Piezoelectric transduction technology enables the direct conversion between mechanical and electrical energy,finding extensive applications in sensing,acoustics,imaging,actuation,and energy harvesting[1].Previous stud...Piezoelectric transduction technology enables the direct conversion between mechanical and electrical energy,finding extensive applications in sensing,acoustics,imaging,actuation,and energy harvesting[1].Previous studies on piezoelectric materials have primarily focused on ceramics or single-crystal materials characterized by wide band gaps(E_(g)>2.0 e V[2])and low electrical conductivity.In contrast,narrow-bandgap(E_(g)<0.5 eV[3])semiconductor materials typically exhibit high electrical conductivity,which is unfavorable for the effective accumulation of charges required to establish a stable voltage response.Consequently,experimental investigations into the piezoelectric effect of narrow-bandgap semiconductors are scarce.展开更多
With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human bod...With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human body and high-fidelity collec-tion of biological information remains a significant challenge.Here,a nanoconfinement self-assembly strategy is developed to prepare elastic phenylalanine dipeptide(FF)crystal fibers,in which FF crystals form a unique Mortise-Tenon structure with oriented styrene-block-butadiene-block-styrene molecular beams and thereby obtain elasticity(≈1200%),flexibility(Young’s modulus:0.409±0.031 MPa),piezoelectricity(macroscopic d_(33):10.025±0.33 pC N^(-1)),breathability,and physical stability.Furthermore,elastic FF crystal fibers are used to develop a flexible human physiological movement sensing system by integrating Ga–In alloy coating and wireless electronic transmission components.The system can undergo conformal deformation with human skin and achieve high-fidelity capture of biological information originating from human body motions to prevent diseases(such as Parkinson’s disease).In addition,this system also displays superior sensitivity and accu-racy in detecting subtle pressure changes in vivo during heartbeats,respiration,and diaphragm movement.Therefore,elastic FF crystal fibers hold great potential for developing new flexible electromechanical sensors that are capable of conformal deformation with the human body,enabling precision medical diagnosis and efficient energy harvesting.展开更多
Piezoelectric ceramics provide high strain and large driving forces in actuators.A large electrostrain can be realized by the introduction of point defects such as vacancies,interstitial defects,and substitution defec...Piezoelectric ceramics provide high strain and large driving forces in actuators.A large electrostrain can be realized by the introduction of point defects such as vacancies,interstitial defects,and substitution defects.With Mn doping,a significant increase in the reversible electrostrain from 0.05%to 0.17%could be achieved in potassium niobite lead-free piezoelectric ceramics.The origins of the large electrostrain were analyzed via in situ X-ray diffraction(XRD)under an electric field.The electrostrain and other typical electrical properties of the samples were measured at various temperatures,which enabled the ceramics to perform under a very wide temperature range,such as−80–130℃ for the 0.5 mol%Mn-doped sample with low dielectric loss(≤0.02).More importantly,combined with characterizations of the defect behavior by thermally stimulated depolarization current(TSDC),the failure mechanisms of electrostrain in a hightemperature environment could be revealed,which was associated with synergistic damage to the defects caused by the electric field and high temperature.The results can provide good ideas and a basis for the design of piezoelectric materials with good electrostrain stability over a wide temperature range.展开更多
In the last few years,there has been tremendous effort to develop lead-free ferroelectric ceramics with high piezoelectric properties by various doping and alloying routes.Several material systems have been explored,h...In the last few years,there has been tremendous effort to develop lead-free ferroelectric ceramics with high piezoelectric properties by various doping and alloying routes.Several material systems have been explored,however,no prominent alternative to the versatile lead zirconate titanate(PZT)system has been found yet.Despite the achieved improvement in piezoelectric properties,there are problems in the synthesis,processing and poling of the sintered ceramics.Various processing techniques including microwave,hydrothermal,solgel,Pechini and spark plasma sintering have been used to overcome the drawbacks related to synthesis issues.In this paper,an attempt is made to review recent developments on lead-free piezo materials emphasizing their preparation,structureproperty relations,and consequent physical properties.In this context,both compositional and structural engineering approaches to achieve acceptable piezoelectric properties in lead-free materials are discussed.Piezoelectric properties of the most promising lead-free compositions/families including titanates,alkaline niobates and bismuth perovskites and their solid solutions,along with non-perovskites such as bismuth layer-structured ferroelectrics are reviewed in detail.A brief coverage of the recent developments in the area of piezoelectric energy harvesting is also encompassed.展开更多
Piezoelectric ceramic materials are important components of piezoelectric buzzers,where the parameter of inverse piezoelectric coefficient(d_(33)^(*))plays a decisive role in the performance of the buzzer.Here,we repo...Piezoelectric ceramic materials are important components of piezoelectric buzzers,where the parameter of inverse piezoelectric coefficient(d_(33)^(*))plays a decisive role in the performance of the buzzer.Here,we report the manufacture and performance of a lead-free ceramic-based(0.96(K_(0.5)Na_(0.5))(Nb_(0.96)Sb_(0.04))O_(3)-0.04(Bi_(0.5)Na_(0.5))ZrO_(3)-1 mol%Al_(2)O_(3),abbreviated as KNNS-BNZ-1 mol%Al_(2)O_(3))piezoelectric buzzer and compare it with commercial(PbZr_(0.5)Ti_(0.5)O_(3),abbreviated as PZT)ceramics.Briefly,KNN-based ceramics have a typical perovskite structure and piezoelectric properties of d_(33)=480 pC/N,k_(p)=0.62 and d_(33)^(*)=830 pm/V,compared to d_(33)=500 pC/N,k_(p)=0.6 and d_(33)^(*)=918 pm/V of the commercial PZT-4 ceramics.Our results show that the KNNS-BNZ-1 mol%Al_(2)O_(3)ceramics have a similar sound pressure level performance over the testing frequency range to commercial PZT ceramics(which is even better in the 3-4 kHz range).These findings highlight the great application potential of KNN-based piezoelectric ceramics.展开更多
The research,fabrication and development of piezoelectric nanofibrous materials offer effective solutions to the challenges related to energy consumption and non-renewable resources.However,enhancing their electrical ...The research,fabrication and development of piezoelectric nanofibrous materials offer effective solutions to the challenges related to energy consumption and non-renewable resources.However,enhancing their electrical output still remains a significant challenge.Here,a strategy of inducing constrained phase separation on single nanofibers via shear force was proposed.Employing electrospinning technology,a polyacrylonitrile/polyvinylidene difluoride(PAN/PVDF)nanofibrous membrane was fabricated in one step,which enabled simultaneous piezoelectric and triboelectric conversion within a single-layer membrane.Each nanofiber contained independent components of PAN and PVDF and exhibited a rough surface.The abundant frictional contact points formed between these heterogeneous components contributed to an enhanced endogenous triboelectric output,showcasing an excellent synergistic effect of piezoelectric and triboelectric response in the nanofibrous membrane.Additionally,the component mass ratio influenced the microstructure,piezoelectric conformation and piezoelectric performance of the PAN/PVDF nanofibrous membranes.Through comprehensive performance comparison,the optimal mass ratio of PAN to PVDF was determined to be 9∶1.The piezoelectric devices made of the optimal PAN/PVDF nanofibrous membranes with rough nanofiber surfaces generated an output voltage of 20 V,which was about 1.8 times that of the smooth one at the same component mass ratio.The strategy of constrained phase separation on the surface of individual nanofibers provides a new approach to enhance the output performance of single-layer piezoelectric nanofibrous materials.展开更多
Recycling plastic waste into triboelectric nanogenerators(TENGs)presents a sustainable approach to energy harvesting,self-powered sensing,and environmental remediation.This study investigates the recycling of polyviny...Recycling plastic waste into triboelectric nanogenerators(TENGs)presents a sustainable approach to energy harvesting,self-powered sensing,and environmental remediation.This study investigates the recycling of polyvinyl chloride(PVC)pipe waste polymers into nanofibers(NFs)optimized for TENG applications.We focused on optimizing the morphology of recycled PVC polymer to NFs and enhancing their piezoelectric properties by incorporating ZnO nanoparticles(NPs).The optimized PVC/0.5 wt%ZnO NFs were tested with Nylon-6 NFs,and copper(Cu)electrodes.The Nylon-6 NFs exhibited a power density of 726.3μWcm^(-2)—1.13 times higher than Cu and maintained 90%stability after 172800 cycles,successfully powering various colored LEDs.Additionally,a 3D-designed device was developed to harvest energy from biomechanical movements such as finger tapping,hand tapping,and foot pressing,making it suitable for wearable energy harvesting,automatic switches,and invisible sensors in surveillance systems.This study demonstrates that recycling polymers for TENG devices can effectively address energy,sensor,and environmental challenges.展开更多
The types of dopants lead to distinctive microstructural evolution behavior and physical properties in materials.In this study,the effect of stoichiometric and non-stoichiometric Mn modification,namely Pb(Mn_(1/3) Nb_...The types of dopants lead to distinctive microstructural evolution behavior and physical properties in materials.In this study,the effect of stoichiometric and non-stoichiometric Mn modification,namely Pb(Mn_(1/3) Nb_(2/3))O_(3)(PMnN)and MnO_(2),on the microstructure and properties of Pb(Yb_(1/2) Nb_(1/2))O_(3)-PbZrO_(3)-PbTiO_(3)(PYN-PZT)piezoelectric ceramics are systematically investigated.It was found that stoichiometric PMnN modification inhibits the grain growth while non-stoichiometric MnO2 modification promotes it,and thus the former yields stronger high-power characteristics(higher internal bias field Ei and larger mechanical quality factor Qm)than the latter.Specifically,with an equivalent amount of Mn modifica-tion(2 mol%),PMnN and MnO_(2) modification PYN-PZT ceramics exhibit significantly different values for average grain size(1.21μm vs.14.12μm),Ei(8.5 kV/cm vs.5 kV/cm),and Qm(2376 vs.1134).To further evaluate high-power performance,the vibration velocity v of these two modified PYN-PZT under high driving conditions was measured.Under an AC electric field of 3.5 V/mm,the PYN-PZT+6PMnN ceram-ics exhibit a v of up to 0.95 m s^(−1),larger than both MnO2-doped PYN-PZT(0.72 m s^(−1))and unmodified PYN-PZT ceramics(0.1 m s^(−1)),and far outperformance than both PZT-4 and PZT-8 ceramics.Furthermore,to elucidate the origin of the exceptional high-power performance of PMnN-modified PYN-PZT,we per-formed phase-field simulations revealing a pinning effect of the grain boundary on domain wall motion.Consequently,the small grain size(high grain boundary density)in PMnN-modified PYN-PZT exhibits a strong pinning effect,resulting in a large Qm and outstanding high-power performance.展开更多
BiVO_(4)porous spheres modified by ZnO were designed and synthesized using a facile two-step method.The resulting ZnO/BiVO_(4)composite catalysts have shown remarkable efficiency as piezoelectric catalysts for degradi...BiVO_(4)porous spheres modified by ZnO were designed and synthesized using a facile two-step method.The resulting ZnO/BiVO_(4)composite catalysts have shown remarkable efficiency as piezoelectric catalysts for degrading Rhodamine B(RhB)unde mechanical vibrations,they exhibit superior activity compared to pure ZnO.The 40wt%ZnO/BiVO_(4)heterojunction composite displayed the highest activity,along with good stability and recyclability.The enhanced piezoelectric catalytic activity can be attributed to the form ation of an I-scheme heterojunction structure,which can effectively inhibit the electron-hole recombination.Furthermore,hole(h+)and superoxide radical(·O_(2)^(-))are proved to be the primary active species.Therefore,ZnO/BiVO_(4)stands as an efficient and stable piezoelectric catalyst with broad potential application in the field of environmental water pollution treatment.展开更多
High temperature piezoelectric energy harvester(HTPEH)is an important solution to replace chemical battery to achieve independent power supply of HT wireless sensors.However,simultaneously excellent performances,inclu...High temperature piezoelectric energy harvester(HTPEH)is an important solution to replace chemical battery to achieve independent power supply of HT wireless sensors.However,simultaneously excellent performances,including high figure of merit(FOM),insulation resistivity(ρ)and depolarization temperature(Td)are indispensable but hard to achieve in lead-free piezoceramics,especially operating at 250°C has not been reported before.Herein,well-balanced performances are achieved in BiFeO3–BaTiO3 ceramics via innovative defect engineering with respect to delicate manganese doping.Due to the synergistic effect of enhancing electrostrictive coefficient by polarization configuration optimization,regulating iron ion oxidation state by high valence manganese ion and stabilizing domain orientation by defect dipole,comprehensive excellent electrical performances(Td=340°C,ρ250°C>10^(7)Ωcm and FOM_(250°C)=4905×10^(–15)m^(2)N^(−1))are realized at the solid solubility limit of manganese ions.The HT-PEHs assembled using the rationally designed piezoceramic can allow for fast charging of commercial electrolytic capacitor at 250°C with high energy conversion efficiency(η=11.43%).These characteristics demonstrate that defect engineering tailored BF-BT can satisfy high-end HT-PEHs requirements,paving a new way in developing selfpowered wireless sensors working in HT environments.展开更多
Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor strugg...Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor struggles to satisfy the requirements for directional recognition due to the limited piezoelectric coefficient matrix,and achieving sensitivity for detecting micrometer-scale deformations is also challenging.Herein,we develop a vector sensor composed of lead zirconate titanate-electronic grade glass fiber composite filaments with oriented arrangement,capable of detecting minute anisotropic deformations.The as-prepared vector sensor can identify the deformation directions even when subjected to an unprecedented nominal strain of 0.06%,thereby enabling its utility in accurately discerning the 5μm-height wrinkles in thin films and in monitoring human pulse waves.The ultra-high sensitivity is attributed to the formation of porous ferroelectret and the efficient load transfer efficiency of continuous lead zirconate titanate phase.Additionally,when integrated with machine learning techniques,the sensor’s capability to recognize multi-signals enables it to differentiate between 10 types of fine textures with 100%accuracy.The structural design in piezoelectric devices enables a more comprehensive perception of mechanical stimuli,offering a novel perspective for enhancing recognition accuracy.展开更多
High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limit...High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limits their use,especially in high-temperature environ-ments.A high-temperature resistant flexible piezoelectric film based on graphene oxide(GO)/polyacrylonitrile(PAN)composites was prepared by electrospinning and thermal treat-ment.It was packed into a micro-device,which could work continuously at 500℃.The intro-duction of GO significantly increased the mechanical properties of the PAN nanofibers because the oxygen-containing func-tional groups(electronegative groups)on the surface of the GO initiated a nucleophilic attack on the PAN molecule during heat treatment,enabling the GO to initiate the cyclization of the PAN at lower heat-treatment temperatures.In addition,the abund-ant oxygen-containing functional groups on GO acted as pro-oxidants to hasten the oxidation of PAN during heat treatment.The effects of GO content and heat treatment temperature on the properties of the nanofiber films were investigated.A GO/PAN nanofiber piezoelectric sensor heat-treated at 300℃had a 9.10 V and 2.25μA peak output,which are respectively 101.3%and 78.6%higher than those of the untreated films.Cyclic testing over 5000 cycles at 350℃confirmed the stable out-put performance of the GO/PAN nanofiber piezoelectric sensor.Furthermore,a sensor heat-treated at 400℃had a sensitivity of 1.7 V/N,which is 83.5%higher than that of an untreated one.The results show that the prepared GO/PAN nanofiber piezo-electric sensor combines high temperature resistance,high flexibility,stability and high sensitivity,and may have broad applic-ations in high temperature environments such as the aerospace and petroleum industries.展开更多
Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application o...Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application of PMN-PT in high-power settings is rapidly evolving,material parameters are typically tested under low signal conditions(1 V),and effects of different PT(PbTiO_(3))contents on the performance of PMN-PT single crystals under high-power conditions remain unclear.This study developed a comprehensive high-power testing platform using the constant voltage method to evaluate performance of PMN-PT single crystals with different PT contents under high-power voltage stimulation.Using crystals sized at 10 mm×3 mm×0.5 mm as an example,this research explored changes in material parameters.The results exhibit that while trend of the parameter changes under high-power excitation was consistent across different PT contents,degree of the change varied significantly.For instance,a PMN-PT single crystal with 26%(in mol)PT content exhibited a 25%increase in the piezoelectric coefficient d_(31),a 13%increase in the elastic compliance coefficient s_(11)^(E),a 17%increase in the electromechanical coupling coefficient k_(31),and a 73%decrease in the mechanical quality factor Q_(m) when the power reached 7.90 W.As the PT content increased,the PMN-PT materials became more susceptible to temperature influences,significantly reducing the power tolerance and more readily reaching the depolarization temperatures.This led to loss of piezoelectric performance.Based on these findings,a clearer understanding of impact of PT content on performance of PMN-PT single crystals under high-power applications has been established,providing reliable data to support design of sensors or transducers using PMN-PT as the sensitive element.展开更多
High-temperature piezoelectric vibration sensors are the preferred choice for structural health monitoring in harsh environments such as high temperatures and complex vibrations.Bismuth layer-structured CaBi_(4)Ti_(4)...High-temperature piezoelectric vibration sensors are the preferred choice for structural health monitoring in harsh environments such as high temperatures and complex vibrations.Bismuth layer-structured CaBi_(4)Ti_(4)O_(15)(CBT)high-temperature piezoelectric ceramics,with high Curie temperature(TC),are the key components for piezoelectric vibration sensors operating at temperatures exceeding 500℃.However,their low piezoelectric coefficient(d_(33))greatly limits their high-temperature applications.In this work,a novel Bi^(3+)self-doping strategy was employed to enhance the piezoelectric performance of CBT ceramics.The enhancement is attributed to an increase in the number of grain boundaries,providing more sites for space charge accumulation and promoting formation of space charge polarization.Furthermore,given that space charge polarization predominantly occurs at low frequencies,dielectric temperature spectra at different frequencies were used to elucidate the mechanism by which space charge polarization enhances piezoelectric properties of CBT ceramics.Excellent overall performance was achieved for the CBT-based high-temperature piezoelectric ceramics.Among them,TC reached 778℃,d_(33) increased by more than 30%,reaching 20.1 pC/N,and the electrical resistivity improved by one order of magnitude(reaching 6.33×10^(6)Ω·cm at 500℃).These advancements provide a key functional material with excellent performance for practical applications of piezoelectric vibration sensors at 500℃and above.展开更多
Pb(Zr,Ti)O_(3)-Pb(Zn_(1/3)Nb_(2/3))O_(3) (PZT-PZN) based ceramics, as important piezoelectric materials, have a wide range of applications in fields such as sensors and actuators, thus the optimization of their piezoe...Pb(Zr,Ti)O_(3)-Pb(Zn_(1/3)Nb_(2/3))O_(3) (PZT-PZN) based ceramics, as important piezoelectric materials, have a wide range of applications in fields such as sensors and actuators, thus the optimization of their piezoelectric properties has been a hot research topic. This study investigated the effects of phase boundary engineering and domain engineering on (1-x)[0.8Pb(Zr_(0.5)Ti_(0.5))O_(3)-0.2Pb(Zn_(1/3)Nb_(2/3))O_(3)]-xBi(Zn_(0.5)Ti_(0.5))O_(3) ((1-x)(0.8PZT-0.2PZN)- xBZT) ceramic to obtain excellent piezoelectric properties. The crystal phase structure and microstructure of ceramic samples were characterized. The results showed that all samples had a pure perovskite structure, and the addition of BZT gradually increased the grain size. The addition of BZT caused a phase transition in ceramic samples from the morphotropic phase boundary (MPB) towards the tetragonal phase region, which is crucial for optimizing piezoelectric properties. By adjusting content of BZT and precisely controlling position of the phase boundary, the piezoelectric performance can be optimized. Domain structure is one of the key factors affecting piezoelectric performance. By using domain engineering techniques to optimize grain size and domain size, piezoelectric properties of ceramic samples have been significantly improved. Specifically, excellent piezoelectric properties (piezoelectric constant d_(33)=320 pC/N, electromechanical coupling factor kp=0.44) were obtained simultaneously for x=0.08. Based on experimental results and theoretical analysis, influence mechanisms of phase boundary engineering and domain engineering on piezoelectric properties were explored. The study shows that addition of BZT not only promotes grain growth, but also optimizes the domain structure, enabling the polarization reversal process easier, thereby improving piezoelectric properties. These research results not only provide new ideas for the design of high-performance piezoelectric ceramics, but also lay a theoretical foundation for development of related electronic devices.展开更多
Flexible piezoelectrics realise the conversion between mechanical movements and electrical power by conformally attaching onto curvilinear surfaces,which are promising for energy harvesting of biomedical devices due t...Flexible piezoelectrics realise the conversion between mechanical movements and electrical power by conformally attaching onto curvilinear surfaces,which are promising for energy harvesting of biomedical devices due to their sustainable body movements and/or deformations.Developing secondary functions of flexible piezoelectric energy harvesters is becoming increasingly significant in recent years via aiming at issues that cannot be addressed or mitigated by merely increasing piezoelectric efficiencies.These issues include loose interfacial contact and pucker generation by stretching,power shortage or instability induced by inadequate mechanical energy,and premature function degeneration or failure caused by fatigue fracture after cyclic deformations.Herein,the expedient secondary functions of flexible piezoelectrics to mitigate above issues are reviewed,including stretchability,hybrid energy harvesting,and self-healing.Efforts have been devoted to understanding the state-of-the-art strategies and their mechanisms of achieving secondary functions based on piezoelectric fundamentals.The link between structural characteristic and function performance is unravelled by providing insights into carefully selected progresses.The remaining challenges of developing secondary functions are proposed in the end with corresponding outlooks.The current work hopes to help and inspire future research in this promising field focusing on developing the secondary functions of flexible piezoelectric energy harvesters.展开更多
Piezoelectric nanogenerators(PENGs) are evolving as next-generation energy harvesters due to their self-powered sensing,multi-stimuli-responsiveness,and wearable electronics.Here,we present a flexible PENG utilizing e...Piezoelectric nanogenerators(PENGs) are evolving as next-generation energy harvesters due to their self-powered sensing,multi-stimuli-responsiveness,and wearable electronics.Here,we present a flexible PENG utilizing electro spun poly(vinylidene fluoride trifluoroethylene)(P(VDF-TrFE)) nanofibers.By optimizing the rotational speeds during the electrospinning process,we have achieved nanofibers with a highly aligned structure and uniform polarβ-phase,an enhancement of piezoelectric response,particularly in terms of sensitivity and power generation.The longitudinal piezoelectric coefficient(d_(33)) reaches-21.6 pC·N^(-1).The transverse piezoelectric measurement yields an output of 26 V and 38.6 nA.The device exhibits an ultra-high sensitivity of 5.76 V·kPa^(-1),surpassing previously reported values by orders of magnitude.The PENG is successfully employed for Braille recognition and the precise manipulation of a robotic hand,indicating its efficacy for tactile interaction systems.This study presents a novel approach to facilitating intelligent human-machine interaction by exploiting the unique properties of organic piezoelectric materials.展开更多
Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoelectrics are considered for potential replacement of the lead-based commercial piezoceramics in high-power transducer applications.We have examined the role of grain size ...Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoelectrics are considered for potential replacement of the lead-based commercial piezoceramics in high-power transducer applications.We have examined the role of grain size in influencing the structural-polar inhomogeneity of stoichiometric and off-stoichiometric Na_(0.5)Bi_(0.5)TiO_(3)(NBT),and its morphotropic-phase-boundary(MPB)derivative 0.94Na_(0.5)Bi_(0.5)TiO_(3)-0.06BaTiO_(3)(NBT-6BT).Our study reveals that size effect comes into play in these systems on a very large length scale(on the scale of microns)considerably affecting its global structure and properties.展开更多
The new component of melilite type crystal CaNdAl_(3)O_(7)(CNA)was grown by the Czochralski pulling method.Single crystal structure analysis was conducted.It is found that the CNA crystal belongs to the tetragonal sys...The new component of melilite type crystal CaNdAl_(3)O_(7)(CNA)was grown by the Czochralski pulling method.Single crystal structure analysis was conducted.It is found that the CNA crystal belongs to the tetragonal system with P-421m space group.The cell parameters a=b=0.77461 nm and c=0.51089 nm.The density and Mohs hardness of CNA crystal are 4.08 g/cm^(3) and 5.45,respectively.The specific heat of the crystal is 0.57-0.77 J/(g·K)in the temperature range of 30-300℃.X-ray photoelectron spectro scopy(XPS)shows that the crystal has stable atomic valence states and chemical environment.The vibration state of polyhedra groups in the crystal was measured by Raman spectra,and the piezoelectric response was analyzed based on the calculated results for the polyhedra polarization dipole moments.The relative dielectric permittivity of the CNA crystal at room temperature was determined to be 11.80 and the electrical resistivity was measured to be on the order of 5×10^(6)Ω·cm at 800℃.展开更多
The mass discarding face masks has caused severe environmental problems during and after the COVID-19 pandemic.To reduce waste and minimize environmental impact,we present a new face mask featuring selfcharging extend...The mass discarding face masks has caused severe environmental problems during and after the COVID-19 pandemic.To reduce waste and minimize environmental impact,we present a new face mask featuring selfcharging extended service time and fully biodegradable materials.To extend the effective service time,we need to supplement the lost electric charge of the electret layer of face masks,for which task we propose to use the piezoelectric effect and generate electricity from breathing motions.However,existing piezoelectric materials are either toxic,impermeable,rigid,costly,or non-degradable.We synthesize a fully biodegradable piezoelectric membrane composed of polyvinyl alcohol(PVA)and glycine(GLY)via the electrospinning process.Parameters are accurately controlled to ensure that glycine crystallizes into a highly piezoelectricβphase during electrospinning and enables piezoelectric responses of the filter membrane.Tested with the standard 0.3μm particles,face masks made of the PVA-GLY membrane show an outstanding filtration efficiency of 97%,which remains stable over at least 10 h of high-concentration continuous filtration.Furthermore,we demonstrated the biodegradability of PVA-GLY masks,which can degrade completely within a few weeks,compared to commonly used surgical masks requiring over thirty years to be decomposed.展开更多
文摘Piezoelectric transduction technology enables the direct conversion between mechanical and electrical energy,finding extensive applications in sensing,acoustics,imaging,actuation,and energy harvesting[1].Previous studies on piezoelectric materials have primarily focused on ceramics or single-crystal materials characterized by wide band gaps(E_(g)>2.0 e V[2])and low electrical conductivity.In contrast,narrow-bandgap(E_(g)<0.5 eV[3])semiconductor materials typically exhibit high electrical conductivity,which is unfavorable for the effective accumulation of charges required to establish a stable voltage response.Consequently,experimental investigations into the piezoelectric effect of narrow-bandgap semiconductors are scarce.
基金support from the National Natural Science Foundation of China(82472159,82302406,52303186)China Postdoctoral Science Foundation(2024T171167,2023M731696,2022TQ0158,2022M721616)+1 种基金Jiangsu Funding Program for Excellent Postdoctoral Talent(2023ZB539,2022ZB250)the Fundamental Research Funds for the Central Universities(30923010307,30920041105).
文摘With the advancement of flexible bioelectronics,developing highly elastic and breathable piezoelectric materials and devices that achieve conformal deformation,synchronous electromechanical coupling with the human body and high-fidelity collec-tion of biological information remains a significant challenge.Here,a nanoconfinement self-assembly strategy is developed to prepare elastic phenylalanine dipeptide(FF)crystal fibers,in which FF crystals form a unique Mortise-Tenon structure with oriented styrene-block-butadiene-block-styrene molecular beams and thereby obtain elasticity(≈1200%),flexibility(Young’s modulus:0.409±0.031 MPa),piezoelectricity(macroscopic d_(33):10.025±0.33 pC N^(-1)),breathability,and physical stability.Furthermore,elastic FF crystal fibers are used to develop a flexible human physiological movement sensing system by integrating Ga–In alloy coating and wireless electronic transmission components.The system can undergo conformal deformation with human skin and achieve high-fidelity capture of biological information originating from human body motions to prevent diseases(such as Parkinson’s disease).In addition,this system also displays superior sensitivity and accu-racy in detecting subtle pressure changes in vivo during heartbeats,respiration,and diaphragm movement.Therefore,elastic FF crystal fibers hold great potential for developing new flexible electromechanical sensors that are capable of conformal deformation with the human body,enabling precision medical diagnosis and efficient energy harvesting.
基金supported by the National Natural Science Foundation of China(Grant Nos.12135019 and 52202154)the 2115 Talent Development Program of China Agricultural University,the Scientific Research Start-up Fund for Outstanding Talent of China Agricultural University,Chinese Universities Scientific Fund,and High-performance Computing Platform of China Agricultural University。
文摘Piezoelectric ceramics provide high strain and large driving forces in actuators.A large electrostrain can be realized by the introduction of point defects such as vacancies,interstitial defects,and substitution defects.With Mn doping,a significant increase in the reversible electrostrain from 0.05%to 0.17%could be achieved in potassium niobite lead-free piezoelectric ceramics.The origins of the large electrostrain were analyzed via in situ X-ray diffraction(XRD)under an electric field.The electrostrain and other typical electrical properties of the samples were measured at various temperatures,which enabled the ceramics to perform under a very wide temperature range,such as−80–130℃ for the 0.5 mol%Mn-doped sample with low dielectric loss(≤0.02).More importantly,combined with characterizations of the defect behavior by thermally stimulated depolarization current(TSDC),the failure mechanisms of electrostrain in a hightemperature environment could be revealed,which was associated with synergistic damage to the defects caused by the electric field and high temperature.The results can provide good ideas and a basis for the design of piezoelectric materials with good electrostrain stability over a wide temperature range.
基金The authors I.C.and N.P.would like to thank the Portuguese foundation FCT through their grants SFRH/BPD/81032/2011 and SFRH/BPD/71289/2010,respectivelyFinancial support from FCT through the projects PTDC/FIS/108025/2008 and PTDC/CTM-CER/115085/2009 is also acknowledged.
文摘In the last few years,there has been tremendous effort to develop lead-free ferroelectric ceramics with high piezoelectric properties by various doping and alloying routes.Several material systems have been explored,however,no prominent alternative to the versatile lead zirconate titanate(PZT)system has been found yet.Despite the achieved improvement in piezoelectric properties,there are problems in the synthesis,processing and poling of the sintered ceramics.Various processing techniques including microwave,hydrothermal,solgel,Pechini and spark plasma sintering have been used to overcome the drawbacks related to synthesis issues.In this paper,an attempt is made to review recent developments on lead-free piezo materials emphasizing their preparation,structureproperty relations,and consequent physical properties.In this context,both compositional and structural engineering approaches to achieve acceptable piezoelectric properties in lead-free materials are discussed.Piezoelectric properties of the most promising lead-free compositions/families including titanates,alkaline niobates and bismuth perovskites and their solid solutions,along with non-perovskites such as bismuth layer-structured ferroelectrics are reviewed in detail.A brief coverage of the recent developments in the area of piezoelectric energy harvesting is also encompassed.
基金Project supported by the Key Research and Develop Projects in Gansu Province(Grant No.23YFGA0002)the project funding of Audiowell Electronics(Guangdong)Co.,Ltd.
文摘Piezoelectric ceramic materials are important components of piezoelectric buzzers,where the parameter of inverse piezoelectric coefficient(d_(33)^(*))plays a decisive role in the performance of the buzzer.Here,we report the manufacture and performance of a lead-free ceramic-based(0.96(K_(0.5)Na_(0.5))(Nb_(0.96)Sb_(0.04))O_(3)-0.04(Bi_(0.5)Na_(0.5))ZrO_(3)-1 mol%Al_(2)O_(3),abbreviated as KNNS-BNZ-1 mol%Al_(2)O_(3))piezoelectric buzzer and compare it with commercial(PbZr_(0.5)Ti_(0.5)O_(3),abbreviated as PZT)ceramics.Briefly,KNN-based ceramics have a typical perovskite structure and piezoelectric properties of d_(33)=480 pC/N,k_(p)=0.62 and d_(33)^(*)=830 pm/V,compared to d_(33)=500 pC/N,k_(p)=0.6 and d_(33)^(*)=918 pm/V of the commercial PZT-4 ceramics.Our results show that the KNNS-BNZ-1 mol%Al_(2)O_(3)ceramics have a similar sound pressure level performance over the testing frequency range to commercial PZT ceramics(which is even better in the 3-4 kHz range).These findings highlight the great application potential of KNN-based piezoelectric ceramics.
基金National Natural Science Foundation of China(No.52373281)National Energy-Saving and Low-Carbon Materials Production and Application Demonstration Platform Program,China(No.TC220H06N)。
文摘The research,fabrication and development of piezoelectric nanofibrous materials offer effective solutions to the challenges related to energy consumption and non-renewable resources.However,enhancing their electrical output still remains a significant challenge.Here,a strategy of inducing constrained phase separation on single nanofibers via shear force was proposed.Employing electrospinning technology,a polyacrylonitrile/polyvinylidene difluoride(PAN/PVDF)nanofibrous membrane was fabricated in one step,which enabled simultaneous piezoelectric and triboelectric conversion within a single-layer membrane.Each nanofiber contained independent components of PAN and PVDF and exhibited a rough surface.The abundant frictional contact points formed between these heterogeneous components contributed to an enhanced endogenous triboelectric output,showcasing an excellent synergistic effect of piezoelectric and triboelectric response in the nanofibrous membrane.Additionally,the component mass ratio influenced the microstructure,piezoelectric conformation and piezoelectric performance of the PAN/PVDF nanofibrous membranes.Through comprehensive performance comparison,the optimal mass ratio of PAN to PVDF was determined to be 9∶1.The piezoelectric devices made of the optimal PAN/PVDF nanofibrous membranes with rough nanofiber surfaces generated an output voltage of 20 V,which was about 1.8 times that of the smooth one at the same component mass ratio.The strategy of constrained phase separation on the surface of individual nanofibers provides a new approach to enhance the output performance of single-layer piezoelectric nanofibrous materials.
基金supported by the research projects AP23486880 from the Ministry of Higher EducationScience of the Republic of Kazakhstan and 111024CRP2010,20122022FD4135 from Nazarbayev University.
文摘Recycling plastic waste into triboelectric nanogenerators(TENGs)presents a sustainable approach to energy harvesting,self-powered sensing,and environmental remediation.This study investigates the recycling of polyvinyl chloride(PVC)pipe waste polymers into nanofibers(NFs)optimized for TENG applications.We focused on optimizing the morphology of recycled PVC polymer to NFs and enhancing their piezoelectric properties by incorporating ZnO nanoparticles(NPs).The optimized PVC/0.5 wt%ZnO NFs were tested with Nylon-6 NFs,and copper(Cu)electrodes.The Nylon-6 NFs exhibited a power density of 726.3μWcm^(-2)—1.13 times higher than Cu and maintained 90%stability after 172800 cycles,successfully powering various colored LEDs.Additionally,a 3D-designed device was developed to harvest energy from biomechanical movements such as finger tapping,hand tapping,and foot pressing,making it suitable for wearable energy harvesting,automatic switches,and invisible sensors in surveillance systems.This study demonstrates that recycling polymers for TENG devices can effectively address energy,sensor,and environmental challenges.
基金supported by the National Key Research and Development Program of China(No.2023YFF0720700)the National Natural Science Foundation of China(Nos.52032010 and 52272120)the Central Government Funds of Guiding Local Scientific and Technological Development for Sichuan Province(No.2022ZYD0018).
文摘The types of dopants lead to distinctive microstructural evolution behavior and physical properties in materials.In this study,the effect of stoichiometric and non-stoichiometric Mn modification,namely Pb(Mn_(1/3) Nb_(2/3))O_(3)(PMnN)and MnO_(2),on the microstructure and properties of Pb(Yb_(1/2) Nb_(1/2))O_(3)-PbZrO_(3)-PbTiO_(3)(PYN-PZT)piezoelectric ceramics are systematically investigated.It was found that stoichiometric PMnN modification inhibits the grain growth while non-stoichiometric MnO2 modification promotes it,and thus the former yields stronger high-power characteristics(higher internal bias field Ei and larger mechanical quality factor Qm)than the latter.Specifically,with an equivalent amount of Mn modifica-tion(2 mol%),PMnN and MnO_(2) modification PYN-PZT ceramics exhibit significantly different values for average grain size(1.21μm vs.14.12μm),Ei(8.5 kV/cm vs.5 kV/cm),and Qm(2376 vs.1134).To further evaluate high-power performance,the vibration velocity v of these two modified PYN-PZT under high driving conditions was measured.Under an AC electric field of 3.5 V/mm,the PYN-PZT+6PMnN ceram-ics exhibit a v of up to 0.95 m s^(−1),larger than both MnO2-doped PYN-PZT(0.72 m s^(−1))and unmodified PYN-PZT ceramics(0.1 m s^(−1)),and far outperformance than both PZT-4 and PZT-8 ceramics.Furthermore,to elucidate the origin of the exceptional high-power performance of PMnN-modified PYN-PZT,we per-formed phase-field simulations revealing a pinning effect of the grain boundary on domain wall motion.Consequently,the small grain size(high grain boundary density)in PMnN-modified PYN-PZT exhibits a strong pinning effect,resulting in a large Qm and outstanding high-power performance.
基金financially supported by the National Natural Science Foundation of China(No.22272151)Public Welfare Technology Application Research Project of Jinhua City,China(No.2023-4-022)。
文摘BiVO_(4)porous spheres modified by ZnO were designed and synthesized using a facile two-step method.The resulting ZnO/BiVO_(4)composite catalysts have shown remarkable efficiency as piezoelectric catalysts for degrading Rhodamine B(RhB)unde mechanical vibrations,they exhibit superior activity compared to pure ZnO.The 40wt%ZnO/BiVO_(4)heterojunction composite displayed the highest activity,along with good stability and recyclability.The enhanced piezoelectric catalytic activity can be attributed to the form ation of an I-scheme heterojunction structure,which can effectively inhibit the electron-hole recombination.Furthermore,hole(h+)and superoxide radical(·O_(2)^(-))are proved to be the primary active species.Therefore,ZnO/BiVO_(4)stands as an efficient and stable piezoelectric catalyst with broad potential application in the field of environmental water pollution treatment.
基金supported by the National Natural Science Foundation of China(Grant Nos.52272103 and 52072010)Beijing Natural Science Foundation(Grant Nos.2242029 and JL23004).
文摘High temperature piezoelectric energy harvester(HTPEH)is an important solution to replace chemical battery to achieve independent power supply of HT wireless sensors.However,simultaneously excellent performances,including high figure of merit(FOM),insulation resistivity(ρ)and depolarization temperature(Td)are indispensable but hard to achieve in lead-free piezoceramics,especially operating at 250°C has not been reported before.Herein,well-balanced performances are achieved in BiFeO3–BaTiO3 ceramics via innovative defect engineering with respect to delicate manganese doping.Due to the synergistic effect of enhancing electrostrictive coefficient by polarization configuration optimization,regulating iron ion oxidation state by high valence manganese ion and stabilizing domain orientation by defect dipole,comprehensive excellent electrical performances(Td=340°C,ρ250°C>10^(7)Ωcm and FOM_(250°C)=4905×10^(–15)m^(2)N^(−1))are realized at the solid solubility limit of manganese ions.The HT-PEHs assembled using the rationally designed piezoceramic can allow for fast charging of commercial electrolytic capacitor at 250°C with high energy conversion efficiency(η=11.43%).These characteristics demonstrate that defect engineering tailored BF-BT can satisfy high-end HT-PEHs requirements,paving a new way in developing selfpowered wireless sensors working in HT environments.
基金financially supported by the National Key Research and Development Program of China(No.2022YFA1205300 and No.2022YFA1205304)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(SL2022ZD103).
文摘Monitoring minuscule mechanical signals,both in magnitude and direction,is imperative in many application scenarios,e.g.,structural health monitoring and robotic sensing systems.However,the piezoelectric sensor struggles to satisfy the requirements for directional recognition due to the limited piezoelectric coefficient matrix,and achieving sensitivity for detecting micrometer-scale deformations is also challenging.Herein,we develop a vector sensor composed of lead zirconate titanate-electronic grade glass fiber composite filaments with oriented arrangement,capable of detecting minute anisotropic deformations.The as-prepared vector sensor can identify the deformation directions even when subjected to an unprecedented nominal strain of 0.06%,thereby enabling its utility in accurately discerning the 5μm-height wrinkles in thin films and in monitoring human pulse waves.The ultra-high sensitivity is attributed to the formation of porous ferroelectret and the efficient load transfer efficiency of continuous lead zirconate titanate phase.Additionally,when integrated with machine learning techniques,the sensor’s capability to recognize multi-signals enables it to differentiate between 10 types of fine textures with 100%accuracy.The structural design in piezoelectric devices enables a more comprehensive perception of mechanical stimuli,offering a novel perspective for enhancing recognition accuracy.
文摘High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limits their use,especially in high-temperature environ-ments.A high-temperature resistant flexible piezoelectric film based on graphene oxide(GO)/polyacrylonitrile(PAN)composites was prepared by electrospinning and thermal treat-ment.It was packed into a micro-device,which could work continuously at 500℃.The intro-duction of GO significantly increased the mechanical properties of the PAN nanofibers because the oxygen-containing func-tional groups(electronegative groups)on the surface of the GO initiated a nucleophilic attack on the PAN molecule during heat treatment,enabling the GO to initiate the cyclization of the PAN at lower heat-treatment temperatures.In addition,the abund-ant oxygen-containing functional groups on GO acted as pro-oxidants to hasten the oxidation of PAN during heat treatment.The effects of GO content and heat treatment temperature on the properties of the nanofiber films were investigated.A GO/PAN nanofiber piezoelectric sensor heat-treated at 300℃had a 9.10 V and 2.25μA peak output,which are respectively 101.3%and 78.6%higher than those of the untreated films.Cyclic testing over 5000 cycles at 350℃confirmed the stable out-put performance of the GO/PAN nanofiber piezoelectric sensor.Furthermore,a sensor heat-treated at 400℃had a sensitivity of 1.7 V/N,which is 83.5%higher than that of an untreated one.The results show that the prepared GO/PAN nanofiber piezo-electric sensor combines high temperature resistance,high flexibility,stability and high sensitivity,and may have broad applic-ations in high temperature environments such as the aerospace and petroleum industries.
基金Research and Development Project on Voltage Sensors by China Southern Power Grid Digital Research Institute(210000KK52220017)。
文摘Lead magnesium niobate-lead titanate(PMN-PT)piezoelectric single crystals are widely utilized due to their outstanding performance,with varying compositions significantly impacting their properties.While application of PMN-PT in high-power settings is rapidly evolving,material parameters are typically tested under low signal conditions(1 V),and effects of different PT(PbTiO_(3))contents on the performance of PMN-PT single crystals under high-power conditions remain unclear.This study developed a comprehensive high-power testing platform using the constant voltage method to evaluate performance of PMN-PT single crystals with different PT contents under high-power voltage stimulation.Using crystals sized at 10 mm×3 mm×0.5 mm as an example,this research explored changes in material parameters.The results exhibit that while trend of the parameter changes under high-power excitation was consistent across different PT contents,degree of the change varied significantly.For instance,a PMN-PT single crystal with 26%(in mol)PT content exhibited a 25%increase in the piezoelectric coefficient d_(31),a 13%increase in the elastic compliance coefficient s_(11)^(E),a 17%increase in the electromechanical coupling coefficient k_(31),and a 73%decrease in the mechanical quality factor Q_(m) when the power reached 7.90 W.As the PT content increased,the PMN-PT materials became more susceptible to temperature influences,significantly reducing the power tolerance and more readily reaching the depolarization temperatures.This led to loss of piezoelectric performance.Based on these findings,a clearer understanding of impact of PT content on performance of PMN-PT single crystals under high-power applications has been established,providing reliable data to support design of sensors or transducers using PMN-PT as the sensitive element.
基金National Natural Science Foundation of China (51932010)。
文摘High-temperature piezoelectric vibration sensors are the preferred choice for structural health monitoring in harsh environments such as high temperatures and complex vibrations.Bismuth layer-structured CaBi_(4)Ti_(4)O_(15)(CBT)high-temperature piezoelectric ceramics,with high Curie temperature(TC),are the key components for piezoelectric vibration sensors operating at temperatures exceeding 500℃.However,their low piezoelectric coefficient(d_(33))greatly limits their high-temperature applications.In this work,a novel Bi^(3+)self-doping strategy was employed to enhance the piezoelectric performance of CBT ceramics.The enhancement is attributed to an increase in the number of grain boundaries,providing more sites for space charge accumulation and promoting formation of space charge polarization.Furthermore,given that space charge polarization predominantly occurs at low frequencies,dielectric temperature spectra at different frequencies were used to elucidate the mechanism by which space charge polarization enhances piezoelectric properties of CBT ceramics.Excellent overall performance was achieved for the CBT-based high-temperature piezoelectric ceramics.Among them,TC reached 778℃,d_(33) increased by more than 30%,reaching 20.1 pC/N,and the electrical resistivity improved by one order of magnitude(reaching 6.33×10^(6)Ω·cm at 500℃).These advancements provide a key functional material with excellent performance for practical applications of piezoelectric vibration sensors at 500℃and above.
基金National Natural Science Foundation of China (52202139, 52072178)。
文摘Pb(Zr,Ti)O_(3)-Pb(Zn_(1/3)Nb_(2/3))O_(3) (PZT-PZN) based ceramics, as important piezoelectric materials, have a wide range of applications in fields such as sensors and actuators, thus the optimization of their piezoelectric properties has been a hot research topic. This study investigated the effects of phase boundary engineering and domain engineering on (1-x)[0.8Pb(Zr_(0.5)Ti_(0.5))O_(3)-0.2Pb(Zn_(1/3)Nb_(2/3))O_(3)]-xBi(Zn_(0.5)Ti_(0.5))O_(3) ((1-x)(0.8PZT-0.2PZN)- xBZT) ceramic to obtain excellent piezoelectric properties. The crystal phase structure and microstructure of ceramic samples were characterized. The results showed that all samples had a pure perovskite structure, and the addition of BZT gradually increased the grain size. The addition of BZT caused a phase transition in ceramic samples from the morphotropic phase boundary (MPB) towards the tetragonal phase region, which is crucial for optimizing piezoelectric properties. By adjusting content of BZT and precisely controlling position of the phase boundary, the piezoelectric performance can be optimized. Domain structure is one of the key factors affecting piezoelectric performance. By using domain engineering techniques to optimize grain size and domain size, piezoelectric properties of ceramic samples have been significantly improved. Specifically, excellent piezoelectric properties (piezoelectric constant d_(33)=320 pC/N, electromechanical coupling factor kp=0.44) were obtained simultaneously for x=0.08. Based on experimental results and theoretical analysis, influence mechanisms of phase boundary engineering and domain engineering on piezoelectric properties were explored. The study shows that addition of BZT not only promotes grain growth, but also optimizes the domain structure, enabling the polarization reversal process easier, thereby improving piezoelectric properties. These research results not only provide new ideas for the design of high-performance piezoelectric ceramics, but also lay a theoretical foundation for development of related electronic devices.
基金The authors acknowledge the support of the Australian Research Council through the ARC Research Hub for Advanced Manufacturing of Medical Devices(IH150100024).
文摘Flexible piezoelectrics realise the conversion between mechanical movements and electrical power by conformally attaching onto curvilinear surfaces,which are promising for energy harvesting of biomedical devices due to their sustainable body movements and/or deformations.Developing secondary functions of flexible piezoelectric energy harvesters is becoming increasingly significant in recent years via aiming at issues that cannot be addressed or mitigated by merely increasing piezoelectric efficiencies.These issues include loose interfacial contact and pucker generation by stretching,power shortage or instability induced by inadequate mechanical energy,and premature function degeneration or failure caused by fatigue fracture after cyclic deformations.Herein,the expedient secondary functions of flexible piezoelectrics to mitigate above issues are reviewed,including stretchability,hybrid energy harvesting,and self-healing.Efforts have been devoted to understanding the state-of-the-art strategies and their mechanisms of achieving secondary functions based on piezoelectric fundamentals.The link between structural characteristic and function performance is unravelled by providing insights into carefully selected progresses.The remaining challenges of developing secondary functions are proposed in the end with corresponding outlooks.The current work hopes to help and inspire future research in this promising field focusing on developing the secondary functions of flexible piezoelectric energy harvesters.
基金fundings of National Key Research and Development program of China (No. 2021YFA1200700)National Natural Science Foundation of China (Nos. T2222025 and 62174053)+3 种基金Natural Science Foundation of Chongqing (CSTB2024NSCQ-JQX0005)Shanghai Science and Technology Innovation Action Plan (21JC1402000 and 21520714100)the Fundamental Research Funds for the Central Universitiesthe Class Ⅲ Peak Discipline of Shanghai—Materials Science and Engineering (High-Energy Beam Intelligent Processing and Green Manufacturing)。
文摘Piezoelectric nanogenerators(PENGs) are evolving as next-generation energy harvesters due to their self-powered sensing,multi-stimuli-responsiveness,and wearable electronics.Here,we present a flexible PENG utilizing electro spun poly(vinylidene fluoride trifluoroethylene)(P(VDF-TrFE)) nanofibers.By optimizing the rotational speeds during the electrospinning process,we have achieved nanofibers with a highly aligned structure and uniform polarβ-phase,an enhancement of piezoelectric response,particularly in terms of sensitivity and power generation.The longitudinal piezoelectric coefficient(d_(33)) reaches-21.6 pC·N^(-1).The transverse piezoelectric measurement yields an output of 26 V and 38.6 nA.The device exhibits an ultra-high sensitivity of 5.76 V·kPa^(-1),surpassing previously reported values by orders of magnitude.The PENG is successfully employed for Braille recognition and the precise manipulation of a robotic hand,indicating its efficacy for tactile interaction systems.This study presents a novel approach to facilitating intelligent human-machine interaction by exploiting the unique properties of organic piezoelectric materials.
文摘Na_(0.5)Bi_(0.5)TiO_(3)-based lead-free piezoelectrics are considered for potential replacement of the lead-based commercial piezoceramics in high-power transducer applications.We have examined the role of grain size in influencing the structural-polar inhomogeneity of stoichiometric and off-stoichiometric Na_(0.5)Bi_(0.5)TiO_(3)(NBT),and its morphotropic-phase-boundary(MPB)derivative 0.94Na_(0.5)Bi_(0.5)TiO_(3)-0.06BaTiO_(3)(NBT-6BT).Our study reveals that size effect comes into play in these systems on a very large length scale(on the scale of microns)considerably affecting its global structure and properties.
基金Project supported by the National Natural Science Foundation of China(52372008)Shandong Provincial Natural Science Foundation(ZR2020KA003,ZR2023QE165)。
文摘The new component of melilite type crystal CaNdAl_(3)O_(7)(CNA)was grown by the Czochralski pulling method.Single crystal structure analysis was conducted.It is found that the CNA crystal belongs to the tetragonal system with P-421m space group.The cell parameters a=b=0.77461 nm and c=0.51089 nm.The density and Mohs hardness of CNA crystal are 4.08 g/cm^(3) and 5.45,respectively.The specific heat of the crystal is 0.57-0.77 J/(g·K)in the temperature range of 30-300℃.X-ray photoelectron spectro scopy(XPS)shows that the crystal has stable atomic valence states and chemical environment.The vibration state of polyhedra groups in the crystal was measured by Raman spectra,and the piezoelectric response was analyzed based on the calculated results for the polyhedra polarization dipole moments.The relative dielectric permittivity of the CNA crystal at room temperature was determined to be 11.80 and the electrical resistivity was measured to be on the order of 5×10^(6)Ω·cm at 800℃.
基金supported by General Research Grants (GRF Project No. 11212021 and No. 11210822) from the Research Grants Council of the Hong Kong Special Administrative Regionthe Innovation and Technology Fund (Project No. ITS/065/20GHP/096/19SZ) from Innovation and Technology Commission of Hong Kong Special Administrative Region
文摘The mass discarding face masks has caused severe environmental problems during and after the COVID-19 pandemic.To reduce waste and minimize environmental impact,we present a new face mask featuring selfcharging extended service time and fully biodegradable materials.To extend the effective service time,we need to supplement the lost electric charge of the electret layer of face masks,for which task we propose to use the piezoelectric effect and generate electricity from breathing motions.However,existing piezoelectric materials are either toxic,impermeable,rigid,costly,or non-degradable.We synthesize a fully biodegradable piezoelectric membrane composed of polyvinyl alcohol(PVA)and glycine(GLY)via the electrospinning process.Parameters are accurately controlled to ensure that glycine crystallizes into a highly piezoelectricβphase during electrospinning and enables piezoelectric responses of the filter membrane.Tested with the standard 0.3μm particles,face masks made of the PVA-GLY membrane show an outstanding filtration efficiency of 97%,which remains stable over at least 10 h of high-concentration continuous filtration.Furthermore,we demonstrated the biodegradability of PVA-GLY masks,which can degrade completely within a few weeks,compared to commonly used surgical masks requiring over thirty years to be decomposed.
