Enhanced Relaxor Behavior Research Articles

Enhanced relaxor behavior and excellent anti-fatigue performance in lanthanum-modified Sr0.7Bi0.2TiO3 ceramics

Ferroelectric ceramics have attracted increasing attention for their wide applications in pulsed-power systems. Wherein relaxor ferroelectric ceramics with fast discharge speed and great stability are considered promising candidate materials. In this study, we introduced the rare-earth element La into Sr0.7Bi0.2TiO3 relaxor ferroelectric ceramics. Due to the lattice distortion triggered by La ions, the microdomains broke and transformed into high dynamic polar nano-regions (PNRs), thus improving the relaxor characteristic. We have identified this phenomenon through various characterizations, including the continuous waveform P-E (CWPE) test and the first-order reversal curve (FORC) test. With the high dynamic PNRs replacing the original domains, a better energy storage performance was achieved (Wrec = 3.22J/cm3 and η = 88.83% under 330kV/cm), and the pulse charge-discharge speed has been further improved (t0.9 = 70-81ns under 40-200kV/cm). Simultaneously, Sr0.658Bi0.188La0.04TiO3 ceramics owed remarkable anti-fatigue characteristics (0.40% attenuation after 107 cycles in the P-E test, 5.82% attenuation after 106 times in the pulse repetition frequency discharge test) due to the weak links of PNRs, revealing the great application potential of the Sr0.658Bi0.188La0.04TiO3 ceramic.

Deciphering the relationships among phase boundary, domain structure, and excellent electrical properties of ternary Bi0.5Na0.5TiO3-Bi0.2Sr0.7TiO3-NaNbO3 ferroelectrics

Bi0.5Na0.5TiO3-based ferroelectric ceramics have broad application prospects due to their excellent electrical properties and are considered to be one of the most promising functional materials to supersede lead-based materials. Here, 0.9Bi0.5Na0.5TiO3-0.1Bi0.2Sr0.7TiO3-xNaNbO3 (BNT-BST-xNN) ternary lead-free ferroelectric ceramics were prepared, and the origin of their excellent dielectric properties was investigated in terms of phase boundary and domain structure. The introduction of NN led to a phase transition from the ferroelectric rhombohedral phase (R3c) to the relaxor tetragonal phase (P4bm), and the two phases coexisted in the BNT-BST-xNN ternary solid solution with x ranging from 0.06 to 0.2. Meanwhile, the macroscopic domain of BNT-BST was destroyed and replaced by highly active polar nano-regions (PNRs) of the P4bm phase, leading to an increase in local structural disorder and enhanced relaxor behavior. A dielectric constant (εr) of ∼1765 (150 °C) with Δε/ε150 °C less than 15 % over a broad range from 80 to 328 °C was achieved in the BNT-BST-0.15NN, and an excellent energy storage property (Wrec = 3.3 J/cm3) was obtained under a low electric field (190 kV/cm). More specifically, the relationship among phase boundary, domain structure, and excellent electrical properties was achieved based on Rietveld refinements and the dielectric/ferroelectric characterizations. This work provides a deep insight into the phase evolution and its impact on the electrical properties of the BNT-based relaxor ferroelectrics.

Improved energy storage performance and thermal stability of hafnium-substituted strontium sodium niobate tungsten bronze ceramics.

Dielectric capacitors are widely used in the field of pulsed power systems owing to their ultra-fast charge and discharge capacity; however, considering the complex environment they face in practical applications, how to further improve their thermal stability is an urgent issue that needs to be solved. Tungsten bronzes have the potential to broaden the temperature stability range owing to their unique structure, but only few studies have focused on them. Herein, lead-free Sr4-x La x Na2Hf x Nb10-x O30 ceramics with a tungsten bronze structure were synthesized, and their energy storage properties were comprehensively characterized. With proper Hf substitution in the B site and rare earth substitution in the A site, significantly enhanced relaxor behavior is induced, leading to a broad plateau of the dielectric curve, slim polarization-electric field loop, high energy storage efficiency and stable capacitive performance over a wide temperature range. In addition, an improved microstructure with fewer defects, decreased average grain size, increased band gap and resistance were obtained, which benefit to the increase in breakdown strength and energy storage density. Finally, improved energy storage performance and thermal stability were achieved for the compounds, with W total = 3.6 J cm-3, W rec = 2.9 J cm-3, η = 80% and stable temperature range = 20-160 °C. Thus, the current system is a promising candidate for application in temperature-stable dielectric capacitors.

Energy storage and electrocaloric properties of lead free (1‐x)(0.6Ba(Zr0.2Ti0.8)O3‐0.4(Ba0.7Ca0.3)TiO3)–xBiZn0.5Ti0.5O3 ferroelectric ceramics

In the present work, we investigated the effect of BiZn0.5Ti0.5O3 composition on energy storage and electrocaloric properties of lead free (1-x)(0.6Ba(Zr0.2Ti0.8)O3‐0.4(Ba0.7Ca0.3)TiO3)–xBiZn0.5Ti0.5O3 [BZCT-BZ] ceramics by varying the x from 0 to 10%. The x-ray diffraction (XRD) analysis evidences the formation of BZCT-BZ solid solution without any secondary or impurity phase. The peaks splitting at 2θ = ∼ 45° and 66° suggested the co-existence of rhombohedral (R) and tetragonal (T) phases (morphotropic phase boundary) at room temperature for x ≤ 1%. Further, BZCT-BZ ceramics with x > 1% exhibited pseudocubic nature. The ferroelectric hysteresis loop confirms relaxor behavior and the decrease in remanent polarization with increase of BZ content is explained based on the back switching calculations. The BZCT-BZ ceramics as function of BZ composition gave the optimum recoverable energy density of 197 mJ/cm3 and an efficiency of 92% at an applied field of 45 kVcm−1. Such an exceptionally high energy storage efficiency is attributed to the enhanced relaxor behavior and superior back switching capability. Further, the values of electrocaloric temperature change and responsivity are found to be 0.67 K at 45 kV/cm and 0.014 Kcm/kV respectively in 0.98BZCT-0.02BZ ceramics. Thus, BZCT-BZ ceramics are appealing candidates for energy storage and electrocaloric application.

Lead-free BiFeO3-BaTiO3 based high-Tc ferroelectric ceramics: Antiferroelectric chemical modification leading to high energy storage performance

Dielectric capacitors have been widely used in pulsed power devices owing to their ultrahigh power density, fast charge/discharge speed, and excellent stability. However, developing lead-free dielectric materials with a combination of high recoverable energy storage density and efficiency remains a challenge. Herein, a high energy storage density of 7.04 J/cm3 as well as a high efficiency of 80.5% is realized in the antiferroelectric Ag(Nb0.85Ta0.15)O3-modified BiFeO3-BaTiO3 ferroelectric ceramic. This achievement is mainly attributed to the combined effect of a high saturation polarization (Pmax), increased breakdown field (Eb), and reduction of the remnant polarization (Pr). The modification of pseudotetragonal BiFeO3 by Ag(Nb0.85Ta0.15)O3 leads to a high Pmax, and the enhanced relaxor behavior gives rise to a small Pr. The promoted microstructure (such as a dense structure, fine grains, and compact grain boundaries) after modification results in a high breakdown strength. Furthermore, both the recoverable energy density and efficiency exhibit high stability over a broad range of operating frequencies (1–50 Hz) and working temperatures (25–120 °C). These results suggest that the (0.67–x)BiFeO3-0.33BaTiO3-xAg(Nb0.85Ta0.15)O3 ceramics can be highly competitive as a lead-free relaxor for energy storage applications.

Multifunctional Characteristics of BCTH:0.5% Sm3+ Ceramics Prepared via Hydrothermal Method and Powder Injection Molding

Briefly, 0.005-mol Sm3+-doped (Ba0.85Ca0.15)(Ti0.9Hf0.1)O3 ([(Ba0.85Ca0.15)0.995Sm0.005](Ti0.9Hf0.1)O3, BCTH:0.005Sm3+) lead-free ceramics were prepared via hydrothermal method and powder injection molding using paraffin and oleic acid as binders, and the effects of preparation method and sintering conditions on microstructure, dielectric behavior and optical properties were investigated. XRD Rietveld refinement reveals the coexistence of orthogonal, rhombohedral and tetragonal phases, in which the crystal structure and phase fraction are influenced greatly by sintering temperature and holding time. The ceramics present enhanced relaxor behavior and frequency dispersion phenomenon as compared with those prepared by the solid-state sintering method, and the diffusive index γ value is within 1.421–1.673. The transition mechanism and luminescence performance of BCTH:0.005 Sm3+ were analyzed by Blasse formula, photoluminescence spectrum and fluorescence lifetimes, where emission peaks show slight blueshift, fluorescence decay lifetime becomes shorter, electric multipole interaction dominates the energy transfer mechanism, and the down-conversion luminescence is one-photon absorption process. The CIE chromaticity color coordinate (0.4746, 0.5048), correlated color temperature 3134 K and color purity 93.58% are achieved, which reveals that the BCTH:0.005 Sm3+ ceramics express high quality yellow emission rather than orange-red light of the hydrothermal method synthesized nano-powder, and have potential application in optical field.

Boosting capacitive performance of lead-free relaxor ferroelectrics by introducing a linear dielectric

As an important core component used in high-power pulse electronic systems, dielectric ceramic capacitors have gained great interest because of their ultrahigh powder density (PD) and fast discharge speed (t0.9). However, inferior energy storage performance (ESP) greatly limits the development of energy storage devices with the requirement of miniaturization and integration. Herein, we propose a feasible approach to introduce linear dielectric CaTiO3 (CT) into (Bi0.5Na0.5)TiO3 (BNT) for the design of engineered relaxor ferroelectrics to tune ESP at the grain, domain, and macroscopic scales. The results demonstrate that introducing CT generates enhanced relaxor behavior with highly dynamic polar nanoregions, refines grain size, and suppresses dielectric loss, synergistically yielding increased breakdown strength, negligible remnant polarization, and a nearly linear polarization hysteresis loop. Consequently, superior ESP is achieved in BNT-0.3CT relaxor ferroelectric ceramics with a large energy density (∼5.65 J/cm3) and a high efficiency (∼88.1 %). Based on CT-induced merits, the excellent temperature/frequency/cycling stabilities and remarkable charge-discharge properties featuring a high PD of 200.4 MW/cm3, high discharge energy density of 2.27 J/cm3 and ultrashort t0.9 of 58 ns of the designed ceramics broaden the actual application prospects. This work demonstrates that introducing linear dielectric CT holds great promise for developing high-performance energy storage dielectrics.

Significant improvement in energy storage for BT ceramics via NBT composition regulation

Dielectric ceramic capacitors play an important part in modern electronics, but the adoption of environmentally friendly lead-free ceramics is often limited by their inferior energy storage efficiency (η) and density (Wrec). One novel ceramic composition, (1-x)(Ba0.7Sr0.3)(Zr0.2Ti0.8)O3-xNa0.5Bi0.5TiO3 (BSZT-NBT, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) was designed to achieve large max polarization (Pmax) and outstanding energy storage performance (ESP). Structural analyses indicate that BSZT-NBT ceramics form stable perovskite solid solutions. Dielectric properties testing confirms the enhanced relaxor behavior. Remarkably, the BSZT-NBT (x = 0.5) ceramics exhibit superb ESP, including ultrahigh η of 94.9%, elevated Wrec of 4.45 J·cm–3, large Pmax of 38.01 μC·cm–2. Furthermore, these ceramics demonstrate excellent temperature and frequency stability for ESP. Charge-discharge performance at room temperature and 120 kV·cm–1 showcases excellent Wdis, t0.9 and PD of 0.64 J·cm–3, 69.8 ns and 48 MW·cm–3, respectively. Our results indicate that the introduction of NBT effectively improves the Pmax and ESP of BT-based ceramics. The BSZT-NBT ceramics hold promise for addressing the limitations of lead-free ceramic capacitors and advancing their practical applications in electronic devices.

Superior Energy Density Achieved in Unfilled Tungsten Bronze Ferroelectrics via Multiscale Regulation Strategy.

The most promising candidates for energy storage capacitor application are relaxor ferroelectrics, among which, the perovskite structure ferroelectric ceramics have witnessed great development progress. However, less attention has been paid on tetragonal tungsten bronze structure (TTBS) ceramics because of their lower breakdown strength and polarization. Herein, a multiscale regulation strategy is proposed to tune the energy storage performances (ESP) of TTBS ceramicsfrom grain, domain, and macroscopic scale. The enhanced relaxor behavior with dynamic polar nanodomains guarantees low remanent polarization, while the refined grains and enlarged bandgap ensure increased breakdown strength. Hence, excellent ESP isrealized in unfilled TTBS Sr0.425 La0.1 □0.05 Ba0.425 Nb1.4 Ta0.6 O6 (SLBNT) ceramics with an ultrahigh recoverable energy density of 5.895 J cm-3 and a high efficiency of 85.37%. This achievement notably surpasses previous studies in TTBS ceramics and is comparable to that of perovskite components. Meanwhile, the energy density exhibits a wide temperature, frequency, and cycling fatigue stability. In addition, high power density (257.89 MW cm-3 ), especially the ultrafast discharge time (t0.9 = 16.4ns) are achieved. The multiscale regulation strategy unlocks the energy storage potential of TTBS ceramics and thus highlights TTBS ceramicsas promising candidates for energy storage, like perovskite structured ceramics.

Realizing high energy density in BiFeO3-based ceramics capacitors via bandgap engineering and polarization optimization

BiFeO3-based lead-free ferroelectrics possess high spontaneous polarization. Nevertheless, achieving ultrahigh recoverable energy density in BiFeO3-based ceramics is limited by large remanent polarization and insufficient breakdown strength. Herein, (0.7-x)BiFeO3-0.3Ba(Hf0.05Ti0.95)O3-xNaTaO3 ceramics were designed and prepared. It exhibited a high recoverable energy density of 6.3 J/cm3 and high efficiency of 86.6 % due to the contribution of large breakdown strength and optimized polarization (high maximum polarization and small remanent polarization). These contributions stem from NaTaO3 being introduced into the 0.7BiFeO3-0.3Ba(Hf0.05Ti0.95)O3 matrix, which successfully brought in widened bandgap Eg, increased resistivity, and enhanced relaxor behavior. Large breakdown strength is also promoted by dense microstructure and decreased average grain size. This work proves that the strategies of bandgap engineering and polarization optimization for improving energy storage performance in BiFeO3 are practicable.

Realizing excellent energy storage performances in tetragonal tungsten bronze ceramics via a B-site engineering strategy

The development of dielectric energy storage capacitors has attracted much research interest in recent years. As an important category of dielectric materials, the energy storage potential of the tetragonal tungsten bronze structure ceramic has been underestimated for a long time due to the lower dielectric constant and low breakdown strength. In this work, a series of Sr0.6Ba0.4Nb2O6-based tungsten bronze ceramics with excellent energy storage performances was prepared based on a B-site engineering strategy. Enhanced relaxor behavior and improved breakdown strength induced by Ta substitution give rise to a high recoverable energy density of 3.95 J/cm3 along with superior efficiency of 93.4 %. Especially, the capacitor based on the Ta-modified Sr0.6Ba0.4Nb2O6 ceramics exhibits a large current density of 845 A /cm2 and a huge power density of 84.5 MW/cm3 accompanied by a fast discharge time of 75 ns. All these results demonstrate the immense potential of the Ta-modified Sr0.6Ba0.4Nb2O6-based tetragonal tungsten bronze ceramics in the high-power energy storage capacitor field.

Enhancement of recoverable energy density and efficiency of K0.5Na0.5NbO3 ceramic modified by Bi(Mg0.5Zr0.5)O3

As one of the most popular lead-free energy storage materials, K0.5Na0.5NbO3 (KNN)-based ceramics are expected to replace lead-based ceramics due to their high dielectric constant, high Curie temperature, and environmental friendliness. However, the high remnant polarization (Pr) and low breakdown strength (BDS) of KNN ceramic lead to its low energy storage properties, which limits its applications in energy storage field. In this work, the energy storage properties of KNN ceramic were improved by reducing average grain size and enhancing relaxor behavior. The 0.85K0.5Na0.5NbO3-0.15Bi(Mg0.5Zr0.5)O3 (0.85KNN-0.15BMZ) ceramic prepared by the solid state method not only has high recoverable energy storage density value (Wrec) of 3.47 J cm-3 but also has high energy storage efficiency value (η) of 89.14% at a high applied electric field of 320 kV/cm. In addition, the Wrec and η of 0.85KNN-0.15BMZ ceramic fluctuate slightly over the whole temperature range of 20–120 °C at 200 kV/cm, showing excellent temperature stability. At the same time, it can be concluded by first-order reversal curve distribution that 0.85KNN-0.15BMZ ceramic has excellent energy storage properties due to their enhanced relaxor behavior. In summary, the 0.85KNN-0.15BMZ ceramic can be used as the novel dielectric capacitor materials.

Significantly Enhanced Energy Storage Performance of Lead-Free BiFeO3-Based Ceramics via Synergic Optimization Strategy.

Owing to the merits of giant power density and ultrafast charge-discharge time, dielectric capacitors including ceramics and films have inspired increasing interest lately. Nevertheless, the energy storage density of dielectric ceramics should be further optimized to cater to the boosting demand for the compact and portable electronic devices. Herein, an ultrahigh recoverable energy storage density Wrec of 13.44 J/cm3 and a high efficiency η of 90.14% are simultaneously realized in BiFeO3-BaTiO3-NaTaO3 relaxor ferroelectric ceramics with high polarization Pmax, reduced remanent polarization Pr, and optimized electric breakdown strength Eb. High Pmax originates from the genes of BiFeO3-based ceramics, and reduced Pr is induced by enhanced relaxor behavior. Particularly, a large Eb is achieved by the synergic contributions from complicated internal and external factors, such as decreased grain size and improved resistivity and electrical homogeneity. Furthermore, the ceramics also exhibit satisfactory frequency, cycling and thermal reliability, and decent charge-discharge property. This work not only indicates that the BiFeO3-based relaxor ferroelectric materials are promising choices for the next-generation electrostatic capacitors but also paves a potential approach to exploit novel high-performance dielectric ceramics.

Energy storage performance of BiFeO3–SrTiO3–BaTiO3 relaxor ferroelectric ceramics

AbstractDielectric capacitors reveal great potential in the application of high power and/or pulsed power electronic devices owing to their ultrafast charge–discharge rate and ultrahigh power density. Among various dielectric capacitors, the environment‐friendly lead‐free dielectric ceramics have drawn extensive investigations in recent years. Nevertheless, the relatively small recoverable energy storage density (Wrec) is still an obstacle for their application. Herein, the (0.55−x)BiFeO3–0.45SrTiO3–xBaTiO3 ternary ceramics with 0.1 wt% MnO2 were prepared by the solid‐state reaction, and achieved enhanced relaxor behavior as well as breakdown strength Eb. As a result, the x = 0.12 ceramic exhibited superior comprehensive energy storage performance of large Eb (50.4 kV/mm), ultrahigh Wrec (7.3 J/cm3), high efficiency η (86.3%), relatively fast charge–discharge speed (t0.9 = 6.1 μs) and outstanding reliability under different frequency, fatigue, and temperature, indicating that the BiFeO3‐based relaxor ferroelectric ceramics are prospective alternatives for electrostatic energy storage.

Enhanced relaxor behavior and high energy storage efficiency in niobium substituted (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics

The microstructure, dielectric properties, relaxor behavior, and energy storage efficiency of un-substituted and niobium (Nb) substituted (Ba0.85 Ca0.15)(Zr0.1 Ti0.9) 1-x NbxO3 (for x = 0, 0.02 and 0.05) samples prepared by the solid-state reaction method has been studied in detail. All the samples exhibited perovskite structure with no trace of impurity. Composition-dependent phase transition was also observed on the addition of Niobium. At room temperature, the co-existence of rhombohedral and tetragonal phases is observed in the unsubstituted samples. As the composition changes from x = 0.02 to x = 0.05, a structural change from tetragonal to cubic is observed. A remarkable reduction in grain size, from 90 μm (for x = 0) to 1.21 μm for (x = 0.05), is observed with the addition of Niobium. This result suggests that Niobium acts as a grain growth inhibiter in barium calcium zirconium titanate (BCZT) ceramics. The effect of Niobium on transition temperature is studied from the temperature-dependent dielectric permittivity graph. It was clear that the transition temperature shifted to a lower temperature region, and for x = 0.05, at a very low temperature (−23 °C/250 K) the tetragonal to cubic transition was observed. At x = 0.05, the temperature-dependent dielectric permittivity showed a broadened curve, indicating a diffuse phase transition. The diffuse phase transition in Nb substituted samples is explained by Uchino and Nomura modified Curie Weiss law.Moreover, the observations on temperature-dependent dielectric permittivity measurements at various frequencies suggest that the substitution of Nb5+ induces relaxor behavior. The energy storage efficiency of unsubstituted and Nb substituted samples was calculated from the polarization versus electric field graph. A high storage efficiency of 84% was obtained for the Nb substituted sample (x = 0.05) at 12 kV cm−1. Enhanced relaxor behavior and increased storage efficiency were observed in (Ba0.85 Ca0.15)(Zr0.1 Ti0.9) 1-x NbxO3 at x = 0.05. Thus we suggest that these are promising materials for energy storage applications.

Ultrahigh Energy Storage Density and High Efficiency in Lead-Free (Bi0.9Na0.1)(Fe0.8Ti0.2)O3-Modified NaNbO3 Ceramics via Stabilizing the Antiferroelectric Phase and Enhancing Relaxor Behavior.

Dielectric capacitors have attracted growing attention because of their important applications in advanced high power and/or pulsed power electronic devices. Nevertheless, the synergistic enhancement of recoverable energy storage density (Wrec > 10 J/cm3) and efficiency (η > 80%) is still a great challenge for lead-free dielectric bulk ceramics. Herein, by introducing complex perovskite compound (Bi0.9Na0.1)(Fe0.8Ti0.2)O3 with a smaller tolerance factor into an NaNbO3 matrix (NN-BNFT), we have achieved and explored stable relaxor antiferroelectric ceramics with enhanced relaxor behavior. Of particular importance is the composition of 0.88NN-0.12BNFT, which exhibits a large electric breakdown strength Eb of 87.3 kV/mm, an ultrahigh Wrec of 12.7 J/cm3, and a high efficiency η of 82.5%, as well as excellent thermal reliability and an ultrafast discharge speed, resulting from the dense microstructure, the moderate dielectric constant, the reduced grain size, the dielectric loss, and the sample thickness. The outstanding energy storage properties of NN-BNFT display great promise in advanced dielectric capacitors for energy storage applications.

Enhanced Relaxor Behavior and Energy‐Storage Properties in Na0.5Bi0.5TiO3‐Based Ceramics by Doping the Complex Ions (Al0.5Nb0.5)4+

Herein, (Na0.5Bi0.5)0.94Ba0.06Ti1‐x(Al0.5Nb0.5)xO3 (NBBT‐xAN) ceramics are fabricated through a solid reaction method. X‐ray diffraction reveals the structure of NBBT‐xAN ceramics transforms from coexistence of rhombohedral and tetragonal structures to a pseudocubic structure with increasing AN content. Raman spectroscopy indicates the long‐range ferroelectric order of NBBT ceramics is broken by AN and the polar nanoregions (PNRs) with weak polarization are formed. The relaxor behavior of NBBT ceramics is enhanced by the enhanced random electric fields (REFs) through the heterovalent cations Al3+/Nb5+. Therefore, a slim and pinched P–E loop is obtained for NBBT ceramics by doping AN and the energy‐storage properties (ESPs) can be improved dramatically under a low electric field. The maximum recoverable energy density (Wrec) of 1.2 J cm−3 is obtained at x = 0.04 under a low electric field of 100 kV cm−1. However, a relatively high Wrec of 1.0 J cm−3 and efficiency (η) of 77% are simultaneously obtained at x = 0.05 under the same electric field strength. Moreover, NBBT‐0.05AN ceramics also exhibit excellent temperature (30–180 °C), fatigue (104) and frequency (1–40 Hz) stabilities. Most important, the study provides a strategy to design high energy‐storage capacitors under a low electric field.

Enhancement of energy storage performance in lead-free barium titanate-based relaxor ferroelectrics through a synergistic two-step strategy design

Dielectric capacitors are widely used because of their advanced performance, including superior power density and high charge–discharge speed. Nevertheless, limitations in energy-storage density (Wrec), efficiency (η) and thermal stability hinder their practical application. Herein, these concerns are addressed using a synergistic two-step strategy of designing the composition of Bi(Zn2/3Nb1/3)O3 and optimizing the preparation for viscous polymer processing (VPP), thus achieving domain engineering, enhanced relaxor behavior, and improved breakdown strength (Eb) in (Ba0.8Sr0.2)TiO3-based ceramics. The broadening of the permittivity peak and highly dynamic polar nanoregions (PNRs) are correlated to expected relaxation characteristics, as indicated by the brightness of atomic position and calculated spontaneous polarization vectors determined through transmission electron microscopy. The relatively small grain size and increased band gap, verified through scanning electron microscopy and ultraviolet − visible spectrophotometry, contribute to the Eb. A prominent Wrec of 5.16 J/cm3 under 540 kV/cm and excellent temperature stability (Wrec = 3.6 J/cm3, η = 92.8%, 20–120 °C) are achieved in 0.91(Ba0.8Sr0.2)TiO3 − 0.09Bi(Zn2/3Nb1/3)O3 ceramics formed by VPP (BZN9VPP). The material possesses an exceptional current density of 647.56 A/cm2, a power density of 113.32 MW/cm3, and a rapid discharge speed of < 60 ns. The comprehensive outstanding performance supports the great potential of this sample for application in pulsed power capacitors.

High Capacitive Performance Achieved in NaNbO3‐Based Ceramics via Grain Refinement and Relaxation Enhancement

Lead‐free antiferroelectric (AFE) energy storage material NaNbO3 has received increasing attention because of the advantages of low density, low cost, and environmental friendliness. Nevertheless, square P–E hysteresis loops and low electric breakdown strength suppress the realistic energy storage applications of the pristine NaNbO3 ceramic. Herein, the Ba0.6Sr0.4TiO3 relaxor ferroelectric is introduced into the NaNbO3 AFE ceramic, aiming to enhance energy storage performances. (1–x)NaNbO3–xBa0.6Sr0.4TiO3 ceramics with different doping levels are manufactured via the conventional solid‐state processing route. A remarkable recoverable energy storage density (W rec ≈ 3.04 J cm−3) and a high efficiency (η ≈ 88.83%) are achieved synchronously in the ceramic with x = 0.20, under an applied electric field of 320 kV cm−1, benefiting from the enhanced relaxor behavior and reduced grain size caused by the introduction of Ba0.6Sr0.4TiO3. Furthermore, excellent frequency stability (5–1000 Hz) and temperature stability (20–150 °C) along with outstanding fatigue resistance (up to 2 × 105cycles) are also achieved. Moreover, the ceramic displays outstanding charge–discharge capabilities such as big current density (C D ≈ 1096.23 A cm−2), high power density (P D ≈ 106.7 MV cm−3) and fast discharge speed (t 0.9 ≈ 142 ns). These results demonstrate that the Ba0.6Sr0.4TiO3 modified NaNbO3‐based ceramics could be competitive candidates for high power systems.

Energy storage properties in a Bi(Mg1/2Ti1/2)O3 modified BiFeO3-Sr0.7Bi0.2TiO3 film

High-performance dielectric capacitor represents an emerging technological goal for energy storage in modern electrical and electronic systems. In this work, we report a lead-free film capacitor based on the Bi(Mg1/2Ti1/2)O3 modified BiFeO3-Sr0.7Bi0.2TiO3 relaxor. A large recoverable energy storage density of 77.5 J/cm3, together with an efficiency of 56.1% is achieved in the film with 15 mol. % Bi(Mg1/2Ti1/2)O3 in composition. The film also exhibits excellent fatigue endurance with a reduction less than 3% over 1 × 108 cycles in both recoverable energy storage density and efficiency. Such good properties are ascribed to the improved electrical insulation and breakdown strength and the enhanced relaxor behavior by introducing the bismuth-based perovskite-like compound.