics x = 0.4 demonstrate excellent piezoelectric properties (including piezoelectric coefficient d33 of 610 pC/N and Curie temperature TC of 290 °C) and favorable temperature stability (i.e., d33 varies less than 10 % within 25–200 °C). The high piezoelectric properties arise from the optimized phase fraction between rhombohedral (R) and tetragonal (T) phases and the increased grain size, which enhance the lattice distortion and the domain switching under electric fields, respectively. The superior temperature stability can be attributed to stable crystal structure and domain structure. These findings indicate that PBZT-PSN-xSm ceramics hold great promise for practical utilization in high-temperature transducers and sensors.

Giant piezoelectric response and structure evolution of Bi0.5(Na0.3K0.3Li(0.4-x)Bax)0.5ZrO3 modified (K0.48Na0.52)(Nb0.95Sb0.05)O3 lead-free piezoelectric ceramics

The composition of materials can significantly affect the structure and properties of KNN based piezoelectric ceramics. Here, 0.965(K0.48Na0.52)(Nb0.95Sb0.05)O3-0.035Bi0.5(Na0.3K0.3Li(0.4-x)Bax)0.5ZrO3 ceramics were designed and synthesized using CuO as a sintering aid to promote densification of ceramics. The results show that these ceramics had orthorhombic-tetragonal phase transition structure, and the ratio of the two phases becomes an important factor affecting the electrical properties. When the ratio of the two is close, the piezoelectric performance is optimized. Under specific composition, the sample exhibits a large piezoelectric effect, with the piezoelectric constant and inverse piezoelectric constant reaching 347 pC/N and 1052 p.m./V, respectively. These results prove that rational composition and structure modulation can effectively improve the performance of KNN-based lead-free piezoelectric ceramics, making it a promising alternative for lead-based piezoelectric ceramic materials.

Simultaneously achieved high piezoelectricity and resistivity in CaBi2Nb2O9-based ceramics with high curie temperature

To guarantee the functional operation of high-temperature piezoceramics in harsh circumstances, both large piezoelectricity and superior resistivity are prerequisites. However, it remains a formidable challenge to achieve these objects. Herein, we report Ce-doped CaBi2Nb2O9-based high-temperature polycrystals, which can simultaneously deliver a high piezoelectric coefficient d33 of 21.8 pC/N and decent resistivity ρ of 7.1 × 107 Ω﹒cm at 500 °C, along with a high Curie temperature of 916 °C. More encouragingly, the materials are also gifted with exceptional thermal stability ( < 10% variation of d33 in a broad range from ambient temperature up to 900 °C). In-depth multiscale structural characterizations unveil that the outstanding comprehensive performance of Ce-doped CaBi2Nb2O9-based ceramics originate from the synergistic effects of refined grain size and domain morphology, and reduced defect concentration. This work not only demonstrates that CaBi2Nb2O9-based ceramics hold enormous potential for high-temperature implements, but also offers prospects to exploit high-performance high-temperature piezoceramics.

Large in-plane negative piezoelectricity and giant nonlinear optical susceptibility in elementary ferroelectric monolayers

Large in-plane negative piezoelectricity and giant nonlinear optical susceptibility in elementary ferroelectric monolayers

Large piezoelectricity with enhanced thermal stability in BiScO3-BiInO3-PbTiO3 ternary perovskite ceramics

Simultaneously achieving large piezoelectricity and excellent thermal stability in a piezoceramic is highly desired for constructing advanced high-temperature electromechanical coupling devices. Here, a large high-temperature piezoelectric coefficient (d33 = 523 pC/N at 200 °C) with a small fluctuation rate (η ≤ ±10 %) over an ultra-broaden temperature range of 48–342 °C was achieved in novel zBiScO3-xBiInO3-yPbTiO3 (zBS-xBI-yPT) ternary perovskite piezoceramics with a high Curie temperature of 440 °C. The morphotropic phase boundary (MPB) of multiphase coexistence can be driven and optimized in this system, which is mainly responsible for the enhanced piezoelectricity, and the optimal MPB composition is located at x/y/z = 0.010/0.625/0.365. The excellent temperature stability of the optimal MPB sample should be attributed to the increase in the number of thermally stable irreversible non-180° domains. zBS-xBI-yPT perovskite ceramics with excellent comprehensive high-temperature piezoelectric properties exceed many reported lead-based counterparts, and are more suitable for electromechanical coupling applications at harsh elevated temperatures.

Engineering Ferroelectricity and Large Piezoelectricity in h-BN.

Hexagonal boron nitride (h-BN) is a well-known layered van der Waals (vdW) material that exhibits no spontaneous electric polarization due to its centrosymmetric structure. Extensive density functional theory (DFT) calculations are used to demonstrate that doping through the substitution of B by isovalent Al and Ga breaks the inversion symmetry and induces local dipole moments along the c-axis, which promotes a ferroelectric (FE) alignment over antiferroelectric. For doping concentrations below 25%, a "protruded layered" structure in which the dopant atoms protrude out of the planar h-BN layers is energetically more stable than the flat layered structure of pristine h-BN or a wurtzite structure similar to w-AlN. The computed polarization, between 7.227 and 21.117 μC/cm2, depending on dopant concentration and the switching barrier (16.684 and 45.838 meV/atom) for the FE polarization reversal are comparable to that of other well-known FEs. Interestingly, doping of h-BN also induces a large negative piezoelectric response in otherwise nonpiezoelectric h-BN. For example, we compute d33 of -24.214 pC/N for Ga0.125B0.875N, which is about 5 times larger than that of pure w-AlN (5 pC/N), although the computed e33 (-1.164 C/m2) is about 1.6 times lower than that of pure w-AlN (1.462 C/m2). Because of the layered structure, the rather small elastic constant C33 provides the origin of the large d33. Moreover, doping makes h-BN an electric auxetic piezoelectric. We also show that ferroelectricity in doped h-BN may persist down to its trilayer, which indicates high potential for applications in FE nonvolatile memories.

Simultaneously Achieving Large Piezoelectricity and Low Dielectric Loss in High-Temperature BiScO3-PbTiO3-Based Ceramics.

High-temperature piezoelectric materials are pivotal to technology applications fields including defense, aerospace, nuclear energy, and oil well logging. However, the acquisition of excellent piezoelectric properties is usually at the cost of temperature stability (reduced Curie temperature and increased high-temperature dielectric loss), which hinders the application of piezoelectric ceramics in harsh environments. In this study, we investigated the effect of Nb5+ donor and Mn2+/3+ acceptor doping on the dielectric and piezoelectric properties of BiScO3-PbTiO3 (BS-PT)-based ceramics. In contrast to the acceptor doping, it was found that the donor doping not only enhances the piezoelectric properties but also effectively suppresses the dielectric loss at a high temperature by reducing the oxygen vacancy concentration. Eventually, we simultaneously attained an excellent piezoelectric performance (d33 is 553 pC/N at room temperature and 1528 pC/N at 400 °C, respectively) and a low dielectric loss (less than 2% in the temperature range of 150-300 °C) but still with a high Curie temperature (TC ∼ 445 °C) in Nb5+-doped BS-PT ceramics. Furthermore, different in situ measurements were used to demonstrate the remarkable temperature stability up to a high depolarization temperature of ∼400 °C. This work represents significant progress in high-temperature piezoelectric materials and provides a guideline for future efforts on enhancing the piezoelectricity and suppressing the dielectric loss at high temperature.

Multiple Local Domain Structural Evolutions at Morphotropic Phase Boundary in BiFeO3–Ba0.9Ca0.1TiO3 Ferroelectric Ceramics

Bismuth ferrite–barium titanate (BFO–BT) is a well‐known lead‐free ferroelectric material with a large electric field‐induced strain; however, its piezoelectricity is very low under low electric fields. Herein, by studying Ca‐doped BFO–BT ceramics, multiple structural evolutions are found in the ferroelectric domains at the morphotropic phase boundary (MPB) in BFO–BT‐based ceramics, where a part of the local ferroelectric domains reveals a transition from rhombohedral to tetragonal and to relaxor phases. The superior electrical properties with large electrostrain Sp of 0.38%, large Pr of 38.4 μC cm−2, intermediate d33 of 132 pCN−1, and high TC of 425 °C are obtained at the MPB in these ceramics. Multiple local domain structural evolutions with compound ferroelectric domains and relaxor phases are responsible for the large electrostrain and intermediate piezoelectricity. This can explain the inconsistent piezoelectric response under high and low electric fields at the MPB in the BFO–BT‐based ferroelectric ceramics.

A magnetoelectric heterostructure employing a magnetic levitation mechanism for harvesting low-frequency vibration energy

A magnetoelectric (ME) heterostructure using shear-mode ME transducers to extract ambient low-frequency vibration energy is proposed. The demand for the traditional mechanical spring is eliminated by utilizing a magnetic levitation mechanism. When the suspending magnet moves relative to the ME transducers, the piezoelectric plates deform in shear mode owing to the magnetostriction of the magnetostrictive plates, and large shear piezoelectric effect is induced. Consequently, larger voltages can be produced by the presented device. The kinetic equation of the energy harvesting system is derived and solved, and the maximum output power is obtained based on the vibration rule and the variation of the sensed magnetic field. The feasibility of the heterostructure is experimentally verified. The maximum load power increases with acceleration. A maximum output power of 1.46mW is generated across a 1.25MΩ resistive load at the acceleration of 0.7g. The generated energy of the heterostructure is sufficient to drive a low-power electronic device. Improvements are feasible, which allow an obvious increase of the maximum output powers by employing a Halbach array with a particular arrangement of the magnets.

High piezoelectricity and low strain hysteresis in PMN–PT-based piezoelectric ceramics

High piezoelectric properties and low strain hysteresis (<i>H</i>) are both equally necessary for practical applications in precisely controlled piezoelectric devices and systems. Unlike most of previous reports, where enhanced piezoelectric performance is typically accompanied by large hysteresis in lead-/lead-free-based ceramics, in this work, we report a reconstructed relaxor ferroelectric composition in 0.68Pb(Mg_1/3Nb_2/3)O₃–0.32PbTiO₃ (0.68PMN–0.32PT) ceramics through the introduction of (Bi_0.5Na_0.5)ZrO₃ (BNZ) to simultaneously achieve low strain hysteresis (~7.68%), superior piezoelectricity (~1040 pC·N⁻¹), and an electric field induced strain of 0.175%. Our work not only paves the way to simultaneously large piezoelectricity and negligible strain hysteresis in ceramic systems, but also lays the foundation for the further development of novel functional materials.

A Poling-Free Supramolecular Crown Ether Compound with Large Piezoelectricity

Supramolecular host-guest ferroelectrics based on solution processing are highly desirable because they are generally created with intrinsic piezoelectricity/ferroelectricity and do not need further poling. Poly(vinylidene fluoride) (PVDF) in the electric-active beta phase after stretching/annealing still shows no piezoelectric response unless poled. Although many supramolecular host-guest ferroelectrics have been discovered, their piezoelectricity is relatively small. Based on H/F substitution, we reported a supramolecular host-guest compound [(CF3-C6H4-NH3)(18-crown-6)][TFSA] (CF3-C6H4-NH3 = 4-trifluoromethylanilinium, TFSA = bis(trifluoromethanesulfonyl)ammonium) with a remarkable piezoelectric response of 42 pC/N under no poling condition. The introduction of F atoms increases phase transition temperature, polar axes, second harmonic generation (SHG) intensity, and piezoelectric coefficient d33. To our knowledge, such a large piezoelectric performance of [(CF3-C6H4-NH3)(18-crown-6)][TFSA] makes its d33, piezoelectric voltage coefficient g33, and mechanical quality factor Qm the highest among the reported supramolecular host-guest ferroelectric compounds and even larger than the values of PVDF. This work provides inspiration for optimizing piezoelectricity on molecular materials.

Hexagonal warping effect in the Janus group-VIA binary monolayers with large Rashba spin splitting and piezoelectricity.

In this paper, the electronic band structure, Rashba effect, hexagonal warping, and piezoelectricity of Janus group-VIA binary monolayers STe2, SeTe2, and Se2Te are investigated based on density functional theory (DFT). Due to the inversion asymmetry and spin-orbit coupling (SOC), the STe2, SeTe2 and Se2Te monolayers exhibit large intrinsic Rashba spin splitting (RSS) at the Γ point with the Rashba parameters 0.19 eV Å, 0.39 eV Å, and 0.34 eV Å, respectively. Interestingly, based on the k·p model via symmetry analysis, the hexagonal warping effect and a nonzero spin projection component Sz arise at a larger constant energy surface due to nonlinear k3 terms. Then, the warping strength λ was obtained by fitting the calculated energy band data. Additionally, in-plane biaxial strain can significantly modulate the band structure and RSS. Furthermore, all these systems exhibit large in-plane and out-of-plane piezoelectricity due to inversion and mirror asymmetry. The calculated piezoelectric coefficients d11 and d31 are about 15-40 pm V-1 and 0.2-0.4 pm V-1, respectively, which are superior to those of most reported Janus monolayers. Because of the large RSS and piezoelectricity, the studied materials have great potential for spintronic and piezoelectric applications.

Large piezoelectricity and high depolarization temperature in BiScO3–BiYbO3–PbTiO3 ceramics for energy harvesting at elevated temperatures

Large high-temperature d33 and high Td are simultaneously realized in new BS–BY–PT ceramics for piezoelectric energy harvesting.