Excellent Piezoelectric Properties Research Articles

Fabricating AC/DC nanogenerators based on single ZnO nanowires by using a nanomanipulator in a scanning electron microscope

Single zinc oxide nanowires (ZnO NWs) are promising for nanogenerators because of their excellent semiconducting and piezoelectric properties, but characterizing the latter efficiently is challenging. As reported here, an electrical breakdown strategy was used to construct single ZnO NWs with a specific length. With the high operability of a nanomanipulator in a scanning electron microscope, ZnO-NW-based two-probe and three-probe structures were constructed for fabricating AC/DC nanogenerators, respectively. For a ZnO NW, an AC output of between −15.31 mV and 5.82 mV was achieved, while for a DC nanogenerator, an output of ∼24.3 mV was realized. Also, the three-probe structure’s output method was changed to verify the distribution of piezoelectric charges when a single ZnO NW is bent by a probe, and DC outputs of different amplitudes were achieved. This study provides a low-cost, highly convenient, and operational method for studying the AC/DC output characteristics of single NWs, which is beneficial for the further development of nanogenerators.

Employing Piezoelectric Mg2+-Doped Hydroxyapatite to Target Death Receptor-Mediated Necroptosis: A Strategy for Amplifying Immune Activation.

Although immunogenic cell death (ICD) inducers evidently enhance the effectiveness of immunotherapy, their potential is increasingly restricted by the development of apoptosis resistance in tumor cells, poor immunogenicity, and low T-cell immune responsiveness. In this study, for the first time, piezoelectrically catalyzed Mg2+-doped hydroxyapatite (Mg-HAP) nanoparticles, which are coated with a mesoporous silica layer and loaded with ONC201 as an agonist to specifically target the death receptor DR5 on tumor cells, ultimately developing an Mg-HAP@MS/ONC201 nanoparticle (MHMO NP) system, are engineered. Owing to its excellent piezoelectric properties, MHMO facilitates the release of a significant amount of reactive oxygen species and Ca2+ within tumor cells, effectively promoting the upregulation of DR5 expression and inducing tumor cell necroptosis to ultimately overcome apoptosis resistance. Concurrently, Mg2+ released in the tumor microenvironment promotes CD8+ T receptor activation in response to the antitumor immune reaction induced by ICD. Using RNA-seq analysis, it is elucidated that MHMO can activate the NF-κB pathway under piezoelectric catalysis, thus inducing M1-type macrophage polarization. In summary, a dual-targeting therapy system that targets both tumor cells and the tumor microenvironment under piezoelectric catalysis is designed. This system holds substantial potential for advancements in tumor immunotherapy.

Piezoelectric Properties and Thermal Stability of Pb(Yb1/2Nb1/2)O3-BiScO3-PbTiO3 Ternary Ceramics

Piezoelectric ceramics with excellent piezoelectric properties and a high Curie temperature are important for numerous electromechanical devices in a broad range of temperature environments. In this work, the relaxor ferroelectric Pb(Yb1/2Nb1/2)O3 end member was selected to be introduced into a BiScO3-PbTiO3 high-temperature piezoelectric ceramic to reduce the dielectric loss and improve the piezoelectric properties while slightly reducing the Curie temperature. The phase structure and dielectric, ferroelectric and piezoelectric properties of 0.025Pb(Yb1/2Nb1/2)O3-(0.975−x)BiScO3-xPbTiO3 (0.60 ≤ x ≤ 0.63) ceramics were systematically analyzed, and the best electrical properties were observed in the morphotropic phase boundary region x = 0.61 with d33 = 370 pC/N, kp = 44%, Pr = 33.9 μC/cm2. Importantly, no significant depolarization was observed in the x = 0.61 ceramic from room temperature to 290 °C, demonstrating its good thermal stability and potential applications in a wide range of temperature environments.

Structural responses of electrospun PVDF fibers induced by specific stretching and ensuing heating

AbstractMicrostructure of electrospun fibers is often invoked to explain their properties but that is challenging to quantify properly. The electrospun PVDF fibers being rich in the β‐phase crystal due to excellent piezoelectric properties are promising energy‐harvesting materials for wearable and implantable applications. In this work, structural responses of electrospun PVDF fibers were investigated under the conditions of specific stretching at 25°C and ensuing heating from 25 to 170°C at strains of 5%, 10%, 20%, respectively, using the in situ WAXD with a thermos‐mechanical coupled equipment. In this process, the fiber morphology, and the crystal orientation, the crystal structure, the β‐phase content, as well as mechanical property of elctrospun PVDF fibers were studied. It is found that the specific stretching affects the β‐phase crystal more than ensuing heating when the heating temperature is lower than the melting temperature of the fibers. Moreover, after 20% stretching and ensuing heating to 150°C, the tensile strength of electrospun PVDF fibers membrane can rise to 12.8 MPa, which is more than three times that of the pristine fibers, which is attributed to the higher crystal orientation and β‐phase content, along with the alignment of the fibers. Therefore, structural responses of electrospun PVDF fibers induced by specific stretching and ensuing heating are propitious to explain and tailor their properties in practical applications, which also gives potential insights into other fibers.

Flexible Film Bulk Acoustic Wave Filter Based on Poly(vinylidene fluoride-trifluorethylene).

Poly(vinylidene fluoride-trifluorethylene) (P(VDF-TrFE)) has promising potential applications in radio-frequency filters due to their excellent piezoelectric properties, flexibility, and stability. In this paper, a flexible film bulk acoustic wave filter is investigated based on P(VDF-TrFE) as piezoelectric film. A new method based on three-step annealing is developed to efficiently remove the porosity inside the P(VDF-TrFE) films so as to improve its properties. The obtained film achieved high β-phase content beyond 80% and a high piezoelectric coefficient of 27.75 pm/V. Based on the low porosity β-phase films, a flexible wide-band RF filter is designed, which consists of a bulk acoustic wave resonator and lumped inductor-capacitor elements as a hybrid configuration. The resonator sets the filter's center frequency, while the lumped LC-based matching network extends the bandwidth and enhances out-of-band rejection. The testing results of the proposed wide-band filter show its good performance, with 12.5% fractional bandwidth and an insertion loss of 3.1 dB. To verify the possibility of folding and stacking the flexible bulk acoustic wave devices for high-density multi-filter integration in MIMO communication, bending tests of the filter are also conducted with the bending strain range up to 5500 με. The testing results show no noticeable performance degradation after four bending cycles. This work demonstrates the potential of β-phase P(VDF-TrFE) bulk acoustic wave filters to expand the scope of future flexible radio-frequency filter applications.

The effect of ZnO and MnO2 as sintering aids in the preparation of potassium sodium niobate ceramics and electrical characterizations

Potassium sodium niobate (KNN) is an environmentally compatible piezoelectric material for substituting harmful lead-based ceramics. KNN-based ceramics have excellent piezoelectric properties with high Curie temperature. But, KNN faces difficulties during the processing like volatilization of alkali elements, chemical inhomogeneity, low densification, etc. The objective of this research is to investigate the impact of certain metal oxides additions like ZnO and MnO2 as sintering aids to solve the problems of the preparation and hence study the structural and electric properties of K0.5N0.5NbO3 (KNN) ceramics. ZnO and MnO2 added potassium sodium niobate, K0.5N0.5NbO3 was prepared by using the ceramic method. The prepared samples were sintered at 1000 °C for 2h conventionally. The structural properties of the ceramics have been analyzed by using X-Ray Diffractometer. The study demonstrates the formation of the orthorhombic-symmetric perovskite phase in all the prepared samples. The microstructural behavior of the ceramics has been characterized by techniques such as scanning electron microscopy (SEM) and compositional properties were studied by energy dispersive x-ray (EDAX). The effects of metal oxide additions on the electronic properties such as dielectric constant, dielectric loss, impedance properties, Nyquist plot, etc., were studied. The results have been analyzed and discussed in the paper.

Piezoelectric properties of (Sr0.2Ca0.8)3TaGa3Si2O14 and Ca3TaGa3Si2O14 single crystals grown via vertical Bridgman method

(Sr0.2Ca0.8)3TaGa3Si2O14 and Ca3TaGa3Si2O14 single crystals were successfully grown using the vertical Bridgman method, and the piezoelectric properties of these crystals were studied.

Asymmetric XMoGeY2 (X = S, Se, Te; Y = N, P, As) monolayers as potential flexible materials for nano piezoelectric devices and nanomedical sensors.

Highly efficient nano piezoelectric devices and nanomedical sensors are in great demand for high-performance piezoelectric materials. In this work, we propose new asymmetric XMoGeY2 (X = S, Se, Te; Y = N, P, As) monolayers with excellent piezoelectric properties, dynamic stability and flexible elastic properties. The piezoelectric coefficients (d11) of XMoGeY2 monolayers range from 2.92 to 8.19 pm V-1. Among them, TeMoGeAs2 exhibits the highest piezoelectric coefficient (d11 = 8.19 pm V-1), which is 2.2 times higher than that of common 2D piezoelectric materials such as 2H-MoS2 (d11 = 3.73 pm V-1). Furthermore, all XMoGeY2 monolayers demonstrate flexible elastic properties ranging from 96.23 to 253.70 N m-1. Notably, TeMoGeAs2 has a Young's modulus of 96.23 N m-1, which is only one-third of that of graphene (336 N m-1). The significant piezoelectric coefficients of XMoGeY2 monolayers can be attributed to their asymmetric structures and flexible elastic properties. This study provides valuable insights into the potential applications of XMoGeY2 monolayers in nano piezoelectric devices and nanomedical sensors.

Effects of electric field and light on resistivity switching of Eu0.7Sr0.3MnO3 thin films.

Based on the excellent piezoelectric properties of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) single crystals, a hole-doped manganite film/PMN-PT heterostructure has been constructed to achieve electric-field and light co-control of physical properties. Here, we report the resistivity switching behavior of Eu0.7Sr0.3MnO3/PMN-PT(111) multiferroic heterostructures under different in-plane reading currents, temperatures, light stimuli and electric fields, and discuss the underlying coupling mechanisms of resistivity change. The transition from the electric-field induced lattice strain effect to polarization current effect can be controlled effectively by decreasing the in-plane reading current at room temperature. With the decrease of temperature, the interfacial charge effect dominates over the lattice strain effect due to the reduced charge carrier density. In addition, light stimulus can lead to the delocalization of eg carriers, and thus enhance the lattice strain effect and suppress the interfacial charge effect. This work helps to understand essential physics of magnetoelectric coupling and also provides a potential method to realize energy-efficient multi-field control of manganite thin films.

First-principles calculation of in-plane and out-of-plane piezoelectric properties of two-dimensional Janus MoSSiX2 (X = N, P, As) monolayers

Janus MoSSiX2 (X = N, P, As) monolayers exhibit excellent piezoelectric properties. The in-plane piezoelectric coefficient is 1.87–5.35 pm V−1, and the out-of-plane piezoelectric coefficient is 0.16–0.34 pm V−1.

Textured Pb(Mg1/3Nb2/3)O3 −Pb(In1/2Nb1/2)O3 −PbTiO3 ceramics with enhanced piezoelectric properties and high Curie temperature prepared by low-temperature sintering

A low-temperature sintering is crucial for the fabrication of multilayer piezoceramic actuators through low-cost internal metal electrodes. Herein, Pb(Mg1/3Nb2/3)O3−Pb(In1/2Nb1/2)O3 −PbTiO3 (PMN−PIN−PT) textured ceramics were prepared by a combined use of refined matrix powder and CuO sintering additive. When the matrix powder was refined by planetary ball-milling for 10 h, the sintering temperature of the textured 0.37PMN−0.29PIN−0.34PT ceramics was lowered to 1175 ºC, and a subsequent addition of 1 mol% CuO further lowered it to 950 ºC. The textured 0.37PMN−0.29PIN−0.34PT ceramics with 3 vol% BaTiO3 (BT) template sintered at 950 ºC for 10 h yielded excellent piezoelectric properties, such as a Lotgering factor (LF) of 97%, a unipolar strain of 0.23% at 2 kV/mm, and a Curie temperature (TC) of 231 ºC. These enhanced piezoelectric properties and high TC result from the high texture, transient liquid phase sintering, Cu2+ ion doping, and minimum BT template content.

The mechanism of ferroelectric phase transformation in Gd2O3 modified BCZT ceramics: Experimental studies and first-principles calculations

Lead-free (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 (BCZT)-based piezoelectric ceramics have attracted considerable interest due to their excellent piezoelectric properties and abundant phase structures. However, there is a serious lack in the theoretical calculations for the ferroelectric phase transition behavior. Here, the experimental and first-principles calculations were utilized to analyze the ferroelectric phase transition process of (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3-xGd2O3(BCZT-xGd, x = 0, 0.02, 0.04, and 0.05) ceramics. The incorporation of Gd2O3 has induced a transformation from tetragonal to rhombohedral phase due to the decrease in the dislocation energy with A-site cations and the attenuation of the bonding energy between B-site cations and the planar O atoms. Moreover, the hybridization between the d orbitals of B-site atoms and the O 2p orbitals, coupled with the reduction of the polarization vector along the [001] axis, leads to enhanced weak coupling relaxation. This work provides a theoretical basis for the ferroelectric phase transition behavior of other piezoelectric systems.

Huge piezoelectricity and electro-optic effects in rhombohedral relaxor ferroelectric single crystals by Sm3+ doping

In recent years, relaxor ferroelectric single crystals have attracted people's attention and research because of their excellent piezoelectric properties at morphotropic phase boundary(MPB). The ternary system Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 (PIN-PMN-PT) crystals have higher Curie temperature and coercive field, which have the opportunity to be applied in high-temperature devices. The crystals of the rhombohedral phase have better stability, but their performance is not as good as that of the MPB component crystals. In this paper, the piezoelectric properties of rhombohedral PIN-PMN-28PT single crystals are improved by Sm3+ doping. The piezoelectric coefficient d33 after AC polarization along [001] direction can reach 3125pC/N, which is 60% higher than that of undoped crystals. Meanwhile, the crystal exhibits excellent optical performance after DC polarization along [110] direction. The crystal has an effective electro-optic coefficient of 386 pm/V at room temperature and a stable frequency-dependent characteristic, which is expected to be an ideal material for electro-optic devices.

Single Crystal (K,Na)Nb)3/CuO Heterostructures for Synergistic Photo-Piezocatalytic Activity

In this study, we designed a heterostructure piezo-photocatalyst composed of Ba, Li doped- (K,Na)NbO3 (KNN) single-crystal microcuboids and CuO nanodots. KNN was selected because of its high piezoelectric coefficient (d33 ), good chemical stability, and environmental friendliness. As a cocatalyst, CuO was considered owing to its advantages such as narrow bandgap, low cost, and nontoxicity. The n-type semiconducting Pb-free KNN single-crystal ferroelectric microcuboids (~30 μm) were synthesized by molten-salt reaction. Then, p-type semiconducting CuO nanodots (less than 5 nm) were uniformly decorated onto KNN microcuboids via deposition of Cu(OH)2, followed by conversion to CuO through calcination. From our heterostructure, it is expected that excellent piezoelectric properties could be obtained from KNN single-crystal microcuboids and a high surface area for catalytic reactions is guaranteed by CuO nanodots that are evenly deposited on the surface of KNN without aggregation. The novel KNN/CuO micro/nano heterostructures exhibited increased current density, and enhanced removal organic dye (RhB) efficiencies under the ultrasonic vibration when compared with bare KNN single-crystal catalysts. Specifically, the reaction rate constant (k) for the photo-piezocatalytic RhB dye degradation of the KNN/CuO micro/nano heterostructure exhibited ~ 0.093 min-1, which is higher when compared with other KNN-based piezo, photo, and photo-piezocatalysts. Additionally, the coupled photo-piezocatalyst for KNN/CuO realized an enhanced RhB dye degradation efficiency of 1.6 times and 48.6 times higher when compared with individual piezocatalytic and photocatalytic dye degradation capabilities, respectively. Our approach could provide insights into the design of heterostructure photo-piezocatalysts containing single-crystal ferroelectrics, which requires the enhancement of the photo-piezocatalytic activities.

Multi‐Length Engineering of (K, Na)NbO3 Films for Lead‐Free Piezoelectric Acoustic Sensors with High Sensitivity

AbstractWith increasing concerns about noise pollution, the pursuit of highly dependable piezoelectric acoustic sensors for real‐time noise monitoring has come to the forefront of scientific research. Lead‐based perovskite piezoelectric films, exemplified by lead zirconate titanate Pb(Zr,Ti)O3 (PZT), surpass traditional piezoelectric materials such as ZnO and AlN in their piezoelectric properties, promising substantial advancements in next‐generation acoustic sensor technologies. However, the toxic nature of lead in PZT materials poses formidable environmental and human health risks. In an unprecedented breakthrough, it presents the pioneering development of an environmentally benign lead‐free piezoelectric Micro‐Electro‐Mechanical System (MEMS) acoustic sensor based on potassium sodium niobate (K,Na)NbO3 (KNN) film. High‐quality <001> textured 3 µm‐thick KNN film is successfully integrated into commercially used Si substrate, rendering exceptional piezoelectricity (transverse piezoelectric coefficients e31* of ≈8.5 C m−2) with satisfactory thermal stability. The atomic‐scale Z‐contrast imaging and piezoresponse force microscopy characterizations reveal that the outstanding piezoresponse originates from the local coexistence of multiple phases and the enhancement of extrinsic piezoelectric contributions from in‐plane polarization anisotropy. Finite element simulation is employed to design the triangular cantilever structure and annular diaphragm structure, each corresponding to different operating bandwidths. The resultant MEMS acoustic sensors stand out with outstanding acoustic performance (the high sensitivity and expansive receiving field of view), which are attributed to the microstructural engineering at multi‐length scales for the excellent piezoelectric properties of KNN film. These features enable sensitive acoustic monitoring in various environments, including large‐scale power grids and urban traffic.

Mechanically Robust Cellulose-Based Piezoelectric Elastomer Formed by Slidable Polyrotaxane Cross-Linker.

Cellulose has great potential in the field of piezoelectricity owing to its high crystallinity; however, it exhibits low processability and poor mechanical robustness. In this study, to enhance the applicability of cellulose-based piezoelectric materials, a robust cellulose-based piezoelectric elastomer with excellent piezoelectric properties was developed by cross-linking cellulose with polyrotaxane (PR). The effects of cross-linking on the mechanical properties and crystalline structures of the resulting elastomers were investigated. The ferroelectric and piezoelectric properties were evaluated from their polarization hysteresis loops and voltage generation characteristics. eHPC25PR75 exhibited 2.7 times higher toughness (20.4 MJ m-3) than eHPC100 (7.57 MJ m-3). It also shows a power density 4.2 times higher (1.34 μW cm-2) than eHPC100 (0.321 μW cm-2). As a result, eHPC25PR75 demonstrated piezosensitivity to mechanical vibrations in a variety of devices that require mechanical robustness. These results can inform the design and development of high-performance piezoelectric devices.

3D-Printed Piezoelectret Based on Foamed Polylactic Acid for Energy-Harvesting and Sensing Applications.

Poly(lactic) acid (PLA) is a bio-compatible polymer widely used in additive manufacturing, and in the form of cellular foam it shows excellent mechanical and piezoelectric properties. This type of structure can be easily 3D-printed by Fusion Deposition Modelling (FDM) with commercially available composite filaments. In this work, we present mechanical and electrical investigations on 3D-printed low-cost and eco-friendly foamed PLA. The cellular microstructure and the foaming degree were tuned by varying extrusion temperature and flowrate. The maximum surface potential and charge stability of disk samples were found in correspondence of extrusion temperature between 230 and 240 °C with a flowrate of 53-44% when charging on a heated bed at 85 °C. The cells' morphology and correlated mechanical properties were analyzed and the measured piezoelectric d33 coefficient was found to be 212 pC/N. These findings show the importance of printing parameters and thermal treatment during the charging process in order to obtain the highest charge storage, stability and material flexibility. These results suggest that 3D-printed cellular PLA is a promising sustainable material for sensing and energy-harvesting applications.

Giant Ferroelectric and Piezoelectric Properties of Lead Free Ba0.85Ca0.15Ti0.90Zr0.10O3 Thin Film in 100 nm Thickness Range

Lead‐free Ba0.85Ca0.15Ti0.90Zr0.10O3/SrRuO3 (BCZT/SRO)‐heterostructured thin film grown on (001)‐SrTiO3 substrate is prepared by pulse laser deposition. The microstructure, ferroelectric, and piezoelectric of the thin film are investigated in detail. Giant ferroelectric properties of the BCZT thin films with thickness ≈100 nm and remanent polarization Pr of 57.1 μC cm−2 are obtained, which are attributed to the (00L)‐oriented epitaxial structure and lower substrate clamping. In addition, the BCZT/SRO heterostructure exhibits excellent piezoelectric properties with the d33 values of different grain size (40–140 nm) varied from 75 to 130 pm V−1, providing a potential candidate used as piezoelectric material for magnetoelectric composite films. The BCZT/SRO‐heterostructured thin film with excellent ferroelectric and piezoelectric properties may be a good alternative to Pb(ZrxTi1−x)O3 thin films for piezoelectric device applications.

Simulating study of cochlear sensors based on PVDF organic polymer materials

Cochlear implant is an effective choice to recover hearing for patients with sensorineural deafness. With the development of society, people’s demand for cochlear implants in all aspects is increasing. Polyvinylidene fluoride (PVDF) film is a kind of high polymer with excellent properties, which has broad application prospects in the field of cochlear implant. This article uses COMSOL software to simulate PVDF films and explore the size effect on the sensor performance. The simulation results show that the eigenfrequency is linearly related to height, meanwhile the vibration mode and electric potential also vary with height. The cochlear sensor is simulated in the range of human ear-sensitive hearing frequency, and the cochlear sensor has excellent piezoelectric properties. The cochlear sensor obtained after simulation can help patients with sensorineural deafness to better identify their hearing.

Improved piezoelectric and luminescent properties in Sm-modified Bi0.5Na0.5TiO3[sbnd]BaTiO3 multifunctional ceramics

The 0.93(Na0.5Bi0.5)1–xSmxTiO3-0.07BaTiO3 multifunctional ceramics were prepared by solid-phase reaction method. The phase structure, microstructure, electrical and photoluminescent properties were systematically studied. With increasing x, the ceramics undergoes the phase transition from rhombohedral to tetragonal with some rhombohedral distortion, along with a reduced grain size and increased relative density. On the other hand, the Sm3+ doping enhances the electric-field driven reversible phase transition and domain size, and reduces the domain walls, thereby contributing to improved piezoelectricity and decreased depolarization temperature (Td) from 91 °C to 40 °C. Excellent piezoelectric properties of d33 = 213 pC/N and kp = 29.9% are achieved in the x = 0.010 ceramic. Under excitation (407 nm), the Sm3+-doped ceramic exhibits bright reddish-orange fluorescence at 564, 599, 646 nm and 710 nm. A polarization-induced enhancement of photoluminescence is obtained in BNBT-xSm ceramics with an improved relative intensity of emission band at 646 nm. These results indicate that Sm3+-doped BNBT ceramics show great potential in electro-optic integration and coupling device applications.