The Ginzburg-Landau theory on ferroelectrics with random field induced by dipole defects is studied by using Monte Carlo simulation, in order to investigate the dipole configuration and the dielectric relaxation of re...The Ginzburg-Landau theory on ferroelectrics with random field induced by dipole defects is studied by using Monte Carlo simulation, in order to investigate the dipole configuration and the dielectric relaxation of relaxor ferro-electrics. With the increase of random field, the dipole configuration evolves from the long-range ferroelectric order into the coexistence of short-range dipole-clusters and less polarized matrix. The dipole-cluster phase above the transition temperature and superparaelectric fluctuations far below this temperature are identified for the relaxor ferroelectrics. We investigate the frequency dispersion and the time-domain spectrum of the dielectric relaxation, demonstrating the Vogel-Fulcher relationship and the multi-peaked time-domain distribution of the dielectric relaxation.展开更多
The dielectric response of complex perovskite relaxor ferrolectrics Pb(Mg1/3Nb2/3) O3 with respect to temperature and frequency was carefully measured. Using a normalized method of the 'universal' many-body t...The dielectric response of complex perovskite relaxor ferrolectrics Pb(Mg1/3Nb2/3) O3 with respect to temperature and frequency was carefully measured. Using a normalized method of the 'universal' many-body theory, the relaxation process was analyzed around the temperature of dielectric absorption maximum. There is no structural phase transition near this temperature and the behavior is closely like that of a polar dipole medium. The functional relationship about frequency and temperature of dielectric pormittivity maximum was also fitted to discuss the dynamic behavior of polar microregion. It is confirmed that a new power exponential Arrhenius relation is better to characterize the relaxation behavior than the Vogel-Fulcher and Debye relations. Based on the polarization theory of polar dipoles, we analyzed the relaxation mechanism of ferroelectric microdomains of relaxor ferroelectrics, and get an ideal distribution function of relaxation time. Consequently, a simulated dielectric response dependence on temperature and frequencies can be expressed, which is well coincided with experiment results.展开更多
For efficient solid-state refrigeration technologies based on electrocaloric effect(ECE),it is a great challenge of simultaneously obtaining a large adiabatic temperature change(DT)within a wide temperature span(Tspan...For efficient solid-state refrigeration technologies based on electrocaloric effect(ECE),it is a great challenge of simultaneously obtaining a large adiabatic temperature change(DT)within a wide temperature span(Tspan)in lead-free ferroelectric ceramics.Here,we studied the electrocaloric effect(ECE)in(1-x)(Na_(0.5)Bi_(0.5))TiO_(3)-xCaTiO_(3)((1-x)NBT-xCT)and explored the combining effect of morphotropic phase boundary(MPB)and relaxor feature.The addition of CT not only constructs a MPB region with the coexistence of rhombohedral and orthorhombic phases,but also enhances the relaxor feature.The ECE peak appears around the freezing temperature(Tf),and shifts toward to lower temperature with the increasing CT amount.The directly measured ECE result shows that the ceramic of x=0.10,which is in the MPB region,has an optimal ECE property of DTmax=1.28 K@60℃under 60 kV/cm with a wide Tspan of 65C.The enhanced ECE originates from the electric-field-induced transition between more types of polar nanoregions and long-range ferroelectric macrodomains.For the composition with more relaxor feature in the MPB region,such as x?0.12,the ECE is relatively weak under low electric fields but it exhibits a sharp increment under a sufficiently high electric field.This work provides a guideline to develop the solidestate cooling devices for electronic components.展开更多
Relaxor ferroelectrics have been extensively studied due to their outstanding dielectric,piezoelectric,energy storage,and electro-optical properties.Although various theories were proposed to elaborate on the relaxati...Relaxor ferroelectrics have been extensively studied due to their outstanding dielectric,piezoelectric,energy storage,and electro-optical properties.Although various theories were proposed to elaborate on the relaxation phenomena,polar nanoregions formed by disruption of the long-range-order structures are considered to play a key role in relaxor ferroelectrics.Generally,relaxor ferro-electrics are formed by aliovalent substitution or isovalent substitution in normal ferroelectrics,or further combinations of solid solutions.Herein,one category of BaTiO_(3)-based relaxor ferroelectrics with abnormal phase transition and polarization mismatch phenomena is focused.Characteristic parameters of such BaTiO_(3)-based relaxor ferroelectrics,including the Curie temperature,polarization,and lattice parameter,show a typical“U”-shaped variation with compositions.The studied BaTiO_(3)-based relaxor ferroelectrics are mostly solid solutions of A-site coupling and B-site coupling ferroelectrics,exhibiting polarization mismatch in certain compositions[e.g.,0.9BaTiO_(3)-0.1BiScO_(3),0.8BaTiO_(3)-0.2Bi(Mg_(1/2)Ti_(1/2)O_(3),0.8BaTiO_(3)-0.2Bi(Mg_(2/3)Nb_(1/3)O_(3),0.5BaTiO_(3)-0.5Pb(Mg_(1/3)Nb_(2/3)O_(3),0.4BaTiO_(3)-0.6Pb(Zn_(1/3)Nb_(2/3)O_(30,etc.].Of particular interest is that excellent electrical properties can be achieved in the studied relaxor ferroelectrics.Therefore,polarization mismatch theory can also provide guidance for the design of new high-performance lead-free relaxor ferroelectrics.展开更多
In this review the dielectric properties of relaxor ferroelectrics are discussed and compared withthe properties of normal dielectrics and ferroelectrics. We try to draw a general picture ofdielectric relaxation start...In this review the dielectric properties of relaxor ferroelectrics are discussed and compared withthe properties of normal dielectrics and ferroelectrics. We try to draw a general picture ofdielectric relaxation starting from a textbook review of the underlying concepts and pay attentionto common behavior of relaxors rather than to the features observed in specific materials. We hopethat this general approach is beneficial to those physicists, chemists, material scientists and deviceengineers who deal with relaxors. Based on the analysis of dielectric properties, a comprehensivedefinition of relaxors is proposed: relaxors are defined as ferroelectrics in which the maximum inthe temperature dependence of static susceptibility occurs within the temperature range ofdielectric relaxation, but does not coincide with the temperature of singularity of relaxation timeor soft mode frequency.展开更多
Advanced lead-free energy storage ceramics play an indispensable role in next-generation pulse power capacitors market.Here,an ultrahigh energy storage density of~13.8 J cm^(-3)and a large efficiency of~82.4%are achie...Advanced lead-free energy storage ceramics play an indispensable role in next-generation pulse power capacitors market.Here,an ultrahigh energy storage density of~13.8 J cm^(-3)and a large efficiency of~82.4%are achieved in high-entropy lead-free relaxor ferroelectrics by increasing configuration entropy,named high-entropy strategy,realizing nearly ten times growth of energy storage density compared with low-entropy material.Evolution of energy storage performance and domain structure with increasing configuration entropy is systematically revealed for the first time.The achievement of excellent energy storage properties should be attributed to the enhanced random field,decreased nanodomain size,strong multiple local distortions,and improved breakdown field.Furthermore,the excellent frequency and fatigue stability as well as charge/discharge properties with superior thermal stability are also realized.The significantly enhanced comprehensive energy storage performance by increasing configuration entropy demonstrates that high entropy is an effective but convenient strategy to design new high-performance dielectrics,promoting the development of advanced capacitors.展开更多
An overview is presented on the order-disorder structural transitions and the dielectric mechanism in the complex-perovskite type relaxor ferroelectrics, i.e., the relaxors. Emphasis is put on the theoretical understa...An overview is presented on the order-disorder structural transitions and the dielectric mechanism in the complex-perovskite type relaxor ferroelectrics, i.e., the relaxors. Emphasis is put on the theoretical understanding of the structural transitions, the macroscopic dielectric properties, and the relationship between them. The influences of the composition, the temperature, and the atomic interactions on the order-disorder microstructures can be well understood in the cluster-variation-method calculations. The criterion drawn from theoretical analysis is successful in predicting the order-disorder structure of relaxors. Among various physical models about relaxors, the dipole glassy model that described the dielectric response as the thermally activated flips of the local spontaneous polarization under random interactions is discussed in details. The Monte Carlo simulation results of this model are consistent with the linear and nonlinear experiments of relaxors.展开更多
Ultrafast charge/discharge process and ultrahigh power density enable dielectrics essential components in modern electrical and electronic devices, especially in pulse power systems. However, in recent years, the ener...Ultrafast charge/discharge process and ultrahigh power density enable dielectrics essential components in modern electrical and electronic devices, especially in pulse power systems. However, in recent years, the energy storage performances of present dielectrics are increasingly unable to satisfy the growing demand for miniaturization and integration, which stimulates further researches on dielectrics with higher energy density and efficiency.Among various inorganic dielectrics, perovskite relaxor ferroelectrics are recognized as promising candidates for energy storage applications, with high permittivity and relatively high efficiency. Here, we focus on recent progress and achievements on optimizing perovskite relaxor ferroelectrics toward better energy storage capability through hierarchical design. The principles and key parameters of dielectric energy storage, together with the definition of majority types of dielectrics, are introduced at first. Strategies within various scales include domain, grain size, orientation, and composite engineering are summarized. The existing challenges are presented and future prospects are proposed in the end, with the background of both academic explorations and industrial applications.展开更多
(1-x)(0.8Bi_(1/2)Na_(1/2)TiO3-0.2Bi_(1/2)K_(1/2)TiO3)-xBi(Ni_(2/3)Nb_(1/3))O3(BNKT-xBNN)solid solution ceramics were fabricated by high temperature solid-state reaction method.All the compositions possess relaxor ferr...(1-x)(0.8Bi_(1/2)Na_(1/2)TiO3-0.2Bi_(1/2)K_(1/2)TiO3)-xBi(Ni_(2/3)Nb_(1/3))O3(BNKT-xBNN)solid solution ceramics were fabricated by high temperature solid-state reaction method.All the compositions possess relaxor ferroelectric features,among which the ergodic BNKT-0.02BNN exhibits large repeatable electrostrain value Suni¼0.51%at electric field of 65 kV/cm,with high piezoelectric stain coefficient d33*of 890 pm/V at 45 kV/cm,while the non-ergodic compositions present unrepeatable large strain response.Based on the electric field-composition phase diagram,the repeatability of strain response in ergodic compositions can be attributed to the reversible electric-field-induced phase transition.In addition,the effects of BNN contents on the macroscopic strain properties are explored by analyzing the existing states of the polar regions with corresponding thermal evolutions and electric-field-induced phase transitions.This research is expected to guide the design of lead free relaxor ferroelectric materials with desired electrostrain properties.展开更多
Organic and inorganic relaxor ferroelectrics used for electrocaloric effect(ECE)applications areintroduced.Relaxor ferroelectrics offer several advantages for ECE devices,e.g.,infinite stateswithout applying electric ...Organic and inorganic relaxor ferroelectrics used for electrocaloric effect(ECE)applications areintroduced.Relaxor ferroelectrics offer several advantages for ECE devices,e.g.,infinite stateswithout applying electric field,field-induced large polarization,no-hysteresis ofheating and cooling,small-hysteresis polarization loss,room temperature phase transition,and broad temperaturerange.The ECE in relaxor ferroelectrics under a high electric field can be described using a theorysimilar to that for first-order phase transition materials.Large ECE was observed directly inhigh-energy electron irradiated poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)68/32 mol%copolymers,P(VDF-TrFE-CFE)(CFE-chlorofluoroethylene)59.2/33.6/7.2 mol%terpolymers,P(vDF-TrFE-CFE)-P(VDF-CTFE)(CTFE-chlorotrifluoroethylene)95/5 wt%terpolymer blended films,and(PbLa)(ZrTi)O_(3)(PLZT)ceramic thin films.ECE reported inPb(Sc_(1/2)Ta_(1/2))O_(3)(PST),Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PMN-PT)thin films is also summarized.Finally,the perspective of ECE devices is llustrated.展开更多
The increasing awareness of environmental concerns has prompted a surge in the exploration of leadfree,high-power ceramic capacitors.Ongoing efforts to develop leadfree dielectric ceramics with exceptional energystora...The increasing awareness of environmental concerns has prompted a surge in the exploration of leadfree,high-power ceramic capacitors.Ongoing efforts to develop leadfree dielectric ceramics with exceptional energystorage performance(ESP)have predominantly relied on multicomponent composite strategies,often accomplished under ultrahigh electric fields.However,this approach poses challenges in insulation and system downsizing due to the necessary working voltage under such conditions.Despite extensive study,bulk ceramics of(Bi_(0.5)Na_(0.5))TiO_(3)(BNT),a prominent lead-free dielectric ceramic family,have seldom achieved a recoverable energy-storage(ES)density(Wrec)exceeding 7 J cm^(−3).This study introduces a novel approach to attain ceramic capacitors with high ESP under moderate electric fields by regulating permittivity based on a linear dielectric model,enhancing insulation quality,and engineering domain structures through chemical formula optimization.The incorporation of SrTiO_(3)(ST)into the BNT matrix is revealed to reduce the dielectric constant,while the addition of Bi(Mg_(2/3)Nb_(1/3))O_(3)(BMN)aids in maintaining polarization.Additionally,the study elucidates the methodology to achieve high ESP at moderate electric fields ranging from 300 to 500 kV cm^(−1).In our optimized composition,0.5(Bi_(0.5)Na_(0.4)K_(0.1))TiO_(3)–0.5(2/3ST-1/3BMN)(B-0.5SB)ceramics,we achieved a Wrec of 7.19 J cm^(−3) with an efficiency of 93.8%at 460 kV cm^(−1).Impressively,the B-0.5SB ceramics exhibit remarkable thermal stability between 30 and 140℃ under 365 kV cm^(−1),maintaining a Wrec exceeding 5 J cm^(−3).This study not only establishes the B-0.5SB ceramics as promising candidates for ES materials but also demonstrates the feasibility of optimizing ESP by modifying the dielectric constant under specific electric field conditions.Simultaneously,it provides valuable insights for the future design of ceramic capacitors with high ESP under constraints of limited electric field.展开更多
Next-generation advanced high/pulsed power capacitors urgently require dielectric materials with outstanding energy storage performance.Bi_(0.5)Na_(0.5)TiO_(3)-based lead-free materials exhibit high polarization,but t...Next-generation advanced high/pulsed power capacitors urgently require dielectric materials with outstanding energy storage performance.Bi_(0.5)Na_(0.5)TiO_(3)-based lead-free materials exhibit high polarization,but the high remanent polarization and large polarization hysteresis limit their applications in dielectric capacitors.Herein,high-entropy perovskite relaxor ferroelectrics(Na_(0.2)Bi_(0.2)Ba_(0.2)Sr_(0.2)Ca_(0.2))(Ti1-x%Zrx%)O_(3)are designed by adding multiple ions in the A-site and replacing the B-site Ti^(4+)with a certain amount of Zr^(4+).The newly designed system showed high relaxor feature and slim polarization-electric(P-E)loops.Especially,improved relaxor feature and obviously delayed polarization saturation were found with the increasing of Zr^(4+).Of particular importance is that both high recoverable energy storage density of 6.6 J/cm^(3) and energy efficiency of 93.5%were achieved under 550 kV/cm for the ceramics of x=6,accompanying with excellent frequency stability,appreciable thermal stability,and prosperous discharge property.This work not only provides potential dielectric materials for energy storage applications,but also offers an effective strategy to obtain dielectric ceramics with ultrahigh comprehensive energy storage performance to meet the demanding requirements of advanced energy storage applications.展开更多
Dielectric capacitors with a fast charging/discharging rate,high power density,and long-term stability are essential components in modern electrical devices.However,miniaturizing and integrating capacitors face a pers...Dielectric capacitors with a fast charging/discharging rate,high power density,and long-term stability are essential components in modern electrical devices.However,miniaturizing and integrating capacitors face a persistent challenge in improving their energy density(W_(rec))to satisfy the specifications of advanced electronic systems and applications.In this work,leveraging phase-field simulations,we judiciously designed a novel lead-free relaxor ferroelectric material for enhanced energy storage performance,featuring flexible distributed weakly polar endotaxial nanostructures(ENs)embedded within a strongly polar fluctuation matrix.The matrix contributes to substantially enhanced polarization under an external electric field,and the randomly dispersed ENs effectively optimize breakdown phase proportion and provide a strong restoring force,which are advantageous in bolstering breakdown strength and minimizing hysteresis.Remarkably,this relaxor ferroelectric system incorporating ENs achieves an exceptionally high W_(rec)value of 10.3 J/cm^(3),accompanied by a large energy storage efficiency(η)of 85.4%.This work introduces a promising avenue for designing new relaxor materials capable of capacitive energy storage with exceptional performance characteristics.展开更多
Electrostrictive materials have wide applications in modern high-precision electronic devices.Driven by growing environmental concerns,there is demand for lead-free materials with superior electrostriction behaviors.I...Electrostrictive materials have wide applications in modern high-precision electronic devices.Driven by growing environmental concerns,there is demand for lead-free materials with superior electrostriction behaviors.In this study,we demonstrate a record-high electrostrictive coefficient of~0.0712 m^(4) C^(-2) in perovskite ferroelectric ceramics,along with hysteresis-free strain as well as excellent frequency and thermal stabilities,in lead-free BaTiO_(3)-based ceramics through a polarization nanocluster design.By appro-priately introducing Li+and Bi^(3+)into the BaTiO 3 lattice matrix,the long-range ferroelectric ordering can be broken,and polarization nanoclusters can be formed,resulting in a relaxor state with concurrently suppressed polariza-tion and maintained electro-strain.A three-dimensional atomic model constructed using advanced neutron total-scattering data combined with the reverse Monte Carlo method indicates the existence of Bi and Li segregations at the subnanometer scale,which confirms the prediction made by density functional theory calculations.Such a short-range chemical order destroys the long-range ferroelectric order of the off-centered Ti polar displacements and leads to the embedding of Li+/Bi ^(3+)-rich polar nanoregions in the Ba^(2+)-rich polarization disorder matrix.Further,a completely reversible electric-field-induced lattice strain is observed,giving rise to pure electrostriction without hysteresis behavior.This work provides a novel strategy for developing lead-free relaxor ferroelectrics with high electrostriction performance.展开更多
Relaxor ferroelectric ceramics have very high dielectric constant(e)but relatively low electrical breakdown strength(Eb),while glass-ceramics exhibit higher E,due to the more uniformly dispersed amorphous phases and s...Relaxor ferroelectric ceramics have very high dielectric constant(e)but relatively low electrical breakdown strength(Eb),while glass-ceramics exhibit higher E,due to the more uniformly dispersed amorphous phases and submicrocrystals/nanocrystals inside.How to effectively combine the advantages of both relaxor ferroelectric ceramics and glass-ceramics is of great significance for the development of new dielectric materials with high energy storage performance.In this work,we firstly prepared BaO-SrO-Bi_(2)O_(3)-Na_(2)0-TiO_(2)-Al_(2)O_(3)-SiO_(2)(abbreviated as GS)glass powders,and then fabricated(Ba_(0.3)Sr_(0.7))_(0.5)(Bi_(0.5)Na_(0.5))_(0.5)TiO_(3)+x wt%GS ceramic composites(abbreviated as BSo.sBNT-xGS,x=0,2,6,10,14,16,and 18).Submicrocrystals/nanocrystals with a similar composition to BSo.sBNT were crystalized from the glass,ensuring the formation of uniform core-shell structure in BSo.sBNT-xGS relaxor ferroelectric ceramic/glass-ceramic composites.When the addition amount of GS was 14 wt%,the composite possessed both high&r(>3200 at 1 kHz)and high E,(~170 kV/cm)at room temperature,and their recoverable energy storage density and efficiency were Wrec=2.1 J/cm’and n=65.2%,respectively.The BSo.sBNT-14GS composite also had several attractive properties such as good temperature,frequency,cycle stability,and fast charge-discharge speed.This work provides insights into the relaxor ceramic/glass-ceramic composites for pulsed power capacitors and sheds light on the utilization of the hybrid systems.展开更多
Inorganic relaxor ferroelectric solid solution single crystals are spurring new generations of high performance electromechanical devices,including transducers,sensors,and actuators,due to their ultrahigh electric fie...Inorganic relaxor ferroelectric solid solution single crystals are spurring new generations of high performance electromechanical devices,including transducers,sensors,and actuators,due to their ultrahigh electric field induced strain,large piezoelectric constant,high electromechanical coupling factor and low dielectric loss.However,relaxor ferroelectric single crystals found in organic-inorganic hybrid perovskites are very limited,but achieving these superior properties in them will be of great significance in the design of modern functional materials.Fortunately,here the first two-dimensional(2D)organic-inorganic hybrid relaxor ferroelectric single crystal,[Br(CH_(2))_(3)NH_(3)]_(2)PbBr_(4)(BPA_(2)-PbBr_(4),BPA=3-bromopropylamine),achieves some of superior properties.Interestingly,BPA_(2)-PbBr_(4)reveals a successive relaxor ferroelectric-ferroelectric-paraelectric phase transitions accompanying by a large degree of relaxationΔT_(relax)=61 K and ultralow energy loss(tanδ<0.001).Meanwhile,it exhibits a superior second harmonic generation(SHG)effect with maximum value accounts for 95%of the standard KDP due to great deformation of structure(3.2302×10^(-4)).In addition,temperature dependent luminescence spectra(80-415 K)exhibit fluorescence and phosphorescence overlapping emission originated from inorganic and organic components with the nanosecond-scale short lifetime and the millisecond-scale long lifetime,respectively,and the color of the emitted light is continuously adjustable,which is the first to achieve luminescence and relaxor ferroelectricity compatibility.展开更多
Inspired by the increasing demand for energy-storage capacitors in electrical and electronic systems, dielectrics with high energy-storage performance have attracted more and more attention. AgNbO_(3) -based lead-free...Inspired by the increasing demand for energy-storage capacitors in electrical and electronic systems, dielectrics with high energy-storage performance have attracted more and more attention. AgNbO_(3) -based lead-free ceramics serve as one of the most promising environmental-friendly candidates. However, their energy storage optimization is seriously limited by the low breakdown strength. Fortunately, thin film as a form of AgNbO3 materials can effectively improve the breakdown strength. In this work, AgNbO_(3)film with ∼550 nm in thickness was deposited on SrRuO_(3 )/(001)SrTiO_(3) using pulsed laser deposition. The AgNbO_(3) film reveals typical relaxor ferroelectric hysteresis loops due to the new nanopillar structure, which contributes to high breakdown strength of up to 1200 kV cm^(-1) . Benefiting from the high breakdown strength, a recoverable energy storage density of 10.3 J cm^(-3) and an energy efficiency of 72.2% are obtained in the AgNbO_(3) film, which demonstrates the promising prospect of AgNbO_(3) film for energy storage applications.展开更多
In this paper,a complete set of elastic,piezoelectric,and dielectric constants of high-quality tetragonal poled0.92Pb(Zn1/3Nb2/3)O3-0.08PbTiO3 single crystal grown by the modified flux method is determined using hig...In this paper,a complete set of elastic,piezoelectric,and dielectric constants of high-quality tetragonal poled0.92Pb(Zn1/3Nb2/3)O3-0.08PbTiO3 single crystal grown by the modified flux method is determined using high-resolution Brillouin scattering.A comparison is made between the results obtained by a hybrid method combining ultrasonic and resonant techniques and the results obtained by the Brillouin scattering.The elastic,piezoelectric,and dielectric constants obtained by the two methods are similar.The Brillouin spectrum consists of one longitudinal and two transverse acoustic phonon modes,and the variations of the Brillouin shifts,the full widths at half maximum,and the scattering intensities of these modes with scattering angle 9 are investigated.In particular,the transverse acoustic phonon mode at the lowfrequency becomes markedly soft from 28.2 GHz to 18.4 GHz and broadens gradually with the increase of θ,while its intensity decreases gradually as compared with that of the original one.The possible origins of the results are discussed.展开更多
To further enhance the property of piezoelectric materials is of great significance to improve the overall performance of electro-mechanical devices.Here in this work,we propose a thermal annealing and high temperatur...To further enhance the property of piezoelectric materials is of great significance to improve the overall performance of electro-mechanical devices.Here in this work,we propose a thermal annealing and high temperature poling approach to achieve significantly enhanced piezoelectricity in Pb(In_(1/2)Nb_(1/2))O_(3)single bondPb(Mg_(1/3)Nb_(2/3))O_(3)single bondPbTiO_(3)(PIN-PMN-PT)crystals with a morphotropic phase boundary(MPB)composition.The main idea of our approach is to realize a more sufficiently polarized crystal via active manipulation of defects and orientation of defect polarization.Manipulation of defect dipoles by the high temperature poling is proved by the piezo-response force microscopy.Finally,a d_(33)of 3300 pC/N and a SE of 0.25%are obtained,nearly 60%higher than that of conventionally poled crystals.Moreover,such a boosting of piezoelectric property is obtained under a maintained Curie temperature.Our research not only reveals the active control of defect dipole via modified poling method in the PIN-PMN-PT crystal,but also provides a feasible strategy to further improve the property of piezoelectric materials.展开更多
Lead-free dielectric ceramics can be used to make quick charge-discharge capacitor devices due to their high power density.Their use in advanced electronic systems,however,has been hampered by their poor energy storag...Lead-free dielectric ceramics can be used to make quick charge-discharge capacitor devices due to their high power density.Their use in advanced electronic systems,however,has been hampered by their poor energy storage performance(ESP),which includes low energy storage efficiency and recoverable energy storage density(Wrec).In this work,we adopted a combinatorial optimization strategy to improve the ESP in(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)-based relaxor ferroelectric ceramics.To begin,the Bi-containing complex ions Bi(Mg_(2/3)Nb_(1/3))O_(3)(BMN)were introduced into a BNT-based matrix in order to improve the diffuse phase transition,increase Bi-O bond coupling,avoid macro domain development,and limit polarization response hysteresis.Second,the viscous polymer process was employed to reduce sample thickness and porosity,resulting in an apparent increase in breakdown strength in(1-x)[0.7(Bi_(1/2)Na_(1/2))TiO_(3)]-0.3SrTiO_(3)-xBi(Mg_(2/3)Nb_(1/3))O_(3)(BS-xBMN)ceramics.Finally,in x=0.20 composition,an amazing Wrecof 5.62 J·cm^(-3)and an ultra-high efficiency of 91.4%were simultaneously achieved at a relatively low field of 330 kV·cm^(-1),together with remarkable temperature stability in the temperature range of 30-140℃(3.5 J·cm^(-3)±5%variation).This research presents a new lead-free dielectric material with superior ESP for use in pulsed power capacitors.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.50832002 and 10874035)the National Basic Research Program of China (Grant No.2009CB623303)
文摘The Ginzburg-Landau theory on ferroelectrics with random field induced by dipole defects is studied by using Monte Carlo simulation, in order to investigate the dipole configuration and the dielectric relaxation of relaxor ferro-electrics. With the increase of random field, the dipole configuration evolves from the long-range ferroelectric order into the coexistence of short-range dipole-clusters and less polarized matrix. The dipole-cluster phase above the transition temperature and superparaelectric fluctuations far below this temperature are identified for the relaxor ferroelectrics. We investigate the frequency dispersion and the time-domain spectrum of the dielectric relaxation, demonstrating the Vogel-Fulcher relationship and the multi-peaked time-domain distribution of the dielectric relaxation.
文摘The dielectric response of complex perovskite relaxor ferrolectrics Pb(Mg1/3Nb2/3) O3 with respect to temperature and frequency was carefully measured. Using a normalized method of the 'universal' many-body theory, the relaxation process was analyzed around the temperature of dielectric absorption maximum. There is no structural phase transition near this temperature and the behavior is closely like that of a polar dipole medium. The functional relationship about frequency and temperature of dielectric pormittivity maximum was also fitted to discuss the dynamic behavior of polar microregion. It is confirmed that a new power exponential Arrhenius relation is better to characterize the relaxation behavior than the Vogel-Fulcher and Debye relations. Based on the polarization theory of polar dipoles, we analyzed the relaxation mechanism of ferroelectric microdomains of relaxor ferroelectrics, and get an ideal distribution function of relaxation time. Consequently, a simulated dielectric response dependence on temperature and frequencies can be expressed, which is well coincided with experiment results.
基金supported by grants from National Natural Science Foundation of China(52173217)and 111 project(B170003).
文摘For efficient solid-state refrigeration technologies based on electrocaloric effect(ECE),it is a great challenge of simultaneously obtaining a large adiabatic temperature change(DT)within a wide temperature span(Tspan)in lead-free ferroelectric ceramics.Here,we studied the electrocaloric effect(ECE)in(1-x)(Na_(0.5)Bi_(0.5))TiO_(3)-xCaTiO_(3)((1-x)NBT-xCT)and explored the combining effect of morphotropic phase boundary(MPB)and relaxor feature.The addition of CT not only constructs a MPB region with the coexistence of rhombohedral and orthorhombic phases,but also enhances the relaxor feature.The ECE peak appears around the freezing temperature(Tf),and shifts toward to lower temperature with the increasing CT amount.The directly measured ECE result shows that the ceramic of x=0.10,which is in the MPB region,has an optimal ECE property of DTmax=1.28 K@60℃under 60 kV/cm with a wide Tspan of 65C.The enhanced ECE originates from the electric-field-induced transition between more types of polar nanoregions and long-range ferroelectric macrodomains.For the composition with more relaxor feature in the MPB region,such as x?0.12,the ECE is relatively weak under low electric fields but it exhibits a sharp increment under a sufficiently high electric field.This work provides a guideline to develop the solidestate cooling devices for electronic components.
基金supported by the National Nature Science Foundation of China(Grant Nos.51772239,51761145024)the National Basic Research Program of China(973 Program)under the Grant No.2015CB654602+1 种基金the International Science&Technology Cooperation Program of China(Grant 2015DFA51100)“111”Project(No.B14040),and Shaanxi Province Project(2017ktpt-21,2018TD-024)。
文摘Relaxor ferroelectrics have been extensively studied due to their outstanding dielectric,piezoelectric,energy storage,and electro-optical properties.Although various theories were proposed to elaborate on the relaxation phenomena,polar nanoregions formed by disruption of the long-range-order structures are considered to play a key role in relaxor ferroelectrics.Generally,relaxor ferro-electrics are formed by aliovalent substitution or isovalent substitution in normal ferroelectrics,or further combinations of solid solutions.Herein,one category of BaTiO_(3)-based relaxor ferroelectrics with abnormal phase transition and polarization mismatch phenomena is focused.Characteristic parameters of such BaTiO_(3)-based relaxor ferroelectrics,including the Curie temperature,polarization,and lattice parameter,show a typical“U”-shaped variation with compositions.The studied BaTiO_(3)-based relaxor ferroelectrics are mostly solid solutions of A-site coupling and B-site coupling ferroelectrics,exhibiting polarization mismatch in certain compositions[e.g.,0.9BaTiO_(3)-0.1BiScO_(3),0.8BaTiO_(3)-0.2Bi(Mg_(1/2)Ti_(1/2)O_(3),0.8BaTiO_(3)-0.2Bi(Mg_(2/3)Nb_(1/3)O_(3),0.5BaTiO_(3)-0.5Pb(Mg_(1/3)Nb_(2/3)O_(3),0.4BaTiO_(3)-0.6Pb(Zn_(1/3)Nb_(2/3)O_(30,etc.].Of particular interest is that excellent electrical properties can be achieved in the studied relaxor ferroelectrics.Therefore,polarization mismatch theory can also provide guidance for the design of new high-performance lead-free relaxor ferroelectrics.
文摘In this review the dielectric properties of relaxor ferroelectrics are discussed and compared withthe properties of normal dielectrics and ferroelectrics. We try to draw a general picture ofdielectric relaxation starting from a textbook review of the underlying concepts and pay attentionto common behavior of relaxors rather than to the features observed in specific materials. We hopethat this general approach is beneficial to those physicists, chemists, material scientists and deviceengineers who deal with relaxors. Based on the analysis of dielectric properties, a comprehensivedefinition of relaxors is proposed: relaxors are defined as ferroelectrics in which the maximum inthe temperature dependence of static susceptibility occurs within the temperature range ofdielectric relaxation, but does not coincide with the temperature of singularity of relaxation timeor soft mode frequency.
基金supported by the National Natural Science Foundation of China(Grant Nos.21825102,22235002,52172181,and 22105017)Key R&D Plan of the Ministry of Science and Technology of China(Grant No.2022YFB3204000)。
文摘Advanced lead-free energy storage ceramics play an indispensable role in next-generation pulse power capacitors market.Here,an ultrahigh energy storage density of~13.8 J cm^(-3)and a large efficiency of~82.4%are achieved in high-entropy lead-free relaxor ferroelectrics by increasing configuration entropy,named high-entropy strategy,realizing nearly ten times growth of energy storage density compared with low-entropy material.Evolution of energy storage performance and domain structure with increasing configuration entropy is systematically revealed for the first time.The achievement of excellent energy storage properties should be attributed to the enhanced random field,decreased nanodomain size,strong multiple local distortions,and improved breakdown field.Furthermore,the excellent frequency and fatigue stability as well as charge/discharge properties with superior thermal stability are also realized.The significantly enhanced comprehensive energy storage performance by increasing configuration entropy demonstrates that high entropy is an effective but convenient strategy to design new high-performance dielectrics,promoting the development of advanced capacitors.
基金State Key Program of Basic ResearchDevelopm ent! (No.G2 0 0 0 0 6 710 8) the NationalNatural Science Foundation of Chin
文摘An overview is presented on the order-disorder structural transitions and the dielectric mechanism in the complex-perovskite type relaxor ferroelectrics, i.e., the relaxors. Emphasis is put on the theoretical understanding of the structural transitions, the macroscopic dielectric properties, and the relationship between them. The influences of the composition, the temperature, and the atomic interactions on the order-disorder microstructures can be well understood in the cluster-variation-method calculations. The criterion drawn from theoretical analysis is successful in predicting the order-disorder structure of relaxors. Among various physical models about relaxors, the dipole glassy model that described the dielectric response as the thermally activated flips of the local spontaneous polarization under random interactions is discussed in details. The Monte Carlo simulation results of this model are consistent with the linear and nonlinear experiments of relaxors.
基金financially supported by the National Natural Science Foundation of China (No.51788104)。
文摘Ultrafast charge/discharge process and ultrahigh power density enable dielectrics essential components in modern electrical and electronic devices, especially in pulse power systems. However, in recent years, the energy storage performances of present dielectrics are increasingly unable to satisfy the growing demand for miniaturization and integration, which stimulates further researches on dielectrics with higher energy density and efficiency.Among various inorganic dielectrics, perovskite relaxor ferroelectrics are recognized as promising candidates for energy storage applications, with high permittivity and relatively high efficiency. Here, we focus on recent progress and achievements on optimizing perovskite relaxor ferroelectrics toward better energy storage capability through hierarchical design. The principles and key parameters of dielectric energy storage, together with the definition of majority types of dielectrics, are introduced at first. Strategies within various scales include domain, grain size, orientation, and composite engineering are summarized. The existing challenges are presented and future prospects are proposed in the end, with the background of both academic explorations and industrial applications.
基金supported by the National Natural Science Foundation of China(51672220,51902258,51972265)Fundamental Research Funds for the Central Universities(3102019GHXM002)+2 种基金State Key Laboratory of Solidification Processing Project(2019-TZ-04)of China,China Postdoctoral Science Foundation(2019M653729)Natural Science Foundation of Shaanxi Province(2019JQ-621)the Shaanxi Province Postdoctoral Science Foundation(2017BSHEDZZ07).
文摘(1-x)(0.8Bi_(1/2)Na_(1/2)TiO3-0.2Bi_(1/2)K_(1/2)TiO3)-xBi(Ni_(2/3)Nb_(1/3))O3(BNKT-xBNN)solid solution ceramics were fabricated by high temperature solid-state reaction method.All the compositions possess relaxor ferroelectric features,among which the ergodic BNKT-0.02BNN exhibits large repeatable electrostrain value Suni¼0.51%at electric field of 65 kV/cm,with high piezoelectric stain coefficient d33*of 890 pm/V at 45 kV/cm,while the non-ergodic compositions present unrepeatable large strain response.Based on the electric field-composition phase diagram,the repeatability of strain response in ergodic compositions can be attributed to the reversible electric-field-induced phase transition.In addition,the effects of BNN contents on the macroscopic strain properties are explored by analyzing the existing states of the polar regions with corresponding thermal evolutions and electric-field-induced phase transitions.This research is expected to guide the design of lead free relaxor ferroelectric materials with desired electrostrain properties.
基金the US DoE,Office of Basic Energy Sciences,Division of Materials Science and Engineering under Award No.DE-FG02-07ER46410.
文摘Organic and inorganic relaxor ferroelectrics used for electrocaloric effect(ECE)applications areintroduced.Relaxor ferroelectrics offer several advantages for ECE devices,e.g.,infinite stateswithout applying electric field,field-induced large polarization,no-hysteresis ofheating and cooling,small-hysteresis polarization loss,room temperature phase transition,and broad temperaturerange.The ECE in relaxor ferroelectrics under a high electric field can be described using a theorysimilar to that for first-order phase transition materials.Large ECE was observed directly inhigh-energy electron irradiated poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)68/32 mol%copolymers,P(VDF-TrFE-CFE)(CFE-chlorofluoroethylene)59.2/33.6/7.2 mol%terpolymers,P(vDF-TrFE-CFE)-P(VDF-CTFE)(CTFE-chlorotrifluoroethylene)95/5 wt%terpolymer blended films,and(PbLa)(ZrTi)O_(3)(PLZT)ceramic thin films.ECE reported inPb(Sc_(1/2)Ta_(1/2))O_(3)(PST),Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)(PMN-PT)thin films is also summarized.Finally,the perspective of ECE devices is llustrated.
基金supported by the National Natural Science Foundation of China(Grant No.51761145024)the Key Research and Development Program of Shaanxi(Program No.2022KWZ-22)+3 种基金the Natural Science Basic Research Program of Shaanxi(Program No.2023-JC-YB-441)the Youth Innovation Team of Shaanxi Universitiesthe Fundamental Research Funds of Shaanxi Key Laboratory of Artificially-Structured Functional Materials and Devices(AFMD-KFJJ-21203)The research was made possible by Russian Science Foundation(Project No.23-42-00116).
文摘The increasing awareness of environmental concerns has prompted a surge in the exploration of leadfree,high-power ceramic capacitors.Ongoing efforts to develop leadfree dielectric ceramics with exceptional energystorage performance(ESP)have predominantly relied on multicomponent composite strategies,often accomplished under ultrahigh electric fields.However,this approach poses challenges in insulation and system downsizing due to the necessary working voltage under such conditions.Despite extensive study,bulk ceramics of(Bi_(0.5)Na_(0.5))TiO_(3)(BNT),a prominent lead-free dielectric ceramic family,have seldom achieved a recoverable energy-storage(ES)density(Wrec)exceeding 7 J cm^(−3).This study introduces a novel approach to attain ceramic capacitors with high ESP under moderate electric fields by regulating permittivity based on a linear dielectric model,enhancing insulation quality,and engineering domain structures through chemical formula optimization.The incorporation of SrTiO_(3)(ST)into the BNT matrix is revealed to reduce the dielectric constant,while the addition of Bi(Mg_(2/3)Nb_(1/3))O_(3)(BMN)aids in maintaining polarization.Additionally,the study elucidates the methodology to achieve high ESP at moderate electric fields ranging from 300 to 500 kV cm^(−1).In our optimized composition,0.5(Bi_(0.5)Na_(0.4)K_(0.1))TiO_(3)–0.5(2/3ST-1/3BMN)(B-0.5SB)ceramics,we achieved a Wrec of 7.19 J cm^(−3) with an efficiency of 93.8%at 460 kV cm^(−1).Impressively,the B-0.5SB ceramics exhibit remarkable thermal stability between 30 and 140℃ under 365 kV cm^(−1),maintaining a Wrec exceeding 5 J cm^(−3).This study not only establishes the B-0.5SB ceramics as promising candidates for ES materials but also demonstrates the feasibility of optimizing ESP by modifying the dielectric constant under specific electric field conditions.Simultaneously,it provides valuable insights for the future design of ceramic capacitors with high ESP under constraints of limited electric field.
基金This work was financially supported by the Guangxi Natural Science Fund for Distinguished Young Scholars(Grant No.2022GXNSFFA035034)National Natural Science Foundation of China(Grant Nos.52072080 and U22A20127)National Key R&D Program of China(Grant No.2022YFC2408600).We also would like to acknowledge the support from Xiaomi Foundation/Xiaomi Young Talents Program.
文摘Next-generation advanced high/pulsed power capacitors urgently require dielectric materials with outstanding energy storage performance.Bi_(0.5)Na_(0.5)TiO_(3)-based lead-free materials exhibit high polarization,but the high remanent polarization and large polarization hysteresis limit their applications in dielectric capacitors.Herein,high-entropy perovskite relaxor ferroelectrics(Na_(0.2)Bi_(0.2)Ba_(0.2)Sr_(0.2)Ca_(0.2))(Ti1-x%Zrx%)O_(3)are designed by adding multiple ions in the A-site and replacing the B-site Ti^(4+)with a certain amount of Zr^(4+).The newly designed system showed high relaxor feature and slim polarization-electric(P-E)loops.Especially,improved relaxor feature and obviously delayed polarization saturation were found with the increasing of Zr^(4+).Of particular importance is that both high recoverable energy storage density of 6.6 J/cm^(3) and energy efficiency of 93.5%were achieved under 550 kV/cm for the ceramics of x=6,accompanying with excellent frequency stability,appreciable thermal stability,and prosperous discharge property.This work not only provides potential dielectric materials for energy storage applications,but also offers an effective strategy to obtain dielectric ceramics with ultrahigh comprehensive energy storage performance to meet the demanding requirements of advanced energy storage applications.
基金National Key Research and Development Program of China,Grant/Award Number:2022YFB3807402National Science Foundation of China,Grant/Award Number:51972215。
文摘Dielectric capacitors with a fast charging/discharging rate,high power density,and long-term stability are essential components in modern electrical devices.However,miniaturizing and integrating capacitors face a persistent challenge in improving their energy density(W_(rec))to satisfy the specifications of advanced electronic systems and applications.In this work,leveraging phase-field simulations,we judiciously designed a novel lead-free relaxor ferroelectric material for enhanced energy storage performance,featuring flexible distributed weakly polar endotaxial nanostructures(ENs)embedded within a strongly polar fluctuation matrix.The matrix contributes to substantially enhanced polarization under an external electric field,and the randomly dispersed ENs effectively optimize breakdown phase proportion and provide a strong restoring force,which are advantageous in bolstering breakdown strength and minimizing hysteresis.Remarkably,this relaxor ferroelectric system incorporating ENs achieves an exceptionally high W_(rec)value of 10.3 J/cm^(3),accompanied by a large energy storage efficiency(η)of 85.4%.This work introduces a promising avenue for designing new relaxor materials capable of capacitive energy storage with exceptional performance characteristics.
基金This work was supported by the National Natural Science Foundation of China(grant nos.21825102,and 22075014)the Fundamental Research Funds for the Central Univer-sities,China(FRF-MP-20-40)+1 种基金National Postdoctoral Program for Innovative Talents(BX20200044,and BX20200043)the State Key Lab of Advanced Metals and Materials(2020-ZD01)。
文摘Electrostrictive materials have wide applications in modern high-precision electronic devices.Driven by growing environmental concerns,there is demand for lead-free materials with superior electrostriction behaviors.In this study,we demonstrate a record-high electrostrictive coefficient of~0.0712 m^(4) C^(-2) in perovskite ferroelectric ceramics,along with hysteresis-free strain as well as excellent frequency and thermal stabilities,in lead-free BaTiO_(3)-based ceramics through a polarization nanocluster design.By appro-priately introducing Li+and Bi^(3+)into the BaTiO 3 lattice matrix,the long-range ferroelectric ordering can be broken,and polarization nanoclusters can be formed,resulting in a relaxor state with concurrently suppressed polariza-tion and maintained electro-strain.A three-dimensional atomic model constructed using advanced neutron total-scattering data combined with the reverse Monte Carlo method indicates the existence of Bi and Li segregations at the subnanometer scale,which confirms the prediction made by density functional theory calculations.Such a short-range chemical order destroys the long-range ferroelectric order of the off-centered Ti polar displacements and leads to the embedding of Li+/Bi ^(3+)-rich polar nanoregions in the Ba^(2+)-rich polarization disorder matrix.Further,a completely reversible electric-field-induced lattice strain is observed,giving rise to pure electrostriction without hysteresis behavior.This work provides a novel strategy for developing lead-free relaxor ferroelectrics with high electrostriction performance.
基金supported by the National Natural Science Foundation of China(52267002)Natural Science Foundation of Jiangxi Province(20212ACB204010)+1 种基金Science&Technology Research Project of Jiangxi Provincial Education Department(GJJ211301)the Graduate Innovation Fund of Jiangxi Province(YC2021-S527).
文摘Relaxor ferroelectric ceramics have very high dielectric constant(e)but relatively low electrical breakdown strength(Eb),while glass-ceramics exhibit higher E,due to the more uniformly dispersed amorphous phases and submicrocrystals/nanocrystals inside.How to effectively combine the advantages of both relaxor ferroelectric ceramics and glass-ceramics is of great significance for the development of new dielectric materials with high energy storage performance.In this work,we firstly prepared BaO-SrO-Bi_(2)O_(3)-Na_(2)0-TiO_(2)-Al_(2)O_(3)-SiO_(2)(abbreviated as GS)glass powders,and then fabricated(Ba_(0.3)Sr_(0.7))_(0.5)(Bi_(0.5)Na_(0.5))_(0.5)TiO_(3)+x wt%GS ceramic composites(abbreviated as BSo.sBNT-xGS,x=0,2,6,10,14,16,and 18).Submicrocrystals/nanocrystals with a similar composition to BSo.sBNT were crystalized from the glass,ensuring the formation of uniform core-shell structure in BSo.sBNT-xGS relaxor ferroelectric ceramic/glass-ceramic composites.When the addition amount of GS was 14 wt%,the composite possessed both high&r(>3200 at 1 kHz)and high E,(~170 kV/cm)at room temperature,and their recoverable energy storage density and efficiency were Wrec=2.1 J/cm’and n=65.2%,respectively.The BSo.sBNT-14GS composite also had several attractive properties such as good temperature,frequency,cycle stability,and fast charge-discharge speed.This work provides insights into the relaxor ceramic/glass-ceramic composites for pulsed power capacitors and sheds light on the utilization of the hybrid systems.
基金supported by the National Natural Science Foundation of China(22001102,21788102)the Jiangxi Provincial Natural Science Foundation(20202BAB213002)+2 种基金the Education Department of Jiangxi Province(GJJ190474)the Fundamental Research Funds for the Central Universities(JXUST,205200100116)the Program for Excellent Young Talents(JXUST,JXUSTQJYX2020018)。
文摘Inorganic relaxor ferroelectric solid solution single crystals are spurring new generations of high performance electromechanical devices,including transducers,sensors,and actuators,due to their ultrahigh electric field induced strain,large piezoelectric constant,high electromechanical coupling factor and low dielectric loss.However,relaxor ferroelectric single crystals found in organic-inorganic hybrid perovskites are very limited,but achieving these superior properties in them will be of great significance in the design of modern functional materials.Fortunately,here the first two-dimensional(2D)organic-inorganic hybrid relaxor ferroelectric single crystal,[Br(CH_(2))_(3)NH_(3)]_(2)PbBr_(4)(BPA_(2)-PbBr_(4),BPA=3-bromopropylamine),achieves some of superior properties.Interestingly,BPA_(2)-PbBr_(4)reveals a successive relaxor ferroelectric-ferroelectric-paraelectric phase transitions accompanying by a large degree of relaxationΔT_(relax)=61 K and ultralow energy loss(tanδ<0.001).Meanwhile,it exhibits a superior second harmonic generation(SHG)effect with maximum value accounts for 95%of the standard KDP due to great deformation of structure(3.2302×10^(-4)).In addition,temperature dependent luminescence spectra(80-415 K)exhibit fluorescence and phosphorescence overlapping emission originated from inorganic and organic components with the nanosecond-scale short lifetime and the millisecond-scale long lifetime,respectively,and the color of the emitted light is continuously adjustable,which is the first to achieve luminescence and relaxor ferroelectricity compatibility.
基金supported by the Natural Science Foundation of Hebei Province,China(No.E2021201044)the National Natural Science Foundation of China(Nos.51802068 and 52073144)+3 种基金the Natural Science Foundation of Jiangsu Province,China(No.BK20201301)State Key Laboratory of New Ceramic and Fine Processing Tsinghua University(No.KF202114)the Research Fund of State Key Laboratory of Mechanics and Control of Mechani-cal Structures(Nanjing University of Aeronautics and Astronautics)(No.MCMS-I-0522G02)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Inspired by the increasing demand for energy-storage capacitors in electrical and electronic systems, dielectrics with high energy-storage performance have attracted more and more attention. AgNbO_(3) -based lead-free ceramics serve as one of the most promising environmental-friendly candidates. However, their energy storage optimization is seriously limited by the low breakdown strength. Fortunately, thin film as a form of AgNbO3 materials can effectively improve the breakdown strength. In this work, AgNbO_(3)film with ∼550 nm in thickness was deposited on SrRuO_(3 )/(001)SrTiO_(3) using pulsed laser deposition. The AgNbO_(3) film reveals typical relaxor ferroelectric hysteresis loops due to the new nanopillar structure, which contributes to high breakdown strength of up to 1200 kV cm^(-1) . Benefiting from the high breakdown strength, a recoverable energy storage density of 10.3 J cm^(-3) and an energy efficiency of 72.2% are obtained in the AgNbO_(3) film, which demonstrates the promising prospect of AgNbO_(3) film for energy storage applications.
基金supported by the National Instrumentation Program of China(Grant No.2011YQ040136)
文摘In this paper,a complete set of elastic,piezoelectric,and dielectric constants of high-quality tetragonal poled0.92Pb(Zn1/3Nb2/3)O3-0.08PbTiO3 single crystal grown by the modified flux method is determined using high-resolution Brillouin scattering.A comparison is made between the results obtained by a hybrid method combining ultrasonic and resonant techniques and the results obtained by the Brillouin scattering.The elastic,piezoelectric,and dielectric constants obtained by the two methods are similar.The Brillouin spectrum consists of one longitudinal and two transverse acoustic phonon modes,and the variations of the Brillouin shifts,the full widths at half maximum,and the scattering intensities of these modes with scattering angle 9 are investigated.In particular,the transverse acoustic phonon mode at the lowfrequency becomes markedly soft from 28.2 GHz to 18.4 GHz and broadens gradually with the increase of θ,while its intensity decreases gradually as compared with that of the original one.The possible origins of the results are discussed.
基金This work is supported by the National Nature Science Foundation of China(Grant Nos.52102143,51772239,62001369 and 51761145024)Shaanxi province project(2017ktpt-21 and 2018TD-024)Jiangxi Technological Innovation Guidance Science and Technology Plan(Grant No.S20212BDH80017)。
文摘To further enhance the property of piezoelectric materials is of great significance to improve the overall performance of electro-mechanical devices.Here in this work,we propose a thermal annealing and high temperature poling approach to achieve significantly enhanced piezoelectricity in Pb(In_(1/2)Nb_(1/2))O_(3)single bondPb(Mg_(1/3)Nb_(2/3))O_(3)single bondPbTiO_(3)(PIN-PMN-PT)crystals with a morphotropic phase boundary(MPB)composition.The main idea of our approach is to realize a more sufficiently polarized crystal via active manipulation of defects and orientation of defect polarization.Manipulation of defect dipoles by the high temperature poling is proved by the piezo-response force microscopy.Finally,a d_(33)of 3300 pC/N and a SE of 0.25%are obtained,nearly 60%higher than that of conventionally poled crystals.Moreover,such a boosting of piezoelectric property is obtained under a maintained Curie temperature.Our research not only reveals the active control of defect dipole via modified poling method in the PIN-PMN-PT crystal,but also provides a feasible strategy to further improve the property of piezoelectric materials.
基金financially supported by the National Natural Science Foundation of China(No.52172127)the International Cooperation Project of Shaanxi Province+4 种基金China(No.2022KWZ-22)the National Key Research and Development Program of China(Nos.2021YFE0115000,2021YFB3800602)the Fundamental Research Funds for the Central Universities(No.XJTU)the Natural Science Basis Research Plan in Shaanxi Province of China(No.2020JM-635)the Youth Innovation Team of Shaanxi Universities and Scientific Research Program Funded by Shaanxi Provincial Education Department(No.21JK0869)。
文摘Lead-free dielectric ceramics can be used to make quick charge-discharge capacitor devices due to their high power density.Their use in advanced electronic systems,however,has been hampered by their poor energy storage performance(ESP),which includes low energy storage efficiency and recoverable energy storage density(Wrec).In this work,we adopted a combinatorial optimization strategy to improve the ESP in(Bi_(0.5)Na_(0.5))TiO_(3)(BNT)-based relaxor ferroelectric ceramics.To begin,the Bi-containing complex ions Bi(Mg_(2/3)Nb_(1/3))O_(3)(BMN)were introduced into a BNT-based matrix in order to improve the diffuse phase transition,increase Bi-O bond coupling,avoid macro domain development,and limit polarization response hysteresis.Second,the viscous polymer process was employed to reduce sample thickness and porosity,resulting in an apparent increase in breakdown strength in(1-x)[0.7(Bi_(1/2)Na_(1/2))TiO_(3)]-0.3SrTiO_(3)-xBi(Mg_(2/3)Nb_(1/3))O_(3)(BS-xBMN)ceramics.Finally,in x=0.20 composition,an amazing Wrecof 5.62 J·cm^(-3)and an ultra-high efficiency of 91.4%were simultaneously achieved at a relatively low field of 330 kV·cm^(-1),together with remarkable temperature stability in the temperature range of 30-140℃(3.5 J·cm^(-3)±5%variation).This research presents a new lead-free dielectric material with superior ESP for use in pulsed power capacitors.