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High-performance potassium-sodium niobate lead-free piezoelectric ceramics based on polymorphic phase boundary and crystallographic texture
摘要： Lead-free piezoelectric ceramics are urgently needed in the field of electromechanical conversion devices due to the restriction on the use of lead-based ceramics. In this study, the polymorphic phase boundary (PPB) were tuned by incorporating different concentration of (Bi0.5K0.5)HfO3 into the matrix (K0.5Na0.5)(Nb0.965Sb0.035)O3-CaZrO3, and the <00l>c crystallographic texture was realized by templated grain growth method. The maximal d33 (~550 pC/N) and kp (~72%) were achieved in the <00l>c textured ceramics with composition around rhombohedral-orthorhombic-tetragonal (R-O-T) phase boundary. It is proposed that the enhanced piezoelectricity should be ascribed to several combined effects, which primarily contain the R-O-T phase boundary facilitating polarization rotation, the crystallographic orientation induced intrinsic piezoelectric anisotropy, electric-field-induced lattice distortion and phase transitions, and NaNbO3 seed-crystal-driven nanodomain structures. This work provides an effective solution to enhance piezoelectric properties by simultaneous tailoring polymorphic phase boundary and using crystallographic texture in potassium-sodium niobate based piezoelectric ceramics. We believe that the simple solution and design principle can also be applied to other piezoelectric ceramic systems, no matter lead-based or lead-free.
关键词： polymorphic phase boundary,piezoelectricity,potassium-sodium niobate,crystallographic texture
更新于2025-11-14 17:28:48
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Origin of giant negative piezoelectricity in a layered van der Waals ferroelectric
摘要： Recent research on piezoelectric materials is predominantly devoted to enhancing the piezoelectric coefficient, but overlooks its sign, largely because almost all of them exhibit positive longitudinal piezoelectricity. The only experimentally known exception is ferroelectric polymer poly(vinylidene fluoride) and its copolymers, which condense via weak van der Waals (vdW) interaction and show negative piezoelectricity. Here we report quantitative determination of giant intrinsic negative longitudinal piezoelectricity and electrostriction in another class of vdW solids—two-dimensional (2D) layered ferroelectric CuInP2S6. With the help of single crystal x-ray crystallography and density-functional theory calculations, we unravel the atomistic origin of negative piezoelectricity in this system, which arises from the large displacive instability of Cu ions coupled with its reduced lattice dimensionality. Furthermore, the sizable piezoelectric response and negligible substrate clamping effect of the 2D vdW piezoelectric materials warrant their great potential in nanoscale, flexible electromechanical devices.
关键词： 2D materials,CuInP2S6,negative piezoelectricity,electrostriction,van der Waals ferroelectric
更新于2025-11-14 17:28:48
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Cellulose/BaTiO3 aerogel paper based flexible piezoelectric nanogenerators and the electric coupling with triboelectricity
摘要： Flexible piezoelectric nanogenerators (PENGs) with high output performance are highly desirable for energy harvesting. Coupling triboelectric nanogenerators (TENGs) with the PENGs is a feasible method to enhance the output performance, while the complicated structure and the requirement of skillful operation limited the development of hybridized nanogenerators. In this work, flexible high-performance PENGs are developed using regenerated cellulose/BaTiO3 (C/BT) aerogel papers based polydimethylsiloxane (PDMS) nanocomposites. Benefiting from the high loading but uniform dispersion of tetragonal BT nanoparticles and the enhanced Young Modulus of the nanocomposites, the PENGs can exhibit a maximum voltage of 15.5 V and a maximum power of 11.8 μW under an external mechanical impact. By introducing a single electrode TENG, an innovative hybridized nanogenerator has been designed and prepared, which combine different mechanical energy harvesting techniques in a single device. Polarized along proper direction of the PENG, the positive coupling effect can efficiently increase the output voltage and power of the hybridized nanogenerator to 48 V and 85 μW, respectively. This research offers new insights into the design and preparation of high output hybridized nanogenerator with simple structure, high flexibility and easy operation.
关键词： Nanocomposites,BaTiO3 nanoparticles,Cellulose,Piezoelectricity,Hybridized nanogenerator,Triboelectricity
更新于2025-09-23 15:23:52
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Inkjet-printed silver as alternative top electrode for lead zirconate titanate thin films
摘要： In the present work, we describe direct patterning of silver top electrodes on polycrystalline Pb(Zr0.53Ti0.47)O3 (PZT) thin films via inkjet printing. The films were first deposited on platinized silicon via chemical solution deposition. Individual nanosilver ink droplets were then printed on the PZT surface to create round top electrodes with tunable diameter from 75 to 93 mm. Printing parameters and strategy were optimized for deposition of homogeneous electrodes. High quality of the printed silver electrodes sintered at 350 °C is confirmed via measurements of the direct piezoelectric response and polarization loops of PZT thin films, whose results are comparable to the ones obtained for sputtered platinum top electrodes, with e31,f = -4.1 C m-2 and Ec ~55 kV cm-1, Pr ~20 mC cm-2.
关键词： Piezoelectricity,Thin films,Silver electrodes,Inkjet printing,Ferroelectrics
更新于2025-09-23 15:23:52
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Integration of organic/inorganic nanostructured materials in a hybrid nanogenerator enables efficacious energy harvesting via mutual performance enhancement
摘要： Recent reports demonstrate that hybrid energy harvesting devices can efficiently convert ubiquitously available but mostly unexploited ambient energies (e.g., mechanical, chemical, thermal, solar) into usable power that can potentially support a new generation of self-powered electronic systems. In this paper, we present a hybrid organic/inorganic nanogenerator on shim substrates, which integrates both piezoelectric and triboelectric components based on inorganic p-n junction ZnO nanostructures and nanostructured organic polytetrafluoroethylene (PTFE) film, respectively. In this design, individual components can be operated independently or concurrently. Moreover, when operated concurrently, component performance is mutually enhanced, enabling more efficient conversion of mechanical energy into electrical energy in a single press-and-release cycle. When triggered with 25 Hz frequency and 1G acceleration of external force, the piezoelectric nanogenerator (PENG) component generates a peak-to-peak output voltage of 34.8V, which is ～3 times higher than its output when it acts alone. Similarly, the triboelectric nanogenerator (TENG) component generates a peak-to-peak output voltage of 356V under the same conditions, which is higher than its initial output of 280V when acting alone. The nanogenerator unit produces an average peak output voltage of 186 V, current density of 10.02 μA/cm2, and average peak power density of 1.864 mW/cm2 when operated in the hybrid configuration. The device can even produce an average peak-to-peak voltage of ~160V from normal hand movement when placed under a wristband fitness tracker, and ~580V from human walking when placed within the walker’s shoe. The device has been demonstrated to charge commercial capacitors up to a few volts within several seconds.
关键词： nanoplates,energy harvesting,hybrid nanogenerators,nanowires,piezoelectricity,triboelectricity
更新于2025-09-23 15:23:52
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Orientation Dependence of Elastic and Piezoelectric Properties in Rhombohedral BiFeO3
摘要： Through a coordinate transformation approach, crystal orientation dependences of elastic and piezoelectric properties at room temperature have been investigated in a three-dimensional space for rhombohedral bismuth ferrite (BiFeO3). Elastic constants (stiffnesses) c11', c12', c13' and piezoelectric constants d15', d31', d33' along arbitrary orientations were obtained based on crystalline asymmetry characteristics of 3m point group BiFeO3. Parameters along specific orientations obtaining the largest values were presented. The max c11' = 213 × 10^9 N/m^2 could be achieved in planes with φ = 0° and 90°. The max c12' = c13' = 132.2 × 10^9 N/m^2 could be achieved along directions at θ = 13° and θ = 77° inside three mirror planes, respectively. The max d15' = 27.6 × 10^{-12} C/N and the max d31' = 12.67 × 10^{-12} C/N could be both obtained along directions at θ = 69° inside mirror planes. The max d33' = 18 × 10^{-12} C/N could be obtained at θ = 0°, along the spontaneous polarization axis. By adopting optimal directions, the elastic and piezoelectric parameters of BiFeO3 could be significantly enhanced which shows applications for the growth of BeFeO3 films with preferred orientations and enhanced properties.
关键词： piezoelectricity,coordinate transformation,orientation dependence,bismuth ferrite,elasticity
更新于2025-09-23 15:22:29
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Enhanced piezoelectric response in nanoclay induced electrospun PVDF nanofibers for energy harvesting
摘要： Templated nanofibers of poly(vinylidene fluoride) have been designed on top of two dimensional nanoclay platelets for energy harvesting application. Dimension of nanofiber has been varied using different nanoclay content prepared through optimized electrospinning. The alteration in structure (electroactive phase) and morphology has been worked out as a function of nanoclay concentration. Nearly 90% piezoelectric active phase has been stabilized in presence of minimum quantity of nanoclay. Hybrid nanofiber is found to be tougher (300%) and stiffer by design, which in turn suitable for device application. Unimorph using hybrid nanofiber exhibits power generation up to 100 ms against less than 50 ms tenure using pristine fiber. Device has been fabricated using various nanofibers and demonstrates very high output voltage (70 V) and power density (68m W.cm-2) from the device made of hybrid nanofiber. Various modes of body movements e.g. bending, twisting, walking, foot and finger tapping can generate considerable power using the hybrid device and are able to transform waste mechanical energy to useful electric power. Underlying mechanism of charge separation in template system has been revealed which explain the high conversion of energy using the hybrid device.
关键词： energy harvesting,piezoelectricity,nanohybrid,device,Electrospinning
更新于2025-09-23 15:22:29
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Piezoelectric and ferroelectric characteristics of P(VDF-TrFE) thin films on Pt and ITO substrates
摘要： Organic P(VDF-TrFE) 70/30 copolymer thin films were fabricated on Pt/Ti/SiO2/Si(1 1 1) and ITO/glass substrates at 140 °C using a spin coater. Both P(VDF-TrFE) thin films exhibited ferroelectric β-phase crystallinity, as confirmed by X-ray diffraction analysis. The polarization–electric hysteresis loops of the P(VDF-TrFE) thin films on the Pt and indium-tin-oxide substrates showed high remnant polarizations of 15.5 and 11.8 μC/cm2, respectively. Atomic force microscopy characterization showed rod-like features of the P(VDF-TrFE) thin films on both substrates, where larger rod diameters were observed on the Pt substrate compared to those fabricated on the ITO substrate. Piezoelectric force microscopy measurements further confirmed the superior piezoelectric and ferroelectric properties of the P(VDF-TrFE) thin films on the Pt substrate compared to those on the ITO substrate, which arose from the increased diameter of the rod-like features.
关键词： Piezoelectricity,Ferroelectricity,P(VDF-TrFE) thin film,ITO substrate,Pt substrate
更新于2025-09-23 15:22:29
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Piezoelectric properties of a near strain-free lead zirconate titanate thin films deposited on a Si substrate
摘要： Chemical solution deposition (CSD)-derived near strain-free lead zirconate titanate (PZT) thin films on a Si substrate were prepared by designing a buffer layer structure. Strain-free PZT thin films with different compositions ranging from Zr/Ti = 50/50 to 58/42 were obtained to demonstrate lattice strain effects on piezoelectric properties. Results show that a near strain-free condition was attained with a SrRuO3 (SRO: 160 nm)/(La0.5,Sr0.5)CoO3 (LSCO: 90 nm)/LaNiO3 (LNO: 120 nm)/stacking structure, even on a Si substrate. The highest effective d33 value of the near strain-free PZT thin film was observed at 53/47 composition, which is the same as bulk materials, although the highest effective d33 value was obtained from 58/42 composition under the compressive lattice strain condition.
关键词： Chemical solution deposition,Piezoelectricity,Thin films,Multilayer structure,Lattice strain,Sol-gel preparation
更新于2025-09-23 15:22:29
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Additional phase transition in a PbZr <sub/>0.87</sub> Ti <sub/>0.13</sub> O <sub/>3</sub> single crystal
摘要： PbZr1-xTixO3 (PZT) ceramics are one of the most known and widely used piezoelectric materials. In order to understand the origin of the high piezoelectricity it is essential to also understand its phase diagram. Many recent papers reported on the modification of PZT phase diagram based on ceramic experimental data. This is due to difficulties to get good quality single crystal samples. We have succeeded in getting a good quality single crystal with x= 0.13. Based on temperature changes of elastic properties we confirmed the existence of additional phase transition appearing in the PbZr0.87Ti0.13O3. The temperature dependence of the elastic properties was investigated by means of piezoelectric measurements and Brillouin light scattering. We discussed the correlation between anomalies of the elastic properties found in these measurements, and suggested that, except for the two well-known phase transitions, these anomalies point to another phase transition below Tc. The structure and symmetry of this crystal have been tested with use of the x-ray diffraction at the room temperature.
关键词： x-ray diffraction,phase transitions,elastic properties,piezoelectricity,PZT single crystals
更新于2025-09-23 15:22:29