The Experts below are selected from a list of 1206 Experts worldwide ranked by ideXlab platform
Qing Wang - One of the best experts on this subject based on the ideXlab platform.
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chirality induced relaxor properties in Ferroelectric Polymers
Nature Materials, 2020Co-Authors: Yang Liu, Aziguli Haibibu, Jerry Bernholc, Bing Zhang, Zhubing Han, Qing WangAbstract:Relaxor Ferroelectrics exhibit outstanding dielectric, electromechanical and electrocaloric properties, and are the materials of choice for acoustic sensors, solid-state coolers, transducers and actuators1-4. Despite more than five decades of intensive study, relaxor Ferroelectrics remain one of the least understood material families in Ferroelectric materials and condensed matter physics5-14. Here, by combining X-ray diffraction, atomic force microscope infrared spectroscopy and first-principles calculations, we reveal that the relaxor behaviour of Ferroelectric Polymers originates from conformational disorder, completely different from classic perovskite relaxors, which are typically characterized by chemical disorder. We show that chain chirality is essential to the formation of the disordered helix conformation arising from local distortions of gauche torsional angles, which consequently give rise to relaxor properties in Polymers. This study not only sheds light on the fundamental mechanisms of relaxor Ferroelectrics, but also offers guidance for the discovery of new Ferroelectric relaxor organic materials for flexible, scalable and biocompatible sensor and energy applications.
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Ferroelectric Polymers exhibiting negative longitudinal piezoelectric coefficient progress and prospects
Advanced Science, 2020Co-Authors: Qing WangAbstract:: Piezoelectric Polymers are well-recognized to hold great promise for a wide range of flexible, wearable, and biocompatible applications. Among the known piezoelectric Polymers, Ferroelectric Polymers represented by poly(vinylidene fluoride) and its copolymer poly(vinylidene fluoride-co-trifluoroethylene) possess the best piezoelectric coefficients. However, the physical origin of negative longitudinal piezoelectric coefficients occurring in the Polymers remains elusive. To address this long-standing challenge, several theoretical models proposed over the past decades, which are controversial in nature, have been revisited and reviewed. It is concluded that negative longitudinal piezoelectric coefficients arise from the negative longitudinal electrostriction in the crystalline domain of the Polymers, independent of amorphous and crystalline-amorphous interfacial regions. The crystalline origin of piezoelectricity offers unprecedented opportunities to improve electromechanical properties of Polymers via structural engineering, i.e., design of morphotropic phase boundaries in Ferroelectric Polymers.
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superior electrostrictive strain achieved under low electric fields in relaxor Ferroelectric Polymers
Journal of Materials Chemistry, 2019Co-Authors: Zhicheng Zhang, Shaobo Tan, Xiao Wang, Qing WangAbstract:Ferroelectric Polymers represented by poly(vinylidene fluoride-trifluoroethylene) show great potential for applications in actuators, sensors and artificial muscles. However, the excellent electrostrictive properties of Ferroelectric Polymers are achieved under high applied electric fields, which not only reduce their lifetime and reliability but also significantly limit their applications in wearable electronics and sensors. Here, we report a new class of relaxor Ferroelectric Polymers, which exhibits outstanding relaxor Ferroelectric behavior including the highest dielectric constant of 75 among the known Polymers, the maximum displacement of 12.3 μC cm−2, and a great dielectric strength of 400 MV m−1. Notably, the record electrostrictive strains in comparison to the state-of-the-art Ferroelectric Polymers have been achieved at both low applied electric fields, e.g. −2.5% at 50 MV m−1 and high electric fields, e.g. −13.4% at 275 MV m−1. The actuation of the relaxor polymer film can be driven even by using a household voltage of 220 V. In addition, the prepared polymer displays the highest elastic energy density and the best electromechanical conversion efficiency when compared to the current Ferroelectric Polymers.
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insights into the morphotropic phase boundary in Ferroelectric Polymers from the molecular perspective
The Journal of Physical Chemistry, 2019Co-Authors: Bing Zhang, Wenhan Xu, Wenchang Lu, Aziguli Haibibu, Jerry Bernholc, Qing WangAbstract:Significantly enhanced electromechanical responses are inherent to piezoelectric materials at the morphotropic phase boundary (MPB). Here we reveal that conformational competition between the trans-planar and 3/1-helical phases of poly(vinylidene fluoride–trifluoroethylene) P(VDF-TrFE) occurs intramolecularly rather than intermolecularly to induce the formation of MPB. We attribute significantly enhanced piezoelectric properties observed near MPB to the polarization rotation between energetically degenerate trans-planar and 3/1-helical phases. Our results offer design principles to search for new MPB Polymers from a molecular perspective.
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Insights into the Morphotropic Phase Boundary in Ferroelectric Polymers from the Molecular Perspective
2019Co-Authors: Yang Liu, Aziguli Haibibu, Jerry Bernholc, Bing Zhang, Zhubing Han, Qing WangAbstract:Significantly enhanced electromechanical responses are inherent to piezoelectric materials at the morphotropic phase boundary (MPB). Here we reveal that conformational competition between the trans-planar and 3/1-helical phases of poly(vinylidene fluoride–trifluoroethylene) P(VDF-TrFE) occurs intramolecularly rather than intermolecularly to induce the formation of MPB. We attribute significantly enhanced piezoelectric properties observed near MPB to the polarization rotation between energetically degenerate trans-planar and 3/1-helical phases. Our results offer design principles to search for new MPB Polymers from a molecular perspective
Q.m. Zhang - One of the best experts on this subject based on the ideXlab platform.
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molecular machine how Ferroelectric Polymers generate giant electroactuation
Electroactive Polymer Actuators and Devices (EAPAD) XX 2018, 2018Co-Authors: Tian Zhang, Qing Xie, Q.m. ZhangAbstract:Electroactive Polymers (EAPs) are novel polymeric materials that generate large displacement or strain under electrical field. EAPs show many attractive features such as high electromechanical response, environmental tolerance, lightweight, flexibility, biocompatibility and long-term durability. In 1998, we reported the discovery of a new class of EAP, e.g., high energy electron irradiated P(VDF-TrFE) (poly(vinylidenefluoride-trifluoroethylene)) based electrostrictive Polymers, showing large electrostrictive strain (-5%) and relaxor Ferroelectric characteristic. Since then, the P(VDF-TrFE) based terPolymers were developed which eliminate the irradiation process. P(VDFTrFE-CFE) terpolymer exhibits very high electromechanical responses (elastic energy density ∼ 1.1 J/cm and electromechanical coupling factor ∼55%). Further, blends approach was studied to increase elastic modulus. Devices based on the high electrostrictive Polymers have also been demonstrated, such as micro pump, braille displays, soft robot, et al. These results suggest that P(VDF-TrFE) based electrostrictive Polymers are promising for many electromechanical device applications.
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Ferroelectric Polymers as multifunctional electroactive materials: recent advances, potential, and challenges
MRS Communications, 2015Co-Authors: Xiaoshi Qian, Shan Wu, Eugene Furman, Q.m. Zhang, Ji SuAbstract:As multifunctional electroactive materials, Ferroelectric Polymers are unique owing to their exceptionally high dielectric strength (>600 MV/m), high flexibility, and easy and low-temperature fabrication into required shapes. Although polyvinylidene difluoride (PVDF)-based Ferroelectric Polymers have been known for several decades, recent findings reveal the potential of this class of electroactive Polymers (EAPs) to achieve giant electroactive responses by tuning the molecular, nano, and meso-structures. This paper presents these advances, including giant electrocaloric effect, giant electroactuation, and large, hysteresis-free polarization response. New developments in materials benefit applications, such as environmentally benign and potentially highly energy-efficient electrical field controlled solid-state refrigeration, artificial muscles, and high-energy and power density electric energy storage devices. The challenges in developing these materials to realize these applications, and strategies to further improve the responses of EAPs will be also discussed.
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novel polymer Ferroelectric behavior via crystal isomorphism and the nanoconfinement effect
Polymer, 2013Co-Authors: Lianyun Yang, Elshad Allahyarov, Xinyu Li, P L Taylor, Q.m. ZhangAbstract:Abstract In contrast to the comprehensive understanding of novel Ferroelectric [i.e., relaxor Ferroelectric (RFE) and antiFerroelectric] behavior in ceramics, RFE and double-hysteresis-loop (DHL) behavior in crystalline Ferroelectric Polymers have only been studied in the past fifteen years. A number of applications such as electrostriction, electric energy storage, and electrocaloric cooling have been realized by utilizing these novel Ferroelectric properties. Nonetheless, fundamental understanding behind these novel Ferroelectric behaviors is still missing for Polymers. In this feature article, we intend to unravel the basic physics via systematic studies of poly(vinylidene fluoride- co -trifluoroethylene) [P(VDF-TrFE)]-based terPolymers, electron-beam (e-beam) irradiated P(VDF-TrFE) coPolymers, and PVDF graft coPolymers. It is found that both the crystal internal structure and the crystal–amorphous interaction are important for achieving the RFE and DHL behaviors. For the crystal internal structure effect, dipole switching with reduced friction and nanodomain formation by pinning the polymer chains are essential, and they can be achieved through crystal repeating-unit isomorphism (i.e., defect modification). Physical pinning [e.g., in P(VDF-TrFE)-based terPolymers] induces a reversible, electric field-induced RFE↔FE phase transition and thus the DHL behavior, whereas chemical pinning [e.g., in e-beam irradiated P(VDF-TrFE)] results in the RFE behavior. Finally, the crystal–amorphous interaction (or the nanoconfinement effect) results in a competition between the polarization and depolarization local fields. When the depolarization field becomes stronger than the polarization field, a DHL behavior is observed. Obviously, the physics for Ferroelectric Polymers is different from that for ceramics/liquid crystals and can be largely attributed to the long-chain nature of semicrystalline Polymers. This understanding will help us to design new Ferroelectric Polymers with improved properties and/or better applications.
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giant electrocaloric effect in Ferroelectric poly vinylidenefluoride trifluoroethylene coPolymers near a first order Ferroelectric transition
Applied Physics Letters, 2012Co-Authors: Xiaoshi Qian, Xiangzhong Chen, Minren Lin, F B Bateman, Q.m. ZhangAbstract:We present directly measured electrocaloric effect (ECE) from the poly(vinylidenefluoride-trifluoroethylene) 65/35 mol. % copolymer. The data reveal a large difference in the ECE between that measured in applying and in removing the electric field. The difference is significantly reduced by modifying the copolymer with 20 Mrad of high energy electron irradiation. Moreover, an isothermal entropy change ΔSint = 160 J kg−1 K−1 and an adiabatic temperature change ΔTint = 35 °C can be induced in the irradiated copolymer. These results demonstrate the promise of achieving a significant ECE in Ferroelectric Polymers near first-order Ferroelectric-paraelectric transition where multiple intermediate phases can exist.
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Electrocaloric effect in Ferroelectric Polymers
Applied Physics A, 2012Co-Authors: Brigita Rožič, Zdravko Kutnjak, Q.m. Zhang, Raša PircAbstract:The electrocaloric effect (ECE) of poly (vinyledene fluoride–trifluoroethylene) (P(VDF–TrFE)) 55/45 mol% coPolymers was directly measured, which confirms the results deduced from Maxwell relation. The adiabatic temperature change Δ T under a given electric field peaks at the Ferroelectric–paraelectric (FE–PE) transition. Away from it, ECE becomes small. Δ T versus applied electric field can be described well by a modified Belov–Goryaga equation. The ECE in Ferroelectric Polymers, especially near FE–PE transition where larger ECE is observed, are analyzed under different boundary conditions employing phenomenological theory and constitutive equations. The secondary pyroelectricity is found to play a significant role which enhances ECE in Ferroelectric Polymers.
Lei Zhu - One of the best experts on this subject based on the ideXlab platform.
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electrostriction enhanced giant piezoelectricity via relaxor like secondary crystals in extended chain Ferroelectric Polymers
Matter, 2021Co-Authors: Zhiwen Zhu, Guanchun Rui, Elshad Allahyarov, Thibaut Soulestin, Fabrice Domingues Dos Santos, Philip L Taylor, Lei ZhuAbstract:Summary Piezoelectricity in Ferroelectric Polymers originates from the electrostrictive effect coupled with a remanent polarization. However, its structural origin remains controversial, and it is not clear how modifying the electrostriction can further improve piezoelectricity for Polymers. Here, we report that electrostriction can be significantly enhanced in poled poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] random coPolymers containing extended-chain primary crystals and relaxor-like secondary crystals in the oriented amorphous fraction (SCOAF). As a result of the high polarizability of dipoles and Ferroelectric nanodomains in the SCOAF, the inverse piezoelectric coefficient d31 reaches as high as 77 ± 5 pm/V for the P(VDF-TrFE) 55/45 copolymer at 55°C. This finding not only extends our understanding of piezoelectricity in Polymers but also provides guidance for further enhancing the piezoelectricity of Ferroelectric Polymers in the future.
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Origins of Electrostriction in Poly(vinylidene fluoride)-Based Ferroelectric Polymers
Macromolecules, 2020Co-Authors: Thumawadee Wongwirat, Zhiwen Zhu, Guanchun Rui, Pitak Laoratanakul, Hathaikarn Manuspiya, Lei ZhuAbstract:Although electrostriction is ubiquitous for dielectric Polymers, giant electrostriction has not been observed until relaxor Ferroelectric (RFE) poly(vinylidene fluoride) (PVDF)-based Polymers are a...
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Exploring strategies for high dielectric constant and low loss polymer dielectrics
Journal of Physical Chemistry Letters, 2014Co-Authors: Lei ZhuAbstract:Polymer dielectrics having high dielectric constant, high temperature capability, and low loss are attractive for a broad range of applications such as film capacitors, gate dielectrics, artificial muscles, and electrocaloric cooling. Unfortunately, it is generally observed that higher polarization or dielectric constant tends to cause significantly enhanced dielectric loss. It is therefore highly desired that the fundamental physics of all types of polarization and loss mechanisms be thoroughly understood for dielectric Polymers. In this Perspective, we intend to explore advantages and disadvantages for different types of polarization. Among a number of approaches, dipolar polarization is promising for high dielectric constant and low loss polymer dielectrics, if the dipolar relaxation peak can be pushed to above the gigahertz range. In particular, dipolar glass, paraelectric, and relaxor Ferroelectric Polymers are discussed for the dipolar polarization approach. [GRAPHICS]
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novel Ferroelectric Polymers for high energy density and low loss dielectrics
Macromolecules, 2012Co-Authors: Lei Zhu, Qing WangAbstract:The state-of-the-art polymer dielectrics have been limited to nonpolar Polymers with relatively low energy density but ultralow dielectric losses for the past decades. With the fast development of power electronics in pulsed power and power conditioning applications, there is a need for next-generation dielectric capacitors in areas of high energy density/low loss and/or high temperature/low loss polymer dielectrics. Given limitations in further enhancing atomic and electronic polarizations for Polymers, this Perspective focuses on a fundamental question: Can orientational polarization in polar Polymers be utilized for high energy density and low loss dielectrics? Existing experimental and theoretical results have suggested the following perspectives. For amorphous polar Polymers, high energy density and low loss can be achieved below their glass transition temperatures. For liquid crystalline side-chain Polymers, dipole mobility is so high that they saturate at relatively low electric fields, and only li...
Jason Claude - One of the best experts on this subject based on the ideXlab platform.
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Electrical energy storage in Ferroelectric polymer nanocomposites containing surface-functionalized BaTiO3 nanoparticles
Chemistry of Materials, 2008Co-Authors: Junjun Li, Jason Claude, Luis Enrique Norena-franco, Sang Il Seok, Qing WangAbstract:Polymer nanocomposites were prepared using surface-functionalized BaTiO3 nanoparticles and Ferroelectric Polymers. The nanocomposites based on the polymer with a higher permittivity exhibit larger electric displacements under the applied fields, thereby leading to higher energy densities. An energy density of 7 J/cm3 has been achieved in a nanocomposite containing 30 vol % BaTiO3 at 150 MV/m, representing an impressive ?120% enhancement in comparison with that in the neat polymer.
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Electrical storage in poly(vinylidene fluoride) based Ferroelectric Polymers: Correlating polymer structure to electrical breakdown strength
Chemistry of Materials, 2008Co-Authors: Jason Claude, Kun Li, Yingying Lu, Qing WangAbstract:The observed positive dependence of breakdown strength of the poly(vinylidene fluoride) based Ferroelectric Polymers on crystallinity and modulus is justified by the electromechanical breakdown mechanism. Also supported by the theoretical calculation, the electromechanical stress has contributions from both the Maxwell and the electrostrictive effects for a Ferroelectric relaxor.
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A modular approach to Ferroelectric Polymers with chemically tunable Curie temperatures and dielectric constants
Journal of the American Chemical Society, 2006Co-Authors: Yingying Lu, Jason Claude, Bret Neese, Q.m. Zhang, Qing WangAbstract:We present a modular approach toward poly(vinylidene fluoride)-based Ferroelectric fluoroPolymers with high dielectric constants. This strategy is based on a two-step reaction, including the copolymerization of vinylidene fluoride and chlorotrifluoroethylene and a subsequent hydrogenation reaction. The chemical structures and compositions of the resulting Polymers can be precisely controlled, leading to tunable Curie temperatures and dielectric constants and a systematical study of structure-property correlations.
Paisan Khanchaitit - One of the best experts on this subject based on the ideXlab platform.
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Ferroelectric polymer networks with high energy density and improved discharged efficiency for dielectric energy storage
Nature Communications, 2013Co-Authors: Matthew R Gadinski, Paisan Khanchaitit, Qi Li, Qing WangAbstract:Ferroelectric Polymers are attractive candidates as dielectric materials for electrical energy storage applications, but suffer from large dielectric loss. Here, the authors report a method for creating Ferroelectric polymer networks with reduced dielectric loss and large charge–discharge efficiencies.
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new route toward high energy density nanocomposites based on chain end functionalized Ferroelectric Polymers
Chemistry of Materials, 2010Co-Authors: Paisan Khanchaitit, Kuo Han, Qing WangAbstract:The synthesis and characterization of novel Ferroelectric polymer based nanocomposites with high energy density is described. The approach includes the preparation of the Ferroelectric Polymers with phosphonic acid end-groups and subsequent utilization of the reactive terminal groups of the polymer for direct coupling with oxide fillers. The prepared nanocomposites have been carefully characterized by solid-state NMR, DMA, DSC, XRD, and TEM. The formation of covalent coupling between the polymer matrix and ZrO2 fillers renders the nanocomposites with great stability and uniform filler dispersion. As a result of the intimating coupling, the interfacial interaction regions between the nanoparticles and the polymer matrix, which is responsible for high polarization under the applied fields, have been clearly observed in the dielectric spectra of the nanocomposites. Excellent breakdown strength and substantial enhancement in the energy density have been demonstrated in the nanocomposites. The improvement in t...
