Relaxor ferroic dielectrics have garnered increasing attention in the past decade as promising materials for energy storage.Among them,relaxor antiferroelectrics(AFEs)and relaxor ferroelectrics(FEs)have shown great pr...Relaxor ferroic dielectrics have garnered increasing attention in the past decade as promising materials for energy storage.Among them,relaxor antiferroelectrics(AFEs)and relaxor ferroelectrics(FEs)have shown great promise in term of high energy storage density and efficiency,respectively.In this study,a unique phase transition from relaxor AFE to relaxor FE was achieved for the first time by introducing strong-ferroelectricity BaTiO_(3)into NaNbO_(3)-BiFeO_(3)system,leading to an evolution from AFE R hierarchical nanodomains to FE polar nanoregions.A novel medium state,consisting of relaxor AFE and relaxor FE,was identified in the crossover of 0.88NaNbO_(3)–0.07BiFeO_(3)–0.05BaTiO_(3)ceramic,exhibiting a distinctive core-shell grain structure due to the composition segregation.By harnessing the advantages of high energy storage density from relaxor AFE and large efficiency from relaxor FE,the ceramic showcased excellent overall energy storage properties.It achieved a substantial recoverable energy storage density W_(rec)~13.1 J/cm^(3)and an ultrahigh efficiencyη~88.9%.These remarkable values shattered the trade-off relationship typically observed in most dielectric capacitors between W_(rec)andη.The findings of this study provide valuable insights for the design of ceramic capacitors with enhanced performance,specifically targeting the development of next generation pulse power devices.展开更多
New lead-free ferroelectric(0.94-x)BioNaTiO-0.06 BaTiOSrTiNbO(BNBT-STN,x = 0 and 0.2)are synthesized by using a solid state reaction process. In this work, an obvious evolution of dielectric relaxation behavior and sl...New lead-free ferroelectric(0.94-x)BioNaTiO-0.06 BaTiOSrTiNbO(BNBT-STN,x = 0 and 0.2)are synthesized by using a solid state reaction process. In this work, an obvious evolution of dielectric relaxation behavior and slim P-E hysteresis loops with high Pmax and low Pr is observed for BNBT-0.2 STN,indicating the dominant of ergodic relaxor phase with dynamic polar nano-regions(PNRs). A relatively large recoverable energy density(Wrec = 1.17 J/cm~3) with high energy efficiency(η= 91%) is obtained. Furthermore, it shows small variation(9%) in the temperature range of 30-150 ℃ and fatigue-free behavior,which can be attributed to the absence of ferroelectric domain in the relaxor phase. The achievement of these characteristics provides that tailoring by B-site vacancies is a potential route when designing a new energy-storage system for BNT-based relaxor ferroelectric materials.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
The microstructure,dielectric and ferroelectric properties of(1-y)Ba(Zr0.1Ti0.9)O3-yBa(Zn1/3Nb2/3)O3(y=0-0.05)ceramics prepared by traditional solid state method were investigated by X-ray diffractometer,scanning elec...The microstructure,dielectric and ferroelectric properties of(1-y)Ba(Zr0.1Ti0.9)O3-yBa(Zn1/3Nb2/3)O3(y=0-0.05)ceramics prepared by traditional solid state method were investigated by X-ray diffractometer,scanning electron microscope,electric parameter testing system and ferroelectric tester.It is found that the barium zirconate titanate based ceramics are single-phase perovskites as y increases up to 0.05 and their average grain size decreases with the increase of y.The permittivity maximumεr,max is suppressed from 8948 to 1611 at 1 kHz with increasing y,and the ferroelectric-paraelectric phase transition temperature Tm decreases from 93 to-89℃at 1 kHz as y increases.The composition-induced diffuse phase transition is enhanced with increasingy.The relaxor-like ferroelectric behavior with a strong frequency dispersion of Tm and permittivity at T<Tm accompanied by a strong diffuse phase transition is found for the system with high y value.The remnant polarization decreases with increasing y,while the coercive field decreases remarkably and then increases with the increase of y.展开更多
Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry.Herein,we design and prepare lead-free0.7Sr_(0....Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry.Herein,we design and prepare lead-free0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3BiFeO_(3)-x%Mn(x=0,0.5,1.5,2,3)thin films via sol-gel method.Mn ions of divalent valence combine with oxygen vacancies,forming defect complex,which results in marked decline in leakage current and obvious enhancement in breakdown strength.A high energy storage density~47.6 J cm^(-3)and good efficiency~65.68%are simultaneously achieved in 2%Mn doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor.Moreover,the 2%Mn-doped thin film exhibits excellent thermal stability in wide operating temperature range(35–115℃)and strong fatigue endurance behaviors after 108 cycles.The above results demonstrate that 2%Mn-doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor with superior energy storage performances is a potential candidate for electrostatic energy storage.展开更多
Investigations on the interconnection between the polarization rotation and crack propagation are performed for [110J-oriented 74Pb（Mg1/3Nb2/3）O3- 26PbTiO3 relaxor ferroelectric single crystal under electric loading...Investigations on the interconnection between the polarization rotation and crack propagation are performed for [110J-oriented 74Pb（Mg1/3Nb2/3）O3- 26PbTiO3 relaxor ferroelectric single crystal under electric loadings along [001] direction. The crystal is of predominantly monoclinic MA phase with scatter dis- tributed rhombohedral （R） phase under a moderate poling field of 900 V/mm in [00l] direction. With magnitude of 800 V/ram, a through thickness crack is initi- ated near the electrode by electric cycling. Static electric loadings is then imposed to the single crystal. As the applied static electric field increases, domain switch- ing in the monoclinic MA phase and phase transition from MA to R phase occur near the crack. The results indicate that the crack features a conducting one. Whether domain switching or phase transition occurs depends on the intensity of the electric field component that is perpendicular to the applied electric field.展开更多
To upgrade the electric properties of lead-free piezoceramics,(1-x)(Ba_(0.98)Ca_(0.02)Ti_(0.94)Sn_(0.04)Zr_(0.02))O_(3)-xY_(2)O_(3)(abbreviated as(1-x)BCTSZ-xY,x=0 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%and 0.1 m...To upgrade the electric properties of lead-free piezoceramics,(1-x)(Ba_(0.98)Ca_(0.02)Ti_(0.94)Sn_(0.04)Zr_(0.02))O_(3)-xY_(2)O_(3)(abbreviated as(1-x)BCTSZ-xY,x=0 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%and 0.1 mol%)ceramics were successfully synthesized by traditional solid-state sintering method.The phase structure and microstructure of ceramics were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM)and piezoresponse force microscopyeramics(PFM).The electric properties of ceramics were researched through piezoelectric,dielectric and ferroelectric test instruments.The results show that all samples have pure perovskite structure and favorable electric properties.The optimal electric properties which especially include superior ferroelectric properties are gained when Y_(2)O_(3)content is 0.06 mol%(d_(33)=419 pC/N,k_(p)=52%,T_(c)=89.5℃,ε_(r)=26900,tanδ=2.86%,P_(r)=14.41μC/cm^(2),Ec=1.8 kV/cm).Moreover,the temperature-dependent dielectricity of samples shows apparent relaxor behavior under different frequencies.The Curie-Weiss law further proves that all samples are typical relaxor ferroelectrics,and the relaxor degree of samples decreases with increase of Y_(2)O_(3)content.In conclusion,Y_(2)O_(3)plays a significant role in enhancing electric properties of BCTSZ ceramics.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
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
Ba（Zr, Ti）O3is a lead-free relaxor ferroelectric. Using the first-principles method, the ferroelectric dipole moments for pure BaTiO3 and Ba（Zr, Ti）O3supercells are studied. All possible ion configurations of Ba Z...Ba（Zr, Ti）O3is a lead-free relaxor ferroelectric. Using the first-principles method, the ferroelectric dipole moments for pure BaTiO3 and Ba（Zr, Ti）O3supercells are studied. All possible ion configurations of Ba Zr0.5Ti0.5O3 and Ba Zr0.25Ti0.75O3 are constructed in a 2 × 2 × 2 supercell. For the half-substituted case, divergence of ferroelectric properties is found from these structures, which greatly depends on the arrangements of Ti and Zr ions. Thus our results provide a reasonable explanation to the relaxor behavior of Ba（Zr, Ti）O3. In addition, a model based on the thermal statistics gives the averaged polarization for Ba（Zr, Ti）O3, which depends on the temperature of synthesis. Our result is helpful to understand and tune the relaxor ferroelectricity of lead-free Ba（Zr, Ti）O3.展开更多
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
The environmentally-friendly(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(x=0,0.02,0.04,0.06,0.08)relaxor ferroelectric ceramics were prepared by the conventional solid-state method and sintered in air at 1...The environmentally-friendly(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(x=0,0.02,0.04,0.06,0.08)relaxor ferroelectric ceramics were prepared by the conventional solid-state method and sintered in air at 1400°C for 2 h.SEM and XRD analyses were utilized to study the surface morphologies and the crystalline structures,respectively.The effects of BaMg_(0.1)Ta_(0.9))O_(3)on the phase transformation,dielectric and ferroelectric properties of Ba(Zr_(1/3)Ti_(2/3))O_(3)ceramics were also investigated.It is found that the average grain size of(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(BZT-BMT)perovskite single-phase ceramics decreases as the content of BaMg_(0.1)Ta_(0.9))O_(3)(BMT)increases.The relaxor ferroelectric behavior with diffuse phase transition and well-defined frequency dispersion of dielectric maximum temperature is found for the ceramic with increasing x values.0.98BZT-0.02BMT ceramic shows very good dielectric properties with the relative permittivity and the dielectric loss,measured at 100 k Hz as 6034 and 0.01399 respectively at room temperature.Both remnant polarization and coercive field decreased with increasing BMT content,indicating a transition from the ferroelectric phase to the paraelectric phase at room temperature.展开更多
Relaxor-PbTiO_(3)ferroelectric single crystals have drawn attention aiming at high-end piezoelectric applications thanks to their excellent piezoelectric properties.Like all the other ferroelectrics,relaxorPbTiO_(3)si...Relaxor-PbTiO_(3)ferroelectric single crystals have drawn attention aiming at high-end piezoelectric applications thanks to their excellent piezoelectric properties.Like all the other ferroelectrics,relaxorPbTiO_(3)single crystals can only be piezoelectrically active upon being electrically poled.However,this poled state is thermally unstable,limiting their uses because of their relatively low depolarization temperature.Here,we show that a non-destructible permanent poled state can be realized in relaxorPbTiO_(3)single crystals by forming a 0e3 composite in the presence of charged mobile point defects.We demonstrate this on solid-state grown 0.71 Pb(Mg1/3Nb2/3)O_(3)-0.29PbTiO_(3)single crystals doped with Mn(Mn-PMNT)as a donor with well-aligned and dispersed boron-rich MgO-based inclusions(MBIs).MnPMNTMBI sharing[001]axis with arrayed MBIs were spontaneously polarized during cooling across the Curie temperature without an external electricfield.The piezoelectric coefficient and dielectric permittivity of self-poled Mn-PMNTMBI crystals were as large as 90%of that achieved by a direct-current poling treatment at room temperature,and such poled state was reproducible against repeated thermal cycles.We expect that the poling-free high-performance piezoelectric relaxor-PbTiO_(3)single crystals offer an avenue for piezoelectric-based devices by removing the working temperature limit as one of the inherent fundamental limitations.展开更多
Dielectric capacitors are independent in advanced electronics and pulse power systems as an energy storage and conversion medium.However,achieving high energy density at a low electric field remains challenging for di...Dielectric capacitors are independent in advanced electronics and pulse power systems as an energy storage and conversion medium.However,achieving high energy density at a low electric field remains challenging for dielectric materials to improve the safety of integrated electronic devices.In this work,the strategy of defect engineering-induced phase competition is proposed to improve the polarization behavior and strengthen dielectric temperature stability of(Bi,Na)TiO_(3)(BNT)-based relaxor ferroelectric,i.e.,Na_(0.325)Sr_(0.245)Ba_(0.105-1.5x)□0.5xBi_(0.325tx)TiO_(3)(NSB_(0.105-1.5x)□0.5xB_(0.325tx)T)ceramics by changing the ratio of Bi^(3+)/Ba^(2+).A high recoverable energy density(Wrec=3.6 J/cm^(3))is achieved at a relatively low electric field of 160 kV/cm for x=0.06 composition together with a high dielectric constant of 3142%±15%in a wide temperature range of 30-386℃,which exceeds other lead-free dielectric ceramics at the same electric field.The results demonstrate that NSB_(0.015)□0.03B_(0.385)T ceramics are desirable for advanced pulsed power capacitors and will push the development of defect-tuned functionality of dielectric ceramics for energy storage applications.展开更多
Bioinspired soft robots hold great potential to perform tasks in unstructured terrains.Ferroelectric polymers are highly valued in soft robots for their flexibility,lightweight,and electrically controllable deformatio...Bioinspired soft robots hold great potential to perform tasks in unstructured terrains.Ferroelectric polymers are highly valued in soft robots for their flexibility,lightweight,and electrically controllable deformation.However,achieving large strains in ferroelectric polymers typically requires high driving voltages,posing a significant challenge for practical applications.In this study,we investigate the role of crystalline domain size in enhancing the electrostrain performance of the relaxor ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene-fluorinated alkynes)(P(VDFTrFE-CFE-FA)).Leveraging its remarkable inverse piezoelectric coefficient(|d33^(*)|=701 pm V^(-1)),we demonstrate that the planar films exhibit a five times larger bending angle than that of commercial PVDF films at low electric fields.Based on this material,we design a petal-structured soft robot that achieves a curvature of up to 4.5 cm^(-1) at a DC electric field of 30 Vμm^(-1).When integrated into a bipedal soft robot,it manifests outstanding electrostrain performance,achieving rapid locomotion of~19 body lengths per second(BL s^(-1))at 10 Vμm^(-1)(560 Hz).Moreover,the developed robot demonstrates remarkable abilities in climbing slopes and carrying heavy loads.These findings open new avenues for developing low-voltage-driven soft robots with significant promise for practical applications.展开更多
Dielectric capacitors with high energy storage performances are exceedingly desired for the nextgeneration advanced high/pulsed power devices that demand miniaturization and integration.However,poor energy-storage den...Dielectric capacitors with high energy storage performances are exceedingly desired for the nextgeneration advanced high/pulsed power devices that demand miniaturization and integration.However,poor energy-storage density(U_(rec))and low efficiency(η)resulted from the large remanent polarization(P_(r))and low breakdown strength(BDS),have been the major challenge for the application of dielectric capacitors.Herein,a high-entropy strategy with superparaelectric relaxor ferroelectrics(SPRFE)was adopted to achieve extremely low Pr and high BDS in BaTiO_(3)system,simultaneously.Due to the high BDS~800 kV/cm and low Pr~0.58 mC/cm^(2),high-entropy SP-RFE(La_(0.05)Ba_(0.18)Sr_(0.18)K_(0.115)Na_(0.115)-Ca_(0.18)Bi_(0.18))TiO_(3)(LBSKNCBT)MLCCs exhibited high Urec~6.63 J/cm^(3)and excellent h~96%.What's more,LBSKNCBT MLCCs with high-entropy and SP-RFE characteristic also possess a good temperature and frequency stability.In a word,this work offers an excellent paradigm for achieving good energy-storage properties of BaTiO_(3)-based dielectric capacitors to meet the demanding requirements of advanced energy storage applications.展开更多
This paper studies the relaxation processes and electromechanical hysteresis in relaxor piezoceramics based on the PzT system.Measurements and analysis of the electric displacement and mechanical strain hysteresis loo...This paper studies the relaxation processes and electromechanical hysteresis in relaxor piezoceramics based on the PzT system.Measurements and analysis of the electric displacement and mechanical strain hysteresis loops recorded in bipolar AC electric fields in the frequency range 0.001-5 Hz were performed by means of the electromechanical response characterization system(STEPHV)and program(STEP).It was found that the coercive field,remnant and saturation electric displacement,area of hysteresis loops and relative mechanical strain values are strongly dependent on frequency.As a result of this study,complete sets of parameters characterizing the switching and ferroelectric hysteresis processes in relaxor piezoceramics were obtained.展开更多
(Ba_((1-x))Bi_(x))(Ti_((1-x))Mg_(2 x/3)Ta_(x/3))O_(3)(BBTMT-x,x=0.075,0.1,0.125,and 0.15)ceramics were manufactured via a solid-phase reaction method.The pseudo-cubic BaTiO_(3)(BT)as the primary phase and Ba_(4)MgTi_(...(Ba_((1-x))Bi_(x))(Ti_((1-x))Mg_(2 x/3)Ta_(x/3))O_(3)(BBTMT-x,x=0.075,0.1,0.125,and 0.15)ceramics were manufactured via a solid-phase reaction method.The pseudo-cubic BaTiO_(3)(BT)as the primary phase and Ba_(4)MgTi_(11)O_(27)as the secondary phase were detected in BBTMT-x ceramics.The elongated rod-shaped grains therein be-came numerous as x increased.The introduction of Bi/Mg/Ta(BMT)elements transformed BT ceramics from ferroelectrics to relaxor ferroelectrics and induced the formation of short-range order polar nanore-gions(PNRs),which were beneficial for the preeminent energy storage properties(ESPs).The highest ESPs(a giant recoverable energy-storage density W_(rec)of 5.97 J cm^(-3)with a high-efficiencyηof 87.4%)were achieved in BBTMT-0.1 ceramics at 710 kV cm^(-1).BBTMT-0.1 ceramics also possessed excellent fre-quency(1-500 Hz),temperature(30-150℃),and fatigue(cycle number of 1-100,000)stabilities.Finite element simulations(FES)demonstrated that elongated rod-shaped grains had stronger obstacles to the development of electrical branches,which was beneficial to improving the comprehensive ESPs.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
基金financially supported by the National Natural Science Foundation of China(Nos.52172181,22105017)Interdisciplinary Research Project for Young Teachers of USTB(No.FRFIDRY-21–002)。
文摘Relaxor ferroic dielectrics have garnered increasing attention in the past decade as promising materials for energy storage.Among them,relaxor antiferroelectrics(AFEs)and relaxor ferroelectrics(FEs)have shown great promise in term of high energy storage density and efficiency,respectively.In this study,a unique phase transition from relaxor AFE to relaxor FE was achieved for the first time by introducing strong-ferroelectricity BaTiO_(3)into NaNbO_(3)-BiFeO_(3)system,leading to an evolution from AFE R hierarchical nanodomains to FE polar nanoregions.A novel medium state,consisting of relaxor AFE and relaxor FE,was identified in the crossover of 0.88NaNbO_(3)–0.07BiFeO_(3)–0.05BaTiO_(3)ceramic,exhibiting a distinctive core-shell grain structure due to the composition segregation.By harnessing the advantages of high energy storage density from relaxor AFE and large efficiency from relaxor FE,the ceramic showcased excellent overall energy storage properties.It achieved a substantial recoverable energy storage density W_(rec)~13.1 J/cm^(3)and an ultrahigh efficiencyη~88.9%.These remarkable values shattered the trade-off relationship typically observed in most dielectric capacitors between W_(rec)andη.The findings of this study provide valuable insights for the design of ceramic capacitors with enhanced performance,specifically targeting the development of next generation pulse power devices.
基金supported by the National Natural Science Foundation of China(51702249,51602252,61741406)the China Postdoctoral Science Foundation(2017M613065)the Shaanxi Province Science Foundation(2017JQ5072)
文摘New lead-free ferroelectric(0.94-x)BioNaTiO-0.06 BaTiOSrTiNbO(BNBT-STN,x = 0 and 0.2)are synthesized by using a solid state reaction process. In this work, an obvious evolution of dielectric relaxation behavior and slim P-E hysteresis loops with high Pmax and low Pr is observed for BNBT-0.2 STN,indicating the dominant of ergodic relaxor phase with dynamic polar nano-regions(PNRs). A relatively large recoverable energy density(Wrec = 1.17 J/cm~3) with high energy efficiency(η= 91%) is obtained. Furthermore, it shows small variation(9%) in the temperature range of 30-150 ℃ and fatigue-free behavior,which can be attributed to the absence of ferroelectric domain in the relaxor phase. The achievement of these characteristics provides that tailoring by B-site vacancies is a potential route when designing a new energy-storage system for BNT-based relaxor ferroelectric materials.
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sponsored by the National Demonstration Center for Experimental Materials Science and Engineering Education (Jiangsu University of Science and Technology, China)the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions, China
文摘The microstructure,dielectric and ferroelectric properties of(1-y)Ba(Zr0.1Ti0.9)O3-yBa(Zn1/3Nb2/3)O3(y=0-0.05)ceramics prepared by traditional solid state method were investigated by X-ray diffractometer,scanning electron microscope,electric parameter testing system and ferroelectric tester.It is found that the barium zirconate titanate based ceramics are single-phase perovskites as y increases up to 0.05 and their average grain size decreases with the increase of y.The permittivity maximumεr,max is suppressed from 8948 to 1611 at 1 kHz with increasing y,and the ferroelectric-paraelectric phase transition temperature Tm decreases from 93 to-89℃at 1 kHz as y increases.The composition-induced diffuse phase transition is enhanced with increasingy.The relaxor-like ferroelectric behavior with a strong frequency dispersion of Tm and permittivity at T<Tm accompanied by a strong diffuse phase transition is found for the system with high y value.The remnant polarization decreases with increasing y,while the coercive field decreases remarkably and then increases with the increase of y.
基金the National Natural Science Foundation of China under Grant No.51332003 and 51372171。
文摘Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry.Herein,we design and prepare lead-free0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3BiFeO_(3)-x%Mn(x=0,0.5,1.5,2,3)thin films via sol-gel method.Mn ions of divalent valence combine with oxygen vacancies,forming defect complex,which results in marked decline in leakage current and obvious enhancement in breakdown strength.A high energy storage density~47.6 J cm^(-3)and good efficiency~65.68%are simultaneously achieved in 2%Mn doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor.Moreover,the 2%Mn-doped thin film exhibits excellent thermal stability in wide operating temperature range(35–115℃)and strong fatigue endurance behaviors after 108 cycles.The above results demonstrate that 2%Mn-doped 0.7Sr_(0.7)Bi_(0.2)TiO_(3)-0.3 BiFeO_(3)thin film capacitor with superior energy storage performances is a potential candidate for electrostatic energy storage.
基金supported by the National Natural Science Foundation of China(11272174)
文摘Investigations on the interconnection between the polarization rotation and crack propagation are performed for [110J-oriented 74Pb（Mg1/3Nb2/3）O3- 26PbTiO3 relaxor ferroelectric single crystal under electric loadings along [001] direction. The crystal is of predominantly monoclinic MA phase with scatter dis- tributed rhombohedral （R） phase under a moderate poling field of 900 V/mm in [00l] direction. With magnitude of 800 V/ram, a through thickness crack is initi- ated near the electrode by electric cycling. Static electric loadings is then imposed to the single crystal. As the applied static electric field increases, domain switch- ing in the monoclinic MA phase and phase transition from MA to R phase occur near the crack. The results indicate that the crack features a conducting one. Whether domain switching or phase transition occurs depends on the intensity of the electric field component that is perpendicular to the applied electric field.
基金Project supported by the Guizhou Province Graduate Research Fund(YJSCXJH2020029)Specialized Funds from Industry and Information Technology Department of Guizhou Province(2016056)+1 种基金the National Natural Science Foundation of China(51602066)High-level Innovative Talents Plan of Guizhou Province((2015)4009)。
文摘To upgrade the electric properties of lead-free piezoceramics,(1-x)(Ba_(0.98)Ca_(0.02)Ti_(0.94)Sn_(0.04)Zr_(0.02))O_(3)-xY_(2)O_(3)(abbreviated as(1-x)BCTSZ-xY,x=0 mol%,0.02 mol%,0.04 mol%,0.06 mol%,0.08 mol%and 0.1 mol%)ceramics were successfully synthesized by traditional solid-state sintering method.The phase structure and microstructure of ceramics were investigated by X-ray diffraction(XRD),scanning electron microscopy(SEM)and piezoresponse force microscopyeramics(PFM).The electric properties of ceramics were researched through piezoelectric,dielectric and ferroelectric test instruments.The results show that all samples have pure perovskite structure and favorable electric properties.The optimal electric properties which especially include superior ferroelectric properties are gained when Y_(2)O_(3)content is 0.06 mol%(d_(33)=419 pC/N,k_(p)=52%,T_(c)=89.5℃,ε_(r)=26900,tanδ=2.86%,P_(r)=14.41μC/cm^(2),Ec=1.8 kV/cm).Moreover,the temperature-dependent dielectricity of samples shows apparent relaxor behavior under different frequencies.The Curie-Weiss law further proves that all samples are typical relaxor ferroelectrics,and the relaxor degree of samples decreases with increase of Y_(2)O_(3)content.In conclusion,Y_(2)O_(3)plays a significant role in enhancing electric properties of BCTSZ ceramics.
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.
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Project supported by the National Natural Science Foundation of China(Grant Nos.51322206 and 11274060)the Natural Science Foundation of Jiangsu ProvinceChina(Grant No.15KJB140009)
文摘Ba（Zr, Ti）O3is a lead-free relaxor ferroelectric. Using the first-principles method, the ferroelectric dipole moments for pure BaTiO3 and Ba（Zr, Ti）O3supercells are studied. All possible ion configurations of Ba Zr0.5Ti0.5O3 and Ba Zr0.25Ti0.75O3 are constructed in a 2 × 2 × 2 supercell. For the half-substituted case, divergence of ferroelectric properties is found from these structures, which greatly depends on the arrangements of Ti and Zr ions. Thus our results provide a reasonable explanation to the relaxor behavior of Ba（Zr, Ti）O3. In addition, a model based on the thermal statistics gives the averaged polarization for Ba（Zr, Ti）O3, which depends on the temperature of synthesis. Our result is helpful to understand and tune the relaxor ferroelectricity of lead-free Ba（Zr, Ti）O3.
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fully sponsored by the National Demonstration Center for Experimental Materials Science and Engineering Education(Jiangsu University of Science and Technology,China)funded by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,China。
文摘The environmentally-friendly(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(x=0,0.02,0.04,0.06,0.08)relaxor ferroelectric ceramics were prepared by the conventional solid-state method and sintered in air at 1400°C for 2 h.SEM and XRD analyses were utilized to study the surface morphologies and the crystalline structures,respectively.The effects of BaMg_(0.1)Ta_(0.9))O_(3)on the phase transformation,dielectric and ferroelectric properties of Ba(Zr_(1/3)Ti_(2/3))O_(3)ceramics were also investigated.It is found that the average grain size of(1-x)Ba(Zr_(1/3)Ti_(2/3))O_(3)-xBaMg_(0.1)Ta_(0.9))O_(3)(BZT-BMT)perovskite single-phase ceramics decreases as the content of BaMg_(0.1)Ta_(0.9))O_(3)(BMT)increases.The relaxor ferroelectric behavior with diffuse phase transition and well-defined frequency dispersion of dielectric maximum temperature is found for the ceramic with increasing x values.0.98BZT-0.02BMT ceramic shows very good dielectric properties with the relative permittivity and the dielectric loss,measured at 100 k Hz as 6034 and 0.01399 respectively at room temperature.Both remnant polarization and coercive field decreased with increasing BMT content,indicating a transition from the ferroelectric phase to the paraelectric phase at room temperature.
基金the Technology Innovation Program funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)(20022441)JHK was supported by the Fundamental Research Program of Korea Institute of Materials Science(PNKA170).
文摘Relaxor-PbTiO_(3)ferroelectric single crystals have drawn attention aiming at high-end piezoelectric applications thanks to their excellent piezoelectric properties.Like all the other ferroelectrics,relaxorPbTiO_(3)single crystals can only be piezoelectrically active upon being electrically poled.However,this poled state is thermally unstable,limiting their uses because of their relatively low depolarization temperature.Here,we show that a non-destructible permanent poled state can be realized in relaxorPbTiO_(3)single crystals by forming a 0e3 composite in the presence of charged mobile point defects.We demonstrate this on solid-state grown 0.71 Pb(Mg1/3Nb2/3)O_(3)-0.29PbTiO_(3)single crystals doped with Mn(Mn-PMNT)as a donor with well-aligned and dispersed boron-rich MgO-based inclusions(MBIs).MnPMNTMBI sharing[001]axis with arrayed MBIs were spontaneously polarized during cooling across the Curie temperature without an external electricfield.The piezoelectric coefficient and dielectric permittivity of self-poled Mn-PMNTMBI crystals were as large as 90%of that achieved by a direct-current poling treatment at room temperature,and such poled state was reproducible against repeated thermal cycles.We expect that the poling-free high-performance piezoelectric relaxor-PbTiO_(3)single crystals offer an avenue for piezoelectric-based devices by removing the working temperature limit as one of the inherent fundamental limitations.
基金supported by National Natural Science Foundation of China(52267002)Natural Science Foundation of Jiangxi Province(20212ACB204010)Science&Technology Research Project of Jiangxi Provincial Education Department(GJJ211301).
文摘Dielectric capacitors are independent in advanced electronics and pulse power systems as an energy storage and conversion medium.However,achieving high energy density at a low electric field remains challenging for dielectric materials to improve the safety of integrated electronic devices.In this work,the strategy of defect engineering-induced phase competition is proposed to improve the polarization behavior and strengthen dielectric temperature stability of(Bi,Na)TiO_(3)(BNT)-based relaxor ferroelectric,i.e.,Na_(0.325)Sr_(0.245)Ba_(0.105-1.5x)□0.5xBi_(0.325tx)TiO_(3)(NSB_(0.105-1.5x)□0.5xB_(0.325tx)T)ceramics by changing the ratio of Bi^(3+)/Ba^(2+).A high recoverable energy density(Wrec=3.6 J/cm^(3))is achieved at a relatively low electric field of 160 kV/cm for x=0.06 composition together with a high dielectric constant of 3142%±15%in a wide temperature range of 30-386℃,which exceeds other lead-free dielectric ceramics at the same electric field.The results demonstrate that NSB_(0.015)□0.03B_(0.385)T ceramics are desirable for advanced pulsed power capacitors and will push the development of defect-tuned functionality of dielectric ceramics for energy storage applications.
基金National Natural Science Foundation of China,Grant/Award Number:U2330120Natural Science Foundation of Sichuan Province of China,Grant/Award Number:2023NSFSC0313Basic Research Cultivation Project of Southwest Jiaotong University,Grant/Award Number:2682023KJ024。
文摘Bioinspired soft robots hold great potential to perform tasks in unstructured terrains.Ferroelectric polymers are highly valued in soft robots for their flexibility,lightweight,and electrically controllable deformation.However,achieving large strains in ferroelectric polymers typically requires high driving voltages,posing a significant challenge for practical applications.In this study,we investigate the role of crystalline domain size in enhancing the electrostrain performance of the relaxor ferroelectric polymer poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene-fluorinated alkynes)(P(VDFTrFE-CFE-FA)).Leveraging its remarkable inverse piezoelectric coefficient(|d33^(*)|=701 pm V^(-1)),we demonstrate that the planar films exhibit a five times larger bending angle than that of commercial PVDF films at low electric fields.Based on this material,we design a petal-structured soft robot that achieves a curvature of up to 4.5 cm^(-1) at a DC electric field of 30 Vμm^(-1).When integrated into a bipedal soft robot,it manifests outstanding electrostrain performance,achieving rapid locomotion of~19 body lengths per second(BL s^(-1))at 10 Vμm^(-1)(560 Hz).Moreover,the developed robot demonstrates remarkable abilities in climbing slopes and carrying heavy loads.These findings open new avenues for developing low-voltage-driven soft robots with significant promise for practical applications.
基金supported by National Natural Science Foundation of China(No.52272104)Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities)(No.FRF-IDRY-21-002).
文摘Dielectric capacitors with high energy storage performances are exceedingly desired for the nextgeneration advanced high/pulsed power devices that demand miniaturization and integration.However,poor energy-storage density(U_(rec))and low efficiency(η)resulted from the large remanent polarization(P_(r))and low breakdown strength(BDS),have been the major challenge for the application of dielectric capacitors.Herein,a high-entropy strategy with superparaelectric relaxor ferroelectrics(SPRFE)was adopted to achieve extremely low Pr and high BDS in BaTiO_(3)system,simultaneously.Due to the high BDS~800 kV/cm and low Pr~0.58 mC/cm^(2),high-entropy SP-RFE(La_(0.05)Ba_(0.18)Sr_(0.18)K_(0.115)Na_(0.115)-Ca_(0.18)Bi_(0.18))TiO_(3)(LBSKNCBT)MLCCs exhibited high Urec~6.63 J/cm^(3)and excellent h~96%.What's more,LBSKNCBT MLCCs with high-entropy and SP-RFE characteristic also possess a good temperature and frequency stability.In a word,this work offers an excellent paradigm for achieving good energy-storage properties of BaTiO_(3)-based dielectric capacitors to meet the demanding requirements of advanced energy storage applications.
基金financially supported by the Russian Science Foundation Grant No.24-22-00063,https:/rscf.ru/project/24-22-00063/at the Southern Federal University.
文摘This paper studies the relaxation processes and electromechanical hysteresis in relaxor piezoceramics based on the PzT system.Measurements and analysis of the electric displacement and mechanical strain hysteresis loops recorded in bipolar AC electric fields in the frequency range 0.001-5 Hz were performed by means of the electromechanical response characterization system(STEPHV)and program(STEP).It was found that the coercive field,remnant and saturation electric displacement,area of hysteresis loops and relative mechanical strain values are strongly dependent on frequency.As a result of this study,complete sets of parameters characterizing the switching and ferroelectric hysteresis processes in relaxor piezoceramics were obtained.
基金supported by the Natural Science Foundation of Shandong Province of China(Nos.ZR2020ME035,ZR2020QE043,and ZR2020QE044)National Natural Science Foundation of China(Nos.51872166,52102132,and 52177020)+1 种基金Postdoctoral Science Foundation of China(No.2017M622196)Opening Project of Key Laboratory of Inorganic Functional Materials and Devices,Chinese Academy of Sciences(No.KLIFMD201705).
文摘(Ba_((1-x))Bi_(x))(Ti_((1-x))Mg_(2 x/3)Ta_(x/3))O_(3)(BBTMT-x,x=0.075,0.1,0.125,and 0.15)ceramics were manufactured via a solid-phase reaction method.The pseudo-cubic BaTiO_(3)(BT)as the primary phase and Ba_(4)MgTi_(11)O_(27)as the secondary phase were detected in BBTMT-x ceramics.The elongated rod-shaped grains therein be-came numerous as x increased.The introduction of Bi/Mg/Ta(BMT)elements transformed BT ceramics from ferroelectrics to relaxor ferroelectrics and induced the formation of short-range order polar nanore-gions(PNRs),which were beneficial for the preeminent energy storage properties(ESPs).The highest ESPs(a giant recoverable energy-storage density W_(rec)of 5.97 J cm^(-3)with a high-efficiencyηof 87.4%)were achieved in BBTMT-0.1 ceramics at 710 kV cm^(-1).BBTMT-0.1 ceramics also possessed excellent fre-quency(1-500 Hz),temperature(30-150℃),and fatigue(cycle number of 1-100,000)stabilities.Finite element simulations(FES)demonstrated that elongated rod-shaped grains had stronger obstacles to the development of electrical branches,which was beneficial to improving the comprehensive ESPs.
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.
