Piezoelectric Charge Constant Research Articles

Improved piezoelectric performances of highly orientated poly(β-hydroxybutyrate) electrospun nanofiber membrane scaffold blended with multiwalled carbon nanotubes

Highly orientated poly(β-hydroxybutyrate)/multiwalled carbon nanotubes (PHB/MWCNTs) composite nanofiber membrane scaffold was fabricated by electrospinning followed by hot-stretching treatment. X-ray diffraction confirmed the presence of MWCNTs in the structure of PHB/MWCNTs composite. Compared with neat PHB nanofiber scaffold, PHB/MWCNTs composite nanofiber scaffolds contained higher content of β-form crystals. The measured piezoelectric charge constant and induced electrical potentials generated on the surface of the nanofiber scaffolds indicated that addition of MWCNTs to PHB nanofiber matrix and hot-stretching treatment contributed to improving piezoelectric performances of PHB. The developed PHB/MWCNTs composite ‘smart’ nanofiber membrane is applicable for biomedical field, electronic sensors and actuators.

Dielectric, ferroelectric, and piezoelectric properties of lead-free Ba0.95Ca0.05Ti1-xZrxO3 ceramics

Ba0.95Ca0.05Ti1-xZrxO3 (BCTZO) ceramics were prepared by a solid state reaction method. The samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and X-ray absorption near edge structure (XANES). The ceramics exhibit a pure perovskite structure. The average grain size gradually decreases with increasing Zr concentration. XANES results indicate that the intensities of pre-edge peaks dropped with increasing Zr concentration. The BCTZO ceramic of x = 0.05 has the optimum electrical properties with the maximum dielectric constant (ε'm), remanent polarization (2Pr), coercive electric field (2Ec) and piezoelectric charge constant (d33) of 7,244, 12.54 (μC/cm2), 5.29 (kV/cm) and 288 (pC/N), respectively.

The effects of conductive nano fillers alignment on the dielectric properties of copolymer matrix

This research focuses on the improvement of the dielectric and energy harvesting properties of piezoelectric P(VDF-TrFE) copolymer matrix by the alignment of conductive reduced graphene oxide nano fillers. The dispersion and the morphology of the conductive nano fillers on the co-polymer matrix were characterized by scanning electron microscopy which showed a configurational phase transition due to highly conductive nano channel formation, steric hindrance, excluded volume interaction van-der-walls forces between adjacent reduced graphene oxide sheets. Five different piezoelectric nanocomposites were prepared by varying the reduced graphene oxide contents in P(VDF-TrFE) matrix to realize its optimum concentration in the matrix. From our analysis, we observed that, an optimized morphological structure plays a vital role in the formation of polar electroactive β phase on the co-polymer matrix through the good dispersion, filler alignment and interfacial interaction of reduced graphene oxide nano fillers. The as prepared nanocomposite film showed an enhanced crystallinity (50 ∼ 52%), dielectric constant (72 at 1 kHz), piezoelectric charge constant (−23 pC/N) with an output power of 3.2 µW at 1.8 MΩ load for 2 N mechanical force. All the outputs were observed without applying poling process. We expect that our synthesized self-poled nanocomposite can be a useful candidate for energy harvesting applications.

Optimization of the Compression-Based Piezoelectric Traffic Model (CPTM) for Road Energy Harvesting Application

This paper employs the Two-Degree-of-Freedom (2DOF) electromechanical model to show the probability of the piezoelectric approach as an option for energy scavenging devices in roadway applications. The passing vehicles are the main energy source for harvesting device. A 2DOF electromechanical model as the piezoelectric harvesting unit is applied to explain the harvester performance in a single lane road. APC piezoelectric ceramic (APC 855) is selected as the optimum piezoelectric material due to its high piezoelectric constant values and high piezoelectric charge constant. Also, in the traffic model, we employ a Cellular Automata (CA) model. The vehicle dynamics model is used to transfer information from the traffic model to the piezoelectric model. Combining both the traffic model, i.e. the piezoelectric and the vehicle dynamics model, results in the compression-based piezoelectric traffic model (CPTM). In a single-lane traffic model with different arrival rate I», a single circle-shaped Piezoelectric Cymbal Transducer (PCT) with thickness of 0.3 mm and diameter of 32 mm is applied, in which the produced power is 14.126 W and 29.746 W and 6.47 W. Based on these outcomes, if we lay multiple PCT arrays along the highway road, a large amount of power can be produced. Hence, a great potential is shown by the proposed electromechanical-traffic model for applications related to the macro-scale roadway electric power generation systems.

Determination of the sonic properties of a Nigerian quartz for ultrasonic transducer.

There is abundant quartz deposit in Nigeria which has been used for export and building purposes. However, its electrical and piezoelectric properties have not been studied. Thus, whether it can be used as raw material for the indigenous electric industries is unknown to date. This study aims to characterize the piezoelectric properties of smoky quartz for ultrasonic transducer and determine its sonic properties. In the research approach, the raw quartz was cut into six crystals of rectangular shape using a universal cutter. The crystals were purified with a 100 ml hydrofluoric and hydrochloric acid solution under a temperature of 250°C in a furnace. The sizes, weights, and capacitance of crystals were determined using the standard measuring instruments. The resonance method was used for the determination of the frequency of minimum and maximum impedance of the crystals. The piezoelectric constants of the crystals were derived using the standard formula for determination of piezoelectric constants. The results show that the sonic properties represented by the piezoelectric charge constant (d31) and the piezoelectric voltage constant (g31) values are 2.52(±1.075)×10-8c/m2 and 1030.6114±250.89v/m2 respectively. The present study has characterized Nigerian quartz for its piezoelectric properties and found that it was suitable for use in the construction of ultrasonic transducers.

Soft piezoelectric polymer of poly[di(ethylene glycol) adipate] plasticized poly vinyl chloride and its strain sensing

This letter reports that a plasticized poly vinyl chloride (PVC) exhibits high dielectric constant with low Young’s modulus which drastically improves its piezoelectric property and strain sensing behavior. PVC was plasticized by poly[di(ethylene glycol) adipate] (PDEGA) and PDEGA-PVC was fabricated by simple solvent mixing process. As increasing the PDEGA content, the dielectric constant of PDEGA-PVC increases meanwhile its Young’s modulus and yield strength decrease, which results in great improvement of the piezoelectric charge constant of PDEGA-PVC (51.2 pC/N), much higher than the pristine PVC (0.34 pC/N). A strain sensor with PDEGA-PVC was tested and its durable strain sensing behavior is demonstrated. The developed PDEGA-PVC is applicable for sensors of wearable and portable devices and soft actuators.

Effect of Mn on Dielectric and Piezoelectric Properties of 71PMN-29PT [71Pb(Mg1/3Nb2/3)O3-29PbTiO3] Single Crystals and Polycrystalline Ceramics

In order to investigate the effect of Mn on the dielectric and piezoelectric properties of PMN-PT [Pb(Mg1/3Nb2/3)O3-PbTiO3], four different types of 71PMN-29PT samples were prepared using the solid-state single crystal growth (SSCG) method: (1) Undoped single crystals, (2) undoped polycrystalline ceramics, (3) Mn-doped single crystals, and (4) Mn-doped polycrystalline ceramics. In the case of single crystals, the addition of 0.5 mol% Mn to PMN-PT decreased the dielectric constant (K3T), piezoelectric charge constant (d33), and dielectric loss (tan δ) by about 50%, but increased the coercive electric field (EC) by 50% and the electromechanical quality factor (Qm) by 500%, respectively. The addition of Mn to PMN-PT induced an internal bias electric field (EI) and thus specimens changed from piezoelectrically soft-type to piezoelectrically hard-type. This Mn effect was more significant in single crystals than in ceramics. These results demonstrate that Mn-doped 71PMN-29PT single crystals, because they are piezoelectrically hard and simultaneously have high piezoelectric and electromechanical properties, have great potential for application in fields of SONAR transducers, high intensity focused ultrasound (HIFU), and ultrasonic motors. Key words: Piezoelectric, Single Crystal, 71PMN-29PT, Mn Doping, Ultrasonic Transducer

Deconstructing collagen piezoelectricity using alanine-hydroxyproline-glycine building blocks

Collagen piezoelectricity has been the focus of a large number of experimental and theoretical studies for over fifty years. Less is known about the piezoelectric properties of its building blocks, in particular but not limited to, proline and hydroxyproline. Spurred by the recent upsurge of interest in piezoelectricity in organic crystals including our own report of unprecedentedly high piezoelectricity in amino acid glycine, we predict and measure the piezoelectric properties of collagen subcomponents in single crystalline forms and the collagen-like alanine-hydroxyproline-glycine trimer peptide. We map the modulation of piezoelectric charge constants in collagen building blocks as the crystal symmetry is lowered and the molecule size increases, finding strong evidence for amino acid-level barcoding of collagen piezoelectricity that can in turn be tuned using very simple chemistry. The simple addition of an -OH group can increase piezoelectric constants by up to two orders of magnitude (d25 = 25 ± 5 pC N-1) as measured in Y-cut hydroxyproline crystals. The value is similar to that obtained from thermoelectrically poled commercial polyvinylidene di fluoride (PVDF) films. Overall, our findings support a simple block by block approach in which first principles calculations can guide the understanding and re-engineering of piezoelectric biomolecules.

Antimony Oxide-Doped 0.99Pb(Zr0.53Ti0.47)O3–0.01Bi(Y1−xSbx)O3 Piezoelectric Ceramics for Energy-Harvesting Applications

The effects of doping antimony oxides (Sb2O3/Sb2O5) on the ferroelectric/piezoelectric and energy-harvesting properties of 0.99Pb(Zr0.53Ti0.47)O3–0.01BiYO3 (PZT–BY) have been studied. The feasibility of doping Sb2O3 and Sb2O5 into the PZT–BY ceramics has also been compared by considering factors such as sintering condition, grain size, density, and electrical properties etc. This work discusses a detailed experimental observation using Sb2O3, because Sb2O5 is relatively expensive and does not follow the stoichiometric reaction mechanism when doped in PZT–BY. The Sb2O3-doped specimens were well sintered by oxygen-rich sintering and reached a maximum density of 99.1% of the theoretical value. X-ray diffraction (XRD) analysis showed a complete solid solution for all the specimens. Scanning electron microscope (SEM) observation revealed that the addition of Sb2O3 inhibits grain growth, and exhibits a denser and finer microstructure. The 0.1 moles of Sb2O3-doped ceramic shows a sharp decrease in the dielectric constant (ε33T = 690), while the piezoelectric charge constant (d33) and electromechanical coupling factor (kp) maintained high values of 350 pC/N and 66.0% respectively. The relatively higher value of d33 and lower ε33T of the 0.99Pb(Zr0.53Ti0.47)O3–0.01Bi(Y0.9Sb0.1)O3 ceramic resulted in an optimum value of piezoelectric voltage constant (g33 = 57.4 × 10−3 Vm/N) and a high figure of merit (d33 × g33 = 20075 × 10−15 m2/N). These values are high compared to recently reported works. Therefore, Sb2O3-doped PZT–BY ceramic could be a promising candidate material for the future study of power-harvesting devices.

Effect of ZnO Nanoparticles on the Sintering Behavior and Physical Properties of Bi0.5(Na0.8K0.2)0.5TiO3 Lead-Free Ceramics

Sintered Bi0.5(Na0.8K0.2)0.5TiO3 + x wt.% ZnO nanoparticle (BNKT–xZnOn) ceramics have been fabricated by conventional annealing with the aid of ultrasound waves for preliminary milling. Because of the presence of the liquid Bi2O3–ZnO phase at the eutectic point of 738°C, the sintering temperature decreased from 1150°C to 1000°C, and the morphology phase boundary of BNKT–xZnOn ceramics can be clarified by two separated peaks at (002)T and (200)T of 2θ in the x-ray diffraction (XRD) patterns. The improvement of ferroelectric properties has been obtained for BNZT–0.2 wt.% ZnOn ceramics by the increase of remanent polarization up to 20.4 μC/cm2 and a decrease of electric coercive field down to 14.2 kV/cm. The piezoelectric parameters of the ceramic included a piezoelectric charge constant of d 31 = 78 pC/N; electromechanical coupling factors k p = 0.31 and k t = 0.34, larger than the values of 42 pC/N, 0.12 and 0.13, respectively, were obtained for the BNKT ceramics.

Powder injection molding of PNN-PMN-PZN doped low temperature sintering PZT ceramics

A complete process of powder injection molding was developed and optimized for the low temperature sintering PZT ceramics. A commercialized PNN-PMN-PZN doped PZT ceramics was used for the process development. The torque rheometer experiment was conducted to determine the optimal solids loading to injection molding rectangular type specimen. Appropriate debinding conditions were developed by thermogravimetry. Holding temperatures were determined based on the decomposition behavior of binder system and the volatilization temperature of Pb. Due to the fine particle size and low solids loading, a slow thermal debinding rate was required to prevent the crack defect. The densification behavior during sintering was analyzed by dilatometry. Low temperature sintering PZT ceramics shows a strain rate peak point at 1015°C which is relatively lower than the peak point of conventional PZT ceramics. Even though a relatively long (3h) holding time was required to achieve 98% of relative density, the powder injection molded low temperature sintering PZT ceramics showed 7.66 (103kg/m3) of density and 635 (pC/N) of piezoelectric charge constant which are 98 and 99% of reference value of powder.

Fabrication Method Study of ZnO Nanocoated Cellulose Film and Its Piezoelectric Property.

Recently, a cellulose-based composite material with a thin ZnO nanolayer—namely, ZnO nanocoated cellulose film (ZONCE)—was fabricated to increase its piezoelectric charge constant. However, the fabrication method has limitations to its application in mass production. In this paper, a hydrothermal synthesis method suitable for the mass production of ZONCE (HZONCE) is proposed. A simple hydrothermal synthesis which includes a hydrothermal reaction is used for the production, and the reaction time is controlled. To improve the piezoelectric charge constant, the hydrothermal reaction is conducted twice. HZONCE fabricated by twice-hydrothermal reaction shows approximately 1.6-times improved piezoelectric charge constant compared to HZONCE fabricated by single hydrothermal reaction. Since the fabricated HZONCE has high transparency, dielectric constant, and piezoelectric constant, the proposed method can be applied for continuous mass production.

Modelling of the resonance and anti-resonance behaviour in free and clamped state of [Ba(Nd0.1Ti0.8Nb0.1)O3]1-x[(Na0.5Bi0.5)TiO3]x piezoelectric ceramics

ABSTRACTModified Lorentz equation which was proposed by us is used to model the resonance and anti-resonance behaviour in free and clamped state of [Ba(Nd0.1Ti0.8Nb0.1)O3]1-x[(Na0.5Bi0.5)TiO3]x piezoelectric ceramics. The modified Lorentz equation gives information about the static dielectric constant, infinite dielectric constant, polarizability, piezoelectric charge constant and piezoelectric voltage constant. The modified Lorentz equation is found to best fit to the experimental data. The validity of modified equation can be known from the regression value obtained. The order of polarizability, piezoelectric charge constant and piezoelectric voltage constant are of the order of 10−37(F.m2), 10−9 m/V and 10−11 m2/C respectively for the present ceramics. The piezoelectric charge constant decreased with the increase of x value. Higher piezoelectric charge constant was observed for the ceramic with x = 0.40 in clamped state when compared to other composition in free and clamped state and the value is 2.288×10−9 m/V. The piezoelectric voltage constant decreased with the increase of x value. Lowest piezoelectric voltage constant was observed for the ceramic with x = 0.40 in clamped state and the value is 1.030 ×10−11 m2/C. Ceramic composition with higher x value and which were studied in clamped state shows better piezoelectricity.

PMN-PT based smart sensing system for viscosity and density measurement

Abstract This paper presents a smart sensing system for viscosity and density measurement of viscous fluids. The proposed system is based on the vibrational properties of a cantilever probe bonded with newly developed piezoelectric materials–Lead Magnesium Niobate/Lead Titanate (PMN-PT) transducer, which has a piezoelectric charge constant (d33) more than 3 times larger than that of traditional piezoelectric material Lead zirconate titanate (PZT). The proposed system utilizes a PMN-PT single crystal for actuation and laser vibrometer for vibration detection. Using the PMN-PT transducer, the measured viscosity and density of fluids were extracted by analyzing the vibrational properties of the smart probe. Finite element analysis was conducted with COMSOL Multiphysics for theoretical calculation and lab tests were carried out to verify and evaluate the simulation results. This smart sensing system can be applied to in-field, in situ and real-time monitoring of viscous fluids, such as blood, engine oil and early-age concrete.

Study of dielectric and resonance and anti-resonance property of dielectric relaxor ceramic: [Ba(Nd0.1Ti0.8Nb0.1)O3]0.50[Na0.5Bi0.5TiO3]0.40[CaTiO3]0.10

ABSTRACT[BaNd0.1Ti0.8Nb0.1O3]0.50[Na0.5Bi0.5TiO3]0.40[CaTiO3]0.10 ceramic was prepared through solid state double sintering method. The XRD results indicate that the ceramic sample have a cubic structure at room temperature. The average grain size was found to be around 4–6 μm. Dielectric studies revealed that the present materials exhibit relaxor behaviour. From piezoelectric studies, it is observed that the resonance and anti-resonance peaks was broad for ceramic sample studied under clamped state when compared to ceramic sample studied under free State. The values of Kt & Keff at room temperature for ceramic samples studied under clamped state were 0.751, 0.718 respectively. Modified Lorentz equation was used to characterize the dielectric and resonance & anti-resonance behaviour and was found to best fit to the experimental data. The activation energy for thermally activated orientation of dipoles was in the range 80–90 μeV. The piezoelectric charge constant (d33) and piezoelectric voltage constant (g33) for the ceramic sample studied under free state are 1.359 × 10−9 (m/V) and 2.526 × 10−11 (m2/C) respectively.

Enhancing energy harvesting potential of (K,Na,Li)NbO3‐epoxy composites via Li substitution

In this study, the influence of Li substitution on the piezoelectric performance of lead‐free K0.5Na0.5NbO3 (KNN)‐epoxy composites is explored. KNN piezoceramic particles modified with 0‐12 mol% of Li are prepared via a double calcination technique, resulting in a perovskite particulate which transitions from an orthorhombic to tetragonal crystal structure between 6 and 9 mol% of Li, and contains a minor nonperovskite second phase from 6 mol%. A cuboid particle morphology is evident in all cases, though tetragonal KNN‐based particles have formed with serrated edges and fractures. The particles are dispersed at 10 vol% in an epoxy matrix to develop both random and dielectrophoretically structured (K,Na,Li)NbO3‐epoxy composites. The dielectric constant of the composites appears almost independent of Li content, while the piezoelectric charge constant of structured composites peaks before the polymorphic phase transition, at 3 mol% of Li. The peak in performance can be attributed to the increased primary particle size of the composition in combination with its single phase orthorhombic crystal structure. The enhancement of the energy harvesting figure of merit, derived from substituting 3 mol% of Li in the KNN particulate, makes these composites an interesting choice for flexible energy generators.

Enhanced temperature stability and quality factor with Hf substitution for Sn and MnO2 doping of (Ba0.97Ca0.03)(Ti0.96Sn0.04)O3 lead-free piezoelectric ceramics with high Curie temperature

In this work, the process of two-stage modifications for (Ba0.97Ca0.03)(Ti0.96Sn0.04-xHfx)O3 (BCTS4-100xH100x) ceramics was studied. The trade-off composition was obtained by Hf substitution for Sn and MnO2 doping (two-stage modification) which improves the temperature stability and piezoelectric properties. The phase structure ratio, microstructure, and dielectric, piezoelectric, ferroelectric, and temperature stability properties were systematically investigated. Results showed that BCTS4-100xH100x piezoelectric ceramics with x=0.035 had a relatively high Curie temperature (TC) of about 112 °C, a piezoelectric charge constant (d33) of 313 pC/N, an electromechanical coupling factor (kp) of 0.49, a mechanical quality factor (Qm) of 122, and a remnant polarization (Pr) of 19μC/cm2. In addition, the temperature stability of the resonant frequency (fr), kp, and aging d33 could be tuned via Hf content. Good piezoelectric temperature stability (up to 110 °C) was found with x =0.035. BCTS0.5H3.5 + a mol% Mn (BCTSH + a Mn) piezoelectric ceramics with a = 2 had a high TC of about 123 °C, kp ∼ 0.39, d33 ∼ 230 pC/N, Qm ∼ 341, and high temperature stability due to the produced oxygen vacancies. This mechanism can be depicted using the complex impedance analysis associated with a valence compensation model on electric properties. Two-stage modification for lead-free (Ba0.97Ca0.03)(Ti0.96Sn0.04)O3 ceramics suitably adjusts the compositions for applications in piezoelectric motors and actuators.

Characterization of piezoelectric ceramics using the burst/transient method with resonance and antiresonance analysis

AbstractIn this paper, a comprehensive methodology for characterizing the high power resonance behavior of bulk piezoelectric ceramics using the burst method is described. In the burst method, the sample is electrically driven at its resonance frequency, and then either a short circuit or an open circuit condition is imposed, after which the vibration decays at the resonance or antiresonance frequency, respectively. This decay can be used to measure the quality factor in either of these conditions. The resulting current in the short circuit vibration condition is related to the vibration velocity through the “force factor.” The generated voltage in the open circuit vibration condition corresponds to the displacement by the “voltage factor.” The force factor and the voltage factor are related to material properties and physical dimensions of the sample. Using this method, the high power behavior of the permittivity, compliance, effective piezoelectric charge constant, electromechanical coupling factor, and material losses can be determined directly by measuring the resonance (short circuit) and antiresonance (open circuit) frequencies, their corresponding quality factors, the force factor A, and the voltage factor B. The experimental procedure to apply this method is described and demonstrated on commercially available hard and semi‐hard PZT materials of geometry.

Effect of vanadium substitution on electrical and piezoelectric properties of lead-free (K0.5Na0.5)NbO3 ceramics

During the last decade, efforts have been made towards developing lead-free piezoelectric ceramics which can replace the currently dominant but highly superior lead-based piezoelectric materials such as PZT. (K0.5Na0.5)NbO3-based piezoelectrics are one promising candidate because of their relatively high Curie temperatures and piezoelectric coefficients. In the present work, powders of (K0.5Na0.5)(Nb1−x V x )O3 (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) were synthesized by conventional solid state reaction of K2CO3, Na2CO3, Nb2O5, and V2O5. The powders were high-energy milled in isopropyl alcohol medium using a Retsch PM 100 planetary ball mill at the speed of 200 rpm for 8 h. The milled powders were sintered at 1080 °C for 1 h in closed alumina crucible. The crystalline phase of the ceramics was found to be perovskite with orthorhombic symmetry. Increasing V5+ content in the ceramics from x = 0 to x = 0.03 gives rise to gradual increase in room temperature dielectric constant (e r ) from 346 to 432, remnant polarization (P r ) from 6.2 to 9.6 μC/cm2, electromechanical coupling factor (k p ) from 0.35 to 0.39, and piezoelectric charge constant (d 33) from 76 to 93 pC/N. The increase in these parameters is attributed to the associated increase in density of the ceramics with increasing V5+ content. Further increase in V5+ content to x = 0.05 results in decrease in e r , P r , k p and d 33 to 390, 4.7 μC/cm2, 0.33 and 67 pC/N respectively. The study reveals that an optimum concentration of V5+ can enhance the dielectric, ferroelectric and piezoelectric properties of (K0.5Na0.5)NbO3 system.

Flexible nano-ZnO/polyvinylidene difluoride piezoelectric composite films as energy harvester

Nanogenerators (NGs) which harvest energy from mechanical vibration have attracted more attention in the past decade. Piezoelectric materials are the most promising candidates for developing NGs. Flexible free-standing nano-ZnO/PVDF composite films are prepared by incorporating different amounts of nano-ZnO fillers in PVDF matrix using sol–gel technique. Poled films show enhanced dielectric constant. The above free-standing films, with appropriate contacts, are subjected to energy harvesting studies. The output voltage increases with nano-ZnO loading in the PVDF matrix and shows enhanced effect for the poled films. Piezoelectric properties are investigated by measuring the piezoelectric charge constant (d 33) and piezoelectric voltage constant (g 33). A maximum AC output voltage ~4 V and output power of the order of few nanowatts are recorded for the nanogenerator which is used to light a red LED using a rectifying circuit through the discharging of a capacitor.