PZT Fibers Research Articles

Stacked macro fiber piezoelectric composite generator for a spinal fusion implant

A manufacturing method was developed to create a piezoelectric 3-layer stacked, macro fiber composite generator operating in d33 mode to promote bone growth in spinal fusion surgeries. A specimen of 9 × 17 × 9 mm thick was constructed from 800 μm diameter PZT fibers and medical grade epoxy. Electromechanical testing was performed at three stages of manufacturing to determine the influence of these processes on power generation. An average peak power of over 335 μW was generated in the heat-treated specimen during simulated human body loads. The work provides insights into manufacturing methods for lowered source impedance power generation for a variety of applications.

Topology optimum design of unimorph piezoelectric cantilevered Mindlin plates as a vibrating electric harvester

An FEM-based topology optimization approach is proposed to calculate the topologies of a substrate plate and a piezoelectric layer used for vibrating unimorph cantilevered plate-like electricity generators (energy harvesters). The Mindlin plate theory was combined with a topology optimization algorithm to consider the shear effect. Each optimum topology for a plate and a piezoelectric layer is computed and combined by reflecting the natural frequencies of the substrate plate, electromechanical couplings of piezoelectric materials, tip masses and method of moving asymptotes. The piezoelectric coefficients such as elasticity, piezoelectric coupling and capacitance are interpolated by element density variables. The cantilevered plate generators with optimal topologies were designed for three piezoelectric materials such as PZT, PMN-PT and PMN-PT single crystal fiber MFC, and their voltage outputs were compared using a developed FEM-based optimization code to investigate the suitable material for harvesters.

Surface-condensed piezoelectric fibers and composites

An extrusion process that combined the surface condensation reaction was used to fabricate PZT fibers to exhibit a smooth surface and a circular morphology, with favorable manipulation strength. The sintered fibers showed more tetragonality. The electromechanical coupling coefficient and the resonant frequency of the PZT fibers had increased, while the aspect ratio of length to diameter (R) was larger than 2.8. Single PZT fibers with R > 2.8 showed larger remanent and saturation polarization values than the 1-3 composite and the PZT bulk. The dielectric constant and saturation polarization were in proportion to the volume filling percentage of the PZT fibers in the 1-3 composite. The piezoelectric coefficient increased with the fraction of the PZT fibers after a threshold volume fraction of 58 vol% was reached. As a proposed mechanism, the boric acid-PVA condensation reaction was initiated at the extruded fiber surface to form a capsule-like web to protect the extruded PZT fiber surface, increase the fiber strength, maintain the circular morphology, and facilitate fiber manipulation.

Analytical, numerical and experimental predictions of the effective electromechanical properties of macro-fiber composite (MFC)

An analytical model based on equivalent layered approach is developed to evaluate the effective properties of macro-fiber composites (MFC) where all the phases (kapton, acrylic, copper, piezoceramic fiber and epoxy) are considered for homogenization. Also, a finite element analysis (FEA) based on representative volume element (RVE) method is performed in the present work to determine the effective properties as MFCs have interdigitated electrode patterns and variations in fiber orientations. Experiments are performed under actuator mode to obtain the coupling constants. Simulations based on the proposed analytical and numerical approaches are validated with experiments and the data provided by the manufacturer. A parametric study is conducted to investigate the variations of overall material behavior of MFC as a function PZT (fiber phase) volume fraction. The outcome of the present study demonstrates the influence of total packaging effect on effective properties of MFC.

Low shear compounding process for thermoplastic fabrication of ferroelectric lead-free fibres

The thermoplastic ceramic extrusion process involves the shaping of a polymer highly filled with inorganic powder, the so-called ceramic–thermoplastic feedstock. The limitation faced with the process is the amount of raw material required to produce the feedstock. Depending on the density and desired volume of the materials used, the typical amount of ceramic powder required is a minimum of ∼100 g. The validation of a low shear feedstock preparation method against a standard high shear mixing method occurred. Microstructure investigation and single electromechanical fibre characterization of low shear produced KNN ( d 33 – 49 pC/N; P r – 3.7 μC/cm 3 ) and PZT ( d 33 – 392 pC/N; P r – 32.4 μC/cm 3 ) fibres, in terms of PE, SE loops and d 33 measurements, demonstrating the reproducibility of the results when compared to a standard ceramic–thermoplastic high shear mixing process. The repeatability of the measurements showed the proposed procedure to be robust, validating the new compounding method for wide-scale use.

Structural Integration of PZT Fibers in Deep Drawn Sheet Metal for Material-integrated Sensing and Actuation

Today, adaptive sheet metal parts are manufactured by surface bonding of sensors and actuators on shaped structural parts. This paper presents a technology for direct structural integration of lead-zirconate-titanate (PZT) fibers in flat sheet metal and subsequent shaping. Microcavities are microformed into the surface of the metal sheet in which piezoceramic fibers are inserted and joined. After that, the composite is shaped by deep drawing into a complex 3D surface. The production technology is discussed in detail with regard to the limits of each process step. Functional shaped prototypes with ten interconnected parallel piezoceramic fibers were fabricated. The function as transducer and sensor for lamb waves is demonstrated and the degradation due to the shaping is compared for different parameters of the deep drawing process. The composite shapes are cups with a double curvature radius of 100 mm and 250 mm respectively. As a result, degradation of the piezoelectric function varies as a consequence of the process parameters. In the best case, a degradation of the transducer function of 33% was shown in the experiments. The cause of the decreased performance after shaping is discussed and explained by debonding mechanisms. Results of numerical simulations show good agreement with the experimental findings of the optimum process parameters.

The effect of localized internal defects on the field distributions of electrostrictive composites

The electromechanical field distributions in electrostrictive periodic composites with localized defects are determined. The composite is subjected to a combined electromechanical loading which is sufficiently far away from the localized internal defects. The present analysis forms a generalization of the linearly constitutive equations based approach for electro–magneto–elastic composites which has been recently presented. Presently, the nonlinear terms in the fully coupled constitutive relations of the phases as well as the effect of defects are combined and represented by eigen-electromechanical field terms which are a priori unknown, thus requiring an iterative procedure for establishing the solution. The analysis is based on the combined use of three approaches. In the first one, a micromechanical analysis establishes the concentration matrices needed for the determination of the far-field distributions in the composite’s phases induced by the remote loading. In the second approach, the representative cell method is employed as a result of which the problem for a periodic composite, discretized into numerous identical cells, is reduced to a problem of a single cell in the discrete Fourier transform domain. The third approach consists of the application of the higher-order theory where the single cell is divided into several subcells, and the governing equations and interfacial conditions in the transform domain, imposed in an average (integral) sense, are solved. The inverse of the Fourier transform provides the actual electroelastic field at any point of the damaged composite. The offered method is verified by comparisons with analytical solutions, and several applications are presented for localized defects in the form of cavities and inclusions in an electrostrictive material subjected to combined electromechanical loadings. Next, the field distributions in two types of unidirectional composites with a missing fiber, subjected to electromechanical loadings are presented. In the first type, the composite consists of electrostrictive ceramic fibers reinforcing a polymeric matrix, whereas in the second one the electrostriction effect is enhanced by PZT fibers reinforcing an electrostrictive polymeric matrix. Comparisons between the resulting responses are discussed.

Topology optimization of piezoelectric materials and application to the cantilever beams for vibration energy harvesting

A new design analysis method based on FEM and a topology optimization for piezoelectric materials was developed for the unimorph cantilevered energy harvesters which can produce the maximum electric power outputs. The optimum topology of a piezoelectric material layer on the harvesting beam has been calculated by considering natural frequencies of beams, electromechanical couplings of piezoelectric materials, tip masses and MMA (method of moving asymptotes). The piezoelectric coefficients such as elasticity, capacitance and piezoelectric coupling were interpolated by element density variables in the topology optimization. The optimum design method was verified by vibration tests and measuring voltage outputs of the harvester and a good correlation between two results has been obtained. The effects of beam geometric parameters and several piezoelectric materials (PZT, PVDF, PMN-PT and piezoelectric fiber composites) on power generation were also investigated. The beam with PMN-PT generated the largest voltage and the next largest is PZT, MFC and PVDF, respectively.

S043012 磁歪振動発電・圧電ファイバを組込んだワイヤレスタイヤセンサの試作([S043]減災・サステイナブル工学)

S043012 磁歪振動発電・圧電ファイバを組込んだワイヤレスタイヤセンサの試作([S043]減災・サステイナブル工学)

Fabrication and piezoresponse of electrospun ultra-fine Pb(Zr0.3, Ti0.7)O3 nanofibers

Ultra-fine Pb(Zr0.3, Ti0.7)O3 (PZT) fibers with diameters down to ~100nm have been synthesized by combing the sol-gel method and elecrospinning technique. The as-spun nanoscopic PZT/PVP composite fibers were annealed for 30min at different temperatures, respectively. The morphology and crystalline structure of the sintered Pb(Zr0.3Ti0.7)O3 (PZT) nanofibers were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-Raman spectroscopy. The ferroelectronic and piezoelectric properties of single PZT nanofiber are investigated by using piezoresponse force microscopy (PFM). The results showed that the well crystallized PZT fibers with diameter of ~100nm can achieve a d33 of ~83.4pm/V, which is much larger than that of the reported PZT thin film, and the domain can be successfully switched, with the switch domain polarity of about 180^o. All these show promise for new nanoscale ferroelectronic devices.

A permendur-piezoelectric multiferroic composite for low-noise ultrasensitive magnetic field sensors

Low-frequency and resonance magnetoelectric (ME) effects have been studied for a trilayer of permendur (alloy of Fe-Co-V) and lead zirconate titanate (PZT). The high permeability and high magnetostriction for permendur, key ingredients for magnetic field confinement, and ME response result in ME voltage coefficient of 23 V/cm Oe at low-frequency and 250 V/cm Oe at electromechanical resonance (EMR) for a sample with PZT fibers and inter-digital-electrodes. Theoretical ME coefficients are in agreement with the data. Measured magnetic noise floor of 25 pT/√Hz at 1 Hz and 100 fT/√Hz at EMR are comparable to best values reported for Metglas-PZT fiber sensors.

Fabrication and Characterization of Flexible PZT Fiber and Composite

Straight lead zirconate titanate (PZT) fibers with round cross sections were fabricated by extrusion with boric acid and polyvinyl alcohol (PVA) condensation. The sintered fibers showed more tetragonality than the bulk. The dielectric constant of the electrode area perpendicular to the PZT fibers (Z1) was higher than the electrode area parallel to the PZT fibers (R1). Single PZT fiber exhibited higher remanent/saturation polarization and coercive field than the bulk and composite. The piezoelectric constant d33 of the Z1 composite was 300 pC/N for the 75 vol% PZT fibers. The Z1 composite had flexibility and high dielectric and ferroelectric properties, and exhibited promise in conformable and large-area applications.

Fabrication and Piezoelectric Property Characterization of New Micro PZT Fibers and 1–3 Piezo-Composites

Fabrication and Piezoelectric Property Characterization of New Micro PZT Fibers and 1–3 Piezo-Composites

Direct strain energy harvesting in automobile tires using piezoelectric PZT–polymer composites

Direct piezoelectric strain energy harvesting can be used to power wireless autonomous sensors in environments where low frequency, high strains are present, such as in automobile tires during operation. However, these high strains place stringent demands on the materials with respect to mechanical failure or depolarization, especially at elevated temperatures. In this work, three kinds of ceramic–polymer composite piezoelectric materials were evaluated and compared against state-of-the-art piezoelectric materials. The new composites are unstructured and structured composites containing granular lead zirconate titanate (PZT) particles or PZT fibers in a polyurethane matrix. The composites were used to build energy harvesting patches which were attached to a tire and tested under simulated rolling conditions. The energy density of the piezoelectric ceramic–polymer composite materials is initially not as high as that of the reference materials (a macro-fiber composite and a polyvinylidene fluoride polymer). However, the area normalized power output of the composites after temperature and strain cycling is comparable to that of the reference devices because the piezoelectric ceramic–polymer composites did not degrade during operation.

Effect of Matrix Properties on the Overall Piezoelectric Constants of Piezocomposite Transducers

Macro fiber composites, or MFCs, consist of PZT fibers with rectangular cross sections embedded into an epoxy matrix. MFCs usually possess orthotropic electromechanical properties and are used as thin and conformable actuators/sensors. This article focuses on the development of a homogenized model for the behavior of MFCs. The effective properties of MFCs with interdigitated electrodes (IDEs) are determined analytically, using the uniform field method, and numerically in terms of the electromechanical properties of the fibers and the epoxy matrix. Results are given for different material properties of the matrix.

Nonlinear electromechanical coupling behavior of 1–3 piezoelectric composites

In this paper the orientation dependence of the electromechanical response of 1–3 piezoelectric composites with PZT5A1 fibers embedded in epoxy matrix are investigated under an AC field. The PZT fibers are initially poled along the axial direction, and when the electric field is applied to the composite at an angle θ with respect to the fiber axis, its nonlinear electromechanical response is measured as a function of θ at 0, 30, 45, 60 and finally 90°. It is found that the magnitude of the electric displacement and mechanical strain of the 1–3 system all decease with θ and the electrical response diminishes to zero at 90°. Then a two-level micromechanics model is developed to study the overall hysteresis of the electric displacement vs. the electric field, and the butterfly-shaped axial strain vs. the electric field. The first level of the model involves a thermodynamically based evolution of the product domain from the parent one in the PZT fibers, and the second one treats the PZT fibers and the inactive polymer as a two-phase composite. In each case the electromechanical interaction of the two constituent phases are fully accounted for. The two-level micromechanics model is then applied to calculate the hysteresis behavior of the PZT/epoxy composite at the tested orientations of θ, and it is observed that comparisons between our experimental data and theoretical calculations are in reasonable agreement.

The performance of integrated active fiber composites in carbon fiber laminates

Piezoelectric elements integrated into fiber-reinforced polymer-matrix laminates canprovide various functions in the resulting adaptive or smart composite. Active fibercomposites (AFC) composed of lead zirconate titanate (PZT) fibers can be used as acomponent in a smart material system, and can be easily integrated into woven composites.However, the impact of integration on the device and its functionality has not been fullyinvestigated. The current work focuses on the integration and performance of AFCintegrated into carbon-fiber-reinforced plastic (CFRP) laminates, focusing on the strainsensor performance of the AFC–CFRP laminate under tensile loading conditions.AFC were integrated into cross-ply CFRP laminates using simple insertionand interlacing of the CFRP plies, with the AFC always placed in the90° ply cutout area. Test specimens were strained to different strain levels and then cycled witha 0.01% strain amplitude, and the resulting signal from the AFC was monitored.Acoustic emission monitoring was performed during tensile testing to provide insightto the failure characteristics of the PZT fibers. The results were compared tothose from past studies on AFC integration; the strain signal of AFC integratedinto CFRP was much lower than that for AFC integrated into woven glass fiberlaminates. However, the profiles of the degradations of the AFC signal resulting fromthe strain were nearly identical, showing that the PZT fibers fragmented in asimilar manner for a given global strain. The sensor performance recovered uponunloading, which is attributed to the closure of cracks between PZT fiber fragments.

Development of 2D Microdisplay Using an Integrated Microresonating Waveguide Scanning System

Our research team has developed a 2D micro image display device that can potentially overcome the size reduction limits while maintaining the high-image resolution and field of view obtained by mirror-based display systems. The basic design of the optical scanner includes a microfabricated SU-8 cantilever waveguide that is electromechanically deflected by a piezoelectric actuator. From the distal tip of the cantilever waveguide, a light beam is emitted and the direction of propagation is displaced along two orthogonal directions. The waveforms for the actuator and the LED light modulation are generated and controlled using a field programmable gate array. Our recent study is an update to the previously-reported mechanical scanner, replacing the hand-built PZT scanner and fiber waveguide with a microfabricated system incorporating aerosol-deposited PZT thin film and a polymeric SU-8 wave guide. In this article, we report on the design and fabrication of a prototype miniaturized 2D scanner, discuss optical and mechanical the modeling of the system's properties and present the experimental results.

Effects of different thermoplastic binders on the processability of feedstocks for ceramic co-extrusion process

Abtract The co-extrusion process involves the simultaneous extrusion of multiple materials, such as ceramic–thermoplastic feedstocks that can be used to manufacture fine-scaled piezocomposites, for both structural and functional applications. The primary step in the development of the feedstocks is the selection of the optimal thermoplastic binder with the function of providing plasticity as well as proper rheological behavior to the ceramic material during processing. The objective of the present work was to investigate the effects of different commercially available thermoplastic binders (polystyrene, low-density polyethylene, poly(ethylene-co-ethyl acrylate) and a blend of poly(ethylene-co-ethyl acrylate) and poly(isobutyl methacrylate)) on the processability of highly loaded lead zirconate titanate (PZT) feedstocks, suitable for the co-extrusion process. After characterizing the thermal behavior of the binders by means of TG and DSC analyses, the flow behavior of the unfilled polymers was analyzed and compared with the corresponding PZT-filled mixture (58 vol.% PZT) applying torque rheometry. Using an Arrhenius relation, the temperature dependency of viscosity was determined and the energy of activation for the viscous flow calculated. Due to the fact that the polyethylene presented a low viscosity with a high solid loading, no indication of degradation, a strong polymer–particle interaction as well as a comparatively low die swell, this thermoplastic binder was used in the formulation of PZT feedstocks to successfully produce thin solid (240 μm diameter) and hollow (800 μm diameter) PZT fibers by the co-extrusion technique.

Synthesis of ferroelectric PZT fibers using sol–gel technique

We report the synthesis technique for fabrication of fine Pb(Zr,Ti)O 3 (PZT) fibers via combination of sol–gel route and pulling method. It was found that spinning characteristics of PZT gel fibers were dependent upon the hydrolysis and molarity of the solution. Long gel fibers (meter scale) were drawn by hand-pulling method from the spinnable PZT sol. The fibers were sintered at 950 °C in air atmosphere and found to exhibit dense microstructure with electrical properties similar to that of bulk. High aspect ratio and homogeneous microstructure resulted in increased mechanical flexibility of sintered fibers.