High Piezoelectric Properties Research Articles

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.

Advancing piezoelectricity and excellent thermal stability: -textured 0.75BF–0.25BT lead-free ceramics for high temperature applications

There is an urgent need for piezoelectric materials possessing both high piezoelectric properties and good thermal stability to facilitate the advancement of high temperature piezoelectric devices. However, conventional strategy for enhancing piezoelectricity via chemical modifications often comes at the cost of thermal stability due to a drop in Curie temperatures. In this study, we achieved remarkable results in <001>-oriented 0.75BiFeO3–0.25BaTiO3 (0.75BF–0.25BT) lead-free textured ceramics. These textured ceramics exhibit a high Curie temperatures Tc of 552 °C, large piezoelectric coefficients d33 of 265 pC/N, and exceptional piezoelectric thermal stability, with minimal variation of 8% across temperature from 25 °C to 300 °C. Compared to randomly oriented ceramics, the piezoelectric coefficient is about 2.5 times higher, marking it as one of the highest reported value for ceramics with Tc near 550 °C. The enhanced piezoelectric properties can be ascribed to improvements in both intrinsic lattice distortions and extrinsic non-180o domain motions, while the excellent piezoelectric thermal stability is attributed to the stable domain texture. These superior properties of the studied textured 0.75BF–0.25BT ceramics position them as competitive lead-free candidates for high-temperature piezoelectric applications.

A strategy for improving piezoelectricity and thermal stability of Na0.25K0.25Bi2.5Nb2O9-based piezoceramics via A/B-site co-doping

Obviously improved piezoelectricity and thermal stability of Na0.25K0.25Bi2.5Nb2O9-based ceramics have been urgently required for high-temperature piezoelectric applications. In this work, Na0.25K0.25Bi2.5-xCexNb2-yWyO9 (NKBCxNWy, x = 0.01, 0.02, 0.03, 0.04; y = 0.02) piezoceramics were developed via a traditional solid-state reaction method. The effect of Ce/W co-doping on the crystal structure and microscopic morphology was systematically investigated, along with the ferroelectric domains and electrical properties. An optimum composition of Na0.25K0.25Bi2.48Ce0.02Nb1.98W0.02O9 was achieved, which shows a high curie temperature of 670 ℃, a good piezoelectric coefficient d33 of 24.4 pC/N. The enhanced d33 stems from small domain sizes and high domain wall density in NKBC0.02NW0.02 ceramics. More importantly, the maximum d33 can remain above 80 % of the d33 (@25 ℃), even if the annealing temperature increases to 500 ℃. This work provides a simple and viable method to obtain high piezoelectric properties and excellent thermal stability in Na0.25K0.25Bi2.5Nb2O9-based ceramics.

High temperature piezoelectric properties and ultra-high temperature sensing properties of bismuth tungstate

High temperature piezoelectric properties and ultra-high temperature sensing properties of bismuth tungstate

Cutting-Edge Perovskite-Based Flexible Pressure Sensors Made Possible by Piezoelectric Innovation.

In the area of flexible electronics, pressure sensors are a widely utilized variety of flexible electronics that are both indispensable and prevalent. The importance of pressure sensors in various fields is currently increasing, leading to the exploration of materials with unique structural and piezoelectric properties. Perovskite-based materials are ideal for use as flexible pressure sensors (FPSs) due to their flexibility, chemical composition, strain tolerance, high piezoelectric and piezoresistive properties, and potential integration with other technologies. This article presents a comprehensive study of perovskite-based materials used in FPSs and discusses their components, performance, and applications in detecting human movement, electronic skin, and wireless monitoring. This work also discusses challenges like material instability, durability, and toxicity, the limited widespread application due to environmental factors and toxicity concerns, and complex fabrication and future directions for perovskite-based FPSs, providing valuable insights for researchers in structural health monitoring, physical health monitoring, and industrial applications.

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

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

Flexible PMN-PT/rGO/PVDF-TrFE based composites for triboelectric and piezoelectric energy harvesting

Flexible piezoelectric nanogenerator (PENG) and triboelectric nanogenerators (TENG) have gained prodigious attention due to the increasing demand of nano and micro energy for driving of miniaturized electronic devices, sensors, and various internet of things. The key challenges that are currently in focus are material selection and simple fabrication techniques for improved electrical performance along with good mechanical properties and flexibility. Herein, a ferroelectric polymer, poly(vinylidenefluoride-co-trifluoroethyne) (PVDF-TrFE), is chosen as a flexible material due to its promising prospect for energy harvesting. To improve the performance, a ceramic material, 0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (PMN-PT), with very high piezoelectric properties has been selected as the reinforcement. Further, reduced graphene oxide has been added as a conducting filler to promote charge conduction. A remarkable enhancement in output voltage of nearly 3 fold is achieved in PVDF-TrFE/PMN-PT (PP) polymer composite as compared to the base polymer PVDF-TrFE (P) TENG device. Furthermore, the PVDF-TrFE/rGO/PMN-PT (PPR) as a PENG illustrates a great improvement in output current of the order of 2 as compared to the pristine polymer. The maximum output voltage as shown by the TENG is 200 V and the maximum current that is shown by the PENG is 30 µA. Therefore, the fabricated PMN-PT based PVDF-TrFE nanogenerators have an immense prospect for applications in self-powered systems.

Sm-doped PZT thin film with high piezoelectric properties by sol-gel method

Sm-doped PZT thin film with high piezoelectric properties by sol-gel method

The synthesis and characterization of alkaline niobate-based ceramic composites containing L-lysine Hydrochloride

Some lead-free piezoelectric ceramics are known to have high dielectric and piezoelectric properties but are limited by their brittle nature. A few amino acids have recently been reported to exhibit rather low dielectric and piezoelectric properties but have the advantage of being biocompatible and flexible. It would therefore be interesting to form a composite that will combine the inherent advantage of high dielectric properties from the ceramics and flexibility from the biomolecule. In this research, the properties of lead-free (K0.45Na0.51Li0.04)(Nb0.85Ta0.1Sb0.05)O3 (KNNLST) ceramics and L-lysine hydrochloride (L-LHCl) have been combined to produce dielectric composites. The samples were produced by mixing the constituents from 0 wt.% to 100 wt.%, pelletising and heat-treating them. Bulk density, X-ray diffraction, scanning electron microscopy, and dielectric characterisation were techniques used to determine the density, phases, morphology, and dielectric properties of the produced composites. The results show an increasing bulk density value from 1.2 g/cm3 for L-LHCl to 4.67 g/cm3 for the KNNLST ceramics. The morphology of the composite shows very tiny grains when small amounts of the ceramics were introduced. The L-LHCl transforms from an amorphous phase to a crystalline phase having the orthorhombic-tetragonal structure with the introduction of the KNNLST ceramics. The dielectric constant values increased with increasing KNNLST ceramics content from 10 @1 kHz to 200 for the composite with 80 wt%. KNNLST content. The dielectric loss values decreased for L-LHCl from 0.9 @1 kHz to 0.2 @1kHz. The electrical conductivity values increased with increasing KNNLST ceramics content. The results show that the composites produced from these constituents may be suitable for dielectric applications.

Nanosheet‐Doped Polymer Composites with High Intrinsic Piezoelectric Properties for Energy Harvesting

Nanosheet‐Doped Polymer Composites with High Intrinsic Piezoelectric Properties for Energy Harvesting

Performance Improvement and Application of Degradable Poly-l-lactide and Yttrium-Doped Zinc Oxide Hybrid Films for Energy Harvesting.

Piezoelectric nanogenerators (PENGs) are booming for energy collection and wearable energy supply as one of the next generations of green energy-harvesting devices. Balancing the output, safety, degradation, and cost is the key to solving the bottleneck of PENG application. In this regard, yttrium (Y)-doped zinc oxide (ZnO) (Y-ZnO) was synthesized and embedded into polylactide (PLLA) for developing degradable piezoelectric composite films with an enhanced energy-harvesting performance. The synthesized Y-ZnO exhibits high piezoelectric properties benefiting from the stronger polarity of the Y-O bond and regulation of oxygen vacancy concentration, which improve the output performance of the composite film with Y-ZnO and PLLA (Y-Z-PLLA). The obtained open-circuit voltage (Voc), short-circuit current (Isc), and instantaneous power density of the optimized Y-Z-PLLA PENG reach 17.52 V, 2.45 μA, and 1.76 μW/cm2, respectively. The proposed PENG also shows good degradability. In addition, practical applications of the proposed PENG were demonstrated by converting biomechanical energy, such as walking, running, and jumping, into electricity.

Low temperature sintering and enhanced piezoelectric properties of BiFeO3–BaTiO3 ceramics by homogeneous calcination

The effect of calcination process on a phase evolution, a microstructure development and the piezoelectric properties were investigated in 0.75BiFeO3-0.25BaTiO3 (0.75BF-0.25BT) ceramics. At the relatively low calcination temperatures of 600 °C–650 °C, a Bi25FeO40 impurity phase was formed in addition to some unreacted raw materials and a perovskite phase. As the calcination temperature increased to the range of 700–900 °C, other intermediate phase BaBi4Ti4O15 was formed concurrently with small amounts of unreacted BaCO3 and perovskite matrix phase. At 950 °C a pure single perovskite phase of 0.75BF-0.25BT solid solution was observed. The sintered samples produced by using the raw powder calcined at a relatively low temperature of 600–900 °C showed a large fraction of pseudo-cubic relaxor phase (0.54–0.71 mass fraction) with the rest of a rhombohedral ferroelectric phase. They showed poor piezoelectric properties at sintering temperature below 1000 °C due to the nonuniform compositional distribution of the calcined powder. The homogeneous calcination at 950 °C for 2 h reduced greatly the optimum sintering temperature and significantly enhanced piezoelectric properties in the BF-BT ceramics. High Curie temperature as well as high piezoelectric properties were obtained at the sintering temperature as low as 920 °C: kp = 0.361, d33 = 123 pC/N and TC = 653 °C in the 0.75BF-0.25BT ceramics and kp = 0.337, d33 = 183 pC/N and TC = 525 °C in the 0.7BF-0.3BT ceramics. This low temperature sintering of the BF-BT ceramics by a homogeneous calcination could be applied to the fabrication of the lead-free multi-layer piezoelectric devices with inexpensive internal electrodes.

Bi compensation and poling process to enhance piezoelectric properties of BiFeO3-BaTiO3 lead-free piezoceramics

BiFeO3-BaTiO3 (BF-BT) ceramics are an excellent choice for high-temperature lead-free piezoelectric ceramic due to their high Curie temperature and good piezoelectric properties, but the volatilization of Bi leads to the formation of A-site cationic vacancies and oxygen vacancies, culminating in heightened leakage currents and detrimental effects on piezoelectric properties. In this study, a chemical composition of 0.70Bi(1+x)Fe0·97Al0·03O3-0.30BaTiO3 ceramics, abbreviated as B1+xFA-BT, where 0 ≤ x ≤ 0.05, were synthesized, with special attention on the effects of Bi compensation and poling process on their insulation and piezoelectric properties. Due to the coexistence of R-PC phases and low leakage current, B1+xFA-BT ceramics exhibit excellent piezoelectric properties and high Curie temperature, among which the B1.02FA-BT ceramic boasts optimal overall properties: d33 = 196 pC N−1, TC = 480 °C, kp = 34%, θmax = 49.5° and Qm = 32, under optimal poling parameters Ep = 50 kV cm−1 and Tp = 100 °C. The poling process is directly linked to the reorientation of domains, the redistribution of positive/negative space charge and the aggregation or injection of holes, which is achieved by tuning the poling field and temperature in a ceramic with optimal integrated piezoelectric properties. The poling process of BF-BT ceramics is significantly influenced by their leakage characteristics, which can have a significant impact on their overall performance. Optimizing electrical poling conditions and minimizing leakage current is crucial to achieving favorable piezoelectric properties in BF-BT ceramics with R-PC coexisting structures.

Microstructure and Biocompatibility of Graphene Oxide/BCZT Composite Ceramics via Fast Hot-Pressed Sintering

Improving fracture toughness, electrical conductivity, and biocompatibility has consistently presented challenges in the development of artificial bone replacement materials. This paper presents a new strategy for creating high-performance, multifunctional composite ceramic materials by doping graphene oxide (GO), which is known to induce osteoblast differentiation and enhance cell adhesion and proliferation into barium calcium zirconate titanate (BCZT) ceramics that already exhibit good mechanical properties, piezoelectric effects, and low cytotoxicity. Using fast hot-pressed sintering under vacuum conditions, (1 − x)(Ba0.85Ca0.15Zr0.1Ti0.9)O3−xGO (0.2 mol% ≤ x ≤ 0.5 mol%) composite piezoelectric ceramics were successfully synthesized. Experimental results revealed that these composite ceramics exhibited high piezoelectric properties (d33 = 18 pC/N, kp = 62%) and microhardness (173.76 HV0.5), meeting the standards for artificial bone substitutes. Furthermore, the incorporation of graphene oxide significantly reduced the water contact angle and enhanced their wettability. Cell viability tests using Cell Counting Kit-8, alkaline phosphatase staining, and DAPI staining demonstrated that the GO/BCZT composite ceramics were non-cytotoxic and effectively promoted cell proliferation and growth, indicating excellent biocompatibility. Consequently, with their superior mechanical properties, piezoelectric performance, and biocompatibility, GO/BCZT composite ceramics show extensive potential for application in bone defect repair.

Synergistic design strategy for enhancing the piezoelectric performance of BiFeO3-Based high-temperature piezoelectric ceramics

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 BO6 octahedral distortions reflecting microstructural changes, thus effectively regulating the piezoelectric behaviors of BiFeO3-based ceramics. As a result, the 0.67BiFeO3-0.32BaTiO3-0.01BiAlO3 component, exhibiting the maximum distortion of the BO6 octahedron and the coexistence of macrodomains and nanodomains, achieved the optimal piezoelectric characteristics (d33 = 225 ± 10 pC N−1, TC = 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 BO6 octahedral distortion, significantly enhancing the development potential of lead-free high-temperature piezoelectric materials in the future.

A high performance nanocellulose-PVDF based piezoelectric nanogenerator based on the highly active CNF@ZnO via electrospinning technology

Piezoelectric polymer composites have attracted much attention due to their high piezoelectric properties and excellent flexibility. In this work, cellulose nanofiber (CNF) was loaded with ZnO by an improved two-step hydrothermal method to obtain CNF@ZnO composites, which have the advantage at high-efficiency one-step film formation and displays considerable piezoelectric performance. Under the optimized hydrothermal conditions, ZnO can be uniformly loaded on CNF sbstrate. The piezoelectric response of CNF at scattered state and micro-nano scale has been successfully characterized to be 5.85 pm·V−1 via piezoelectric force microscopy (PFM), which can be increased to 9.49 pm·V−1 after loaded with ZnO. The obtained CNF@ZnO was dispersed in polyvinylidene fluoride (PVDF) to prepare a large-format tough PVDF/CNF@ZnO composite membrane (E-PVDF/CZ) by electrospinning. CNF@ZnO can effectively increase β phase in PVDF to be 87.36%, and its piezoelectric response was further enhanced to be 24.65 pm·V−1, along with longitudinal piezoelectric coefficient (d33) of 31±2.07 pC·N−1 higher than that of E-PVDF (20.25±2.05 pC·N−1). It also exhibits excellent mechanical performance and flexibility with the tensile strengthen of 16.12±2.35 MPa and elongation at break of 16.21±2.17%. Under the force of 45 N, the open-circuit voltage (VOC) and short-circuit current (ISC) of E-PVDF/CZ are as high as 11.8 V and 452 nA, respectively. Finally, the prepared flexible sensor has an VOC up to 31.2 V under the fist hitting state, while it is about 1.68 V stimulated by water droplets which can also weakly light a LED. The strategy will exactly facilitate the cellulose material in the application in energy harvesting and environmental monitoring.

Modification of domain construction in PNN-PIN-PT piezoelectric ceramics for high electromechanical performance using defect engineering

Good piezoelectric properties and low mechanical losses are prerequisites for the application of high-power devices. In this study, an appropriate amount of Mn ions was introduced into a piezoelectric 0.46Pb(Ni1/3Nb2/3)O3-0.23Pb(In1/2Nb1/2)O3-0.31PbTiO3 ceramic to enhance its electromechanical properties. The results revealed that the mechanical quality factor(Qm) value of the ceramic was improved while maintaining high piezoelectric properties, and the dielectric loss was reduced. When Mn doping is 1.0 mol%, the d33 component decreased by only ∼21%, while Qm increased by ∼13 times (d33 = 750 pC/N, Qm = 385, tanδ = 0.66%). The measurement of the internal bias field (Ei) in the P-E loops of aged and nonaged samples showed that aging promoted the directional alignment of defect dipoles and improved their Qm. According to the PFM data, significant increase in Qm was mainly due to the "bulk effect" caused by low domain wall density. In turn, widening and lengthening of domains promoted the accumulation of most defective dipoles in the ceramic body, which greatly amplified the hardening effect. This work provides a good example of enhancing Qm in ceramic systems with high d33 values through the construction of low domain wall densities.

Crystalline water induced nonpolar‐to‐polar transition and high piezoelectric response in lamivudine hydrate crystal

AbstractElectromechanically converted piezoelectric materials have great applications in actuators, sensors, and energy harvesters. Organic piezoelectric materials are environmentally friendly, easy to prepare, and have a low molecular mass compared to conventional inorganic piezoelectric materials. Here, we present an organic hydrogen bonding piezoelectric material, lamivudine hydrate, which crystallized in the P21 space group at room temperature and exhibits a decent d33 value of 21 pC N−1. This value is comparable to that of the commercial piezoelectric material, Tri‐Glycine Sulfate (TGS, d33=22 pC N−1). Moreover, lamivudine hydrate possesses a superior g33 value of 826×10−3 V m N−1, which is much higher than that of commercial TGS and most of the piezoelectric ceramics. While the lamivudine crystal was refined in the P43212 space group, showing no piezoelectric activity. The presence of crystalline water plays a crucial role in establishing its polar structure and achieving high piezoelectric properties of lamivudine hydrate crystal. The decent d33 and g33 values make it a promising candidate for advanced materials in high‐performance piezoelectric sensors, particularly in applications involving flexible, wearable, and biomechanical devices.

Giant piezoresponse in nanoporous (Ba,Ca)(Ti,Zr)O3 thin film.

Lattice strain effects on the piezoelectric properties of crystalline ferroelectrics have been extensively studied for decades; however, the strain dependence of the piezoelectric properties at nano-level has yet to be investigated. Herein, a new overview of the super-strain of nanoporous polycrystalline ferroelectrics is reported for the first time using a nanoengineered barium calcium zirconium titanate composition (Ba0.85Ca0.15)(Ti0.9Zr0.1)O3 (BCZT). Atomic-level investigations show that the controlled pore wall thickness contributes to highly strained lattice structures that also retain the crystal size at the optimal value (<30 nm), which is the primary contributor to high piezoelectricity. The strain field derived from geometric phase analysis at the atomic level and aberration-corrected high-resolution scanning transmission electron microscopy (STEM) yields of over 30% clearly show theoretical agreement with high piezoelectric properties. The uniqueness of this work is the simplicity of the synthesis; moreover the piezoresponse d 33 becomes giant, at around 7500 pm V-1. This response is an order of magnitude greater than that of lead zirconate titanate (PZT), which is known to be the most successful ferroelectric over the past 50 years. This concept utilizing nanoporous BCZT will be highly useful for a promising high-density electrolyte-free dielectric capacitor and generator for energy harvesting in the future.

Enhanced electrical properties of lead-free sodium potassium niobate piezoelectric ceramics prepared via cold sintering assisted sintering

The CSAS method can increase the density of the ceramics and reduce the volatilization of the A-site elements, thus changing the phase structure of the ceramics and making them high piezoelectric properties.