Enhancement Of Piezoelectric Performance Research Articles

Synergistic improvement of mechanical and piezoelectric properties of the flexible piezoelectric ceramic composite and its high-precision preparation

Flexible piezoelectric ceramic composites (FPCCs) hold promising applications in fields such as flexible sensing and energy harvesting. However, the previous methods are difficult to achieve high-precision preparation of the FPCCs with complex structures, as well as the synergistic enhancement of piezoelectric performance and flexibility. In this study, by configuring a flexible resin matrix and employing a surface functionalization treatment on the piezoelectric ceramic particles, the flexibility and piezoelectric performance of the FPCCs are synergistically improved. Moreover, the addition of a light absorber, TiO2, significantly improves the 3D printing precision. The mechanical properties, piezoelectric performance, and printing precision of the FPCCs are analyzed. It is found that the printing error is less than 2 μm, the tensile fracture strength is 4.07 MPa, the elongation at break is 350 %, and the piezoelectric constant d33 can reach 7.7 pC/N. In addition, the cyclic loading tests show that FPCCs with high-precision 3D complex microstructure have good recovery performance. This study not only enriches the formulation of FPCCs slurry for 3D printing, but also provides a research foundation for the multifunctional applications.

Remarkable enhancement in piezoelectric performance of [001] textured Na0.4K0.1Bi0.5TiO3 ceramic

This study explores the dependence of dielectric and piezoelectric properties on the grain morphology, orientation, and electric field in the [001] textured Na0.4K0.1Bi0.5TiO3 (NKBT-T) piezoceramics, fabricated via reactive template grain growth and tape-casting methods. A high degree of [001] texturing with Lotgering factor (f) of ∼0.92 was confirmed by X-ray diffraction, electron backscattered diffraction, and bulk texture measurements. A large average plate length of ∼8.5 ± 1 μm with an aspect ratio of ∼11 was achieved in NKBT-T ceramic. An extremely large value of piezoelectric voltage coefficient (g33) of ∼100×10−3 Vm/N was observed in poled NKBT-T ceramics, originating from a low dielectric constant (∼230) and high piezoelectric charge coefficient (d33 ∼205 pC/N). The transduction coefficient (d33•g33) of NKBT-T ceramic was estimated at ∼20,000 × 10−15 m2N−1 and the mechanical energy harvesting responses of ∼1.8 µA and ∼4 V were recorded in the NKBT-T ceramic-based piezoelectric device.

Interface Optimizing Core-Shell PZT@Carbon/Polyurethane Composites with Enhanced Passive Piezoelectric Vibration Damping Performance.

Presently, piezoelectric materials are gradually playing a significant role within composites to improve the damping and vibrational attenuation capacities of host composites. Previous studies paid attention to isolating the mechanical damping contribution and piezoelectric contribution of polymer-based piezoelectric composites (PPCs). However, reports detailing the piezoelectric damping of such materials have not paid sufficient attention to the technologies and methods to improve the piezoelectric damping of PPCs. In this study, we propose novel damping polyurethane (PU)-based piezoelectric composites with carbon-coated piezoelectric fillers (PZT@C/PU) with improved piezoelectric damping ability. The mechanical damping and piezoelectric damping of composites were theoretically decoupled, and we elaborate on the mechanism enhancing piezoelectric damping through the carbon coating strategy by comparing with the composites with nonpiezoelectric fillers. The as-fabricated core-shell structure having an optimized interface exhibits the proposed PZT@C/PU composite pads with relatively prominent damping ability (loss factor tan δmax = 1.0, tan δRT = 0.3), ductility (400.63%), and sound isolating behavior (transmission loss TL > 23 dB). Moreover, the vibration test results of as-fabricated sandwich structural PZT@C/PU composite damping devices exhibit outstanding vibration attenuating behavior (damping ratio ζ = 0.198). The study herein validates that the carbon shell coated on piezoelectric fillers would effectively increase damping performance of PU-based piezoelectric composites by the enhancement of piezoelectric performance caused by carbon coating piezoelectric fillers, which indicates that this material has potential for future applications in the field of vibration and noise reduction, thereby driving forward and expanding the fundamental understanding in the area of PPCs damping and vibration attenuation.

Poling above the Curie temperature driven large enhancement in piezoelectric performance of Mn doped PZT-based piezoceramics

The enhancement of piezoelectricity is usually in sacrifice of Curie temperature, which in turn limits its working temperature range. It is well known that there are some trade-off among the various performance parameters of most piezoelectric ceramics, and it is still difficult to achieve synergistic improvement in multiple parameters. Here, it is reported that the piezoelectric coefficient d33 of a 0.6 mol% Mn-doped Pb(Sb0.5Nb0.5)0.02Zr0.51Ti0.47O3 piezoelectric ceramics is increased to 436 pC N−1, and its electro-strain can reach 0.16% (d33* = 800 pm/V) at 2 kV mm− 1 by high-temperature poling, whose Curie temperature can still keep at 347 ℃. The features of "hard" piezoelectric ceramics such as low dielectric loss (tgδ = 0.23%) and high mechanical quality factor (Qm = 546) are also preserved. Through structural characterization, combined with the theoretical results of phase field simulation, it is shown that its excellent piezoelectric performance originates from the highly oriented domain structure and small domain size after high temperature poling. On the other hand, the valence state transition of Mn3+ ions during high-temperature poling increases the defect vacancies and lattice distortion in ceramics, which keeps the acceptor-doped characteristic of the ceramics.

Synergistic approach for enhancement of piezoelectricity in the lead-free BiFeO3-BaTiO3 ceramics

Large piezoelectric actuator coefficient (d33*) and enhanced piezoelectric sensor coefficient (d33) with high Curie temperature (TC) are desired for real applications. In this work, a synergistic approach of bipolar cycling and donor doping strategy was applied for the enhancement of piezoelectric performance. An excellent d33 value of 382 pC/N was achieved by the novel (AC-bias and DC-bias) poling method in the lead-free Nb-modified 0.67Bi1.03FeO3-0.33BaTiO3 quenched ceramics. In addition, a large d33* of ∼ 400 pm/V has been obtained under a very low electric field of 25 kV/cm along with a high TC ≈ 473 °C. This enhanced piezoelectric performance is related to the crystal structure morphotropic phase boundary, bipolar cycling, optimum grain size (∼5 µm), maximum lattice distortion, and soft-ferroelectric effect induced by the donor doping. The small strain hysteresis, Hs ≈ 20%, and temperature-insensitive piezoelectric strain, Δd33*(T) = d33*(T)/d33*(RT) ≈ 24% suggest the accurate and precise positioning in the piezoelectric actuator devices. The simultaneously improved d33 and temperature-stable d33* with a high TC are promising results in the lead-free BFBT ceramics.

Self‐Poled Sausage‐Like PVDF Nanowires Produced by Confined Phase Inversion as Novel Piezoelectric Nanogenerators

AbstractPiezoelectric poly(vinylidene fluoride) (PVDF) nanowires are of particular interest for energy harvesting as they are ultra‐sensitive to small vibrations. Here, a new, cost‐effective, and scalable approach to producing PVDF nanowires with strongly enhanced power output is presented. The method combines template‐wetting in cylindrical nano‐confinement with anisotropic solvent‐nonsolvent phase inversion to yield a fully novel nanowire morphology consisting of “sausage‐like” strings of nano‐domains. Dynamic numerical simulations of the phase inversion reveal the formation of these structures to be subject to a very rich and complex phenomenology. The simulated dependence of the feature size on the degree of confinement agrees with the experimentally observed trend. It is unambiguously demonstrated that the sausage‐like nano‐generators upsurge the power density to 280% compared to normal nanowires. Finite element modeling explains how the higher deformability of the sausage‐like nanostructures gives rise to this significant enhancement in piezoelectric performance.

The performance enhancement and temperature dependence of piezoelectric properties for Pb(Mg1/3Nb2/3)O3-0.30PbTiO3 single crystal by alternating current polarization

The comparison and analysis of piezoelectric properties for [001]-oriented PMN-0.30PT by different polarization conditions were investigated. It should be noticed that the average piezoelectric coefficients d33 of PMN-0.30PT crystals were 1860 pC/N by alternating current (AC) polarization and 1380 pC/N by direct current (DC) polarization, which indicates a promotion of 35.3%. The domain patterns in the [001] surface of PMN-0.30PT single crystals under different polarization conditions are obtained by piezo-response force microscopy. The enhancement of piezoelectric performance by AC polarization is attributed to the regular stripe domains with high domain wall density. With the temperature increased to TR-T, both the values of dielectric constant εrT and piezoelectric coefficients d33 under AC polarization condition maintain higher compared to traditional DC poled samples. In addition, both the values of e33 and ε33S under AC polarization retain higher than that of DC polarization, suggesting that the special domain structure with high domain wall density by AC polarization keeps a stable state as the temperature increased to TR-T. When the temperature increased from TR-T to TT-C, the piezoelectric properties of crystals (εrT and d33) under different polarization conditions become the same status, which indicates that the domain structure under the different conditions of polarization may tend to the similar state and the extrinsic contribution from the domain wall motion by AC polarization is disappeared.

Dielectric and piezoelectric properties of porous lead-free 0.5Ba(Ca0.8Zr0.2)O3-0.5(Ba0.7Ca 0.3)TiO3 ceramics

Porous barium calcium zirconate titanate 0.5Ba(Ca0.8Zr0.2)O3-0.5(Ba0.7Ca0.3)TiO3 (BCZT) lead-free ferroelectric ceramics were fabricated via a burnt polymer spheres (BURPS) technique by introducing corn starch as the pore-forming agent. The effect of porosity on the microstructure, dielectric, and piezoelectric properties of the porous materials were investigated. An increase in porosity volume fraction from 10% to 25% resulted in an increase in the hydrostatic charge coefficient (dh), which was 140 to 560% higher than that of the dense BCZT material. An increase in porosity fraction from 10% to 25% also lead to a decrease in relative permittivity that was 16.7% to 60.4% lower than the dense material. These two changes in properties provided a significant enhancement of the hydrostatic figure of merit (dh∙gh) for the porous ceramic; for example the dh∙gh of the 25 vol.% porous BCZT ceramic was 158 times more than the dense ceramic and demonstrates the potential of porous lead-free ferroelectrics for piezoelectric transducer devices. Reasons for the significant enhancement in piezoelectric performance of the porous ceramics are discussed.

Poling direction driven large enhancement in piezoelectric performance

This study proposes enhancement in piezoelectric performance by tuning the poling direction in polycrystalline ceramics. Theoretically, it has been proven that transverse piezoelectric strain coefficient (d31) and d31effε33eff, governing factors for actuation and sensing respectively, get modified by altering poling direction. Finally, different polycrystalline materials have been employed to explore the effect of poling orientation on sensing and actuation capabilities. Optimised orientations were calculated for case of sensing and actuation. Among all materials under study, maximum increment in d31eff and d31effε33eff was observed for 0.3BaTiO3−0.7NaNbO3 (BT-Nb). d31eff and d31effε33eff were as high as −356pm/V and −0.152pm/V respectively for BT-Nb at optimised orientation.

Transformative piezoelectric enhancement of P(VDF-TrFE) synergistically driven by nanoscale dimensional reduction and thermal treatment.

Despite the significant potential of organic piezoelectric materials in the electro-mechanical or mechano-electrical applications that require light and flexible material properties, the intrinsically low piezoelectric performance as compared to traditional inorganic materials has limited their full utilization. In this study, we demonstrate that dimensional reduction of poly(vinylidene fluoride trifluoroethylene) (P(VDF-TrFE)) at the nanoscale by electrospinning, combined with an appropriate thermal treatment, induces a transformative enhancement in piezoelectric performance. Specifically, the piezoelectric coefficient (d33) reached up to -108 pm V-1, approaching that of inorganic counterparts. Electrospun mats composed of thermo-treated 30 nm nanofibers with a thickness of 15 μm produced a consistent peak-to-peak voltage of 38.5 V and a power output of 74.1 μW at a strain of 0.26% while sustaining energy production over 10k repeated actuations. The exceptional piezoelectric performance was realized by the enhancement of piezoelectric dipole alignment and the materialization of flexoelectricity, both from the synergistic effects of dimensional reduction and thermal treatment. Our findings suggest that dimensionally controlled and thermally treated electrospun P(VDF-TrFE) nanofibers provide an opportunity to exploit their flexibility and durability for mechanically challenging applications while matching the piezoelectric performance of brittle, inorganic piezoelectric materials.

Structural and electrical properties of Aurivillius oxide K0.25Na0.25Bi2.5Nb2O9 with potassium and cerium modification

K0.25Na0.25Bi2.5Nb2O9 (KNBN) ceramics with (K,Ce) additives modification were synthesized by using the conventional solid-state reaction method. Phase structure and morphology were characterized by using X-ray diffraction analyses and scanning electron microscopy. Effects of (K,Ce) additives on structural and electrical properties of the KNBN ceramic are investigated. Piezoelectric properties of the KNBN ceramic are improved significantly and the piezoelectric permittivity of the (K,Ce) modified KNBN ceramics shows a temperature-independent characteristics. A maximum of piezoelectric coefficients of 28 pC/N, a high Curie temperature of 593 °C and high resistivity of higher than 108 Ω cm at 500 °C for the KNBN + 1.0 % (K,Ce) ceramic are obtained. The governing mechanism for the enhancement of piezoelectric performance of the KNBN ceramic is discussed.

Lattice Strain Induced Remarkable Enhancement in Piezoelectric Performance of ZnO-Based Flexible Nanogenerators.

In this work, by employing halogen elements (fluorine, chlorine, bromine, and iodine) as dopant we demonstrate a unique strategy to enhance the output performance of ZnO-based flexible piezoelectric nanogenerators. For a halogen-doped ZnO nanowire film, dopants and doping concentration dependent lattice strain along the ZnO c-axis are established and confirmed by the EDS, XRD, and HRTEM analysis. Although lattice strain induced charge separation was theoretically proposed, it has not been experimentally investigated for wurtzite structured ZnO nanomaterials. Tuning the lattice strain from compressive to tensile state along the ZnO c-axis can be achieved by a substitution of halogen dopant from fluorine to other halogen elements due to the ionic size difference between dopants and oxygen. With its focus on a group of nonmetal element induced lattice strain in ZnO-based nanomaterials, this work paves the way for enhancing the performance of wurtzite-type piezoelectric semiconductor nanomaterials via lattice strain strategy which can be employed to construct piezoelectric nanodevices with higher efficiency in a cost-effective manner.