Dielectric ceramics with ultrahigh power density and ultrafast charge/discharge rates are crucial components of advanced dielectric capacitors. However, enhancing their comprehensive performance remains a major challe...Dielectric ceramics with ultrahigh power density and ultrafast charge/discharge rates are crucial components of advanced dielectric capacitors. However, enhancing their comprehensive performance remains a major challenge for cutting-edge applications. Here, a high-entropy strategy is proposed to construct multiple local distortions, including various types of oxygen octahedral tilts, highly dynamic polar nanoregions, and lattice distortions. This approach effectively delays polarization saturation, reduces energy loss, and, in conjunction with the ultrafine grains induced by the high-entropy effect, enhances mechanical properties and breakdown field. Therefore, a remarkable recoverable energy density of 9.1 J cm-3, a high conversion efficiency of 82.7 %, and a large Vickers hardness of 8.77 GPa are simultaneously achieved in 0.73Bi_(0.47)Na_(0.47)Ba_(0.06)TiO_(3)-0.27Ca_(0.7)La_(0.2)Zr_(0.15)Ti_(0.85)O_(3) lead-free high-entropy relaxors. Additionally, superior frequency and temperature stability, as well as excellent charge/discharge performance, are also obtained. These findings demonstrate that the high-entropy strategy is a promising method for designing high-performance dielectric ceramics.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
(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
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
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
Cutting-edge high/pulsed power capacitors with satisfactory power density are fundamental units in modern power storage systems.However,a persistent challenge is how to overcome the trade-off between recoverable energ...Cutting-edge high/pulsed power capacitors with satisfactory power density are fundamental units in modern power storage systems.However,a persistent challenge is how to overcome the trade-off between recoverable energy storage density(W_(rec))and efficiency(η)for meeting the miniaturization and integration of advanced applications.Here,multiple local distortions including inhomogeneous functional nanoclusters,(anti)ferro-distortions and highly dynamic polar nanoregions are modulated through a highentropy strategy to design a stable ergodic-relaxor-state-dominated structure.Of great importance,this strategy delay polarization saturation,reduces hysteresis and improves breakdown strength,so that an ultrahigh W_(rec)~11.94J/cm^(3)with a η~82,4%is realized in Pb-free ergodic-relaxors.Moreover,a significant Vickers hardness of 10.04 GPa as well as superior temperature,cycling and frequency stabilities are also obtained.This work demonstrates that designing multiple local distortions via a high-entropy strategy is a promising way to realize superior comprehensive energy storage properties in high/pulsed power capacitors.展开更多
Developing high-performance lead-free electrostrain materials is key to advancing next-generation electromechanical technologies.Here we report an aliovalent co-doping strategy in(Bi_(0.5)Na_(0.5))TiO_(3)-based(BNT-ba...Developing high-performance lead-free electrostrain materials is key to advancing next-generation electromechanical technologies.Here we report an aliovalent co-doping strategy in(Bi_(0.5)Na_(0.5))TiO_(3)-based(BNT-based)ceramics,where simultaneous A-site(Li^(+))and B-site(Nb^(5+))co-doping yields(1−x)Bi_(0.5)(Na_(0.81)K_(0.19))0.5TiO_(3)-xLiNbO_(3)(BNKT-xLN,x=0.01-0.04)compositions.The aliovalent substitution disrupts long-range ferroelectric order,enhances lattice distortion,and promotes a relaxor-like state with diffuse phase transitions and strong dielectric dispersion.Complementary polarization-electric field(P-E)and strain-electric field(S-E)measurements demonstrate a progressive evolution from classical ferroelectrisc to nonergodic relaxor behavior as the doping level increases.The optimized composition at x=0.02 exhibits a large reversible electrostrain of approximately 0.55% associated with a temperature-driven reversible phase transition.Notably,BNKT-xLN ceramics achieve electric-field-induced polarizations exceeding 50μC/cm^(2),while exhibiting a relatively low electrostrictive coefficient Q33 of∼0.018 m^(4)/C^(2),suggesting their potential as energy storage matrices due to the weak polarization-strain coupling effect.These results underscore the importance of aliovalent co-doping strategy in modulating the energy landscape of BNT-based systems,offering a viable strategy for developing high-strain,lead-free electroceramics suited to next-generation actuators and energy storage devices.展开更多
Dielectric ceramics have attracted extensive attention for high-power energy storage applications due to their fast charge-discharge capabilities and high power density.Bi_(0.5)Na_(0.5)TiO_(3)(BNT)-based lead-free cer...Dielectric ceramics have attracted extensive attention for high-power energy storage applications due to their fast charge-discharge capabilities and high power density.Bi_(0.5)Na_(0.5)TiO_(3)(BNT)-based lead-free ceramics are notable for their high saturation polarization and moderate breakdown electric field(Eb),but they still suffer from a low breakdown field,large hysteresis losses and insufficient efficiency.Here,we propose a strategy of dual-site ion-pair engineering by introducing Ba(Sr_(0.5)W_(0.5))O_(3)(BSW)into the BNT matrix.In this design,Ba^(2+)-Ba^(2+)pairs at the A-site and Sr^(2+)-W^(6+)pairs at the B-site induce local lattice distortion and generate strong random fields,which effectively promote the formation of multiple relaxor phases with polymorphic nanodomains.The features of electrical properties and phase-field simulations indicate that BSW doping facilitates greater compositional disorder and disruption of long-range FE order,integrating the short-range ordered antiferroelectric(AFE)nanodomains with highly disordered relaxor ferroelectric(RFE)regions to reduce the electric field-induced AFE-FE phase transition barrier.Additionally,the incorporation of BSW refines the grain size and increases microstructural homogeneity,enhancing the breakdown strength and delaying the polarization saturation.Accordingly,the 0.90BNT-0.10BSW ceramic exhibited an outstanding energy storage performance with a high W_(rec) of 6.57 J cm^(-3) and anηof 72%under an electric field of 450 kV cm^(-1).In addition,the ceramic synchronously possesses an excellent transient discharge rate t0.9 of 90 ns and a high power density PD of 121.9 MW cm^(-3).This work suggests that dual-site ion-pair engineering is an effective approach for regulating structure-property relationships in BNT-based ceramics and provides a viable pathway for the development of high-performance lead-free dielectric materials for advanced energy storage applications.展开更多
Lead-free ceramic-based dielectric capacitors demonstrate significant potential for pulse power energy storage applications due to their high power density and rapid charge/discharge characteristics.In this study,high...Lead-free ceramic-based dielectric capacitors demonstrate significant potential for pulse power energy storage applications due to their high power density and rapid charge/discharge characteristics.In this study,highly dynamic polar nanoregions(PNRs)were constructed in(1-x)[_(0.9)_(2)Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)-0.08Bi(Zn_(2/3)Ta_(1/3))O_(3)]-xBi_(0.5)Na_(0.5)TiO_(3)(abbreviated as BNTx)dielectric ceramics by introducing the strongly polar relaxor end-member Bi_(0.5)Na_(0.5)TiO_(3)(BNT).Meanwhile,the hybridization of Bi 6s and O 2p orbitals improves the polarization capability of the ceramics,resulting in a larger polarization difference(ΔP~47.8μC cm^(-2)).Furthermore,due to the high doping concentration of BNT and Ta donor doping,BNTx relaxor ferroelectrics exhibit high bulk resistivity,submicron grain size(~0.57μm),and wide bandgap characteristics,leading to a remarkable improvement in breakdown strength(E_(b)~710 kV cm^(-1)).Both the electroactive regions corresponding to the bulk and grain boundaries showed similar characteristics,indicating a homogeneous electrical microstructure and intrinsic resistance which significantly contributed to maintaining the high resistivity of the samples.Through compositional optimization,the 20%BNT-doped BCZT-based relaxor ferroelectric ceramic(BNT20)achieves a Vickers hardness of~8.608 GPa while demonstrating exceptional energy storage performance,including an outstanding recoverable energy density(W_(rec))of~10.6 J cm^(-3)and ultrahigh energy efficiency(η)of~87%.Notably,the stable PNRs significantly improved the temperature and frequency stability of the dielectric constant and energy storage performance.Furthermore,the BNT20 ceramic exhibits a high current density(C_(D)~1108.3 A cm^(-2)),power density(P_(D)~132.99 MW cm^(-3)),and an ultrafast discharge speed(t_(0.9)~79.9 ns),demonstrating its promising application prospects in pulse power systems.展开更多
The electro-optical(E-O)properties of relaxor ferroelectric single crystals have received extensive attention in recent years,but their light transmittance is still a major obstacle limiting their optical properties.T...The electro-optical(E-O)properties of relaxor ferroelectric single crystals have received extensive attention in recent years,but their light transmittance is still a major obstacle limiting their optical properties.This study successfully grew the Eu-doped Pb(In_(1/2) Nb_(1/2))O_(3)-Pb(Mg_(1/3) Nb_(2/3))O_(3)-PbTiO_(3)(PIN-PMN-PT)relaxor ferroelectric single crystal using the modified Bridgman method.The Eu-PIN-PMN-PT crystal had high piezoelectric properties,high coercive fields,and temperature stability.The dielectric behavior at low temperatures showed that the Eu-PIN-PMN-PT crystal had more polar nano-regions(PNRs)than the undoped PIN-PMN-PT crystal to improve its piezoelectric properties.A thorough evaluation of the full matrix of electromechanical parameters was conducted,yielding a comprehensive understanding of the material’s properties in different directions.Meanwhile,after polarization along the[110]direction,the crystal obtained a high transmittance along the[001]direction,and an effective electro-optical coefficient of up to 420 pm/V was measured at room temperature.Due to excellent comprehensive properties,Eu-PIN-PMN-PT crystals are expected to be ideal materials for piezoelectric and electro-optical devices.展开更多
基金supported by the National Natural Science Foundation of China(No.52102129)the Hunan Provin-cial Natural Science Foundation of China(No.2023JJ30138)the Science and Technology Innovation Program of Hunan Province(2023RC3094).
文摘Dielectric ceramics with ultrahigh power density and ultrafast charge/discharge rates are crucial components of advanced dielectric capacitors. However, enhancing their comprehensive performance remains a major challenge for cutting-edge applications. Here, a high-entropy strategy is proposed to construct multiple local distortions, including various types of oxygen octahedral tilts, highly dynamic polar nanoregions, and lattice distortions. This approach effectively delays polarization saturation, reduces energy loss, and, in conjunction with the ultrafine grains induced by the high-entropy effect, enhances mechanical properties and breakdown field. Therefore, a remarkable recoverable energy density of 9.1 J cm-3, a high conversion efficiency of 82.7 %, and a large Vickers hardness of 8.77 GPa are simultaneously achieved in 0.73Bi_(0.47)Na_(0.47)Ba_(0.06)TiO_(3)-0.27Ca_(0.7)La_(0.2)Zr_(0.15)Ti_(0.85)O_(3) lead-free high-entropy relaxors. Additionally, superior frequency and temperature stability, as well as excellent charge/discharge performance, are also obtained. These findings demonstrate that the high-entropy strategy is a promising method for designing high-performance dielectric ceramics.
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supported by the National Natural Science Foundation of China(No.52102129)the Hunan Provincial Natural Science Foundation of China(No.2023JJ30138)+1 种基金the Science Technology Innovation Program of Hunan Province(No.2023RC3094)the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China。
文摘Cutting-edge high/pulsed power capacitors with satisfactory power density are fundamental units in modern power storage systems.However,a persistent challenge is how to overcome the trade-off between recoverable energy storage density(W_(rec))and efficiency(η)for meeting the miniaturization and integration of advanced applications.Here,multiple local distortions including inhomogeneous functional nanoclusters,(anti)ferro-distortions and highly dynamic polar nanoregions are modulated through a highentropy strategy to design a stable ergodic-relaxor-state-dominated structure.Of great importance,this strategy delay polarization saturation,reduces hysteresis and improves breakdown strength,so that an ultrahigh W_(rec)~11.94J/cm^(3)with a η~82,4%is realized in Pb-free ergodic-relaxors.Moreover,a significant Vickers hardness of 10.04 GPa as well as superior temperature,cycling and frequency stabilities are also obtained.This work demonstrates that designing multiple local distortions via a high-entropy strategy is a promising way to realize superior comprehensive energy storage properties in high/pulsed power capacitors.
基金supported by the National Natural Science Foundation of China(Grant Nos.52302153 and 52402155)the China Postdoctoral Science Foundation(Grant Nos.GZC20232075 and 2023M742767)the Youth Innovation Team of Shaanxi Universities,and the Scientific Research Program Funded by Shaanxi Provincial Education Department,China(Grant No.22JP073)。
文摘Developing high-performance lead-free electrostrain materials is key to advancing next-generation electromechanical technologies.Here we report an aliovalent co-doping strategy in(Bi_(0.5)Na_(0.5))TiO_(3)-based(BNT-based)ceramics,where simultaneous A-site(Li^(+))and B-site(Nb^(5+))co-doping yields(1−x)Bi_(0.5)(Na_(0.81)K_(0.19))0.5TiO_(3)-xLiNbO_(3)(BNKT-xLN,x=0.01-0.04)compositions.The aliovalent substitution disrupts long-range ferroelectric order,enhances lattice distortion,and promotes a relaxor-like state with diffuse phase transitions and strong dielectric dispersion.Complementary polarization-electric field(P-E)and strain-electric field(S-E)measurements demonstrate a progressive evolution from classical ferroelectrisc to nonergodic relaxor behavior as the doping level increases.The optimized composition at x=0.02 exhibits a large reversible electrostrain of approximately 0.55% associated with a temperature-driven reversible phase transition.Notably,BNKT-xLN ceramics achieve electric-field-induced polarizations exceeding 50μC/cm^(2),while exhibiting a relatively low electrostrictive coefficient Q33 of∼0.018 m^(4)/C^(2),suggesting their potential as energy storage matrices due to the weak polarization-strain coupling effect.These results underscore the importance of aliovalent co-doping strategy in modulating the energy landscape of BNT-based systems,offering a viable strategy for developing high-strain,lead-free electroceramics suited to next-generation actuators and energy storage devices.
基金supported by the National Natural Science Foundation of China(Grant No.52202142)the Science and Technology Serving Enterprise Project in Universities and Colleges of Xi’an Science and Technology Bureau(Grant No.24GXFW0002)the Natural Science Basic Research Program of Shaanxi Province(Grants No.2025JC-YBMS-133 and 2023-JC-QN-0066).
文摘Dielectric ceramics have attracted extensive attention for high-power energy storage applications due to their fast charge-discharge capabilities and high power density.Bi_(0.5)Na_(0.5)TiO_(3)(BNT)-based lead-free ceramics are notable for their high saturation polarization and moderate breakdown electric field(Eb),but they still suffer from a low breakdown field,large hysteresis losses and insufficient efficiency.Here,we propose a strategy of dual-site ion-pair engineering by introducing Ba(Sr_(0.5)W_(0.5))O_(3)(BSW)into the BNT matrix.In this design,Ba^(2+)-Ba^(2+)pairs at the A-site and Sr^(2+)-W^(6+)pairs at the B-site induce local lattice distortion and generate strong random fields,which effectively promote the formation of multiple relaxor phases with polymorphic nanodomains.The features of electrical properties and phase-field simulations indicate that BSW doping facilitates greater compositional disorder and disruption of long-range FE order,integrating the short-range ordered antiferroelectric(AFE)nanodomains with highly disordered relaxor ferroelectric(RFE)regions to reduce the electric field-induced AFE-FE phase transition barrier.Additionally,the incorporation of BSW refines the grain size and increases microstructural homogeneity,enhancing the breakdown strength and delaying the polarization saturation.Accordingly,the 0.90BNT-0.10BSW ceramic exhibited an outstanding energy storage performance with a high W_(rec) of 6.57 J cm^(-3) and anηof 72%under an electric field of 450 kV cm^(-1).In addition,the ceramic synchronously possesses an excellent transient discharge rate t0.9 of 90 ns and a high power density PD of 121.9 MW cm^(-3).This work suggests that dual-site ion-pair engineering is an effective approach for regulating structure-property relationships in BNT-based ceramics and provides a viable pathway for the development of high-performance lead-free dielectric materials for advanced energy storage applications.
基金supported by the Projects of Jilin Provincial Science and Technology Department(Grant No.YDZJ202201ZYTS420)the National Science Foundation for Yong Scientists China(Grant No.62004081).
文摘Lead-free ceramic-based dielectric capacitors demonstrate significant potential for pulse power energy storage applications due to their high power density and rapid charge/discharge characteristics.In this study,highly dynamic polar nanoregions(PNRs)were constructed in(1-x)[_(0.9)_(2)Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)-0.08Bi(Zn_(2/3)Ta_(1/3))O_(3)]-xBi_(0.5)Na_(0.5)TiO_(3)(abbreviated as BNTx)dielectric ceramics by introducing the strongly polar relaxor end-member Bi_(0.5)Na_(0.5)TiO_(3)(BNT).Meanwhile,the hybridization of Bi 6s and O 2p orbitals improves the polarization capability of the ceramics,resulting in a larger polarization difference(ΔP~47.8μC cm^(-2)).Furthermore,due to the high doping concentration of BNT and Ta donor doping,BNTx relaxor ferroelectrics exhibit high bulk resistivity,submicron grain size(~0.57μm),and wide bandgap characteristics,leading to a remarkable improvement in breakdown strength(E_(b)~710 kV cm^(-1)).Both the electroactive regions corresponding to the bulk and grain boundaries showed similar characteristics,indicating a homogeneous electrical microstructure and intrinsic resistance which significantly contributed to maintaining the high resistivity of the samples.Through compositional optimization,the 20%BNT-doped BCZT-based relaxor ferroelectric ceramic(BNT20)achieves a Vickers hardness of~8.608 GPa while demonstrating exceptional energy storage performance,including an outstanding recoverable energy density(W_(rec))of~10.6 J cm^(-3)and ultrahigh energy efficiency(η)of~87%.Notably,the stable PNRs significantly improved the temperature and frequency stability of the dielectric constant and energy storage performance.Furthermore,the BNT20 ceramic exhibits a high current density(C_(D)~1108.3 A cm^(-2)),power density(P_(D)~132.99 MW cm^(-3)),and an ultrafast discharge speed(t_(0.9)~79.9 ns),demonstrating its promising application prospects in pulse power systems.
基金supported by the Key Research and Development Program of China(No.2022YFC3104500)the Natural Science Basic Research Program of Shaanxi Province(No.2023-JC-QN-0539)the National Natural Science Foundation of China(No.52032010).
文摘The electro-optical(E-O)properties of relaxor ferroelectric single crystals have received extensive attention in recent years,but their light transmittance is still a major obstacle limiting their optical properties.This study successfully grew the Eu-doped Pb(In_(1/2) Nb_(1/2))O_(3)-Pb(Mg_(1/3) Nb_(2/3))O_(3)-PbTiO_(3)(PIN-PMN-PT)relaxor ferroelectric single crystal using the modified Bridgman method.The Eu-PIN-PMN-PT crystal had high piezoelectric properties,high coercive fields,and temperature stability.The dielectric behavior at low temperatures showed that the Eu-PIN-PMN-PT crystal had more polar nano-regions(PNRs)than the undoped PIN-PMN-PT crystal to improve its piezoelectric properties.A thorough evaluation of the full matrix of electromechanical parameters was conducted,yielding a comprehensive understanding of the material’s properties in different directions.Meanwhile,after polarization along the[110]direction,the crystal obtained a high transmittance along the[001]direction,and an effective electro-optical coefficient of up to 420 pm/V was measured at room temperature.Due to excellent comprehensive properties,Eu-PIN-PMN-PT crystals are expected to be ideal materials for piezoelectric and electro-optical devices.
