Showing papers on "Lead zirconate titanate published in 2019"

A molecular perovskite solid solution with piezoelectricity stronger than lead zirconate titanate.

Abstract: Piezoelectric materials produce electricity when strained, making them ideal for different types of sensing applications. The most effective piezoelectric materials are ceramic solid solutions in which the piezoelectric effect is optimized at what are termed morphotropic phase boundaries (MPBs). Ceramics are not ideal for a variety of applications owing to some of their mechanical properties. We synthesized piezoelectric materials from a molecular perovskite (TMFM)x(TMCM)1–xCdCl3 solid solution (TMFM, trimethylfluoromethyl ammonium; TMCM, trimethylchloromethyl ammonium, 0 ≤ x ≤ 1), in which the MPB exists between monoclinic and hexagonal phases. We found a composition for which the piezoelectric coefficient d33 is ~1540 picocoulombs per newton, comparable to high-performance piezoelectric ceramics. The material has potential applications for wearable piezoelectric devices.

Ferroelectricity-free lead halide perovskites

Abstract: Direct piezoelectric force microscopy (DPFM) is employed to examine whether or not lead halide perovskites exhibit ferroelectricity. Compared to conventional piezoelectric force microscopy, DPFM is a novel technique capable of measuring piezoelectricity directly. This fact is fundamental to be able to examine the existence of ferroelectricity in lead halide perovskites, an issue that has been under debate for several years. DPFM is used to detect the current signals, i.e. changes in the charge distribution under the influence of the scan direction and applied force of the atomic force microscope (AFM) tip in contact mode. For comparison, (i) we use DPFM on lead halide perovskites and well-known ferroelectric materials (i.e. periodically poled lithium niobate and lead zirconate titanate); and (ii) we conduct parallel experiments on MAPbI3 films of different grain sizes, film thicknesses, substrates, and textures using DPFM as well as piezoelectric force microscopy (PFM) and electrostatic force microscopy (EFM). In contrast to previous work that claimed there were ferroelectric domains in MAPbI3 perovskite films, our work shows that the studied perovskite films Cs0.05(FA0.83MA0.17)0.95Pb(I0.83Br0.17)3 and MAPbI3 are ferroelectricity-free. The observed current profiles of lead halide perovskites possibly originate from ion migration that happens under an applied electrical bias and in strained samples under mechanical stress. This work provides a deeper understanding of the fundamental physical properties of the organic–inorganic lead halide perovskites and solves a longstanding dispute about their non-ferroelectric character: an issue of high relevance for optoelectronic and photovoltaic applications.

Pure Piezoelectricity Generation by a Flexible Nanogenerator Based on Lead Zirconate Titanate Nanofibers.

Abstract: Lead zirconate titanate (PbZr0.52Ti0.48O3, PZT) alloys have been extensively studied to be used for piezoelectric nanogenerators to harvest energy from mechanical motions. In this study, PZT nanofiber-based nanogenerators were fabricated to test their true piezoelectric performance without the triboelectric effect. Aligned PZT nanofibers were fabricated by a sol-gel electrospinning process. The thickness, area, and orientation of the PZT textile made by electrospinning a PZT solution onto multipair metal wires or metal mesh were controlled to form a composite textile. After the calcination, the PZT textile mixed with polydimethylsiloxane was placed between two flexible indium-doped tin oxide-polyethylene naphthalate substrates. The performance parameters of the nanogenerators were investigated under the bending motion, which excludes the triboelectric effect. An assembled nanogenerator of an area of 8 cm2 and a thickness of 80 μm could generate an electrical output voltage of 1.1 V and a current of 1.4 μA under the bending strain. The piezoelectric voltage depended on the thickness of the PZT textile, whereas the piezoelectric current depended on both the thickness and the area of the PZT textile. The electrical performance of the device was significantly affected by the orientation of the PZT fiber and the bending direction. The output voltage and the output current were strain-dependent, whereas the total integrated charge was independent of the strain rate. The properties of the flexible nanogenerator could be quantified to verify the pure piezoelectric performance of the device.

Skin-Integrated Graphene-Embedded Lead Zirconate Titanate Rubber for Energy Harvesting and Mechanical Sensing

Abstract: Thin, soft skin-integrated electronics have attracted great attentions due to their advantages such as flexible, lightweight, and mechanical compatible with human body, thus offer unique capabilities in detecting vital information and continuous monitoring human health.[1–8] Recent advances in materials development,[9–15] electronics miniaturization,[16–20] mechanics optimization,[18,21–24] and system-level integration[17,25–28] build up the foundations for flexible and stretchable electronics[29–32] which are able to be integrated together with skin. Considering power supply for this new kind of soft electronics, conversion of mechanical energy from human body activities and motions to electricity is a considerable route.[4,5,13,33,34] Various kinds of technologies, such as piezoelectric,[35–40] triboelectric,[41–47] electromagnetic,[48] and pyroelectric[49–51] have been considered and studied. Among these self-powered technologies, piezoelectric generators have proven to be a great candidate as energy harvesters for skin-integrated or even biointegrated electronics, due to the combination of their excellent electrical properties and advanced mechanical designs.[5,18,52,53] Materials and mechanical engineering in piezoelectric materials, including lead zirconate tinanate (PZT),[1,11,18,19,24,38] PVDF,[20,21,53] BaTiO3, NaNbO3, and ZnO[35,56] have been made great progress and realized outstanding electromechanical properties. However, complicated fabrication processes involving high temperature deposition, multiple steps photolithographs, physical/chemical etchings, and transfer printings are typically needed to meet the requirement of flexibility.[17,18,57–59] To realize rapid and low-cost processing techniques for soft piezoelectric based electronics, inherent flexibility of the materials should be carefully considered, as which affords the possibility for large-area fabrication relevant routes, such as screen-printing and roll to roll technologies.[9] One promising method for realizing inherent flexible piezoelectric materials is designing polymer-matrix composites which typically consist of piezoelectric ceramic powders and silicone rubbers (polydimethylsiloxane, PDMS).[11,15,60–63] This Thin, soft, skin-like electronics capable of transforming body mechanical motions to electrical signals have broad potential applications in biosensing and energy harvesting. Forming piezoelectric materials into flexible and stretchable formats and integrating with soft substrate would be a considerable strategy for this aspect. Here, a skin-integrated rubbery electronic device that associates with a simple low-cost fabrication method for a ternary piezoelectric rubber composite of graphene, lead zirconate tinanate (PZT), and polydimethylsiloxane (PDMS) is introduced. Comparing to the binary composite that blend with PZT and PDMS, the grapheneembedded ternary composite exhibits a significant enhancement of selfpowered behavior, with a maximum power density of 972.43 μW cm−3 under human walking. Combined experimental and theoretical studies of the graphene-embedded PZT rubber allow the skin-integrated electronic device to exhibit excellent mechanical tolerance to bending, stretching, and twisting for thousands of cycles. Customized device geometries guided by optimized mechanical design enable a more comprehensive integration of the rubbery electronics with the human body. For instance, annulus-shape devices can perfectly mount on the joints and ensure great power output and stability under continuous and large deformations. This work demonstrates the potential of large-area, skin-integrated, self-powered electronics for energy harvesting as well as human health related mechanical sensing.

A High Sensitivity Optical Fiber Sensor for GIS Partial Discharge Detection

Abstract: We propose a high sensitivity optical fiber sensor for detecting the acoustic emission generated by the partial discharge in gas-insulated-switchgear (GIS). A model is established to investigate the effects of the cylinder coil on the sensitivity, the bandwidth, and the detection limit. After that, the proposed sensor was modified based on the effects. The average sensitivity of the optimized acoustic emission (AE) optical fiber sensor is 32 dB higher than that of the conventional lead zirconate titanate (PZT) in the frequency range from 20 kHz to 100 kHz. Moreover, the experimental results show that the detectable partial discharge initial voltage for the proposed optical system is 17.1% lower than that for the PZT system, and the amplitude of the signal detected by the proposed optical system is 525% higher than that detected by the PZT system.

A gullwing-structured piezoelectric rotational energy harvester for low frequency energy scavenging

Abstract: A gullwing-structural piezoelectric energy harvester mainly consisting of two typical nonlinear buckled-bridges is proposed to effectively scavenge low-frequency rotational kinetic energy based on a gear mechanism induced interwell oscillation. A natural buckled piezoelectric unit and a flexible polymer substrate are used for the buckled-bridge. A thinned bulk lead zirconate titanate ceramic is employed for the piezoelectric layer in consideration of its excellent electromechanical factor. The presented harvester can generate a peak open-circuit voltage of 20 V at a rotational frequency of 7.8 Hz, which has a low dependence on the applied frequency. A 100 μF capacitor reaches a charging voltage of 14.7 V after 38 s and is saturated at 16.05 V for 122 s. Through the power management circuit, the harvester generates an output power of 0.4 mW and the effective power density of 6.54 μW mm−3 at the low rotational frequency. These results indicate that this strategy is promising for self-powered sensors, especially at changeable and low-frequency ambient, such as tire pressure monitoring.

AlN PMUT-based Ultrasonic Power Transfer Links for Implantable Electronics

Abstract: The present work reports on the first demonstration of acoustic power transfer through the use of Aluminum Nitride (AlN) Piezoelectric Micro Machined Ultrasonic Transducer (PMUT) arrays at transmission distances suitable for intra-body powering applications. In contrast to Lead Zirconate Titanate (PZT), used as the piezoelectric in state-of-the-art devices, AlN offers higher biocompatibility and the possibility of single chip integration with Complementary Metal Oxide Semiconductor (CMOS) technology. An output power of 1 μW, from a minute (8 mm x 8 mm x 300 μm) PMUT array chip, was achieved on an optimal 330 Ω load. The operating frequency was 2 MHz, through a distance of 4 cm, in an oil medium resembling intra-body conditions. This implementation is a critical step towards increasingly miniaturized, highly integrated implantable circuits.

A One-step Residue-free Wet Etching Process of Ceramic PZT for Piezoelectric Transducers.

Abstract: Lead zirconate titanate (PZT) has wide applications in microelectromechanical systems (MEMS) due to its large piezoelectric coefficients. However, there exist serious issues during PZT wet etching even with multiple etching steps, such as residues on etching fronts and large undercut. In this paper, a one-step residue-free wet etching process of ceramic PZT is developed with fluoroboric acid. In this work, the design of experiments (DOE) method is employed to minimize undercut and residues without sacrificing etching rate. The acid concentration, temperature, and agitation are the process parameters considered in the DOE. Through DOE analysis of the experimental data, an optimal recipe is identified as the volume ratio of HBF4:H2O=1:10 at 23 °C. This new PZT etching recipe leads to a high etching rate (1.54 μm/min) with no observable residues and a small undercut (0.78:1) as well as a high selectivity over the photoresist (900:1). This etching recipe can be used for making various piezoelectric transducers.

A Flexible e-skin based on micro-structured PZT thin films prepared via a low-temperature PLD method

Abstract: The e-skin based on lead zirconate titanate (PZT) exhibits excellent electrical sensing performance, and it is widely used in clinical trials owing to its prominent piezoelectric, ferroelectric and pyroelectric performance. However, the complicated fabrication procedure and fatigue during long-term use still limit its application. In this study, a flexible e-skin withstanding fatigue over extended periods of use (more than 10 000 cycles) was facilely constructed by combining polydimethylsiloxane (PDMS) with a highly crystalline PZT thin film. Note that the sensor was first fabricated using the micro-structured PZT thin film via a low-temperature pulsed laser deposition system (PLD) method, which could be easily combined with other processes. The sensor highlighted an ultra-high detection sensitivity (S, ∼5.82 kPa−1) and almost negligible hysteresis rate or degree of hysteresis (DH, ∼0.45%) in the pressure-sensing test. Moreover, the obtained sensor exhibited the lower limit of detection (LOD) of 30 Pa as well as a faster response (∼0.38 s) and release time (∼0.79 s). Importantly, due to the excellent performance of this sensor, various dynamic and static signals of the human body could be detected within the maximum range allowed under the septal fracture effect.

Ferroelectric Field Effect Transistors Based on PZT and IGZO

Abstract: Ferroelectric field effect transistors (FeFETs) based on lead zirconate titanate (PZT) ferroelectric material and amorphous-indium-gallium-zinc oxide (a-IGZO) were developed and characterized. The PZT material was processed by a sol-gel method and then used as ferroelectric gate. The a-IGZO thin films, having the role of channel semiconductor, were deposited by radio-frequency magnetron sputtering, at a temperature of ~50°C. Characteristics of a typical field effect transistor with SiO2 gate insulator, grown on highly doped silicon, and of the PZT-based FeFET were compared. It was proven that the FeFETs had promising performances in terms of Ion/Ioff ratio (i.e., 106) and IDS retention behavior.

Flexible Ultrasonic Transducer Array with Bulk PZT for Adjuvant Treatment of Bone Injury

Abstract: Flexible electronic devices are developing rapidly, especially in medical applications. This paper reports an arrayed flexible piezoelectric micromachined ultrasonic transducer (FPMUT) with a sandwich structure for adjuvant treatment of bone injury. To make the device conformable and stretchable for attaching to the skin surface, the flexible substrate of polydimethylsiloxane (PDMS) was combined with the flexible metal line interconnection between the bulk lead zirconate titanate (PZT) arrays. Simulations and experiments were carried out to verify the resonant frequency and tensile property of the reported FPMUT device. The device had a resonant frequency of 321.15 KHz and a maximum sound pressure level (SPL) of 180.19 dB at the distance of 5 cm in water. In addition, detailed experiments were carried out to test its acoustic performance with different pork tissues, and the results indicated good ultrasound penetration. These findings confirm that the FPMUT shows unique advantages for adjuvant treatment of bone injury.

Electrical studies of Barkhausen switching noise in ferroelectric PZT: Critical exponents and temperature dependence

Abstract: Crackling noise of ferroelectric lead zirconate titanate samples during ferroelectric switching is demonstrated to be compatible with avalanche statistics. The peaks of the slew rate (time derivative of current $dI/dt$ squared), defined as ``jerks,'' were statistically analyzed and shown to obey power laws. The critical exponent obtained is $1.64\ifmmode\pm\else\textpm\fi{}0.15$, in agreement with predictions from avalanche theory. The exponent is independent of temperature within experimental error margins.

Dielectric, Piezoelectric and Ferroelectric Properties of Flexible 0–3 Type PZT/PVDF Composites Doped with Graphene

Abstract: A 0–3 type PZT/PVDF composite was fabricated from lead zirconate titanate (PZT) and polyvinylidene fluoride (PVDF) by tape casting. Different amounts of graphene (GR) (0–0.9 wt.%) were added to study the electrical properties of the PZT/PVDF composite. The dielectric, piezoelectric and ferroelectric properties of the composites were investigated when the grain size of the PZT powder and the mass fraction of graphene were varied. The dielectric constant and dielectric loss tangent increased with the graphene content. When 0.6 wt.% graphene was added, the PZT/PVDF/GR composite had a piezoelectric constant of 27.62 pC/N, which is 21.6% higher than that of the composite without graphene.

Highly-Loaded Thermoplastic Polyurethane/Lead Zirconate Titanate Composite Foams with Low Permittivity Fabricated using Expandable Microspheres.

Abstract: The sensitivity enhancement of piezocomposites can realize new applications. Introducing a cellular structure into these materials decreases the permittivity and thus increases their sensitivity. However, foaming of piezocomposites is challenging because of the high piezoceramic loading required. In this work, heat-expandable microspheres were used to fabricate thermoplastic polyurethane (TPU)/lead zirconate titanate (PZT) composite foams with a wide range of PZT content (0 vol % to 40 vol %) and expansion ratio (1–4). The microstructure, thermal behavior, and dielectric properties of the foams were investigated. Composite foams exhibited a fine dispersion of PZT particles in the solid phase and a uniform cellular structure with cell sizes of 50–100 μm; cell size decreased with an increase in the PZT content. The total crystallinity of the composites was also decreased as the foaming degree increased. The results showed that the relative permittivity (er) can be effectively decreased by an increase in the expansion ratio. A maximum of 7.7 times decrease in er was obtained. An extended Yamada model to a three-phase system was also established and compared against the experimental results with a relatively good agreement. This work demonstrates a method to foam highly loaded piezocomposites with a potential to enhance the voltage sensitivity.

Label-free sensitive detection of influenza virus using PZT discs with a synthetic sialylglycopolymer receptor layer

Abstract: We describe rapid, label-free detection of Influenza A viruses using the first radial mode of oscillations of lead zirconate titanate (PZT) piezoelectric discs with a 2 mm radius and 100 µm thickness fabricated from a piezoelectric membrane. The discs are modified with a synthetic sialylglycopolymer receptor layer, and the coated discs are inserted in a flowing virus suspension. Label-free detection of the virus is achieved by monitoring the disc radial mode resonance frequency shift. Piezo transducers with sialylglycopolymer sensor layers exhibited a long lifetime, a high sensitivity and the possibility of regeneration. We demonstrate positive, label-free detection of Influenza A viruses at concentrations below 105 virus particles per millilitre. We show that label-free, selective, sensitive detection of influenza viruses by home appliances is possible in principle.

A MEMS-Scale Ultrasonic Power Receiver for Biomedical Implants

Abstract: Bio-implantable medical devices need a reliable and stable source of power to perform effectively. Although batteries are typically the first candidate to power implantable devices, they have a limited lifetime and must be periodically replaced or recharged. To alleviate this issue, ultrasonic power transfer systems can wirelessly power bio-implantable devices. Diaphragm structures which use piezoelectric materials (also known as piezoelectric micromachined ultrasonic transducers) can be fabricated on a small scale suitable for implantable devices. Diaphragms can be fabricated by deposition of lead zirconate titanate (PZT) films on a non-piezoelectric material. However, current deposition techniques cannot provide PZT thicknesses more than about 6 μm. We numerically investigate the performance of a square ultrasonic PZT receiver with inner and outer electrodes. Using COMSOL simulations, we optimize the piezoelectric film thickness for a 2 mm × 2 mm diaphragm with a silicon substrate of 50 μm and find the optimal thickness to be 20 μm for a maximum output power delivered to an optimal load. We fabricate a micromachined ultrasonic power-generating receiver capable of providing sufficient power for implantable medical devices using bulk PZT. We show that when a transmitter is generating an input power intensity of 322 mW/cm 2 at 88 kHz, less than Food and Drug Administration limit of 720 mW/cm 2 , the receiver delivers a power of 0.7 mW to an optimal resistive load of 4.3 kΩ when the distance between the transmitter and the receiver is 20 mm. Furthermore, the process developed can be used to fabricate devices that are significantly smaller than the one characterized, which enables further miniaturization of bio-implanted systems.

Nonlinear ultrasonic inspection of smart carbon fibre reinforced plastic composites with embedded piezoelectric lead zirconate titanate transducers for space applications

Abstract: Carbon fibre reinforced plastic composites used in spacecraft structures are susceptible to delamination, debonds and fibre cracking that may arise during manufacturing, assembly or in-service oper...

Characterization of Epitaxial-PZT/SI Piezoelectric Micromachined Ultrasonic Transducer (PMUT) and its Phased Array System

Abstract: In this study, we have demonstrated the usability of an epitaxial lead zirconate titanate (Epi-PZT) thin film for a piezoelectric micromachined ultrasonic transducer (pMUT) imager. At first, transmitting abilities and receiving sensitivities of the single-element pMUT based on Epi PZT and polycrystalline PZT (Poly-PZT) were evaluated as a fundamental study. Then, the 8-ch linear array system driven by a commercially-available pulser board was built, and successfully formed a focused ultrasonic beam. Finally, we obtained the ultrasonic images of a polydimethylsiloxane-based phantom by using the Epi-PZT and Poly-PZT pMUT linear array, and experimentally proved that Epi-PZT pMUT array can obtain higher contrast image compared to Poly-PZT device.