Piezoelectric Charge Research Articles

Structural and piezoelectric properties of textured NLKNS‐CZ thick films and their application in planar piezoactuator

Abstract0.97(Na0.5‐xLixK0.5)(Nb0.89Sb0.11)O3‐0.03CaZrO3 [(N0.5‐xLxK)(NS)‐CZ] piezoceramic (x = 0.325) has a pseudocubic‐tetragonal‐orthorhombic (PC‐T‐O) multi‐structure. The PC structure formed in this piezoceramic was identified as the R3m rhombohedral structure. This piezoceramic showed the large piezoelectric charge constant (d33) of 515 pC/N due to the PC‐T‐O multi‐structure. The NaNbO3 (NN) templates were used to texture the (N0.5‐xLxK)(NS)‐CZ thick films along the (001) direction, and the textured thick film (x = 0.0375) had a large Lotgering factor of 95.6%. The PC‐T‐O multi‐structure was observed in this thick film (x = 0.0375), but the thick film (x = 0.0325) showed a PC‐O structure owing to the diffusion of the NN templates into the thick film. The textured thick film (x = 0.0375) exhibited an increased d33 of 625 pC/N because of the PC‐T‐O multi‐structure and the lineup of grains along the [001] direction. A textured thick film (x = 0.0375) was used to fabricate a planar‐type actuator to confirm its applicability to electrical devices. This actuator exhibits large acceleration (580.3 G) and displacement (150 μm) at a low electric field of 0.2 kV/mm with a short response time of 3.0 ms. Therefore, the (N0.5‐xLxK)(NS)‐CZ thick films are excellent lead‐free piezoceramics.

Observation of Enhanced Unipolar Strain and Piezoelectric Charge Co-Efficient in K0.5Na0.5NbO3 Simultaneously Doped with Lithium and Antimony

The author reports an enhanced strain and piezoelectric charge coefficient (d33*) in lead-free Lix(K0.5Na0.5)1−x(Nb1−ySby)O3 (x and y = 0,0.02,0.04,0.06) ceramics synthesized through the standard solid-state reaction route. X-ray diffraction analysis of the samples predicts a structural phase transition from orthorhombic to tetragonal with the presence of phase boundary (coexistence of orthorhombic and tetragonal phases) for the Li0.04(K0.5Na0.5)0.96(Nb0.96Sb0.04)O3 sample supported by Raman spectroscopy. The Lix(K0.5Na0.5)1−x(Nb1−ySby)O3 (x and y = 0.04) ceramics exhibited enhanced electrical properties with Ps∼13 µC/cm2, Ec∼15 kV/cm, an electrostrictive strain of 0.38% and piezoelectric charge coefficient (d33*) of 950 pm/V, making it promising for sensor and actuator applications.

Lead-Free AE Sensor Based on BZT-BCT Ceramics.

In this study, an acoustic emission (AE) sensor was fabricated using lead-free Ba(Zr0.2Ti0.8)O3–0.5(Ba0.7Ca0.3)TiO3 (BZT–BCT) ceramics. The acoustic and electromechanical properties of the AE sensor were determined by the shapes of the piezoelectric ceramics. To optimize the AE sensor performance, the shapes of the ceramics were designed according to various diameter/thickness ratios (D/T) = 0.5, 1.0, 1.5, 2.0, 2.5, 3.0. The BZT–BCT ceramic with D/T = 1.0 exhibited excellent values of a piezoelectric charge coefficient (d33), piezoelectric voltage coefficient (g33), and electromechanical coupling factor (kp), which were 370 (pC/N), 11.3 (10−3 Vm/N), and 0.58, respectively. Optimum values of resonant frequency (fr) = 172.724 (kHz), anti-resonant frequency (fa) = 196.067 (kHz), and effective electromechanical coupling factor (keff) = 0.473 were obtained for the manufactured BZT–BCT ceramic with D/T = 1.0. The maximum sensitivity and frequency of the AE sensor made of the BZT–BCT ceramic with a D/T ratio of 1.0 were 65 dB and 30 kHz, respectively.

Effect of neodymium and zirconium substitution on electrical properties of SrBi4Ti4O15

Neodymium and zirconium modified strontium bismuth titanate ceramics with content changing from 2.5 to 10 at% Nd and a 2.5 at% Zr of SrBi4Ti4O15 (SrNdxBi4-xZryTi4-yO15, (x = 0.00, 0.025, 0.05, 0.075, and 0.1, y = 0.00 and 0.025) have been prepared by solid state reaction method and analyzed by X-ray diffraction (XRD), dielectric response, ferroelectric hysteresis, electromechanical coupling coefficient, and piezoelectric charge coefficient. From hysteresis loop, the remnant polarization and coercive field were calculated and explained. Dielectric analysis explained the sample behavior. Piezoelectric charge and electromechanical coupling coefficients were found to be increased with the addition of Zr and Nd.

Antifungal Effect of Piezoelectric Charges on PMMA Dentures.

Candida-associated denture stomatitis is a recurring disease affecting up to 67% of denture wearers. Poly(methyl methacrylate) (PMMA) remains the main material employed in the fabrication of dentures due to its desirable physical, mechanical, and aesthetic properties. However, the improvement of its antimicrobial properties remains a challenge. To address this need, we developed PMMA composite filled with piezoelectric nanoparticles of barium titanate (BaTiO3) for therapeutic effects. Candida albicans biofilms were cultivated on the surface of the composites under continuous cyclic mechanical loading to activate the piezoelectric charges and to resemble mastication patterns. The interactions between biofilms and biomaterials were evaluated by measuring the biofilm biomass, metabolic activity, and the number of viable cells. To explore the antifungal mechanisms, changes in the expression of genes encoding adhesins and superoxide dismutase were assessed using reverse transcription-polymerase chain reaction. With the addition of piezoelectric nanoparticles, we observed a significant reduction in the biofilm formation and interference in the yeast-to-hyphae transition compared to the standard PMMA. Moreover, we observed that the cyclic deformation of biomaterial surfaces without antifungal agents produced increased biomass, metabolic activity, and a number of viable cells compared to the static/no-deformed surfaces. Cyclic deformation appears to be a novel mechanobiological signal that enables pathogenicity and virulence of C. albicans cells with increased expression of the yeast-to-hyphae transition genes. The outcome of this study opens new opportunities for the design of antifungal dentures for improved clinical service and reduced need for cleaning methods.

Effect of chromium substitution on the dielectric, ferroelectric and piezoelectric properties of PLNZNT ceramics (P=Pb2+, L=La3+, N=Nd3+, Z=Zr4+, N=Nb5+, T=Ti4+)

Piezoelectricity is one of the renewable and clean electrical energy sources, as it is generated from materials specially manufactured for this purpose in proportions and scales called piezoelectric materials, that is, electricity resulting from mechanical work that produces the electric field, and this is known as the direct piezoelectric effect. An inverse mechanical effect can also be observed when an electric field is applied to the same piezoelectric material that deforms and returns to its original shape after the electric field is removed. In order to contribute to improving the properties of these materials that have been prepared from insulating ceramic materials having an equivalent formula: Pb0.975 La0.015 Nd0.01 [(Zr 0,524 Ti 0,476) 0.9875 -3/4 z Nb0.005 Crz]O3 abbreviated PLNZCNT (z = 0%, 0.5%, 0.75%, 1%, 1.25%, 1,5% and 2%). The formation of pure single-phase perovskite compounds of tetragonal symmetry for all samples was confirmed by X-ray diffraction (XRD) analyzes. The scanning electron micrographs show that the grains have melted, most of the separating walls have disappeared, and the average grain size has increased. Information about the effects of chromium concentration on the measured properties was obtained based on temperature and frequency measurements of the dielectric properties of PLNZNT ceramics, represented by an increase in Curie temperature with increasing Cr3+ concentration. The ferroelectric properties of materials are characterized by the presence of a polarization hysteresis cycle as a function of the applied electric field (P-E). To measure the piezoelectric and electromechanical properties at room temperature, was used by the standard resonance and anti-resonance method. It was found that the sample E2 (0.75%) sintered at 1200°C achieves excellent dielectric, ferroelectric and piezoelectric properties (𝜺r=24394.51, tan δ =0.072 and Tc = 378K). The values of saturated electric polarization (Ps=29.61 µC/cm²), remnant electric polarization (Pr=24.63 µC/cm²) and coercive electric field (Ec=0.905kV/mm), as well as piezoelectric charge coefficient (d33 = 435 pC/N) for sample E2 (0.75%).

Energy Harvesting from Ceramic/Blended Polymer Nanocomposites: Ba0.85Ca0.15Zr0.10Ti0.90O3/Polyvinylidene Fluoride–Polytetrafluoroethylene

The mechanical impact‐based energy harvesting characteristics of 0–3ϕBa0.85Ca0.15Zr0.10Ti0.90O3/(1−ϕ)polyvinylidene fluoride–polytetrafluoroethylene (BCZT/PVDF–PTFE); volume fraction (0 ≤ ϕ ≤ 0.25) nanocomposites, fabricated using a melt‐mixing method, are presented. A scanning electron microscope is utilized to investigate the distribution of BCZT nanoceramic powder as filler in the blended polymer (PVDF–PTFE; 80:20). The X‐ray diffraction method is applied to ascertain the formations of BCZT and BCZT/PVDF–PTFE. The values of apparent porosity, water absorption, shore D hardness, dielectric constant (εr), tangent loss (tan δ), piezoelectric charge coefficient (d33) and voltage constant (g33), and figure of merit (FM) are found to increase upon increasing ϕ. A significant increment in the impact‐generated electric voltage (25.38–77.73 V) and energy (9.42–243.9 nJ) is noticed with the increasing ϕ. In addition, the small values of water absorption (<0.091%) and tan δ (≈10−2) with relatively higher values of εr, d33, g33, FM, and shore D hardness, power out (Pdc = 0.47 mW using 470 Ω resistive load ϕ = 0.25 sample) as well as improved voltage generation and energy harvesting characteristics, prefigure the promise of the present composite system a superior lead‐free alternative for the applications in energy harvesting, detection/sensing, and structural health monitoring.

Second harmonic generation, optical, thermal, piezoelectric and mechanical properties of adipic acid-doped ADP crystals

Single crystals of pure and 2[Formula: see text]mol.% adipic acid (hexanedioic acid) -doped ammonium dihydrogen phosphate (ADP) were grown by conventional slow evaporation of aqueous solution technique. The powder X-ray diffraction and FT-IR analyses indicate that the crystals undergo considerable stress as a result of doping. UV–Vis studies show that the absorption of the adipic acid-doped crystals is less than that of pure ADP. Thermal studies (TG/DTG) disclose that the decomposition temperature of doped ADP is more than that of pure ADP. Vicker’s microhardness study reveals that the addition of adipic acid increases the hardness of the ADP. SHG efficiency and piezoelectric charge coefficient of adipic acid-doped ADP are higher than that of pure ADP.

Comprehensive predictive control for vibration suppression based on piecewise constant input formulation

We propose a novel semi-active vibration suppression method based on model predictive control (MPC). Semi-active vibration suppression provides excellent damping performance, energy consumption, and stability during control. As the semi-active control input is often discontinuous, it may be difficult to predict. Hence, we combine semi-active vibration suppression and MPC to determine the control input trajectory arbitrarily. The proposed method, called predictive switching based on piecewise constant input (PSPCI), assumes that the piezoelectric charge remains constant when the control circuit is in the open state. Under this assumption, the future system state can be predicted for semi-active vibration suppression while reducing the computational load. The PSPCI method predicts the future work done by the transducer and effectively suppresses vibrations. Its effectiveness and robustness are demonstrated through simulations and experiments. The proposed PSPCI method enables the prediction of the semi-active control input and diversifies the control input determination for effective semi-active vibration suppression.

Bulk Ferroelectric Metamaterial with Enhanced Piezoelectric and Biomimetic Mechanical Properties from Additive Manufacturing.

Three-dimensional (3D) ferroelectric materials are electromechanical building blocks for achieving human-machine interfacing, energy sustainability, and enhanced therapeutics. However, current natural or synthetic materials cannot offer both a high piezoelectric response and desired mechanical toughness at the same time to meet the practicality. Here, a lamellar ferroelectric metamaterial was created with a ceramic-like piezoelectric property and a bone-like fracture toughness through a low-voltage-assisted 3D printing technology. The one-step printed bulk structure, consisting of periodically intercalated soft ferroelectric and hard electrode layers, exhibited a significantly enhanced longitudinal piezoelectric charge coefficient (d33) of over 150 pC N-1, as well as a superior fracture resistance of ∼5.5 MPa·m1/2, more than three times higher than conventional piezo-ceramics. The excellent printability together with the combination of both high piezoelectric and mechanical behaviors allowed us to create a bone-like structure with tunable anisotropic piezoelectricity and bone-comparable mechanical properties, showing a potential of manufacturing practical, high-performance, and smart biological systems.

Impact of ionizing radiation on structural, dielectric, and piezoelectric properties of Sr modified PZT

Ion irradiation effects on piezoceramic (Pb0.94 Sr0.04) (Zr0.52 Ti0.48)O3 (PSZT) are investigated by using 4 MeV carbon (C), 9 MeV copper (Cu), and 20 MeV gold (Au) ions. The energies of incident ions are selected in order to target the same range of all incident ions in the material, while producing different amounts of vacancies. The ion irradiation is performed with fluences of 1×1013, 1×1014, and 1×1015 ions/cm2 using Tandem Pelletron accelerator (5UDH-2). Post irradiation changes in PSZT are investigated via various structural, dielectric, and piezoelectric measurement techniques. Results divulge that the irradiation process disturbs the crystallinity along with reduction in X-ray diffraction (XRD) peak intensities owing to strain induced structural defects. A small decrease in dielectric constant is observed due to trapped charges, which screen the depolarization after irradiation. However, a significant decrease is detected in piezoelectric charge coefficients (d33) and piezoelectric voltage coefficients (g33) due to switching of micro domains of PSZT as a result of energy observed during irradiation process. These results indicate that ion irradiation has damaging effects on the properties of PSZT. The discussed information may be utilized to assess performance of PSZT based devices under radiation rich environments such as space.

Enhanced electrocatalytic hydrogen evolution performance of 2D few-layer WS2 nanosheets via piezoelectric effects

Two-dimensional transition metal disulfides are considered a great candidate for non-noble metal catalyst because of their abundant reserves and excellent electrochemical activity in hydrogen evolution reaction (HER). Herein, two-dimensional (2D) few-layer WS2 nanosheets were synthesized via a facile liquid phase stripping technique. The piezoelectricity of the synthesized WS2 nanosheets was verified by piezoelectric force microscope (PFM) and used to promote the piezo-catalytic hydrogen generation, where the piezoelectric charges generated under ultrasound vibration are utilized for hydrogen evolution. Moreover, the effect of various mechanical vibration conditions on the piezo-catalytic HER of WS2 was also discussed. The results show that under the same overpotential, the hydrogen production rate with ultrasound vibration (40 kHz, 40 W) is 6 times higher and the impedance is 4 times lower than that without ultrasound. The catalytic efficiency of WS2 can be significantly increased through this method, which paves the way towards non-noble metal HER catalysts to produce hydrogen with aid of piezoelectricity.

Autonomous Microcapillary Drug Delivery System Self‐Powered by a Flexible Energy Harvester

AbstractImplantable bioelectronic devices pave the way for novel biomedical applications operating at high spatiotemporal resolution, which is crucial for neural recording and stimulation, drug delivery, and brain–machine interfaces. Before successful long‐term implantation and clinical applications, these devices face a number of challenges, such as mechanical and operational stability, biocompatibility, miniaturization, and powering. To address two of these crucial challenges—miniaturization and powering—the development and characterization of an electrophoretic drug delivery device, manufactured inside fused quartz fibers (outer diameter of 125 µm), which is self‐powered by a flexible piezoelectric energy harvester, are reported. The resulting device—the first integration of piezoelectric charging with “iontronic” delivery—exhibits a high delivery efficiency (number of neurotransmitters delivered per charges applied) and a direct correlation between the piezoelectric charging and the amount delivered (number of dynamic bends versus pmols delivered).

Metallic Bi self-deposited BiOCl promoted piezocatalytic removal of carbamazepine

Development of high-performance piezocatalyst has attracted much attention for efficiently piezocatalytical removal of pharmaceuticals and personal care products in the wastewater. In this work, metallic Bi nanoparticles were successfully self-deposited on the surface of piezocatalyst BiOCl via an in-situ reduction method to modify the piezoelectric response for the piezocatalytic degradation of carbamazepine (CBZ). The present of Bi nanoparticles significantly enhanced piezocatalytic performance of BiOCl, in which 75.11% of CBZ (5 mg/L) was removed under ultrasonic vibration in the presence of Bi/BiOCl-50 (0.5 g/L) after 30 min, being 52.72% higher than that of pure BiOCl. Through scavenger test, electron paramagnetic resonance detection and electrochemical analysis, the enhanced piezocatalytic activity was due to that Bi nanoparticles improved the separation efficiency of piezoelectric charges to generate more reactive oxygen species. The stability of the piezocatalyst, effects of reaction parameters, treatment performance of real wastewater, and the possible pathways of CBZ degradation were systematically investigated. The work provides a deep understanding on the piezocatalytic process and brings a new track to enhance the piezocatalytic performance for Bi-based piezoelectric materials without introducing any impurities in water purification.

Polymer conformation-dependent piezoelectric properties and self-bias magnetoelectric responses in adhesive-free laminate composites of Ni-foam/PVDF/Ni-foam

In the past decade, polymer-based magnetoelectric (ME) laminate composites have been developed for feasible applications such as flexible energy harvesters and wearable sensors. The 2-2-type ME laminate composites have been typically prepared by epoxy adhesion of piezoelectric and magnetostrictive layers, which is a drawback that disrupts strain transfer from the magnetostrictive phase to the piezoelectric phase due to its strong hardness after epoxy curing. In this study, to overcome the disadvantage of insufficient strain transfer due to the adhesive layers, we designed adhesive-free laminate composites consisting of porous magnetostrictive nickel foam (NF) and soft poly (vinylidene fluoride) (PVDF) films, which exhibited good physical coupling via the sandwich hot-pressing of NF/PVDF/NF. In addition, the self-bias ME effect could be expected from NF, since it exhibits butterfly-shaped magnetostrictive hysteresis loops. Therefore, NF/annealed PVDF(AP)/NF and NF/hot-pressed PVDF(HP)/NF were prepared for investigating the polymer conformation during the fabrication process of ME laminates. Polymer conformation-dependent piezoelectric properties were investigated after annealing and hot-pressing, respectively. The NF/AP/NF laminates (mM/mP = 0.88) were found to exhibit a β/α phase ratio of 2.07, degree of crystallinity (χc) of 46.5%, piezoelectric charge constant (d33) of 17.7 pC/N, and self-bias ME response of 1.88 mV/cm Oe (94% of the maximal ME response at Hbias = 20 Oe). The NF/HP/NF laminates (mM/mP = 1.26) were found to exhibit a β/α phase ratio of 1.40, χc of 32.2%, d33 of 12.4 pC/N, and self-bias ME response of 2.27 mV/cm Oe (92% of the maximal ME response at Hbias = 10 Oe). The high β/α phase ratio were carried out sufficient stretching effect during hot-press laminating process. The optimal piezoelectric properties of β/α phase ratio and χc were induced by predominant stretching of PVDF chains rather than recrystallization during the hot-press. Further, reliable self-bias ME responses were obtained in the adhesive-free laminate composites by enhancement of coupling effect between magnetostrictive and piezoelectric phases. As a result, the sandwich laminate composites of NF/PVDF/NF were successfully prepared via hot-pressing and reliable ME responses were obtained without requiring the electroding process. This demonstrates the feasibility of ME laminate composites for use in wearable energy harvesters or sensors through removal of the hard adhesive layer.

Piezoelectric Properties of (1 – X)BiScO3 – XPbTiO3 System for Actuator Applications

ABSTRACTIn this research, the crystalline and piezoelectric properties of (1 – X )BiScO3–XPbTiO3 (X = 0.60, 0.62, 0.64, 0.66 and 0.68) ceramics were investigated to determine the optimized composition for energy harvester and sensor applications. BS-PT ceramics have strong merits in terms of their high Curie temperature and piezoelectric charge coefficient. Devices of the (1 – X )BS-XPT ceramics were fabricated by a conventional mixed-oxide sintering process with nano-powders. By employing the X-ray diffraction patterns, the morphotropic phase boundary (MPB) region of the monoclinic and tetragonal phases was identified at X = 0.64. Near the MPB region, the piezoelectric and dielectric properties of BS-PT ceramics were improved compared with those of other composition. By optimizing the compositions of the BS-PT ceramics, the maximum values of the dielectric constant (εr), piezoelectric charge coefficient (d33), electromechanical coupling factor (kp) and remanent polarization (Pr) were obtained, with values of 1387, 417 pC/N, 51.4% and 44.8 µC/cm2, respectively. Moreover, a high Curie temperature of 399.2 °C and inverse piezoelectric charge coefficient of 574 pm/V were observed for the 0.36BS–0.64PT composition, which can be a huge merit for actuator applications. These high piezoelectric charge coefficients and inverse piezoelectric charge coefficients can be the strong merits for energy harvester and actuator applications.

Piezoelectric and structural properties of bismuth sodium potassium titanate lead-free ceramics for energy harvesting

The development of piezoelectric ceramics with high energy conversion efficiency is of decisive importance for the requirements of the advanced energy harvesting devices toward miniaturization and integration. Lead titanate-zirconate (PZT) piezoceramics are the most widely used energy harvesting (EH) materials due to their excellent piezoelectric properties. However, the presence of more than 60% lead in the PZT composition is a serious threat to human health and the environment. Consequently, greater efforts being made to develop lead-free alternatives to PZT-based materials. Here, we propose the Bi0.5(Na0.8K0.2)0.5TiO3 (BNKT) lead-free piezoceramics as a good candidate for the replacement of toxic lead compounds for energy harvesting applications. For that, we have carried out a systematic study of the voltage generation of BNKT-based piezoceramics for (EH) purposes. Specifically, the obtained piezoelectric charge coefficients (d33 = 129 pC/N and d31 = − 12.8 pC/N) and maximum generated output voltage (19.9 V/g) values reveal the good ferro-piezoelectric properties and potential technological applications for energy harvesting of the BNKT–based lead-free piezoceramics. Finally, we consider that the design of new lead-free piezoceramics with superior property coefficients and functionalities, such as the BNKT-based piezoceramics, should be seriously considered as candidates for the replacement of the current toxic lead-based compounds.

An Analytical Model for Dual Gate Piezoelectrically Sensitive ZnO Thin Film Transistors.

We report the experimental realization of piezoelectric ZnO dual-gate thin film transistors (TFTs) as highly sensitive force sensors and discuss the physical origins of its electrically tunable piezoelectric response using a simple analytical model. A dual gate TFT is fabricated on a polyimide substrate using radio-frequency (RF) magnetron sputtering of piezoelectric ZnO thin film as a channel. The ZnO TFTs exhibited a field effect mobility of ~ 5 cm2/Vs, I max to I min ratio of 107, and a subthreshold slope of 700 mV/dec. Notably, the TFT exhibited static and transient current changes under external force stimuli, with varying amplitude and polarity for different gate bias regimes. To understand the current modulation of the dual-gate TFT with independently biased top and bottom gates, an analytical model is developed. The model includes accumulation channels at both surfaces and a bulk channel within the film and accounts for the force-induced piezoelectric charge density. The microscopic piezoelectric response that modulates the energy-band edges and correspondent current-voltage characteristics are accurately portrayed by our model. Finally, the field-tunable force response in single TFT is demonstrated as a function of independent bias for the top and bottom gates with a force response range from -0.29 nA/mN to 22.7 nA/mN. This work utilizes intuitive analytical models to shed light on the correlation between the material properties with the force response in piezoelectric TFTs.

Engineered hard piezoelectric materials of MnO2 doped PZT-PSN ceramics for sensors applications

ABSTRACT In this study, MnO2-doped 0.96Pb(Zr0.515,Ti0.485)O3-0.04Pb(Sb0.5,Nb0.5)O3 (0.96PZT-0.04PSN) hard piezoelectric ceramics were fabricated by employing a conventional mixed-oxide process. Hard piezoelectric materials are suitable for mechanical device applications such as transducers or piezoelectric ultrasonic motors owing to their high mechanical quality factor. To improve the hard piezoelectric properties, MnO2 was selected and doped into 0.96PZT-0.04PSN ceramics in this study. When MnO2 was introduced into piezoelectric lead zirconate titanate (PZT) ceramics, the resistivity and dielectric permittivity decreased, leading to an increase in the mechanical quality factor. MnO2-doped 0.96PZT-0.04PSN ceramics have a lower piezoelectric charge coefficient and dielectric permittivity compared to those of 0.96PZT-0.04PSN ceramics. However, an enhanced mechanical quality factor of 1600 was obtained for the 0.96PZT-0.04PSN ceramics doped with 0.5 wt% of MnO2. In contrast to other hard piezoelectric materials, MnO2 doped 0.96Pb(Zr0.515,Ti0.485)O3-0.04Pb(Sb0.5,Nb0.5)O3 ceramics have a high Qm value while having an appropriate piezoelectric charge coefficient d33 and electromechanical coupling coefficient kp.

Comparative Study of PVDF Sheets and Their Sensitivity to Mechanical Vibrations: The Role of Dimensions, Molecular Weight, Stretching and Poling.

This paper is focused on the comparative study of the vibration sensing capabilities of poly(vinylidene fluoride) (PVDF) sheets. The main parameters such as molecular weight, initial sample thickness, stretching and poling were systematically applied, and their impact on sensing behavior was examined. The mechanical properties of prepared sheets were investigated via tensile testing on the samples with various initial thicknesses. The transformation of the α-phase to the electro-active β-phase was analyzed using FTIR after applying stretching and poling procedures as crucial post-processing techniques. As a complementary method, the XRD was applied, and it confirmed the crystallinity data resulting from the FTIR analysis. The highest degree of phase transformation was found in the PVDF sheet with a moderate molecular weight (Mw of 275 kDa) after being subjected to the highest axial elongation (500%); in this case, the β-phase content reached approximately 90%. Finally, the vibration sensing capability was systematically determined, and all the mentioned processing/molecular parameters were taken into consideration. The whole range of the elongations (from 50 to 500%) applied on the PVDF sheets with an Mw of 180 and 275 kDa and an initial thickness of 0.5 mm appeared to be sufficient for vibration sensing purposes, showing a d33 piezoelectric charge coefficient from 7 pC N−1 to 9.9 pC N−1. In terms of the d33, the PVDF sheets were suitable regardless of their Mw only after applying the elongation of 500%. Among all the investigated samples, those with an initial thickness of 1.0 mm did not seem to be suitable for vibration sensing purposes.