Relaxor Ferroelectric Ceramics Research Articles

Simultaneously realizing high energy density and high efficiency in NaNbO3–BaTiO3‐based ceramic capacitors

AbstractDielectric capacitors, which can achieve tremendous power density and ultrafast charge/discharge speed, are crucial components for high power equipment. Yet, the synchronous achievement in high recoverable energy density (Wrec) and high efficiency (η) is a long‐term difficulty for dielectric ceramics. Herein, the (0.85 − x)NaNbO3–0.15BaTiO3–xBi(Mg1/3Ta2/3)O3 (NN–BT–xBMT) relaxor ferroelectric ceramics were proposed and studied. The doping of BMT was conducive to promoting the microstructure and bandgap and improving the dielectric relaxation properties of NN–BT ceramics. Finally, the sample of x = 0.10 presented a high Wrec of 5.9 J/cm3 and a high η of 90% simultaneously. In addition, the sample also exhibited superb charge/discharge performances with large power density (PD = 137 MW/cm3) and fast charge/discharge speed (t0.9 = 39 ns). The above results reveal that the NaNbO3‐based ceramics could serve as potential alternatives for advanced dielectric capacitors.

Improved energy storage density of Sr0.7Bi0.2TiO3-based relaxor ferroelectric ceramics via a core-shell-structural optimization strategy

Improved energy storage density of Sr0.7Bi0.2TiO3-based relaxor ferroelectric ceramics via a core-shell-structural optimization strategy

Excellent energy storage properties in ZrO2 toughened Ba0.55Sr0.45TiO3-based relaxor ferroelectric ceramics via multi-scale synergic regulation

Lead-free ceramic capacitors offer ultrahigh power density and ultrafast discharging rates, making them critical energy storage components for advanced pulsed power systems. However, the greatest obstacle to broader applications remains the relatively low energy storage density. In this study, a relaxor ferroelectric ceramic based on (0.6-x)Ba0.55Sr0.45TiO3-0.4Bi0.5Na0.5TiO3-xSrZrO3 ((0.6-x)BST-0.4BNT-xSZ) is prepared using the tape casting method, resulting in an excellent energy density (Wrec ≈ 10.0 J cm−3) and high energy storage efficiency (η ≈ 91 %). The solid solution of linear dielectrics SrZrO3 synergistically regulates both relaxor properties and breakdown strength. The variation of relaxor property was explored utilizing New Glass model and the multi-polarization model, with confirmation provided by piezoresponse force microscopy. Furthermore, the breakdown strength could be attributed to improvements in electric insulation and the widening of the bandgap. As SrZrO3 content increases, the in-situ emergence of the second phase ZrO2, accompanied by a martensitic transformation, not only improves the fracture toughness of ceramics but also serves to elongate the breakdown path. Encouragingly, x = 0.20 ceramics also achieve excellent temperature stability (−95–125 ℃), frequency stability (1–1000 Hz), cycling reliability (1–106 cycles), and great charging-discharging properties. This multiscale synergic regulation strategy plays a guiding role in the screening of high-performance energy storage dielectric materials.

Innovative Design of BNKT-xSLZT Ceramics: Maximizing the Polarization Difference for Enhanced Energy Storage.

Lead-free relaxor ferroelectric ceramics with outstanding energy-storage (ES) density (Wrec) and high ES efficiency (η) are crucial for advanced pulse-power capacitors. This study introduces a strategic approach to maximizing the polarization difference (ΔP) by inducing a transition from the ferroelectric phase to the ergodic relaxor (ER) phase. By employing this strategy, a series of ceramics, (1 - x)(Bi0.5Na0.4K0.1)TiO3-x(Sr0.85La0.1)(Zr0.5Ti0.5)O3 (BNKT-xSLZT), with varying SLZT content (x = 0.05, 0.10, 0.15, and 0.20), were designed. The addition of SLZT enhances cationic disorder, induces vacancies at A sites, and disrupts long-range ferroelectric order, facilitating the formation of polar nanoregions and enhancing relaxor ferroelectric behavior. Furthermore, a viscous polymer process (VPP) technology is employed to optimize the ceramics' structure, aiming to increase the breakdown strength (Eb) and enhance ΔP. Ultimately, enhanced ES performance is demonstrated in BNKT-0.15SLZTVPP, achieving a remarkable Wrec of 6.85 J/cm3 and η of 84% under 470 kV/cm. This composition demonstrates excellent stability with minimal variations in Wrec (3.0%) and η (4.4%) over the temperature range of 20-110 °C. Additionally, BNKT-0.15SLZTVPP exhibits exceptional pulse charge-discharge properties, featuring a high discharge density of 3.72 J/cm3, a large power density of 164.2 MW/cm3, and a short discharge time (t0.9) of 193 ns under 300 kV/cm. The study validates the practicality of BNKT-0.15SLZTVPP for pulse capacitors and underscores the potential to enhance ES performance through A-site donor doping and VPP technology. This work provides a comprehensive understanding of the interplay among composition, structure, and ES properties in lead-free relaxor dielectric ceramics, laying the groundwork for innovative advancements in the field.

Ultrafast discharge properties and enhanced energy density in lead‐free NaNbO3‐based relaxor ferroelectric ceramics

AbstractNaNbO3‐based (NN) energy storage ceramics are known for exhibiting high maximum polarization (Pmax) and large recoverable energy density (Wrec). However, the huge energy loss density (Wloss) has been a limiting factor in improving energy storage performance. Therefore, a ternary system was designed to achieve both huge Wrec and efficiency (η). The combination of 0.35Bi(Zn0.5Ti0.5)O3–0.65BaTiO3 (BZTBT) was chosen to reduce grain size and disrupt the long‐range ordered domains, thereby inducing the polar‐nano‐regions to mitigate Wloss. The optimal performance was achieved with the 0.75NaNbO3–0.25(0.35Bi(Zn0.5Ti0.5)O3–0.65BaTiO3) (0.75NN–0.25BZTBT) ceramic, which exhibited a high Wrec = 2.68 J/cm3 and superior η = 82.7% under 310 kV/cm. Remarkably, the 0.75NN–0.25BZTBT ceramic displayed an exceptionally fast discharge time to 90%, t0.9 = 88 ns, coupled with a huge energy density Wd = 0.95 J/cm3. This study demonstrates the significant potential of 0.75NN–0.25BZTBT ceramic in the realm of energy storage and rapid charge–discharge applications.

Achieving High Energy Storage Performance in Lead-Free Relaxor Ferroelectric Ceramics of (1-x)Bi0.88Nd0.10Sm0.02FeO3-xBaTiO3

BiFeO3-based lead-free ferroelectrics have attracted great interest in energy storage applications due to their high spontaneous polarisation strength, however, the high residual polarisation strength (Pr) has become a serious obstacle to their practical application. In this work, (1-x)Bi0.88Nd0.10Sm0.02FeO3-xBaTiO3+0.1 wt% MnO2 ceramics were designed by ion doping and solid solution modification strategies, where Sm3+ and Nd3+ promote ionic disorder and reduce leakage current, and the introduction of nano-BaTiO3 induces the crushing of long-range ferroelectric structure into polar nano-regions with enhanced relaxation. As a result, the ceramic is able to maintain a high maximum polarisation intensity while possessing a low residual polarisation.The recoverable energy density (Wrec) of the 0.50BSNF-0.50BT ceramic is as high as 3.61 J/cm3 with an efficiency of 70.11%. In addition, the 0.50BSNF-0.50BT has good thermal stability (Wrec variation <7%) at 25-120°C. In the charge/discharge test, the Wdis was 2.58 J/cm3 and the discharge time was 273 ns. These results indicate that the 0.50BSNF-0.50BT ceramic is an ideal candidate as a material for energy storage applications.

The thermal depolarization behavior of PMN-PT-BZT relaxor ferroelectric ceramics from the standpoint of domain structure transitions

The thermal depolarization behavior of PMN-PT-5BZT relaxor ferroelectric ceramics was studied, and the depolarization mechanism was discussed from the perspective of domain structure transitions. In addition to the transition from MPB structure at room temperature to cubic phase at high temperature, the structure symmetry of PMN-PT-5BZT ceramics has no obvious change with increasing temperature. However, the ceramic had experienced a transition process from ferroelectric state to nonergodic relaxor state, and then to ergodic relaxor state. The results of temperature dependence of ferroelectric properties showed that the depolarization temperature Td corresponds to the transition temperature TF-NR from ferroelectric state to nonergodic relaxor state, and there is an obvious dielectric abnormal peak at this temperature, which is mainly due to the depolarization behavior caused by the decrease of macrodomain size and the beginning of transition to nanodomains.

Enhanced relaxation behavior and energy storage properties in (Al0.5Nb0.5)4+ complex ions modified Na0.5Bi0.5TiO3-based ceramics under low electric field

In recent decades, high polarization and low residual polarization lead-free relaxor ferroelectric ceramics have attracted lots of focus due to their great potential in dielectric capacitors for energy storage. In this work, Na0.35Bi0.35Sr0.3Ti(1-x)(Al0.5Nb0.5)xO3 (x = 0.00, 0.01, 0.02, 0.03, 0.04, 0.05) lead-free ceramics have been fabricated by the traditional solid-stated reaction method. By doping (Al0.5Nb0.5)4+ complex ions into 0.7Na0.5Bi0.5TiO3-0.3SrTiO3, pure perovskite phases and reduced grain sizes are obtained. Increasing the AN concentration not only moves the Ts toward the lower temperature, but also keeps the permittivity at a high average value, which shows a good thermal stability of the dielectric properties (εr150°C∼3903 ± 15% in the range of 42–232 °C). Furthermore, Na0.35Bi0.35Sr0.3Ti(1-x)(Al0.5Nb0.5)xO3 presents a reduced residual polarization due to the improved relaxor behavior, and achieves a moderate energy storage property at low electric field of 155 kV/cm (when x = 0.04, Wrec is 1.85 J/cm3, and η is 89.0%). More importantly, the ceramic also possesses great frequency, temperature and cycle stability. Hence, the (Al0.5Nb0.5)4+ modified 0.7Na0.5Bi0.5TiO3-0.3SrTiO3 ceramics have exhibited a potential application in dielectric capacitors for energy storage.

Enhanced energy storage performance of Na0.5Bi0.5TiO3-based relaxor ferroelectric ceramics by synergistic optimization strategies

Despite the fact that Na0.5Bi0.5TiO3 (NBT) based lead-free ceramics have attracted widespread interest due to their various advantages, their lower recoverable energy storage density (Wrec) and energy storage efficiency (η) limit their development in pulsed power capacitors. In this work, we propose a synergistic optimization strategy to enhance the energy storage performance of 0.65Na0.5Bi0.5TiO3-0.35SrTiO3(NBST) based lead-free ceramics by introducing Bi0.8La0.2(Ni0.5Zr0.5)O3 (BLNZ) and employing viscous polymer process (VPP). The former converts the macroscopic domains into microscopic domains, limiting the polarization response hysteresis to give a large Pm–Pr. The latter reduces the thickness and porosity of the samples, resulting in a substantial increase in breakdown strength. Ultimately, by stepwise optimization of this strategy, the x = 0.15 ceramic by VPP (0.15VPP) achieves excellent energy storage performance (Wrec = 7.6 J/cm3, η = 92%) under 620 kV/cm and reliable temperature stability from 20-140 °C. The combined excellent results of this study show that our synergistic optimization strategy can effectively enhance the energy storage performance of NBT-based dielectric ceramics and could be further extended to other ceramic materials for pulsed power capacitors.

Enhanced dielectric energy storage performance of Na0.5Bi0.5TiO3-LiTaO3-based lead-free relaxor ferroelectric ceramics through domain structural regulation and improved densification

Ceramic materials with relaxor dielectric properties, expressed as (1-x)(0.94Na0.5Bi0.5TiO3-0.06LiTaO3)-xCaTiO3 [(1-x)(NBT-LT)-xCT] with x values of 0.12, 0.15, 0.18, and 0.21, were synthesized through an A-site doping method to enhance energy storage capabilities. The linear dielectric CaTiO3 was chosen as the acceptor additive, and ceramic samples were prepared using conventional solid-phase and molding techniques. A comprehensive investigation evaluated the influence of different CT concentrations on the phase and energy storage/release characteristics of NBT-LT.Optimal performance was notably achieved with a 15% CT doping concentration, resulting in Wrec and η values of 2.16 J/cm³ and 70%, respectively, for a 100 μm thick sample under a 210 kV/cm voltage. When the film was rolled to a 60 μm thickness, the voltage strength increased to 330 kV/cm, leading to enhanced Wrec (5.33 J/cm³) and η (80%). Within the temperature range of 30 °C to 150 °C, only a marginal change in Wrec (less than 10%) was observed. Frequency conversion tests across the 1 Hz to 100 Hz range demonstrated the material's relative stability, with Wrec exhibiting minimal fluctuations. These findings emphasize the outstanding temperature and frequency stability of the material. During discharge, the material displayed a power density of up to 152 MW/cm³, coupled with a discharge time of 0.3 μs, showcasing remarkable pulse discharge capabilities. The experimental results affirm the promising potential of (NBT-LT)-0.15CT lead-free relaxor ferroelectric ceramics for application in commercial capacitors.

Remarkable improvement of energy storage performance of Gd2O3-doped BNT-based relaxor ferroelectric ceramics

Remarkable improvement of energy storage performance of Gd2O3-doped BNT-based relaxor ferroelectric ceramics

Fulfilling X9R specification in CeO2 modified BNBST-based relaxor ferroelectric energy storage ceramic capacitors

Future low-voltage driven capacitor devices are appealed to employ the eco-friendly ceramics featured with high-stable dielectric energy storage capabilities. Herein, the dielectric energy storage properties of (Bi0·5Na0.5)0.65(Ba0·3Sr0.7)0.35(Ti0·98Ce0.02)O3+8 wt% K0·5Na0·5NbO3+x wt% CeO2 (BNBSTCK + Cx) lead-free relaxor ferroelectric ceramics were comprehensively investigated. By maintaining the relaxor ferroelectric phases near room temperature and disrupting the ferroelectric long-range order via CeO2 additive, the EIA X9R specification was fulfilled at the best composition of x = 8 over a wide range of −74∼208 °C with a relatively high dielectric constant εr = 904 and low loss tanδ = 10−3 (@25 °C & 1 kHz). Meanwhile, the good recoverable energy storage density Wrec = 0.77 J/cm3 and high efficiency η = 91.6% were achieved only at a low electric field of 95 kV/cm. Furthermore, these ceramics exhibited exceptional frequency and cycle dependent energy storage stability, which could guide the design ideas of long-life X9R ceramic capacitors suitable for high and low working temperature environments in low-voltage driven energy storage applications.

Optimization in the energy storage properties of Bi0.5Na0.5TiO3–SrTiO3 ceramics by introducing Bi(Mg0.5Zr0.5)O3

AbstractAs one of the important electronic components, the dielectric capacitors for energy storage applications have been extensively studied in recent years. Among various dielectric materials, the perovskite oxide Bi0.5Na0.5TiO3‐based ceramics have become promising candidates due to their high polarization, dielectric tunability, environment‐friendly composition, and so forth. Herein, the relaxor ferroelectric ceramics of Bi0.5Na0.5TiO3–SrTiO3–Bi(Mg0.5Zr0.5)O3 were prepared via solid‐state reaction method. The sample with optimal composition not only retains the high polarization by introducing Bi3+ ions, but also achieves the reduced remanent polarization by enhancing relaxor behavior and the promoted electric breakdown strength by the grain size refinement. Accordingly, a high recoverable energy density of 8.3 J/cm3 under 450 kV/cm and the superb charge/discharge properties (current density CD = 1200 A/cm2, power density PD = 150 MW/cm3, charge/discharge time t0.9 = 0.15 µs) are achieved, revealing great prospect in energy storage applications.

Improved energy storage performance achieved in (Bi0.5Na0.5)TiO3-based relaxor ferroelectrics via composition engineering

The utilization of relaxor-ferroelectrics is considered to become a feasible scheme to achieve high energy storage performance owing to their high polarization and low hysteresis loss. Herein, the (1-x)(Bi0.5Na0.5)TiO3-x(Sr0.7La0.2)(Ti0.9Zr0.1)O3 ((1-x)BNT-xSLTZ) ceramics were synthesized by using the traditional solid-state reaction method. A favorable recoverable energy density (Wrec) of 4.0 J cm−3 could be obtained at 295 kV cm−1 by combining composition-driven intensive relaxation behaviors and fine grains. Further, the high stabilities for temperature and frequency, with energy density of 1.56–1.41 J cm−3 over a range of 25–150 °C at 150 kV cm−1 and energy density of 1.48–1.67 J cm−3 at 150 kV cm−1 ranging from 1 Hz to 200 Hz, are achieved in 0.6BNT-0.4SLTZ. These results suggest that the BNT-SLTZ relaxor ferroelectric ceramics have capacity of becoming a promising candidate for high-power energy storage applications.

Optimizing energy storage under low electric field in A-site dysprosium modified BiFeO3-BaTiO3 ceramics

Electric recoverable energy density and dielectric breakdown strength are crucial factors in the high power-density capacitors. This study highlights the A-site dysprosium (Dy) substituted perovskite 0.5(Bi1−xDyx)FeO3-0.5BaTiO3 relaxor ferroelectric ceramics (x = 0–0.30) in O2-atmosphere sintering. An overall pseudo-cubic structure with a major cubic Pm-3m symmetry was observed in all compositions accompanied by multiple lattice symmetries. Anti-polar orthorhombic Pbam space group and non-polar orthorhombic Pnma symmetry gradually increase while ferroelectric tetragonal P4mm symmetry decreases as Dy content approaches x = 0.3. Recoverable energy densities (Wrec) of 4.8 J/cm3 and 3.6 J/cm3, storing efficiencies (η) of 68% and 75%, and recoverable energy storage intensities (ρ) of ∼3.2×10−2 J/kV·cm2 and ∼2.1×10−2 J/kV·cm2 were attained at x = 0 and 0.10 at electric fields of 150 and 175 kV/cm, respectively. The breakdown strength is improved from 150 to 200 kV/cm as x increases from 0.0 to 0.30. This study suggests that grain boundaries and local nanoclusters may act as barriers to inhibit charge transport and consequently increase the breakdown strength.

Domain engineered lead-free Bi0.5Na0.5TiO3-Bi(Ni0.5Hf0.5)O3 relaxor ferroelectric ceramics for energy storage with low electric field applications

Lead-free materials for energy storage are increasingly receiving attention due to their exceptional properties of high charging and discharging rates, high power density, and eco-friendliness. In this work, (1−x)Bi0.5Na0.5TiO3-xBi(Ni0.5Hf0.5)O3 (BNT-BNH, x = 0.05, 0.10, 0.15 and 0.20) ceramics were prepared for electrostatic energy storage. P-E loops results show that the introduction of Ni2+ and Hf4+ induces the formation of polar nanoregions (PNRs) and the phase transition from ferroelectric to relaxor ferroelectric in BNT ceramics. Transmission Electron Microscopy directly confirm the increase of crystal plane spacing implies a good solid solution of BNT-BNH, and the number of spherical PNRs increases significantly with increasing the BNH content. Herein, a recoverable energy storage density of 2.68 J/cm3 and relative efficiency of 72.1 % are achieved for 0.8BNT-0.2BNH ceramics under 210 kV/cm. The 0.8BNT-0.2BNH ceramics also exhibit a fast discharge rate (t0.9 = 76 ns), high current density (403.1 A/cm2), and high power density (12.85 MW/cm3), which illustrates that BNT-BNH material systems have good application potential in electrostatic energy storage.

Preparation of Barium Titanate-Based Ferroelectric Ceramics by Solid-Phase Sintering and Its Energy Storage Performance

Barium titanate has been a widely used dielectric material due to its favorable properties, including high dielectric constant, low dielectric loss, stable dielectric behavior and a cost-effective price. In this study a novel barium titanate-based relaxor ferroelectric ceramics, Nax/2Lax/2Ba1−x TiO3, was prepared using multi-element chemical doping substitution and solid-phase sintering method. Investigations into the optimal processing conditions and compositional ratios for ceramics have led to significant insights into their microstructural and macroscopic attributes. Specifically, the ceramic composed of Na0.075La0.075Ba0.85, with a composition parameter x equal to 0.15, has demonstrated prominent characteristics of a relaxor ferroelectric. This ceramic composition achieved an impressive energy storage efficiency, reaching up to 93.9%. In the context of energy storage under specific conditions, notable efficiencies were observed. The highest density of energy storage achieved was 0.342 J/cm3, while the energy that could be effectively recovered registered at 0.304 J/cm3. These measurements were recorded under the influence of an electric field with an intensity of 60 kilovolts per centimeter. These findings suggest that ceramics based on barium titanate possess considerable potential for application in energy storage systems, marking them as promising materials in this field.

The enhancement of energy storage performance of BaTiO3–Bi(Mg0·5Ti0.5)O3 Pb-free ceramics via an optimized viscous polymer process route

In this study, the viscous polymer processing (VPP) technique is implemented to optimize the characteristics of bulk (1-x)BaTiO3-xBi(Mg0·5Ti0.5)O3 (BT-xBMT) lead-free relaxor ferroelectric ceramics, with a focus on enhancing the recoverable energy storage density (Wrec), improving breakdown strength resistance (Eb), and increasing storage efficiency (η). The influence of polyvinyl alcohol (PVA) inclusion in the VPP process on the resulting dielectric ceramics is thoroughly investigated, covering rheological, dielectric, and ferroelectric properties. The results reveal that a gradual increase in PVA quantity during the VPP process effectively improves the density of ceramic blanks. However, an excess of PVA leads to void formation in the ceramic blanks post-debinding, hindering the achievement of a dense structure in the final ceramics and causing performance degradation. The resulting BT-0.405BMT-40 wt% PVA ceramic showed excellent storage performance, with Wrec, η, and Eb of 6.55 J/cm3 81.45 %, and 480 kV/cm, respectively. In comparison to bulk BT-0.405BMT ceramics, there is a notable 2.47-fold increase in Wrec and a 1.92-fold increase in Eb, accompanied by a substantial improvement in η. Moreover, the BT-BMT-40 wt% PVA ceramic exhibits favorable temperature stability (30–150 °C), frequency stability (1–50 Hz), and commendable charge/discharge performance.

Moderate Fields, Maximum Potential: Achieving High Records with Temperature-Stable Energy Storage in Lead-Free BNT-Based Ceramics

HighlightsAchieving ultrahigh energy-storage density (7.19 J cm−3) and outstanding storage efficiency (93.8%) at 460 kV cm−1 in BNT-based relaxor ferroelectric ceramics under a moderate electric field.Superior energy-storage performance accomplished through meticulous regulation of permittivity, enhancement of insulation quality, and strategic domain engineering via chemical formula optimization.The intricate structure–property relationship elucidated with precision using high-resolution transmission electron microscopy.

Energy storage properties and stability in Nd3+/Ta5+ modified 0.6Na0.5Bi0.5TiO3-0.4Sr0.7Bi0.2TiO3 lead-free relaxor ferroelectric ceramics under a low electric field

Due to the prevalence of wearable electronic devices, Lead-free dielectric ceramics with excellent recoverable energy storage density and efficiency at low electric fields are well worth investigating. Moreover, maintaining excellent energy storage performance (ESP) in different environments is a huge challenge for researchers. In this study, 0.6Na0·5Bi0·5TiO3-0.4Sr0·7Bi0·2TiO3 lead-free relaxor ferroelectric ceramics were modified by (Sr0.7Nd0.2) (Ta0·4Ti0.5)O3 (BNST-xSNTT x = 0, 0.02, 0.04, 0.06). On one hand, BNT has a very high polarization strength, making it a very suitable basic element for designing high energy storage dielectric materials. On the other hand, Sr0·7Bi0·2TiO3 and (Sr0.7Nd0.2) (Ta0·4Ti0.5)O3 were introduced to improve the performance of ceramics, such as inducing polar nanoregions (PNRs), refining grain size, and increasing impedance. The results demonstrate that the energy storage characteristics of BNST-xSNTT were enhanced by introducing SNTT to the BNST. The ceramics exhibited a significant grain size reduction from 0.946 μm (x = 0) to 0.346 μm (x = 0.06). In addition, a great polarization difference (ΔP = 44.29 μC/cm2) was simultaneously achieved in the x = 0.02 sample. As a result, BNST-2SNTT (x = 0.02) ceramic obtained an excellent recoverable energy density of 3.24 J/cm3 and a satisfactory efficiency of 81.4 % at a low electric field of 190 kV/cm. Furthermore, the BNST-2SNTT ceramic exhibits excellent temperature stability (20°C–140 °C), frequency stability (1 Hz–500 Hz), and cycling reliability (10°-106 cycles). The corresponding fluctuation of ESP is less than 5 %. These properties indicate that the BNST-2SNTT ceramic is an excellent dielectric material for energy storage.