Tunable antiferroelectric ceramic polarization via regulating incommensurate phase and domain features

Due to the high demand for dielectric materials with high energy density, the energy storage performance of antiferroelectric ceramic capacitors has always gained much attention. Polarization intensity is a key factor that is closely related to the energy storage density. However, thus far, there has been a lack of research studies or successful methods to effectively modulate polarization intensity. The behavior of the polarization process is complex and contains domain nucleation, growth, and flip-flapping. Based on this finding, the introduction of Nb⁵⁺ at the B-site was designed to influence the three stages of antiferroelectric polarization by regulating the balance between the ferroelectric and antiferroelectric phases, and eventually realized regulation of the saturation polarization intensity in the (Pb_1-1.5xLa_x)(Zr_0.5Sn_0.43Ti_0.07)O₃ antiferroelectric ceramics. The saturation polarization intensity has increased from 25.56 to 42 μC/cm² with Nb⁵⁺ content increases from 0 to 4 mol% and the hysteresis was kept low, Pb_0.94La_0.04(Zr_0.65Sn_0.35)_0.975Nb_0.02O₃ is the optimal component with a high releasable energy density of 8.26 J/cm³ and an energy storage efficiency of 90.31%. This work provides an in-depth explanation of the microscopic mechanism of antiferroelectric ceramic polarization and presents a novel approach for the composition design of high-energy storage density antiferroelectric ceramics.     

Enhanced energy storage properties and stability in (Pb0.895La0.07)(ZrxTi1-x)O3 antiferroelectric ceramics

Recently, the (Pb,La)(Zr,Ti)O₃ antiferroelectric materials with slim-and-slanted double hysteresis loops have been widely drawn in the application of advanced pulsed power capacitors due to its low strain characteristic. In this work, the energy storage properties of (Pb_0.895La_0.07)(Zr_xTi_1-x)O₃ ceramics with different Zr contents are researched thoroughly because the substitution of Ti⁴⁺ by Zr⁴⁺ can reduce the tolerance factor t, enhancing the antiferroelectricity. The polarization-electric field hysteresis loops of the PLZT ceramics become slimmer with increasing Zr content. The highest recoverable energy storage density (W_re) of 3.38 J/cm³ and ultrahigh energy efficiency (η) of 86.5% are achieved in (Pb_0.895La_0.07)(Zr_0.9Ti_0.1)O₃ ceramic. The (Pb_0.895La_0.07)(Zr_0.9Ti_0.1)O₃ ceramic also hold fairly thermal stability (relative variation of W_re is less than 28% over 30 °C-120 °C), excellent frequency stability (10–1000 Hz) and good fatigue endurance. These results demonstrate that the (Pb_0.895La_0.07)(Zr_0.9Ti_0.1)O₃ ceramic can be a desirable material for dielectric energy storage capacitors, especially for pulse power technology.     

Structure variation and energy storage properties of acceptor-modified PBLZST antiferroelectric ceramics

Energy storage capacitors with high recoverable energy density and efficiency are greatly desired in pulse power system. In this study, the energy density and efficiency were enhanced in Mn-modified (Pb_0.93Ba_0.04La_0.02)(Zr_0.65Sn_0.3Ti_0.05)O₃ antiferroelectric ceramics via a conventional solid-state reaction process. The improvement was attributed to the change in the antiferroelectric-to-ferroelectric phase transition electric field (E_F) and the ferroelectric-to-antiferroelectric phase transition electric field (E_A) with a small Mn addition. Mn ions as acceptors, which gave rise to the structure variation, significantly influenced the microstructures, dielectric properties and energy storage performance of the antiferroelectric ceramics. A maximum recoverable energy density of 2.64 J/cm³ with an efficiency of 73% was achieved when x = 0.005, which was 40% higher than that (1.84 J/cm³, 68%) of the pure ceramic counterparts. The results demonstrate that the acceptor modification is an effective way to improve the energy storage density and efficiency of antiferroelectric ceramics by inducing a structure variation and the (Pb_0.93Ba_0.04La_0.02)(Zr_0.65Sn_0.3Ti_0.05)O₃-xMn₂O₃ antiferroelectric ceramics are a promising energy storage material with high-power density.     

Enhancement of energy storage and thermal stability of relaxor Pb0.92La0.08Zr0.52Ti0.48O3-Bi(Zn0.66Nb0.33)O3 thick films through aerosol deposition

Relaxor ferroelectric Pb_0.92La_0.08Zr_0.52Ti_0.48O₃ (PLZT 8/52/48) has been studied widely for applications to high energy storage capacitors because of its polarization-electric (P-E) field hysteresis. On the other hand, its energy storage characteristics are unsatisfactory because the dielectric properties deteriorate with temperature. In the present study, a dense nano-composite thick film (∼5 μm) was fabricated by the aerosol deposition (AD) of mixed powders of BZN [Bi(Zn_0.66Nb_0.33)O₃] corresponding to 0, 5, and 10 at.% with lanthanum-doped lead zirconate titanate ceramics (PLZT) at room temperature, followed by post-annealing for crystallization recovery. The composition of 0.95(Pb_0.92La_0.08Zr_0.52Ti_0.48O₃)-0.05Bi(Zn_0.66Nb_0.33O₃) PLZT-BZN5 was made artificially, which accommodates the coexistence of two different phases, demonstrating superior energy storage performance. The 550°C-annealed PLZT-BZN5 film showed a superior energy density of 14.7 J/cm³ under an electric field of 1400 kV/cm and an efficiency of 81%. The PLZT-BZN5 film also exhibited low dielectric loss and improved temperature stability.     

Achieving excellent energy storage density of Pb0.97La0.02(ZrxSn0.05Ti0.95-x)O3 ceramics by the B-site modification

The applications of antiferroelectric (AFE) materials in miniaturized and integrated electronic devices are limited by their low energy density. To address the above issue, the antiferroelectricity of the reinforced material was designed to improve its AFE-ferroelectric (FE) phase transition under electric fields. In this present study, the composition of Zr⁴⁺ (0.72 Å) and Ti⁴⁺ (0.605 Å) at B-site of Pb_0.97La_0.02(Zr_xSn_0.05Ti_0.95-x)O₃ ceramics with orthogonal reflections are synthesized via the tape-casting method. These ceramics are modified to enhance their antiferroelectricity by reducing their tolerance factor. A recoverable energy storage density W_rec 12.1 J/cm³ was obtained for x = 0.93 under 376 kV/cm, which is superior value than reported until now in lead-based energy storage systems. Moreover, the discharge energy density can reach 10.23 J/cm³, and 90 % of which can be released within 5.66 μs. This work provides a new window and potential materials for further industrialization of pulse power capacitors.     

Enhanced energy storage and breakdown strength in barium titanate zirconate solid solutions with niobates and tantalates

Lead-free relaxor compounds are considered as promising materials for the development of dielectric capacitors with a high energy storage density. This has stimulated many research groups around the world to search for the optimal composition and microstructure. In this paper, we report about two novel lead-free ceramic systems, (1-x)Ba(Ti_0.85Zr_0.15)O₃–(x)Bi(Zn_2/3Nb_1/3)O₃ (BTZ-BZNb) and (1-x)Ba(Ti_0.85Zr_0.15)O₃–(x)Bi(Zn_2/3Ta_1/3)O₃ (BTZ-BZTa), prepared by the solid-state method. Ba(Ti_0.85Zr_0.15)O₃ was chosen as starting compositions due to its ferroelectric-relaxor crossover behavior which combines slim hysteresis loops with high a maximum polarization. By substituting with niobates and tantalates, we have investigated their influence on the polarization, dielectric properties and energy storage performance. Moderate doping enhances the relaxor behavior of BTZ while maintaining a large polarizability, which is beneficial for a high recoverable energy density. The substitution with Nb seems to affect the lattice distortion more than Ta, which can be related to a lower degree of covalency of the Nb-O bonds. This effect does not affect the polarization behavior, and the niobate-doped materials achieve higher breakdown strength than the tantalate-doped materials. The breakdown strength is more influenced by the grain size distribution of the ceramics than by the substitution content and the band gap. Overall, the 6BZNb ceramic shows the most favorable energy storage properties with a high energy density of 1.53 J/cm³ at 244 kV/cm, a high energy efficiency of 91%, and a high breakdown strength of 239 kV/cm.     

Superior energy-storage properties in (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric ceramics with appropriate La content

Antiferroelectric (AFE) ceramics based on Pb(Zr,Sn,Ti)O₃ (PZST) have shown great potential for applications in pulsed power capacitors because of their fast charge-discharge rates (on the order of nanoseconds). However, to date, it has been proven very difficult to simultaneously obtain large recoverable energy densities W_re and high energy efficiencies η in one type of ceramic, which limits the range of applications of these materials. Addressing this problem requires the development of ceramic materials that simultaneously offer a large ferroelectric-antiferroelectric (FE-AFE) phase-switching electric field E_A, high electric breakdown strength E_b, and narrow polarization-electric field (P-E) hysteresis loops. In this work, via doping of La³⁺ into (Pb_1-1.5xLa_x)(Zr_0.5Sn_0.43Ti_0.07)O₃ AFE ceramics, large E_A and E_b due to respectively enhanced AFE phase stability and reduced electric conductivity, and slimmer hysteresis loops resulting from the appearance of the relaxor AFE state, are successfully obtained, and thus leading to great improvement of the W_re and η. The most superior energy storage properties are obtained in the 3?mol% La³⁺-doped (Pb_1-1.5xLa_x)(Zr_0.5Sn_0.43Ti_0.07)O₃ AFE ceramic, which simultaneously exhibits at room temperature a large W_re of 4.2?J/cm³ and a high η of 78%, being respectively 2.9 and 1.56 times those of (Pb_1-1.5xLa_x)(Zr_0.5Sn_0.43Ti_0.07)O₃ AFE ceramics with x?=?0 (W_re?=?1.45?J/cm³, η?=?50%) and also being superior to many previously published results. Besides, both W_re and η change very little in the temperature range of 25–125?°C. The large W_re, high η, and their good temperature stability make the Pb_0.955La_0.03(Zr_0.5Sn_0.43Ti_0.07)O₃ AFE ceramic attractive for preparing high pulsed power capacitors useable in various conditions.     

Large energy storage density,low energy loss and highly stable (Pb0.97La0.02)(Zr0.66Sn0.23Ti0.11)O3 antiferroelectric thin-film capacitors

In this work, high performance (Pb_0.97La_0.02)(Zr_0.66Sn_0.23Ti_0.11)O₃ polycrystalline antiferroelectric thin-film was successfully fabricated on (La_0.7Sr_0.3)MnO₃/Al₂O₃(0001) substrate via a cost-effectively chemical solution method. A large recoverable energy storage density (W_re) of 46.3?J/cm³ and high efficiency (η) of 84% were realized simultaneously under an electric field of 4?MV/cm by taking full advantage of the linear dielectric response after the electric field induced antiferroelectric-ferroelectric transition. Moreover, the PLZST thin-film displayed high temperature stability. With increasing temperature from 300?K to 380?K, the W_re decreased only 1.3%. The film also exhibited good fatigue endurance up to 1?×?10⁵ cycling under an electric field of 2.2?MV/cm. Our work underlines the importance of the interface quality between the film and the substrate and the important role of linear dielectric answer after saturation in the improvement of the energy storage density and efficiency of antiferroelectric materials.     

Systematical investigation on energy-storage behavior of PLZST antiferroelectric ceramics by composition optimizing

Featured with high polarization and large electric field-induced phase transition, PbZrO₃-based antiferroelectric (AFE) materials are regarded as prospective candidates for energy-storage applications. However, systematical studies on PbZrO₃-based materials are insufficient because of their complex chemical compositions and various phase structures. In this work, (Pb_0.94La_0.04)(Zr_1-x-ySn_xTi_y)O₃ (abbreviated as PLZST, 0 ≤ x ≤ 0.5, 0.01 ≤ y ≤ 0.1) AFE system was selected and the energy-storage behavior was regulated. It is found that low Ti content benefits to obtain satisfactory electric breakdown strength, realizing high energy-storage density. With Sn content increasing, the electric hysteresis decreases gradually, which is beneficial to improve energy conversion efficiency. As a result, a large recoverable energy-storage density of 9.6 J/cm³ and a high energy conversion efficiency of 90.2% were achieved in (Pb_0.94La_0.04)(Zr_0.49Sn_0.5Ti_0.01)O₃ ceramic. This work reveals energy-storage behavior of PLZST AFE materials systematically, providing reference for performance tailoring and new material designing in energy-storage applications.     

Antiferroelectric-liner dielectric solid solutions leading to large energy density and ultrahigh efficiency in PBLZST-CZT ceramics

A novel strategy to improve the energy-storage density and efficiency of the antiferroelectric (Pb_0.93Ba_0.04La_0.02)(Zr_0.65Sn_0.3Ti_0.05)O₃ (PBLZST) ceramics is presented by forming ceramic solid solutions. The introduction of linear dielectric Ca(Zr_0.5Ti_0.5)O₃ into PBLZST can effectively increase the breakdown strength, the antiferroelectric-to-ferroelectric phase transition field (E_F) and the ferroelectric-to-antiferroelectric phase transition field (E_A), while decreasing ΔE = E_F - E_A and the dielectric loss. This novel strategy leads to an ultrahigh efficiency of 94% and a remarkably high density of 4.14 J/cm³ in the PBLZST-based ceramics. The fundamental origins of high energy-storage density and efficiency are attributed to the enhanced tolerance factor and electronegativity difference in the complex perovskite structure, as well as the linear dielectric properties of Ca(Zr_0.5Ti_0.5)O₃. Our results qualify the antiferroelectric PBLZST ceramics as innovative and promising candidate for energy storage applications. Furthermore, it points out an effective approach to achieve high efficiency in antiferroelectric by forming ceramics with linear dielectric.     

Modulating the energy storage performance of NaNbO3-based lead-free ceramics for pulsed power capacitors

Nb-containing antiferroelectric materials have recently attracted great research interest as energy storage materials for pulsed power capacitors due to their extraordinary energy storage performances. In this case, the optimization of the energy storage performance is obtained by a compositional modulation of NaNbO₃-Bi(Zn_2/3Nb_1/3)O₃ bulk ceramics. An optimal energy performance can be obtained with a composition of 0.85NaNbO₃-0.15Bi(Zn_2/3Nb_1/3)O₃, which is accompanied by a stable charge energy density in temperatures up to 150 °C owing to its relaxor characteristics and excellent cycling stability after 10⁵ cycles. This work further broadens the scope of NaNbO₃-based ceramic applications in the area of pulsed power sources.     

High thermal stability in PLZST anti-ferroelectric energy storage ceramics with the coexistence of tetragonal and orthorhombic phase

The orthorhombic phase Pb_0.97La_0.02(Zr_0.93Sn_0.05Ti_0.02)O₃ (PLZST) and the tetragonal phase (Pb_0.93Ba_0.04La_0.02)(Zr_0.65Sn_0.3Ti_0.05)O₃ (PBLZST) were composited by the conventional solid state method to acquire high energy storage density and high thermal stability. X-ray diffraction spectra revealed the coexistence of orthorhombic and tetragonal structure, indicating that the ceramics were successfully composited. The component ratio of PLZST/PBLZST significantly influenced the thermal stability as well as the energy storage density due to the opposite energy storage performance-temperature trend of PLZST and PBLZST. The phase composition, microstructure and electric properties were discussed to explain the performance in the ceramic composites. High energy storage density of 3.20?±?0.02?J/cm³ at 20?°C with a variation <15% over a temperature range from 20?°C to 150?°C were found in the ceramic composite with a PLZST/PBLZST ratio of 55:45. This work provide an effective method to broaden applications of energy storage ceramics in high temperature.     

High‐Energy Storage Performance in (Pb0.98La0.02)(Zr0.45Sn0.55)0.995O3 AFE Thick Films Fabricated via a Rolling Process

(Pb_0.98La_0.02)(Zr_0.45Sn_0.55)_0.995O₃ antiferroelectric (AFE) thick films with a thickness of about 85 μm were successfully fabricated via a rolling process using an improved sintering method, and all specimens showed high‐energy‐storage performance. The X‐ray diffraction, SEM pictures, and hysteresis loops confirmed that the sintering temperature had an important influence on the microstructures, dielectric properties and energy storage performance of AFE thick films. The grain size and the storage efficiency increased with the increasing sintering temperature, the energy storage performance was enlarged by the rolling process. As a result, a maximum recoverable energy density of 7.09 J/cm³ with an efficiency of 88% was achieved at room temperature, together with stable energy‐storage behavior, which was almost three times higher than that (2.43 J/cm³) of the bulk ceramics counterparts. The results demonstrated that the improved method was an effective way to improve the breakdown strength and energy storage performance of AFE thick films, and (Pb_0.98La_0.02)(Zr_0.45Sn_0.55)_0.995O₃ AFE thick films were a promising material for high‐power energy storage.     

Effect of compositional variations on phase transition and electric field-induced strain of (Pb,Ba) (Nb,Zr, Sn,Ti)O3 ceramics

(Pb_0.97Ba_0.02)Nb_0.02(Zr_0.55Sn_0.45?xTi_x)_0.98O₃ (PBNZST, 0.03≤x≤0.06) ceramics were prepared by conventional solid state synthesis and their crystal structure, ferroelectric, dielectric, and electric field-induced strain properties were systemically investigated. A transformation from antiferroelectric (AFE) phase to ferroelectric (FE) phase was observed at 0.05<x<0.06. Besides, with the increase of Ti content, the electric field-induced strain decreased, due to the larger strain of AFE ceramics compared to FE ceramics. Further, when the measuring frequency decreased, the strain improved, because the electric field at low frequency allows a more efficient switching of domains, resulting in larger strain. The maximum strain of 0.55% was obtained in (Pb_0.97Ba_0.02)Nb_0.02(Zr_0.55Sn_0.45?xTi_x)_0.98O₃ antiferroelectric ceramics with x=0.03 at 2 Hz.     

Energy storage property of (Pb0.97La0.02)(Zr0.5Sn0.4Ti0.1)O3-(Na0.5Bi0.5)0.94Ba0.06TiO3 ceramics: Effects of antiferroelectric-relaxor transition and improved breakdown strength

(1-x)(Pb_0.97La_0.02)(Zr_0.5Sn_0.4Ti_0.1)O₃-x(Na_0.5Bi_0.5)_0.94Ba_0.06TiO₃ (x = 0 ∼ 0.4) ceramics have been prepared and investigated. The ceramics consist of perovskite solid solution matrix and precipitated, isolated SnO₂ particle, resulting in 0–3 type composite structure. With increasing x value, the room temperature crystal structure of perovskite solid solution transforms from tetragonal to pseudocubic, therefore, the electrical property evaluates form robust antiferroelectric at x = 0, metastable antiferroelectric at x = 0.1, and then relaxor ferroelectric at x > 0.1. Moreover, the breakdown strength is enhanced due to the composite structure and reaches maximum value of 190 kV/cm at x = 0.2. Both the phase transition and enhanced breakdown strength are helpful to improve energy storage property, the x = 0.2 ceramic shows largest recoverable energy density w_rec of 1.84 J/cm³, discharge efficiency $\eta$ of 86.6 %. Especially, both w_rec and $\eta$ illustrates significantly improved thermal stability within 25−125 °C.     

High-performance La-doped BCZT thin film capacitors on LaNiO3/Pt composite bottom electrodes with ultra-high efficiency and high thermal stability

Dielectric capacitors possessing large energy storage density, high efficiency and high thermal stability simultaneously are very attractive in modern electronic devices to be operated in harsh environment. Here, it is demonstrated that large energy storage density (W?～?15.5?J/cm³), ultra-high efficiency (η ～93.7%) and high thermal stability (the variation of both W from 20?°C to 260?°C and η from 20?°C to 140?°C is less than 5%) have been simultaneously achieved in the La-doped (Ba_0.904Ca_0.096)_0.9775+xLa_0.015(Zr_0.136Ti_0.864)O₃ (x?=?0.0075) lead-free relaxor ferroelectric thin film capacitors deposited on LaNiO₃/Pt composite bottom electrodes by using a sol-gel method. The good energy storage property of the thin film capacitors at x?=?0.0075 is mainly ascribed to the diversity of the structure of the nano-clusters around the three-phases coexisting component point (Ba_0.904Ca_0.096)(Zr_0.136Ti_0.864)O₃ where cubic, tetragonal and rhombohedral phases coexisted, as well as the ultra-high quality of thin film due to the utilization of the LaNiO₃/Pt composite bottom electrode, making it a promising candidate for dielectric capacitors working in harsh environments.     

Preparation of PLZST antiferroelectric ceramics by hydroxide coprecipitation method

An improved coprecipitation method using buffer solution was developed for synthesizing Pb_0.97La_0.02(Zr_0.75Ti_0.08Sn_0.17)O₃ antiferroelectric ceramics. It was found that the perovskite phase was formed when the precursor powders were calcined at 550 °C for 2 h and the average diameter of these particles was less than 100 nm. Moreover, the results showed that when the pH value of the precipitating solution was in the range of 8.9–9.0, in comparison with the ceramics prepared by conventional solid state reaction, the samples synthesized by coprecipitation method had a larger electric field-induced phase transition and higher breakdown strength, which lay a basis for preparing high power energy storage capacitors and pulsed power applications.     

Triple Hysteresis Loops of PLZST Ceramics Related to Coexistence of Ferroelectricity and Antiferroelectricity

The hysteresis behaviors and phase characteristics of Pb_0.97La_0.02(Zr_0.90Sn_0.025Ti_0.075)O₃ (PLZST) ceramics were investigated in this work. A single mini hysteresis loop at 3 kV/mm with the maximum polarization (P_max) of 8.3 μC/cm² and triple hysteresis loops at 6.6 kV/mm were observed, which indicates the coexistence of rhombohedral ferroelectric phase and tetragonal antiferroelectric phase. The X‐ray Diffraction patterns and dielectric temperature spectra both demonstrate this coexistence. Moreover, the hysteresis loops with increasing temperature indicated that a ferroelectric–antiferroelectric phase transition occurred at about 60°C. These phenomena would be useful for understanding the domain evolution during ferroelectric and antiferroelectric phase transition.     

Phase transition and energy storage behavior of antiferroelectric PLZT thin films epitaxially deposited on SRO buffered STO single crystal substrates

(Pb_0.98, La_0.02)(Zr_0.95, Ti_0.05)O₃ (PLZT) thin films of 300 nm thickness were epitaxially deposited on (100), (110), and (111) SrTiO₃ single crystal substrates by pulsed laser deposition. X-ray diffraction line and reciprocal space mapping scans were used to determine the crystal structure. Tetragonal ((001) PLZT) and monoclinic M_A ((011) and (111) PLZT) structures were found, which influenced the stored energy density. Electric field-induced antiferroelectric to ferroelectric (AFE→FE) phase transitions were found to have a large reversible energy density of up to 30 J/cm³. With increasing temperature, an AFE to relaxor ferroelectric (AFE→RFE) transition was found. The RFE phase exhibited lower energy loss, and an improved energy storage efficiency. The results are discussed from the perspective of crystal structure, dielectric phase transitions, and energy storage characteristics. Besides, unipolar drive was also performed, providing notably higher energy storage efficiency values due to low energy losses.     

High energy-storage density and efficiency in PbZrO3-based antiferroelectric multilayer ceramic capacitors

The utilization of antiferroelectric (AFE) materials is commonly believed as an effective strategy to improve the energy-storage density of multilayer ceramic capacitors (MLCCs). Unfortunately, the inferior energy conversion efficiency (η) leads to high energy dissipation, which severely restricts the broader applications of MLCCs due to the increased probability of materials and/or devices failure. Herein, AFEs featuring large polarization response and small hysteresis loss are proposed to make up for deficiencies. Guided by this proposal, (Pb_0.94La_0.04)(Zr_0.69Sn_0.30Ti_0.01)O₃ AFE MLCC (abbreviated as M2) are manufactured. An ultrahigh W_rec of 16.1 J/cm³ and an excellent η of 90.9% are achieved simultaneously. Additionally, a great discharge energy density (W_dis) of 8.8 J/cm³ and a large power density (P_D) of 165.6 MW/cm³ are obtained synchronously. Noticeably, M2 exhibits excellent frequency-insensitive, temperature-bearable, and fatigue cycle-endurable energy-storage performances and/or charge-discharge properties. These results indicate that M2 has a promising prospect in advanced power electronic and/or pulsed power systems.