Relaxor Antiferroelectrics Research Articles

Superior energy storage properties of BiFeO3 doped NaNbO3 antiferroelectric ceramics

NaNbO3 (NN)-based dielectric ceramics for energy storage have garnered significant interest due to their high saturation polarization, low residual polarization, and superior breakdown strength (Eb). However, the low recoverable energy storage density (Wrec) and efficiency (η) significantly limited their practical application. Herein, BiFeO3 (BF) was incorporated into NN to optimize the energy storage performance. The NN-BF ceramics exhibited pronounced antiferroelectric (AFE) relaxor phase, alongside grain size reduction and Eb enhancement, which contributed to a significant increase of Wrec and η. Specially, the optimum Wrec of 4.43 J/cm³ and η of 71.51 % were achieved at the composition of 0.9NN-0.1BF. Besides, stable energy storage performance was maintained over a wide temperature range (20–120 °C). These results highlight the potential of NN-BF relaxor AFE ceramics as promising candidates for high-performance energy storage applications.

Local defect structure design enhanced energy storage performance in lead-free antiferroelectric ceramics

Antiferroelectrics (AFEs) are ideal candidates in dielectric, electromechanical, and electrothermal applications. NaNbO3 (NN), as a lead-free antiferroelectric (AFE) material under extensive investigation, exhibits ferroelectric (FE)-like polarization–electric field (P-E) hysteresis loops, characterized by high remnant polarization and large hysteresis. Herein, the local defect structure design is proposed to achieve high energy storage (ES) density in NN-based AFE ceramics. The pinning effect of defect dipoles and the enhancement of local structural disorder stabilize the AFE phase and reduce hysteresis losses. Consequently, an excellent ES performance of large recoverable energy density (Wrec) of 9.70 J/cm3 and high efficiency (η) of 88.75 % is concurrently obtained in NN-based relaxor AFE ceramics, with outstanding charge–discharge performance (PD∼413.2 MW/cm3, WD∼4.47 J/cm3), which are significantly improved compared to other reported values in lead-free ES ceramics. This indicates that NN-based ceramics are candidates for advanced ES capacitors and provides a feasible modulation approach for the development of new lead-free high-performance dielectric materials.

Enhancing comprehensive energy storage properties in Pb-free relaxor AFE/FE system via heterogeneous structure tuning and defect engineering

Multi-phase NaNbO3 (NN) exhibits high adjustability on the ordering of both polarization and oxygen octahedral tilt, becoming a perfect carrier to design heterogeneous structure for boosting comprehensive energy storage properties. To balance the energy storage density and efficiency, the coexistence of the relaxor antiferroelectric (AFE) with high polarization capability and the relaxor ferroelectrics (RFE) with high efficiency is designed in this work by introducing Sr0.7Bi0.2□0.1Ti0.75Ta0.2□0.05O3 (SBTT) into NaNbO3-BiFeO3. As a result, an outstanding capacitive energy density (Wrec) of 12.25 J cm−3 with a high η of 83 % can be achieved in NN-BF-SBTT ceramic, which can be identified as a novel heterogeneous coexisting structure with the crossover of high polarization capability in relaxor AFE and high efficiency in RFE in terms of high-resolution TEM. Furthermore, grain refinement and the dense structure inhibit the leak current, suppress the concentration of oxygen vacancy defects and raise the activation energy (Ea), thus enhancing the EB. These excellent energy storage properties overcome the trade-offs between the two sets of parameters (Wrec-η, ΔP-EB), offering a refreshing strategy for the development of high-performance ceramic capacitors.

Designing silver niobate-based relaxor antiferroelectrics for ultrahigh energy storage performance

Designing silver niobate-based relaxor antiferroelectrics for ultrahigh energy storage performance

Linear-like NaNbO3-based Lead-free Relaxor Antiferroelectric Ceramics with Excellent Energy-storage and Charge-discharge Properties

Linear-like NaNbO₃-based Lead-free Relaxor Antiferroelectric Ceramics with Excellent Energy-storage and Charge-discharge Properties

Stepwise-design activated high capacitive energy storage in lead-free NaNbO3-based relaxor antiferroelectric ceramics

Although comparable energy storage performance (ESP) has been realized in NaNbO3 (NN)-based antiferroelectric (AFE) ceramics, how to simultaneously realize large energy density (Wrec), large storage efficiency (η), and outstanding thermal stability still remains a remarkable challenge. Herein, by progressively substituting BiFeO3 (BF) and CaTiO3 (CT), we propose a stepwise-design strategy to activate comprehensive exceptional ESP in NN-based relaxor AFE ceramics. The substitution of BF with high spontaneous polarization and CT with high breakdown strength (Eb) into NN generates stabilized AFE R phase, strong tilt distortions of oxygen octahedron, ultrasmall and highly dynamic polar nanoregions, and refined grains, thus manifesting enhanced high-field polarizability, significantly delayed polarization saturation, and ultrahigh Eb macroscopically. With the deliberate stepwise-design route, we realize an optimal overall ESP in 0.6(0.96NN-0.04BF)-0.4CT relaxor AFE ceramics, featuring a high Wrec of 6.84 J/cm3, a large η of 81.5 %, along with super temperature/frequency/fatigue stabilities, which shows great performance merits compared with previous reports. This work demonstrates that stepwise-design engineering approach by manipulating the crucial structures exerts a positive size effect on the polarization and breakdown response of dielectrics, and can be exploited for designing more high-performance energy storage ceramics.

Comprehensive energy-storage performance enhancement in relaxor anti-ferroelectrics via strengthening local polarization

Lead-free dielectric capacitors with excellent energy-storage performance have gained much attention for their remarkable potential applications in pulsed power electronic systems and devices. However, the large recoverable energy-storage density Wrec is usually accompanied with low efficiency η, hindering their practical applications. Such performance deterioration occurs because the large polarization is generally linked with strong reversal hysteresis, making the synergetic optimization of energy-storage density and efficiency a great challenge. Here we develop a strategy of constructing strengthened local polarization in the lead-free relaxor anti-ferroelectric ceramics 0.9NaNbO3-0.1Bi(Ni2/3Nb1/3)O3 by carefully manipulating the microstructures, the ultrahigh Wrec ∼ 11.2 J/cm3 and large η ∼ 90.5 % have been simultaneously achieved. Moreover, superior charge/discharge performances (power density PD ∼ 548 WM/cm3, discharge speed t0.9 ∼ 27 ns) and outstanding temperature (up to 160 °C) and cycling (up to 106) stabilities are also ensured. The excellent overall properties are mainly attributed to the stabilized antiferroelectric phase, the strong relaxation characteristic, as well as the enhanced local polarization in the polar nano-regions (PNRs) caused by the introduction of Bi(Ni2/3Nb1/3)O3. This work not only provides a lead-free system with remarkable energy-storage performance that demonstrates great potential in the application field of high-power pulse electronic devices, but also proposes a convenient and efficient strategy to design new dielectric materials with excellent energy-storage performance.

Superior energy-storage performances achieved in NaNbO3-based antiferroelectric ceramics by phase-structure and relaxation regulation

Lead-free NaNbO3-based antiferroelectric (AFE) ceramics are highly considered as promising substitutes of lead-based ones in dielectric energy-storage field. However, their low breakdown strength and large electric hysteresis loss originating from the field-induced metastable ferroelectric (FE) Q phase and/or AFE P phase still remains challenging, which severely impedes the further improvement of energy-storage performances. Herein, an effective phase-structure and relaxation regulation via A-site cation substitution strategy has been proposed to solve this issue. The phase-structures of the designed NN-based AFE ceramics evolve from orthorhombic P phase to R phase accompanying with the enhancement of relaxation behavior. Accordingly, an effective transformation from a plump and pinched polarization–electric field (P–E) hysteresis loop to a slim and slanted one has undergone, contributing to superior energy-storage performances. Noticeably, an expected large recoverable energy density (Wrec) of 4.0 J/cm3 with a high energy conversion efficiency (η) of 80.0 % was realized in 0.94(Na0.88Sm0.04NbO3)-0.06(BiFeO3) relaxor AFE ceramics at 460 kV/cm. Meanwhile, a great discharge energy density (Wdis) of 1.2 J/cm3 and a large power density (PD) of 92.4 MW/cm3 were achieved at 200 kV/cm. Furthermore, the favorable functional reliabilities in frequency, temperature, and fatigue cycle were also confirmed. These results not only demonstrate the great potential of NaNbO3-based relaxor AFE ceramics for dielectric energy-storage applications, but also confirm the validity of the strategy proposed in this work to obtain superior energy-storage performances.

Achieving Ultrahigh Energy Storage Performance for NaNbO3-Based Lead-Free Antiferroelectric Ceramics via the Coupling of the Stable Antiferroelectric R Phase and Nanodomain Engineering.

NaNbO3(NN)-based lead-free eco-friendly antiferroelectric (AFE) ceramics with an extremely high maximum polarization (Pm) are believed to be a promising alternative to traditional lead-based ceramics. Nevertheless, the high energy dissipation resulting from the large polarization hysteresis, which arises from the AFE-ferroelectric (FE) phase transition, poses a great challenge to the application of this promising ceramic. Herein, an excellent recoverable energy storage density (Wrec) was attained by intentionally designing a (0.86 - x) NaNbO3-0.14CaTiO3-xBiMg2/3Nb1/3O3 (NN-CT-xBMN) relaxor antiferroelectric ceramic, attributed to the synergistic effect of the stable AFE R phase and nanodomain engineering to overcome the bottleneck. The obtained results illustrate that the inclusion of BMN causes the transition from AFE microdomains to nanodomains and stabilizes the relaxor AFE orthorhombic R phase, which generates a highly stable polarization field response with low hysteresis and delays the AFE-FE phase transition, thus improving energy storage density. As a consequence, a high Wrec of 5.41 J cm-3 with an excellent conversion efficiency η of 86.7% was obtained in the NN-CT-0.08BMN ceramic. Moreover, the NN-CT-0.08BMN ceramic exhibits superior stability in temperature (25-150 °C), frequency (1-600 Hz), and fatigue behavior (10°-104 cycles) together with a large current density (CD = 810 A cm-2), ultrahigh power density (PD = 118 MW cm-3), and ultrafast discharge rate (t0.9 < 0.7 μs). This superior energy storage density, coupled with outstanding stability, suggests that the NN-CT-0.08BMN ceramic has the potential to be a promising candidate for pulsed power applications and power electronics.

Relaxor antiferroelectric-relaxor ferroelectric crossover in NaNbO3-based lead-free ceramics for high-efficiency large-capacitive energy storage

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 BaTiO3 into NaNbO3-BiFeO3 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 0.88NaNbO3–0.07BiFeO3–0.05BaTiO3 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 Wrec ∼ 13.1 J/cm3 and an ultrahigh efficiency η ∼ 88.9%. These remarkable values shattered the trade-off relationship typically observed in most dielectric capacitors between Wrec and η. 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.

Remarkably minimized domain and elevated energy storage properties in Na0.48Bi0.48Ba0.04TiO3-based relaxor antiferroelectrics by interposing Bi(Mg2/3Ta1/3)O3

Lead-free dielectric capacitors have been embraced recently due to their tiny volume, large energy density and superfast charge–discharge speed. Here, a recoverable energy storage density of ∼ 10.73 J cm−3 and an efficiency of ∼ 80.5% were simultaneously revealed in traditional sintering (1 − x) (Na0.48Bi0.48Ba0.04TiO3)-xBi(Mg2/3Ta1/3)O3 (x = 0.16) ceramics (BNBT-0.16BMT) under an applied electric field of 540 kV cm−1 via disordering B-site ions and modifying the B-site cation ratio. Specifically, the disorder of B-site ions was found to alter the crystal structure, delaying maximum polarization. Phase switching between rhombohedral and tetragonal was characterized with transmission electron microscopy, Raman scattering and dielectric constant curves. Mg/Ta dopant was shown to cause electric charge mismatch and change dielectric anomaly peaks, leading to a large maximum polarization value. Finally, BNBT-0.16BMT stabilizes the relaxor antiferroelectrics (RAFE) system, with a significant broad frequency (0.5–120 Hz), broad temperature stability (20–160 °C), and excellent discharge performance (WD ∼ 5.23 J cm−3; Ea ∼ 350 kV cm−1). This preparation shows potential for broad application in dielectric capacitors.

Dynamic FET-based memristor with relaxor antiferroelectric HfO2 gate dielectric for fast reservoir computing

Reservoir computing (RC), as a framework for artificial intelligence (AI) computation, is derived from recurrent neural networks, but with higher efficiency benefits from its much simpler training process. A hardware-based physical RC employs a reservoir that is a fixed non-linear system, and in a simple RC structure, the reservoir is ideally a short-term dynamic field effect transistor-based memristor. In this work, we demonstrate that reservoir computing employing a polarization-modulated transistor as a physical reservoir with a relaxor antiferroelectric back gate significantly reduces parameters, power consumption, and calculation steps of the neural network. Here, relaxor antiferroelectricity is realized in an Al-doped Hf0.5Zr0.5O2 (Al:HZO) thin film, and with the poling process-sensitive modulation of the Al:HZO gate dielectric, a dynamic and polarization field-modulated transistor is demonstrated as a short-term memristor. This short-term memory behavior is further used to encode binary images to form a reservoir for fast image processing, where the reservoir mimics small convolution operations to convert images. This reservoir computing is also applied to image classification, denoising, and similarity judgment, and very reliable results are obtained. This work provides a new approach to hardware-based physical reservoir computing.

Excellent Energy-Storage Performance of (0.85 – x)NaNbO3–xNaSbO3–0.15(Na0.5La0.5)TiO3 Antiferroelectric Ceramics through B-Site Sb5+ Driven Phase Transition

NaNbO3-based relaxor antiferroelectric (AFE) ceramics are receiving more and more attention for high power pulse applications. A commonly used design strategy is to add complex perovskites with lower tolerance factors. Herein, a new lead-free AFE system of (0.85 - x)NaNbO3-xNaSbO3-0.15(Na0.5La0.5)TiO3 was specially designed considering the substitution of Sb5+ for Nb5+ reduces the polarizability of B-site ions but increases the tolerance factor. The formation of nanodomains with stable AFE orthorhombic R phase symmetry contributes to a slim and double-like polarization-field hysteresis loop, while the increased resistivity and activation energy as a result of sintering aids lead to an enhanced breakdown strength. Therefore, an excellent energy density Wrec ≈ 6.05 J/cm3, a high energy efficiency η ≈ 80.5%, and good charge-discharge performances (power density PD ≈ 155 MW/cm3 and discharging rate t0.9 ≈ 44.6 ns) were achieved in MnO2-doped x = 0.03 ceramics. The experimental results demonstrate that the B-site Sb5+ driven orthorhombic P-R phase transition and increased local structure disorder should provide a new strategy to design high-performance NaNbO3-based relaxor AFE capacitors.

High energy storage density and efficiency in AgNbO3 based relaxor antiferroelectrics with reduced silver content

Silver niobate based lead-free antiferroelectric ceramics have demonstrated great advantages, but the high consumption of noble metal silver may restrict their commercial application. In this work, Na+ and Ta5+ co-modified (Ag1-xNax)(Nb1-yTay)O3 (100xNa-100yTa) ceramics were investigated, aiming to reduce the silver consumption and achieve good energy storage properties. The Na+ tended to increase M2-M3 phase transition temperature (TM2-M3), while Ta5+ was more likely to reduce TM2-M3. A new current peak (ER) was observed for the first time in all current-electric field curves. As expected, a room temperature M2-M3 phase boundary with relaxor AFE property was realized in 40Na-65Ta with obviously reduced silver content, in which high recoverable energy storage density (Wrec) of 6.5 J/cm3 and good energy storage efficiency (η) of 78% were achieved. This work demonstrates a strategy to realize relaxor antiferroelectrics in AgNbO3 based ceramics for energy storage performance, and promotes the commercialization potential.

Remarkably Minimized Domain and Elevated Energy Storage Properties in Na0.48bi0.48ba0.04tio3-Based Relaxor Antiferroelectrics by Interposing Bi(Mg2/3ta1/3)O3

Remarkably Minimized Domain and Elevated Energy Storage Properties in Na0.48bi0.48ba0.04tio3-Based Relaxor Antiferroelectrics by Interposing Bi(Mg2/3ta1/3)O3

Enhanced Energy Density and Efficiency in Lead‐Free Sodium Niobate‐Based Relaxor Antiferroelectric Ceramics for Electrostatic Energy Storage Application

AbstractAntiferroelectric ceramics are recently, a research hotspot for electrostatic energy storage because of their large electric‐field induced polarization. Lead‐free sodium niobate (NaNbO3)‐based ceramics are one of the emerging antiferroelectric counterparts. However, the unstable antiferroelectric phase seriously restricts the further improvement of energy density and efficiency. In this work, by introducing binary perovskite end‐member BiFeO3–BaTiO3 with lower tolerance factor and average electronegativity into NaNbO3 ceramics, the stablized antiferroelectric phase with improved relaxation characteristic is identified by slim double‐like polarization‐electric field (P–E) loops and four‐peak current–electric field (I–E) curves. Meanwhile, the antiferroelectric P to R phase transition is verified through Raman spectra, X‐ray diffraction (XRD) patterns, and dielectric performance. In particular, the enhanced electric breakdown strength Eb is achieved by synergic contributions from ultralow dielectric loss, reduced grain size, and so on. Consequently, the sample with optimized composition displays ultrahigh recoverable energy storage density (Wrec) of 14.5 J cm−3 and satisfied efficiency (η) of 83.9%, which shows the superiority in the state‐of‐the‐art dielectric ceramics. These results provide a feasible route by regulating the relationship between antiferroelectric structure and properties to explore high‐performance dielectrics for electrostatic energy storage applications.

Phase structure and defect engineering in (Bi0.5Na0.5)TiO3-based relaxor antiferroelectrics toward excellent energy storage performance

Dielectric ceramics with outstanding energy storage performance are urgently expected for energy storage capacitors. In this work, high energy storage density were achieved by deliberately designing a (1-x)Bi0.5Na0.5TiO3-xAgNb0.5Ta0.5O3 (100xANT) relaxor antiferroelectrics, associating with defect engineering. Both relaxor behaviour and evident antiferroelectric characteristic were successfully realized through phase structure engineering to an antiferroelectric tetragonal (T) dominant structure. Furthermore, defect engineering was also adopted by sintering in a flowing oxygen atmosphere to eliminate various defects (such as metal silver and oxygen vacancies), which significantly improved the breakdown strength and reduced the hysteresis loss. As a consequence, ultrahigh recoverable energy storage density of 6.6 J/cm3 and good efficiency of 72% were achieved in O2-sintered 15ANT ceramics, accompanying with excellent frequency stabilities and outstanding low field performance. This work not only provides a promising dielectric material for energy storage applications, but also proves that phase structure and defect engineering are effective ways for designing new high-performance Bi0.5Na0.5TiO3-based dielectric material.

Relaxor antiferroelectric-like characteristic boosting enhanced energy storage performance in eco-friendly (Bi0.5Na0.5)TiO3-based ceramics

Ideal relaxor antiferroelectrics (RAFEs) have high field-induced polarization, low remnant polarization and very slim hysteresis, which can generate high recoverable energy storage Wrec and high energy storage efficiency η, thus attracting much attention for energy storage applications. True RAFEs, on the other hand, are extremely rare, and the majority of them contain environmentally hazardous lead. In this work, we use a viscous polymer rolling process to synthesize a novel and eco-friendly 0.65Bi0.5Na0.4K0.1TiO3-0.35[2/3SrTiO3-1/3Bi(Mg2/3Nb1/3)O3] (BNKT-ST-BMN) dielectric material, which possesses a very typical RAFE-like characteristic. As a result, this material has a high Wrec of 4.43 J/cm3 and a η of 86% at an electric felid of 290 kV/cm, as well as a high thermal stability of Wrec (>3 J/cm3) over a wide range of 30–140 °C at 250 kV/cm. Our findings suggest that the BNKT-ST-BMN material could be a potential candidate for use in energy storage pulse capacitors.

Synergy of a Stabilized Antiferroelectric Phase and Domain Engineering Boosting the Energy Storage Performance of NaNbO3-Based Relaxor Antiferroelectric Ceramics.

Relaxor antiferroelectric (AFE) ceramic capacitors have drawn growing attention in future advanced pulsed power devices for their superior energy storage performance. However, state of the art dielectric materials are restricted by desirable comprehensive energy-storage features, which have become a longstanding hurdle for actual capacitor applications. Here, we report that a large energy density Wrec of 5.52 J/cm3, high efficiency η of 83.3% at 560 kV/cm, high power density PD of 114.8 MW/cm3, ultrafast discharge rate t0.9 of 45 ns, and remarkable stability against temperature (30-140 °C)/frequency (5-200 Hz)/cycles (1-105) are simultaneously achieved in 0.7 NaNbO3-0.3 CaTiO3 relaxor AFE ceramics via the synergy of stabilized AFE R phase and domain engineering in combination with breakdown strength enhancement. The structural origin for these achievements is disclosed by probing the in situ microstructure evolution by means of the first-order reversal curve method, piezoelectric force microscopy, and Raman spectroscopy. The highly dynamic polar nanoregions and stabilized AFE R phase synergistically generate a linear-like and highly stable polarization field response over a wide temperature and field scope with concurrently improved energy density and efficiency. This work offers a new solution for designing high-performance next-generation pulsed power capacitors.

Phase Structure and Defect Engineering in (Bi0.5na0.5)Tio3-Based Relaxor Antiferroelectrics Toward Excellent Energy Storage Performance

Phase Structure and Defect Engineering in (Bi0.5na0.5)Tio3-Based Relaxor Antiferroelectrics Toward Excellent Energy Storage Performance