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In the present study, Electromechanical Impedance (EMI) technique is utilized to assess the application of the microbially induced calcium carbonate precipitation (MICCP) to restore the integrity of cracked concrete. The artificial crack width of approximately 0.5 mm is healed autonomously using a bacteria-based healing agent, using flyash (FA) as a carrier material. Lead Zirconate Titanate sensors were bonded on the cracked specimen to monitor the continuous healing process. The EMI signatures were captured over the healing period using an impedance analyser in the frequency range of 100 to 250 kHz. Statistical crack healing indicator, root mean square deviation (RMSD) was employed for evaluating crack efficiency based on extracted signatures. Results revealed that the RMSD values were effective in quantifying the progressive healing achieved due to MICCP precipitation. This is the first study with a successful implementation of the EMI technique to monitor the crack sealing in concrete through MICCP. Healing capacity was also correlated with the crack width reduction that was evaluated by optical imaging of repaired cracked surface. Also, the bacterial mineralization products were analyzed by FESEM, EDX, XRD and TGA. The results give clear proof that the FA-based carrier material can be effectively used in healing the cracks. [ABSTRACT FROM AUTHOR]

A new piezoelectric actuator based on the stick–slip working principle inspired by the predation of the snake is proposed and developed in this work. A lead zirconate titanate (PZT) stack is used and inserted into the stator with an asymmetric configuration. Then, the elongation of the PZT stack can be transmitted into the vertical and horizontal displacements on the driving foot. They are used to press and drive the slider, respectively. In this design, the motion of the actuator imitates the predation process of the snake. The principle of the proposed actuator is clarified in detail. The statics characteristics are conducted by using the FEM method. The dynamics model of the actuator was established to show the motion behavior of the slider in theory. Finally, the output characteristics of the developed piezoelectric actuator are tested. The results stated that this actuator obtained the maximum output speed of 11.44 mm/s under a voltage of 100 V and a frequency of 600 Hz. The output force of the developed actuator was 2.8N under the preload force of 3N. In conclusion, the feasibility of the proposed piezoelectric stick–slip type actuator inspired by the predation of the snake is verified. [ABSTRACT FROM AUTHOR]

Traditional methods for estimating structural deterioration are generally costly and inefficient. Recent studies have demonstrated that implementing a network of piezoelectric transducers mounted to critical regions of concrete structural members substantially increases the efficacy of the structural health monitoring (SHM) method. This study uses a recently developed electro-mechanical-admittance (EMA)-based SHM system for real-time damage diagnosis of carbon FRP (C-FRP) ropes installed as shear composite reinforcement in RC deep beams. The applied SHM technique uses the frequency response measurements of a network of piezoelectric lead zirconate titanate (PZT) patches. The proposed strengthening methods using C-FRP ropes as ETS and NSM shear reinforcement and the applied anchorage techniques significantly enhanced the strength and the overall performance of the examined beams. The retrofitted beams exhibited increased shear capacity and improved post-peak response with substantial ductility compared with the brittle failure of the non-strengthened specimens. The health condition and the potential debonding failure of the applied composite fiber material were also examined and quantified using the proposed SHM technique. Damage quantification of C-FRP ropes is achieved by comparing and assessing the values of several statistical damage indices. The experimental results demonstrated that the proposed monitoring system successfully diagnosed the region where the damage occurred by providing early warning of the forthcoming critical shear cracking of concrete and C-FRP rope debonding failures. Furthermore, the internal PZT transducers showed sound indications of the C-FRP rope's health condition, demonstrating a direct correlation with the mechanical performance of the fibers. [ABSTRACT FROM AUTHOR]

In this study, using a solution casting process, thermoplastic polyurethane elastomer (TPU) composites containing different contents of lead zirconate titanate (PZT) ferroelectric particles were produced. The damping treatment of composites at high volume of fillers was investigated. SEM micrographs showed that PZT particles had a proper distribution in the PU matrix. Differential scanning calorimetry (DSC) thermograms indicates that melting enthalpy decreases by raising PZT filler content. The results of the dynamic mechanical thermal analysis (DMTA) proved that the magnitude of loss factor (tan δ) strongly depends on PZT content, and it decreased from 0.51 to 0.27 as PZT content increased. The value of E 0 increases to 0.32 GPa in the composite reinforced with 50 v% of PZT. The role of PZT on the acoustic behavior of TPU was measured using the acoustic absorption coefficient (a). The results showed that as PZT content increased from 0 to 50%, the acoustic absorption coefficient reached 0.25 at 6000 Hz frequency. The composites of PZT/PU with 0–3 connectivity were poled, and the optimal poling conditions that could be applied without sample breakdown were studied. Moreover, we prepared composites containing 70 vol% PZT particles by modifying the particles. Modification of PZT particles caused a decrease in both d 33 and g 33 constants of the PZT/PU composites. [ABSTRACT FROM AUTHOR]

In recent decades, many studies have been conducted on the use of smart materials in order to dampen and control vibrations. Lead zirconate titanate piezoceramics (PZT) are very attractive for such applications due to their ability of delivering high energy strain in the structure. A pair of piezoelectric actuators can actively dampen the resonances of the structure, but the damping effectiveness strongly relies on its location. Damping effectiveness can be substantially increased if the structure is fully covered with PZT actuator pairs and the voltage distribution on each pair is optimized. In this way, each actuator pair contributes to the vibration attenuation and only the driving voltage's sign, distributed on each actuator pair, needs to be identified for each resonance. This approach is here applied to the case of Euler–Bernoulli beams with constant cross-section and the optimal voltage distribution is investigated for several boundary conditions. The theoretical model results were corroborated with finite element simulations, which were carried out considering beams covered by ten PZT actuator pairs. The numerical results agree remarkably well with the theoretical predictions for each examined case (i.e., free-free, pinned-pinned, and fixed-fixed). [ABSTRACT FROM AUTHOR]

Lead lanthanum zirconate titanate (PLZT) ceramics exhibit excellent dielectric, ferroelectric and piezoelectric properties, and they can be used in many applications, including actuators. In this review, the processing and properties of PLZT-based ceramics will be the main focus of the first part. An introduction to PLZT ceramics is given and the methods to improve processing of PLZT-based ceramics are explained in terms of the addition of sintering aids, fabrication in the form of composites, and the application of dopants. The second part will be related to strain measurement to investigate converse piezoelectric properties (actuating effect). Strain measurement techniques by Michelson interferometry and case studies in PLZT-based ceramics (aging effect, temperature dependence and magnetic field effect) are included. [ABSTRACT FROM AUTHOR]

There was a fast development of various piezoelectric materials in the past two decades due to their numerous applications. Piezoelectric materials made up of natural quartz crystals were used in ultrasonic detectors in the early days. Later, the modern synthetic piezoelectric materials known as ferroelectric ceramics, such as Lead zirconate titanate (PZT), were developed, which were capable of exhibiting piezoelectricity several times greater than natural crystals. Later, the declination of ceramics began as they contained large amounts of lead content, which was considered harmful to both humans and the environment. Finally, a new era in the history of piezoelectric materials boomed with the outbreak of polymer materials. Polyvinylidene fluoride (PVDF) is a piezoelectric polymer material that has drawn the attention of researchers, from the family of fluoropolymers and has paved a new path in the field of polymer science and technology. PVDF has earned the renown of being an excellent piezoelectric material due to its unique and versatile exhibition of piezoelectric and dielectric properties. Furthermore, PVDF can exhibit incredible thermal stability and mechanical strength with flexible processing and low cost compared with the other piezoelectric crystals and ceramics. This comprehensive review mainly focuses on the evolution of piezoelectric materials from crystals to polymers with their advantages and significant drawbacks. Thus, the main objective of this review is to present a detailed description of PVDF concerning its uniqueness as a piezoelectric material and versatile properties, followed by various advanced fabrication techniques and their impact on doping various nanofillers with respective applications. Though PVDF is renowned for its significant applications such as sensors, actuators, energy harvesting and biomedical devices, a tabular chart has been specially framed in one‐liners which highlights the real‐time experimental outcomes where PVDF can be specified as a futuristic polymer for multifunctional applications. A few reports resulted that with increasing graphite and MWCNT fillers into PVDF film, the EMI shielding effectiveness value rose to 14.64 dB at a frequency of 8‐12 Hz. A few reports resulted that by adding ZnO and BaTiO3, the electrical output increased significantly, which is more suitable as a nanogenerator. After an extensive literature survey, we found that reviews are very limited and restricted to specific applications and properties. This review is an overall brief explanation of enormous research works carried out by various experts and presented in a modest way with pictorial and tabular representation for the convenience of researchers. Finally, this review attempts to provide source material to direct researchers towards a fertile area of research with a better understanding of the fundamentals and advancement of polymer piezoelectric materials. [ABSTRACT FROM AUTHOR]

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Sensing performance is crucial for real-world applications of the embedded piezoelectric lead zirconate titanate (PZT) sensors in concrete structures. Based on the electromechanical impedances (EMIs) obtained numerically and experimentally from the embedded PZT sensors, effects of installation orientation and interfacial roughness were investigated on their sensitivity and reliability for quantitative concrete stress monitoring. The numerical results suggest a better sensitivity in the embedded 90° PZT sensors, with planar normal perpendicular to the loading direction, where the conductance amplitude variation is 6.5 times of that of the 0° PZT sensors, with normal parallel to load direction. Further, the improved reliability of the PZT sensors with rough interfaces is observed experimentally, which makes them robust for concrete stress monitoring over a wider sensing range from 0 to 20 MPa. Based on the static analyses, it is noted that the sensing performance of the embedded sensor is significantly affected by the interfacial stiffness degradation induced by the enhanced strain surrounding the sensor. These findings suggest that delaying the interfacial stiffness degradation, i.e., with proper installation orientation and interfacial treatment, could improve the sensing performance of the embedded sensors for quantitative concrete stress monitoring. [ABSTRACT FROM AUTHOR]

Novel hybrid organic/inorganic flexible devices with composite films, consisting of Ba0.5Sr0.5TiO3 (BST), were prepared by inserting BST nanocoating under spray deposited Poly-vinylidene fluoride-based co-polymer PVDF-TrFE. The study validated that the crystalline structure of BST remains unaffected by the presence of polymer. The 3D atomic force microscopic image of the composite sample confirmed the improved surface roughness and contact conditions after spraying the polymer. As a result, the hybrid sample exhibited a higher polarization current with reduced impedance and parasitic inductance. The enhancement of the stability of the piezoelectric parameters at multiple bending was observed for the hybrid sample in comparison with the BST single film transducer. The drop of the root mean square (RMS) voltage was 70% after approximately 340,000 numbers of bending against less than 3% for the hybrid BST+PVDF-TrFE device. Due to the effect of the separate layers and summed net charges, the piezoelectric voltage of the hybrid device was competitive to the piezoelectric oxide films, despite the lower piezoelectric coefficient of the polymer. The proposed solution paves the path toward lead-free, wearable energy harvesting devices for low-power consuming electronic devices. [ABSTRACT FROM AUTHOR]

The azimuthal dependences of the optical second harmonic generation signal from crystallized regions (spherulites) of the ferroelectric phase in lead zirconate titanate films are investigated to determine the symmetry and orientation of crystallites. These dependencies in different regions of the same spherulite have different shapes, which indicates a difference in crystallographic orientations and/or symmetry. Based on the assumption of the possible presence of two syngonies and three orientations for each, the fitting of experimental azimuthal dependences by model curves was carried out, which provided information about the ratio of these phases and orientations in different areas of the film. [ABSTRACT FROM AUTHOR]

• Piezo sensors effectively capture the dynamic strain response under simulated pedestrian motions. • Strain modal parameters are obtained with a good correlation to acceleration-based modal parameters. • Lower-frequency strain modes are obtained with higher stability than the higher-frequency strain modes. • Piezo sensors effectively capture the strain modes of pedestrian footover bridge under pedestrian traffic with excellent repeatability. This study evaluates piezo sensors for modal identification of a scaled-down prototype of a pedestrian foot-over bridge under pedestrian motions and further extends the application in real-life structures. The piezo sensors-based results are compared with the accelerometers-based displacement modal parameters. Pedestrian motions are adopted to simulate the operational conditions of a pedestrian footover bridge with different patterns of pedestrian motions. Piezo sensors are found to effectively capture the low amplitude dynamic strain response under pedestrian motions. Strain modal testing captures the modal parameters positively correlated with conventional acceleration modal testing. Staggered pedestrian motions are best suited for actuating the structure uniformly at all instrumented nodes. Piezo sensor-based modal testing is extended to modal testing of real-life footover bridges under low amplitude ambient pedestrian traffic. Piezo sensors successfully capture the bending and torsion modes with good correlation with accelerometers-based modes. The strain-based modal parameters are obtained with excellent repeatability and negligible deviation. [ABSTRACT FROM AUTHOR]

• Derived the motion equation of Rayleigh waves. • Conducted external pressure tests on prototype PCCP. • Used PZT patches as transducers. • Monitored cracking using Rayleigh waves. • Determined the optimal monitoring frequency and damage indices. Prestressed concrete cylinder pipe (PCCP) is a critical type of pressure pipe widely used in major water conveyance projects worldwide. As essential components of a PCCP, the mortar coating and concrete core are directly linked to its operational safety. This study employed piezoelectric lead zirconate titanate (PZT) devices as transducers to generate excitation vibrations and measure the resulting Rayleigh waves, thereby providing a means to detect cracking in and monitor the health of the mortar coating and concrete core of a prototype 1400 mm inner-diameter PCCP under external pressure. First, a theoretical analysis was conducted to define the propagation laws of Rayleigh waves. Next, a finite element analysis was undertaken to identify the tensile regions of the PCCP mortar coating and concrete core when under external pressure applied along the length of the PCCP and thereby establish the locations for the PZT devices. Experiments were subsequently conducted by incrementally increasing the external pressure load from 0 to 700 kN while monitoring the cracking in the mortar coating and concrete core using sinusoidal excitation signals with frequencies of 5, 10, and 20 kHz. The voltage amplitudes measured at each external pressure load were analysed, confirming the Rayleigh wave propagation laws and revealing that the change in the measured voltage amplitude curve aligned with the experimental observations, thereby validating the proposed measurement method. Finally, the relative percentage deviation of amplitude (RPDA) and relative percentage deviation of energy (RPDE) damage indices were established based on the voltage measurements to further evaluate the damage state of the mortar coating and concrete core. The RPDA measured at an excitation frequency of 20 kHz was best for detecting cracks in the PCCP mortar coating, whereas the RPDA and RPDE measured at excitation frequencies of 20 and 10 kHz, respectively, were best for monitoring concrete core cracking. [ABSTRACT FROM AUTHOR]

Piezoelectric ceramics are extensively used in several engineering applications in the field of sensors, actuators, energy harvesting, biomedical, and many more. Traditional ways of manufacturing piezoelectric devices result in better piezoelectric/ferroelectric performance. However, they are restricted to only simple shapes. With the widespread influence of additive manufacturing (AM), it is now possible to fabricate complex structures which were not possible by conventional technologies. In order to fabricate such complex structures with precision, it is necessary to understand in detail the factors influencing the feedstock preparation and the challenges associated with different AM technologies. With an emphasis on the most commonly used AM techniques (direct ink writing, fused filament fabrication, vat photopolymerization, binder jetting, and selective laser sintering) for fabricating ceramic parts, this review paper intends to provide a deep insight into the factors affecting the feedstock preparation as well as post-processing conditions required to develop a high-performance piezoelectric device. The summarized tables detailing the various piezoelectric ceramic compositions and additives or ingredients used in formulating a printable feedstock, along with the optimum printing and post-processing conditions, will aid the readers in developing their own printable formulations and determining the best post-processing parameters to achieve the best performance out of the fabricated piezoelectric device. The advantages and disadvantages of the AM technologies are analyzed with specific reference to piezoceramic materials and the remaining challenges that require further research are emphasized. Furthermore, with the ongoing and continuous developments in additive manufacturing of piezoelectric materials, it is expected that such advancements will progressively transition towards commercialization, with the ultimate goal of widely incorporating additively manufactured devices into practical applications. [Display omitted] • Overview of the most widely used additive manufacturing (AM) techniques for piezoelectric ceramics. • Key factors influencing feedstock formulation and step-by-step guidelines for its preparation. • Comprehensive discussion of post-processing methods, including debinding and sintering. • Insights into how piezoelectric and ferroelectric properties are influenced by various parameters. • Advantages of additive manufacturing compared to traditional processing methods. [ABSTRACT FROM AUTHOR]

This study introduces an innovative wet etching method for magnetron sputtering lead zirconate titanate (PZT) thin films, leveraging a solution of HBF 4 as the etchant and HCl for intermediate product removal. Compared to traditional dry etching techniques, the focus is on improving cost efficiency and etching performance. Wet etching offers numerous advantages, including lower costs, faster etching rates, minimal lateral etching, and smoother etch profiles, making it a viable alternative for fabricating MEMS piezoelectric devices. The effectiveness of this method was substantiated through the production and performance assessment of a 1D scanning mirror, demonstrating that the wet etched PZT retained its piezoelectric properties and was efficiently integrated into MEMS applications without adverse effects on its piezoelectric functionality. Results confirm that this wet etching approach not only maintains the structural integrity of PZT films but also supports the manufacturing of MEMS devices with precise dimensional control and reliable operational performance. • An efficient wet etching method for etching lead zirconate titanate (PZT) was studied. • This etching method has minimal lateral etching and is nearly residue-free. • This method does not significantly affect piezoelectric properties when used for scanning mirror fabrication. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT) based piezoelectric ceramics are applied in ultrasonic transducers and multilayer actuators fields universally. Excellent piezoelectric properties of PZT-based ceramics of low sintering temperature are crucial for the applications of high-power motors and multilayer piezo-actuators due to the reduction of cost and energy consumption. In this paper, a ternary solid-solution ceramic system 0.05Pb(Mn 1/3 Sb 2/3)O 3 -0.47PbZrO 3 -0.48PbTiO 3 (PMS-PZT) was studied. A new complex additive composed of SiO 2 -Li 2 O 3 -CuO was doped into the PMS-PZT ceramics. The doping of CuO and Li 2 O 3 was discovered to be able to lower the sintering temperature and remain electric properties efficiently, while the doping of SiO 2 can decrease the grain size and increase the density. All ceramic samples were fabricated by solid-phase reaction method and sintered in the low temperature range from 800 °C to 1000 °C. The phase structure, morphology of natural surface and electrical properties of ceramics doped by 0.5 wt% additive were characterized. The 0.5 wt% additive doped PMS-PZT ceramics exhibit remarkable comprehensive piezoelectric properties sintered at 900 °C (d 33 = 343 pC/N, Q m = 1016, T c = 328 °C, tan δ = 0.4 % (at 25 °C), ε r = 1344, d 33 * = 490 pm/V). The sintering temperature 900 °C is significantly below the melting point of Ag (961.9 °C) and Cu (1083.4 °C), so the more cost-effective Cu internal electrodes and Ag rich Ag/Pd electrodes can be used to substitute the expensive Pd rich Ag/Pd internal electrodes in the production of devices composed of multilayer ceramic. The research of this work provides an important candidate additive for the applications of high-performance transducers and multilayer actuators with low cost. • The sintering temperature of PMS-PZT ceramic is reduced to 850 °C with high piezoelectricity by the SiO 2 -Li 2 O 3 -CuO additive. • The doped PMS-PZT achieved its best properties at 900 °C: d 33 = 343 pC/N, Q m = 1016, tanδ = 0.4%, d 33 * = 490 pm/V. • The high T c = 328 °C coupled with T s = 900 °C is beneficial to the multilayer ceramic applications. [ABSTRACT FROM AUTHOR]

It is challenging but meaningful to detect and image the micro-damage in the early stages of engineering structure failure. The nonlinear ultrasonic technique has gained considerable attention for micro-damage detection, meanwhile, the Lamb wave phased array technique has become a practical tool for macro-damage imaging. The combination of these two techniques can pave a promising way for micro-damage imaging in plate-like structures. However, the research on nonlinear Lamb wave phased array imaging is complicated and not reported. The weak nature and hard extraction of the nonlinear features, such as the second harmonic generation, limits the application of the nonlinear Lamb wave phased array. A framework of nonlinear Lamb wave phased array for micro-damage imaging in the plate-like structure is developed. To maximize the second harmonic response of the recorded Lamb waves, two kinds of lead zirconate titanate (PZT) wafers are selected to compose the nonlinear phased array. Furthermore, focusing on the nonlinear feature extraction, the sparse representation approach is introduced for reconstructing the time-domain second harmonic generated by the micro-damage, from which a wealth of waveform information corresponding to the micro-damage can be extracted. The total focusing method (TFM) is used for micro-damage imaging based on the reconstructed second harmonic. Numerical simulation and experimental validation demonstrate the capability of the proposed framework to image the local contact acoustic nonlinearity represented by the barely visible closed fatigue crack with the nonlinear Lamb wave phased array. [ABSTRACT FROM AUTHOR]

In this study, we improve the performance of vibration energy harvesting by adopting a different working mode of piezoelectric material. We propose a harvester that is composed of an inverted beam and a branch structure. The branch can produce an amplified inertial force under vibration and passes it to a lead zirconate titanate (PZT) sheet. The resultant force acts on the PZT sheet as a dynamic normal force, not as a dynamic flexural one in the classical harvester. This change can increase the output significantly. First, the theoretical model is established and solved. The results show that the design can induce a super-harmonic vibration and produce a large output. Then, the validation experiments are carried out. The experimental results prove the occurrence of super-harmonic vibration and show that under weak stochastic excitation the branch structure can promote the electric output significantly. For a stochastic excitation of PSD = 0.06 g2 Hz−1, the average power of the novel harvester can reach 0.344 mW by a small PZT sheet with the dimensions of 24 × 6 × 0.2 m m 3 . This study may provide a novel scheme in improving the vibration energy harvesting efficiency. [ABSTRACT FROM AUTHOR]

Graphene oxide (GO) incorporated ultra‐high molecular weight polyethylene (UHMWPE) nanocomposites were prepared by encapsulating GO by UHMWPE in an aqueous media via high‐shear mixing, which were subsequently dried and compression molded. Morphological characterizations via scanning electron microscopy revealed the intercalation of UHMWPE chains in the graphitic stacks corresponding to GO. Further, dielectric permittivity of UHMWPE/GO nanocomposite of 1 wt% GO showed a drastic increase (~61) as compared to pure UHMWPE (~2) due to an enhanced interfacial polarization. A significantly higher value of remnant polarization (~10 nC/cm2) and coercive field (~3 kV/cm) was observed in UHMWPE/GO nanocomposite of 1 wt% GO, which showed a strong hysteresis loop of polarization versus electric field plot as compared to pure UHMWPE, which displayed a very weak hysteresis loop. The piezoelectric coefficient (d33) of ~9.5 pm/V was estimated in UHMWPE/GO nanocomposite of 1 wt% GO via piezoresponse force microscopy. Nanocomposite sensor devices were also fabricated and piezoelectric output voltage of ~6 V was recorded in UHMWPE/GO nanocomposite of 1 wt% of GO. We report here for the first time the unique ferroelectric and piezoelectric properties displayed by UHMWPE/GO nanocomposites. [ABSTRACT FROM AUTHOR]

Poly(vinylidene fluoride) (PVDF) has been a kind of particularly attractive piezoelectric materials for its excellent piezoelectric property. Due to its light weight, impedance characteristic is very similar to water, and good mechanical flexibility, PVDF piezoelectric film is very suitable for the field of hydrophones. Although the piezoelectric ceramic hydrophone has been widely used, but due to the disadvantage of high inherent frequency and fragile characteristics of the piezoelectric ceramics slice, the development of the piezoelectric hydrophone is limited. The application of PVDF piezoelectric film has solved many problems encountered in the use of piezoelectric ceramics. In this article, the classification of hydrophone is briefly introduced at first, and then the current status of hydrophone research is involved. And then, by analyzing the electrical equivalent model of the PVDF piezoelectric sensitive unit, the signal conditioning circuit of the PVDF piezoelectric hydrophone is summarized as well. After that, the current status of PVDF hydrophone research is discussed. Finally, a summary of all the work listed in this article is given and an outlook of PVDF hydrophone is proposed. [ABSTRACT FROM AUTHOR]

In this study, a piezoelectric active sensing-based time reversal method was investigated for monitoring pipeline internal corrosion. An effective method that combines wavelet packet energy with a Convolutional Neural Network (CNN) was proposed to identify the internal corrosion status of pipelines. Two lead zirconate titanate (PZT) patches were pasted on the outer surface of the pipeline as actuators and sensors to generate and receive ultrasonic signals propagating through the inner wall of the pipeline. Then, the time reversal technique was employed to reverse the received response signal in the time domain, and then to retransmit it as an excitation signal to obtain the focused signal. Afterward, the wavelet packet transform was used to decompose the focused signal, and the wavelet packet energy (WPE) with large components was extracted as the input of the CNN model to rapidly identify the corrosion degree inside the pipeline. The corrosion experiments were conducted to verify the correctness of the proposed method. The occurrence and development of corrosion in pipelines were generated by electrochemical corrosion, and nine different depths of corrosion were imposed on the sample pipeline. The experimental results indicated that the classification accuracy exceeded 99.01%. Therefore, this method can quantitatively monitor the corrosion status of pipelines and can pinpoint the internal corrosion degree of pipelines promptly and accurately. The WPE-CNN model in combination with the proposed time reversal method has high application potential for monitoring pipeline internal corrosion. [ABSTRACT FROM AUTHOR]

La‐ and Sn‐cosubstituted lead zirconate titanate (PbLaZrSnTiO3) ceramics are synthesized using a solid‐state reaction route. These PbLaZrSnTiO3(PLZST) ceramics in pure form are found to exist in dual phase (Cc+P4mm) and single phase (Cc) depending on the amount of La/Sn cosubstitution. PLZST ceramics exhibit thin P–E loops with enhanced polarization when measured at 393 K. Olsen cycle method is used to estimate the pyroenergy harvesting abilities of the samples under study. The estimated maximum energy storage density for PLZST (50/30/20) ceramics at 393 K is 1.16 J cm−3 [efficiency (η) > 96%]. The PLZST ceramics exhibit a remarkable hardness of 9.08 GPa. These results indicate that PLZST ceramics with excellent multifunctional properties are potential candidates in the field of electroceramic devices. [ABSTRACT FROM AUTHOR]

The favorable contribution of externally bonded fiber-reinforced polymer (EB-FRP) sheets to the shear strengthening of reinforced concrete (RC) beams is widely acknowledged. Nonetheless, the premature debonding of EB-FRP materials remains a limitation for widespread on-site application. Once debonding appears, it is highly likely that brittle failure will occur in the strengthened RC structural member; therefore, it is essential to be alerted of the debonding incident immediately and to intervene. This may not be always possible, particularly if the EB-FRP strengthened RC member is located in an inaccessible area for fast inspection, such as bridge piers. The ability to identify debonding immediately via remote control would contribute to the safer application of the technique by eliminating the negative outcomes of debonding. The current investigation involves the detection of EB-FRP sheet debonding using a remotely controlled electromechanical admittance (EMA)-based structural health monitoring (SHM) system that utilizes piezoelectric lead zirconate titanate (PZT) sensors. An experimental investigation on RC T-beams strengthened for shear with EB-FRP sheets has been performed. The PZT sensors are installed at various locations on the surface of the EB-FRP sheets to evaluate the SHM system's ability to detect debonding. Additionally, strain gauges were attached on the surface of the EB-FRP sheets near the PZT sensors to monitor the deformation of the FRP and draw useful conclusions through comparison of the results to the wave-based data provided by the PZT sensors. The experimental results indicate that although EB-FRP sheets increase the shear resistance of the RC T-beams, premature failure occurs due to sheet debonding. The applied SHM system can sufficiently identify the debonding in real-time and appears to be feasible for on-site applications. [ABSTRACT FROM AUTHOR]

Silicon photonics has gained great success mainly due to the promise of realizing compact devices in high volume through the low-cost foundry model. It is burgeoning from laboratory research into commercial production endeavors such as datacom and telecom. However, it is unsuitable for some emerging applications which require coverage across the visible or mid infrared (mid-IR) wavelength bands. It is desirable to introduce other wideband materials through heterogeneous integration, while keeping the integration compatible with wafer-scale fabrication processes on silicon substrates. We discuss the properties of silicon-family materials including silicon, silicon nitride, and silica, and other non-group IV materials such as metal oxide, tantalum pentoxide, lithium niobate, aluminum nitride, gallium nitride, barium titanate, piezoelectric lead zirconate titanate, and 2D materials. Typical examples of devices using these materials on silicon platform are provided. We then introduce a general fabrication method and low-loss process treatment for photonic devices on the silicon platform. From an applications viewpoint, we focus on three new areas requiring integration: sensing, optical comb generation, and quantum information processing. Finally, we conclude with perspectives on how new materials and integration methods can address previously unattainable wavelength bands while maintaining the advantages of silicon, thus showing great potential for future widespread applications. [ABSTRACT FROM AUTHOR]

Nanoporous silicon and ceramics based on lead zirconate titanate (PZT-ceramics) have unique properties. It is shown that their mechanochemical interaction makes it possible to create compositions with a metallic type of conductivity. The formation of conductive paths occurs when silicon particles are wedged into microcracks creating unique highly sensitive layers of piezoceramic compounds including intercalates. The embedded silicon atoms deform the elementary cells of crystals and redistribute charges in them. The connection with the lattice is formed due to the transition of electrons to the boundary layers or the space between them. In the transition layers at T < 260 K, chains with electrical conductivity of the metallic type, shunting the piezodielectric, appear. [ABSTRACT FROM AUTHOR]

To suppress the nonlinear vibration of the flexible manipulator during motion, this article presents a hybrid control strategy based on a servo motor and a piezoelectric actuator. The dynamic model of the piezoelectric flexible manipulator is established first. To realize the trajectory tracking, a proportional derivative control method is used to schedule the control torque. Because the Volterra filter can approximate the nonlinear system model, a Volterra filtered-xLMS algorithm based on a second-order Volterra filter structure is proposed, by which the active nonlinear vibration control of flexible link is realized. Simulation results show that the proposed Volterra filtered-xLMS algorithm can not only make use of the advantages of the classical filtered-xLMS algorithm but also solve the problem of effective modeling of nonlinear secondary path. The proposed hybrid control strategy based on Volterra filtered-xLMS algorithm and proportional derivative control algorithm can improve the position accuracy of joint and effectively suppress the vibration response of the nonlinear flexible link. A piezoelectric flexible manipulator with PZT (lead zirconate titanate) sensor and actuator is designed to demonstrate the validity and efficiency of the proposed method by experiments. Experiment results demonstrate that the attenuation time of vibration response is reduced from 5 s to 1.5 s, the vibration response at the first-order frequency is reduced by 60%, and the proposed methodology has an important advantage in application of active vibration control of piezoelectric flexible manipulator. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT)–based piezoelectric ceramics as important functional materials are widely used in many electromechanical devices. The piezoelectric coefficient and mechanical quality factor are vital property parameters for piezoelectric applications. However, the piezoelectric coefficient is inversely proportional to the mechanical quality factor, resulting in a strong limitation among wide applications. Herein, piezoelectric ceramics composed of (xSb2O3, 0.3‐wt% MnCO3)‐doped (Pb0.92Sr0.08)(Zr0.533Ti0.443Nb0.024)O3 ((xSb, Mn)‐PSZTN) were prepared by a conventional solid‐state process. The excellent piezoelectric properties d33 = 554 pC/N, kp = 0.645, and high mechanical quality factor Qm = 540 were simultaneously obtained at x = 0.1 ceramic in the morphotropic phase boundary region. The enhancement of piezoelectric properties was mainly due to the contribution of irreversible domain wall motion. In particular, the regulation of different defect chemical reactions on the properties showed that Sb2O3 could play the role of both donor and acceptor dopant. This work demonstrated that (0.1Sb, Mn)‐PSZTN ceramic was a good candidate material for high‐power piezoelectric devices. [ABSTRACT FROM AUTHOR]

Bimorph mirrors place stringent requirements on the welding technology of silicon substrates and piezoelectric ceramics to ensure their ultrahigh-vacuum compatibility. Conventional welding techniques usually require high temperature and pressure, which have a high impact on the welding substrate, while the use of organic adhesives for bonding does not guarantee their stability in ultrahigh vacuum. Here, the transient liquid phase bonding technology based on an Au–In metal system was studied to meet the requirement for ultrahigh-vacuum application. The microstructure, chemical composition, and related mechanical properties of the bonding at different welding conditions were investigated. Meanwhile, the piezo ceramics and the bond were baked at 150 °C to test the stability. The results show that a stable bonding was achieved between centimeter-scaled single crystal silicon and lead zirconate titanate ceramics at 200 °C temperature and 2.5 MPa pressure, and the piezo ceramics and the bond are not damaged by baking to 150 °C for 48 h. [ABSTRACT FROM AUTHOR]

The main method to expand the operating bandwidth of the transducer is by exciting multi-order vibration modes, which develop from the earliest excitation of odd-order modes to the excitation of multi-order continuous modes. However, no detailed theoretical characterization of the excitation mechanism and electroacoustic properties of continuous-order modes has been given. In this paper, the excitation mechanism of continuous-order modes for one-dimensional thickness vibration is studied in detail. From the perspective of analytical characterization, the mathematical and physical conditions of mode excitation are analyzed and extended to continuous-order modes. Partial 1–3 piezocomposite consists of two parts; one part is complete lead zirconate-titanate and the other part is 1–3 composite, which is helpful for exciting continuous-order modes. Based on the excitation mechanism of continuous-order modes, a design method of broadband transducer used of partial 1–3 piezocomposite is proposed, and large bandwidth and good pulse response are obtained. The excitation mechanism of continuous-order modes proposed in this paper provides an idea for the theoretical analysis and design of multi-resonant broadband transducers. [ABSTRACT FROM AUTHOR]

[Display omitted] Piezoelectric semiconductor zinc oxide (ZnO) shows promising applications in many fields, however, its excellent piezoelectric performance is limited by the intrinsic screening effect. Forming p-n junction through interface engineering is an effective strategy to enhance its piezoelectric output, but the unclear regulation mechanism is a bottleneck in developing high-performance devices. In this work, the enhancement mechanism of interface engineering on the piezoelectric performance of ZnO nanorods (NRs) based devices is revealed from the perspective of carrier concentration. Both the theoretical and experimental results show that the piezoelectric output is significantly correlated with the carrier concentration, which is mainly attributed to the suppression of screening effect and the modulation of the device capacitance. After a reasonable matching design of carrier concentration, the piezoelectric potential of the ZnO NRs-based device is greatly enhanced by about 12 times. Apparently, these findings provide a fresh insight to further understand the enhancement mechanism of interface engineering on the electrical output of piezoelectric semiconductor devices, and provide effective support for the design of p-n junction piezoelectric devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • The KNN6L-PDMS porous composites have been successfully achieved with both the excellent piezoelectric properties and mechanical flexibility. • The piezo-catalytic activity exhibited a high efficiency and superior repeatability for degrading organic pollutants. • COMSOL simulations determined that piezo-catalysis was originated from the generated potential of piezoelectric composites. Piezoelectricity as a physical property has received great attention due to its excellently functional applications, especially in piezoelectric catalysis and mechanical energy harvesting. To take full advantage of the functions of piezoelectric materials, (K 0.5 Na 0.5) 0.94 Li 0.06 NbO 3 (KNN6L) piezoelectric powders were compounded with polydimethylsiloxane (PDMS) in this work. The developed KNN6L-PDMS porous piezoelectric composites with flexible and recyclable characteristics could achieve ∼ 91% degradation rate of Rhodamine B (RhB) dye wastewater under mechanical vibration, and the outstanding piezocatalytic activity was still maintained after repeated decomposition multiple times. Besides, the relationship between piezoelectric potential and piezocatalysis was validated by COMSOL simulations. The content of piezoelectric powders played a positive effect on the magnitude of piezoelectric potential generated by the KNN6L-PDMS porous composites. Moreover, the catalytic mechanism was found to be originated by generation of various reactive oxygen species (mainly •O 2 – and •OH) in water environment as a result of strong piezoelectric effect by the porous composites. The porous piezoelectric composites with flexible and recyclable characteristics exhibited excellent performance in piezoelectric catalysis which has promising applications in the field of environmental remediation. [ABSTRACT FROM AUTHOR]

Achieving both the large transduction coefficient (the product of piezoelectric charge d 33 and voltage coefficients g 33) and high Curie temperature is very important to improve the power generation performance and their thermal stability of piezoelectric energy harvesters. It is difficult to improve the transduction coefficient of the commercial PZT based piezoelectric ceramics due to the same variation trend of piezoelectric charge coefficient and dielectric constant with chemical modifications. In this work, Bi 2 O 3 and Fe 2 O 3 co-modified ((Pb 1-x Bi x)((Zr 0.53 Ti 0.47) 1-x Fe x)O 3) ceramics were prepared by conventional solid state reaction method, and their dielectric and piezoelectric properties were studied. The piezoelectric charge coefficient d 33 increases by Bi and Fe co-modifications due to the enlarged grain size and reduced lattice distortion, while the dielectric constant ε 33 deceases mainly owing to the increased micro-pores in grains, leading to the enhancement transduction coefficient d 33 × g 33. The Curie temperature T c and maximum transduction coefficient d 33 × g 33 are 346 °C and 17169 × 10−15 m2/N, respectively, which are both higher than those of commercial PZT and PZN-PZT based piezoelectric ceramics. This work provides a new way to enhance the transduction coefficient of PZT based ceramics for piezoelectric energy harvesters used in wide temperature range. [ABSTRACT FROM AUTHOR]

The increased demand for electricity with low environmental impact has prompted researchers to find solutions to obtain the maximum output. This effort has imparted a significant focus on piezoelectric materials owing to their high piezoelectric coefficient and electromechanical coupling factor. In this study, reduced graphene oxide encapsulated with polydopamine and incorporated with zinc manganate hybrid nanocomposite (rGO‒pDA‒ZnMnO 3 HNC) was prepared. The as-prepared HNC, of different weight percentages, was blended with 15 wt% poly(vinylidene fluoride) (PVDF) to form different PVDF@rGO‒pDA‒ZnMnO 3(R) thin films. Subsequently, the flexible piezoelectric sensors (FPSs) were fabricated by a solution-casting method. The as-prepared HNC and thin films were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The PXRD data revealed the increased degree of crystallinity of the thin films from 54% to 68% with the increase in filler loading. The β-phase of PVDF also increased, as obtained from the FT-IR analysis. Electrical characterization of the prepared FPSs was carried out by estimating the sensitivity of the devices on different loads. The acquired response at a force of 1 N for PVDF@rGO‒pDA‒ZnMnO 3(0.2 wt%) improved by 44% than that of PVDF@rGO‒pDA‒ZnMnO 3(0 wt%). The force applied by the finger on the device also generated voltages, which were used to charge the capacitor, thereby used to glow the light-emitting diodes with amplifications. These promising results demonstrate the potential for developing lead-free efficient piezoelectric nanogenerators for energy-harvesting applications and self-powered devices. [ABSTRACT FROM AUTHOR]

This article presents a design, modeling and optimization of Surface Acoustic Wave (SAW) resonator with CMOS compatible piezoelectric crystal material and characterized for wireless 915 MHz ISM frequency band. Simulation study for the realization of SAW resonator based on CMOS compatible piezoelectric thin film of Zinc oxide (ZnO) on passivated silicon (SiO2/Si) substrate is performed. The SAW properties of ZnO film on SiO2/Si were analyzed with three composite structures as (IDT)/ZnO/SiO2/Si, ZnO/(IDT)/ZnO/SiO2/Si, and ZnO/(IDT)/SiO2/Si using COMSOL Multiphysics Software. The properties of ZnO/(IDT)/SiO2/Si structure revealed good SAW properties such as maximum coupling coefficient and acoustic velocity compared to other structures. The effects of piezoelectric Zinc oxide (ZnO) layer, interdigital transducer (IDT) materials, and SiO2 thin film thickness on the evolution of the phase velocity and electromechanical coupling coefficient (K²) were studied by employing a finite element method. The design and simulations of multilayered SAW structure carried out for 915 MHz and ZnO/(IDT)/SiO2/Si structure provide excellent overall performance. [ABSTRACT FROM AUTHOR]

Bolted spherical joints are widely used in space grid structures. However, the preload loss, which may arise from fabrication error, insufficient twist of the screw and some other unknown reasons can undermine the structural integrity and even lead to the collapse of the whole structure. Therefore, a method for evaluating the preload status of bolted spherical joints is vital to the structural health monitoring of the space grid structures. To this end, a non-destructive evaluation of the preload loss of bolted spherical joints based on time reversal acoustics (TRA) is presented. In this method, an excited signal generated by a lead zirconate titanate (PZT) patch at the bolted sphere is reconstructed after the signal recorded by another PZT patch at the bar is time-reversed and re-emitted. The deviation of the reconstructed signal from the initial signal allows identification of preload loss of the bolted spherical joint. This method is demonstrated to be effective by a finite element simulation. Furthermore, the effect of preload loss of the bolted spherical joint on its ultimate flexural capacity is studied, which highlights the necessity for the non-destructive evaluation. [ABSTRACT FROM AUTHOR]

Robotic prostheses and powered exoskeletons are novel assistive robotic devices for modern medicine. Muscle activity sensing plays an important role in controlling assistive robotics devices. Most devices measure the surface electromyography (sEMG) signal for myoelectric control. However, sEMG is an integrated signal from muscle activities. It is difficult to sense muscle movements in specific small regions, particularly at different depths. Alternatively, traditional ultrasound imaging has recently been proposed to monitor muscle activity due to its ability to directly visualize superficial and at-depth muscles. Despite their advantages, traditional ultrasound probes lack wearability. In this paper, a wearable ultrasound (US) transducer, based on lead zirconate titanate (PZT) and a polyimide substrate, was developed for a muscle activity sensing demonstration. The fabricated PZT-5A elements were arranged into a 4 × 4 array and then packaged in polydimethylsiloxane (PDMS). In vitro porcine tissue experiments were carried out by generating the muscle activities artificially, and the muscle movements were detected by the proposed wearable US transducer via muscle movement imaging. Experimental results showed that all 16 elements had very similar acoustic behaviors: the averaged central frequency, −6 dB bandwidth, and electrical impedance in water were 10.59 MHz, 37.69%, and 78.41 Ω, respectively. The in vitro study successfully demonstrated the capability of monitoring local muscle activity using the prototyped wearable transducer. The findings indicate that ultrasonic sensing may be an alternative to standardize myoelectric control for assistive robotics applications. [ABSTRACT FROM AUTHOR]

Structural health monitoring systems must provide accuracy and robustness in predicting the structure's health using the minimum intervention to ensure commercial viability. Characterization of impact is useful in assessing its severity, deciding if detailed damage analysis is necessary, and re-evaluating the present health of the structure under monitoring with better confidence. In this characterization process, the impact location is significant since some positions within a structure are more sensitive to damage. The inherent noise and uncertainties present in the sensor response pose a substantial hurdle to estimating the external impact correctly. This paper quantitatively compares three of the widely used neural networks, namely, Artificial Neural Network (ANN), Convolutional Neural Network (CNN), and Long Short-Term Memory network (LSTM), to estimate impact location from the lead zirconate titanate (PZT) sensor response. For this purpose, a square aluminum plate of 500 × 500 mm was equipped with four PZT sensors; each placed 100 mm away in both the plate directions from a corner and impact loads were given on a grid covering the whole plate. The PZT responses were used to train the three neural networks under study here, and their estimations were compared based on the Mean Absolute Error (MAE). In addition, increasing Gaussian noise was added to the PZT responses, and the robustness of the three neural networks was monitored. It was found that the ANN gives better accuracy with a Mean Absolute Error of 22 mm compared to Convolutional Neural Network (MAE = 31 mm) and Long Short-Term Memory (MAE = 25 mm). However, CNN is more robust when encountering noise with a 2% reduction in accuracy, while LSTM and ANN lost 7% and 11% accuracy, respectively. [ABSTRACT FROM AUTHOR]

Thin film ferroelectric capacitors of composition Pb(Zr0.52Ti0.48)O3 were exposed to Fe3+ radiation (1011 to 1013 ions/cm2), and the change in the defect structure was investigated by Doppler broadening positron annihilation spectroscopy and other characterization techniques. As the radiation fluence increases, a systematic drop of the S parameter of the positron annihilation photopeak is observed and attributed to an increase in the Zr- and Ti-site related vacancies relative to the Pb-sites. The results demonstrate that the radiation has a more significant influence on the Zr- and Ti-sites relative to the Pb-sites. It is also observed that the S parameter of the Mn-doped samples is higher than the undoped counterparts. Coupled with ferroelectricity measurements and X-ray diffraction, the results suggest that the Mn dopant modifies the initial structure of the material and leads to a different functional response. [ABSTRACT FROM AUTHOR]

A drift-diffusion model of unsteady carrier transport in an M/lead zirconate titanate (PZT)/M structure is proposed. It is assumed that the PZT film has electronic conductivity. Electrons are generated by oxygen vacancies and trapped by Ti+3 deep centers. It is assumed that electrons move in the electric field by hopping between titanium atoms, with an effective mobility that is considered constant. To account for the polarization, it is believed that, near the contacts, there are thin defective layers in which the polarization is zero, while outside these layers, the polarization does not vary across the film thickness and depends on the applied bias. The model was used to account for the formation of the current peak in the current–voltage curves, which is not caused by the domain switching and observed in epitaxial films only when the bias and polarization directions coincide. It is shown that a pronounced current peak is formed when (а) an accumulated space-charge layer appears near one of the contacts under the action of polarization and (b) this contact is cathode, which is only possible when the polarization and bias directions coincide. As a result, electrons flow between space-charge layers, and the film resistance first decreases and then starts to increase again, and this gives rise to a current peak. It is shown that this effect is purely nonstationary. The model also made it possible to estimate the basic parameters of the structure: electron mobility, density of oxygen vacancies, dielectric constant, defect layer thickness, and barrier height. [ABSTRACT FROM AUTHOR]

We report the dielectric response and resistive switching properties of bilayers of PbZr0.40Ti0.60O3 [PZT (40:60)] and HfO2 of varying thickness on platinized Si substrates. PZT (40:60) and HfO2 films were grown using chemical solution deposition and atomic layer deposition, respectively. We show here that the addition of an interposed linear dielectric layer with a high permittivity between the ferroelectric film and the top electrode modifies the polarization and resistive switching characteristics of the multilayer stack. We observe an increase in the coercive field by 45% for PZT films of 250 nm thickness with a 20 nm HfO2 layer compared to 250 nm thick PZT films grown under identical conditions. Simultaneously, the dielectric constant decreases by 43% from 409 to 175 for a 250 nm PZT film with 20 nm HfO2, accompanied by a significant improvement in the leakage current density from 5.6 × 10−4 A/cm2 to 8.7 × 10−8 A/cm2. Our resistance measurements show that there are two separate resistance states that are accessible with at least an order of magnitude in resistance difference from 5 × 108 to 5 × 109 Ω. We show that the dielectric response and the coercivity of the bilayer system can be explained by a capacitors-in-series model. This indicates that the PZT and the HfO2 layer could effectively be considered decoupled, presumably due to bound/trapped charges at the interlayer interface. This charged ferroelectric/dielectric interface could be the reason for the intermediate resistance states which could be used as multistate resistive memories in neuromorphic computing applications. [ABSTRACT FROM AUTHOR]

In this study, we improve the performance of vibration energy harvesting by adopting a different working mode of piezoelectric material. We propose a harvester that is composed of an inverted beam and a branch structure. The branch can produce an amplified inertial force under vibration and passes it to a lead zirconate titanate (PZT) sheet. The resultant force acts on the PZT sheet as a dynamic normal force, not as a dynamic flexural one in the classical harvester. This change can increase the output significantly. First, the theoretical model is established and solved. The results show that the design can induce a super-harmonic vibration and produce a large output. Then, the validation experiments are carried out. The experimental results prove the occurrence of super-harmonic vibration and show that under weak stochastic excitation the branch structure can promote the electric output significantly. For a stochastic excitation of PSD = 0.06 g2 Hz−1, the average power of the novel harvester can reach 0.344 mW by a small PZT sheet with the dimensions of 24 × 6 × 0.2 m m 3 . This study may provide a novel scheme in improving the vibration energy harvesting efficiency. [ABSTRACT FROM AUTHOR]

A damage detection scheme using the electro-mechanical impedance based signatures for detection of multiple damages is proposed. A beam and a stiffened plate are considered as two example structures in this study. Cracks of 1 mm width and varying depth have been considered as damages for the beam structure. On the other hand, disbonds between the plate and stiffener along the stiffener length have been considered as damage in the stiffened plate structure. Drive point and cross conductance at two piezoelectric patch transducers in a chosen frequency range have been obtained using the finite element based software ANSYS. Result of ANSYS has been validated through experimental result. Root mean square deviation (RMSD) and the correlation coefficient (CC) of the conductance of the structure from the baseline conductance have been used as damage features. An artificial neural network with one hidden layer has been trained considering the damage features as input and crack depths/disbond lengths at different locations as output. Accuracy of the trained network in detecting crack depths/disbonds has been observed through a set of test cases. [ABSTRACT FROM AUTHOR]

The electrodynamic properties of lead zirconate titanate ceramic solid solutions, exhibiting ferro-antiferroelectric phase transition, are investigated at microwave frequencies in a wide temperature range. Significant changes in the electrodynamic response are found, presumably associated with structural rearrangements accompanying the sequence of phase transitions between para-, ferro-, and antiferroelectric states. The phenomena observed in the experiments are considered under conditions of changing temperature and concentrations of the components; several independent measurement techniques were used for their unambiguous identification. [ABSTRACT FROM AUTHOR]

Effective converse piezoelectric coefficient (d33,eff) mapping of poly(vinylidene fluoride) (PVDF) nanofibers with ceramic BaTiO3 nanoparticle inclusions obtained by electrospinning was carried out by piezoresponse force microscopy (PFM) in a peculiar dynamic mode, namely constant-excitation frequency-modulation (CE-FM), particularly suitable for the analysis of compliant materials. Mapping of single nanocomposite fibers was carried out to demonstrate the ability of CE-FM-PFM to investigate the nanostructure of semicrystalline polymers well above their glass transition temperature, such as PVDF, by revealing the distribution of piezoelectric activity of the nanofiber, as well as of the embedded nanoparticles employed. A decreased piezoelectric activity at the nanoparticle site compared to the polymeric fiber was found. This evidence can be rationalized in terms of a tradeoff between the dielectric constants and piezoelectric coefficients of the component materials, as well as on the mutual orientation of polar axes. [ABSTRACT FROM AUTHOR]

The ultrasonic transmission detection method is used to investigate the applicability for the second-harmonic generation (SHG) technology of longitudinal wave to quantitatively assess carbonated concrete. The principal of this method is to use the piezoelectric lead zirconate titanate (PZT) patch to detect the second-harmonic of longitudinal waves during the concrete carbonation process and extract non-linear parameters from observed signals. Non-linear parameters of concretes with two water–cement ratios (CI (w / c = 0.47) , CII (w / c = 0.53) ), two moisture contents (CI 0 % , CI-W 100 % ), and three ultrasonic incident frequencies (50 kHz, 75 kHz, 100 kHz) were measured in this study. Results of the experiment demonstrate that non-linear ultrasonic parameters of longitudinal ultrasonic waves with high frequencies (75 kHz, 100 kHz) exhibit a better resolution regarding changes in concrete microstructure. Moisture (CI 0 % , CI-W 100 % ) has little effect on the rate (CI: 62.73%, CI-W: 60.25, carbonation depth: 15 mm) for the change in relative non-linear parameters in the same concrete. The carbonation depth of concrete (CI (w / c = 0.47) , CI-W (w / c = 0.47) , CII (w / c = 0.53) ) can be well reflected by the change in relative non-linear parameters. Furthermore, there exists a good fit between the relative non-linear parameters of longitudinal waves and the concrete carbonation process. The relative non-linear parameters of longitudinal waves demonstrate feasibility in the quantitative assessment of concrete carbonation. [ABSTRACT FROM AUTHOR]

Nonlinear phenomenon is presently attracting considerable attention in the field of microelectromechanical systems (MEMS). By adjusting a controllable tuning voltage, the nonlinearity of microdevices, especially on microactuators, can be precisely manipulated. To trap and separate small particles, generating a large and stable rotation force is critical in micromanipulations. Here, we report a simple and potential angular momentum cell comprising a piezoelectric MEMS-based nonlinear multi-mode resonator with integrated electrodes. A nonlinear rotating nodal line has been observed in specific frequency bands by applying a controllable low voltage of sub 5 V on a 4-port resonator made of lead zirconate titanate (PZT) thin films. The magnitude of the actuated voltage is Complementary-Metal-Oxide-Semiconductor (CMOS)-compatible and easy to integrate with the circuit. Furthermore, the real-time rotation motion of the MEMS-based nonlinear multi-mode resonator is also verified by a laser doppler vibrometer (LDV) at both chirp and single input frequencies, respectively. Therefore, this angular momentum cell shows great potential in the application of micromanipulation. [ABSTRACT FROM AUTHOR]

All dielectrics exhibit electrostriction, i.e., display a quadratic strain response to an electric field compared to the linear strain dependence of piezoelectrics. As such, there is significant interest in discovering new electrostrictors with enhanced electrostrictive coefficients, especially as electrostrictors can exhibit effective piezoelectricity when a bias electric field is applied. We present the results of a study combining data mining and first-principles computations that indicate that there exists a group of iodides, bromides, and chlorides that have electrostrictive coefficients exceeding 10 m4 C–2 which are substantially higher than typical oxide electrostrictive ceramics and polymers. The corresponding effective piezoelectric voltage coefficients are three orders of magnitude larger than lead zirconate titanate. [ABSTRACT FROM AUTHOR]

In the ongoing fourth industrial revolution, the internet of things (IoT) will play a crucial role in collecting and analyzing information related to human healthcare, public safety, environmental monitoring and home/industrial automation. Even though conventional batteries are widely used to operate IoT devices as a power source, these batteries have a drawback of limited capacity, which impedes broad commercialization of the IoT. In this regard, piezoelectric energy harvesting technology has attracted a great deal of attention because piezoelectric materials can convert electricity from mechanical and vibrational movements in the ambient environment. In particular, piezoelectric-based flexible energy harvesters can precisely harvest tiny mechanical movements of muscles and internal organs from the human body to produce electricity. These inherent properties of flexible piezoelectric harvesters make it possible to eliminate conventional batteries for lifetime extension of implantable and wearable IoTs. This paper describes the progress of piezoelectric perovskite material-based flexible energy harvesters for self-powered IoT devices for biomedical/wearable electronics over the last decade. [ABSTRACT FROM AUTHOR]

Lead Zirconate Titanate (PZT) is used to make ultrasound transducers, sensors, and actuators due to its large piezoelectric coefficient. Several micro-defects develop in the PZT sensor due to delamination, corrosion, huge temperature fluctuation, etc., causing a decline in its performance. It is thus necessary to identify, locate, and quantify the defects. Non-Destructive Structural Health Monitoring (SHM) is the most optimal and economical evaluation method. Traditional ultrasound SHM techniques have a huge impedance mismatch between air and solid material, and most of the popular signal processing methods define time series signals in only one domain, which provides sub-optimal results for non-stationary signals. Thus, to improve the accuracy of detection, the point contact excitation and detection method is implemented to determine the interaction of ultrasonic waves with micro-scale defects in the PZT. The signal generated from this method being non-stationary in nature, it requires signal processing with changeable resolutions at different times and frequencies. The Haar Discrete Wavelet Transformation (DWT) is applied to the time series data obtained from the coulomb coupling setup. Using the above process, defects up to 100 μm in diameter could be successfully distinguished. [ABSTRACT FROM AUTHOR]