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.     

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.     

High breakdown strength and energy density in antiferroelectric PLZST ceramics with Al2O3 buffer

In this work, a new core-shell structure of antiferroelectric ceramic powder (Pb_0.97La_0.02Zr_0.85Sn_0.12Ti_0.03O₃-PLZST) coated with linear dielectric (Al₂O₃) has been successfully prepared to realize high energy density through tape-casting process. According to the experimental results of electron microscope, the sol-gel derived Al₂O₃ layer was uniformly coated on the PLZST particles and the Al₂O₃ layer can be taken as the buffer layer to effectively refine the grain growth as well. Therefore, the modified PLZST particles were fine and uniform compared with the pure PLZST. It was found that the buffer layer could undertake higher electric field and the electric field applied to PLZST particles was weakened based on finite element analysis, which can avoid the premature breakdown of PLZST. And the actual measured breakdown strength was significantly enhanced from 22.2 kV/mm to 35.5 kV/mm. Correspondingly, an extremely high recoverable energy storage density of 5.3 J/cm³ was obtained for PLZST with 0.5%wt Al₂O₃, an 204% enhancement over the pure PLZST ceramics (2.6 J/cm³), and the corresponding efficiency was up to 88.3%. In addition, impedance spectroscopy measurement was carried out to further confirm the better insulation of the ceramic with Al₂O₃ buffer.     

High energy storage density and stable fatigue resistance of Na0.46Bi0.46Ba0.05La0.02Zr0.03Ti0.97-xSnxO3 ceramics

Energy density and fatigue resistance properties were investigated for lead-free Na_0.46Bi_0.46Ba_0.05La_0.02Zr_0.03Ti_0.97-xSn_xO₃ (for 0 ≤ x ≤ 0.15) ceramics, synthesized via solid-state reaction technique. Perovskite pseudo-cubic crystal structure was revealed for all ceramics using X-ray diffraction. Polarization and current density versus electric field were perceived and suggested the relaxor behavior with increasing composition. A high storage energy density ~1.58 J/cm³, and conversion efficiency ~71.7% at ~110 kV/cm applied field was obtained for x = 0.03 composition at room temperature. Energy storage density was revealed ~1.53 J/cm³, and efficiency ~88.6% at 110 °C with a 100 kV/cm applied field. In addition, ceramic x = 0.03 was fatigue-free from 1 to 10⁵ cycles. Hence, the composition x = 0.03 might be applicable for high energy storage devices.     

Energy storage and release properties of Sr-doped (Pb,La)(Zr,Sn,Ti)O3 antiferroelectric ceramics

Pb_0.94−xLa_0.04Sr_x[(Zr_0.6Sn_0.4)_0.84Ti_0.16]O₃ (x=0,0.02,0.04,0.06) antiferroelectric ceramics were fabricated via conventional solid-state reaction. The increase of Sr content enhanced the stability of antiferroelectric phase, which resulted in the rise of phase transition fields and energy density. When x=0.06, the releasable energy density was 1.52 J/cm³ and the efficiency was 93.3% under 129 kV/cm. The pulsed discharge current was also measured to evaluate the energy release properties. Under 129 kV/cm, the obtained current density could be as high as 165.5 A/cm². The pulsed discharge energy density was 1.21 J/cm³ and 90% of that could be released in less than 200 ns. The high energy density, high efficiency and fast energy release time indicate that the obtained AFE ceramics are very promising for pulsed power capacitors.     

Electrical properties and energy-storage performance of (Pb0.92Ba0.05La0.02)(Zr0.68Sn0.27Ti0.05)O3 antiferroelectric thick films prepared by tape-casing method

The energy-storage performance and dielectric properties of tape-cast (Pb_0.92Ba_0.05La_0.02)(Zr_0.68Sn_0.27Ti_0.05)O₃ (PBLZST) antiferroelectric (AFE) thick films with different thicknesses were systematically studied. As the thickness of the thick films increased from 40 to 80 µm, the dielectric constant and saturation polarization (P_s) of the thick films were gradually increased, while their corresponding breakdown strength (BDS) was decreased. A maximum recoverable energy-storage density of 6.8 J/cm³, companied by an efficiency of 61.2%, was achieved in the PBLZST AFE thick film with a thickness of 40 µm at room temperature. Moreover, the energy density of the PBLZST AFE thick films also displayed good thermal stability over 25–200 °C. In addition, all the samples had a low leakage current density of ~10⁻⁶ A/cm² at room temperature. These findings demonstrated that the PBLZST thick films should be a promising candidate for applications in high energy-storage capacitors.     

High-energy density of Pb0.97La0.02(Zr0.50Sn0.45Ti0.05)O3 antiferroelectric ceramics prepared by sol-gel method with low-cost dibutyltin oxide

Lead lanthanum zirconate stannate titanate (PbLa(ZrSnTi)O₃) antiferroelectric (AFE) ceramics are widely used in dielectric capacitors due to their superior energy-storage capacity. Generally, these ceramics can be synthesized by solid-state reaction and sol-gel methods. Ceramics prepared using the sol-gel method have a purer phase than those prepared using the solid-state reaction method because the sol-gel method can avoid the segregation of Sn. However, because the commonly used raw material tin acetate is very expensive, the preparation of PbLa(ZrSnTi)O₃ AFE ceramics via the sol-gel method is not cost-effective, which prevents the use of sol-gel method for manufacturing PbLa(ZrSnTi)O₃ in a large scale. In this work, low-cost dibutyltin oxide instead of expensive tin acetate is used to synthesize Pb_0.97La_0.02(Zr_0.50Sn_0.45Ti_0.05)O₃ (PLZST) nanopowders, and single-phase powders with a perovskite structure and average grain size of 200 nm are obtained at a calcination temperature of 580°C. In addition, dense PLZST AFE ceramics with a pure perovskite structure are obtained by sintering the PLZST nanopowders at temperatures as low as 1100°C. The sintered PLZST ceramics exhibit a room-temperature recoverable energy-storage density as high as 1.93 J/cm³ with an efficiency of 75%, which varies only slightly in the temperature range of 20-120°C. The high energy-storage density (>1.9 J/cm³) over a wide temperature range illustrates that the sol-gel-derived PLZST ceramics with low-cost dibutyltin oxide are quite promising for manufacturing pulse power capacitors.     

Enhanced breakdown strength and energy density of antiferroelectric Pb,La(Zr,Sn,Ti)O3 ceramic by forming core-shell structure

Antiferroelectric Pb_0.97La_0.02(Zr_0.33Sn_0.55Ti_0.12)O₃@SiO₂ (with 5% mole of SiO₂) particles were synthesized by a citric acid sol-gel method. Transmission electron microscopy(TEM) results illustrated the formation of core–shell nanostructures with controllable shell thicknesses about 3–5?nm. X-ray diffraction(XRD) patterns displayed that a stable perovskite phase was preserved and no other crystallization peaks were discovered from the shell component. Scanning electron microscopy(SEM) and Energy Dispersive Spectrometer(EDS) investigations confirmed that core-shell structures were inherited from particles to ceramics after sintering. As a result, through the coating process, the breakdown strength of the ceramic increases by 95% from 12.2?kV/mm to 23.8?kV/mm and the recoverable energy density was greatly enhanced from 1.76?J/cm³ to 2.68?J/cm³. These results demonstrate a promising reaction method to enhance breakdown strength in antiferroelectrics for energy storage capacitor applications.     

Ultrahigh and field-independent energy storage efficiency of (1-x)(Ba0.85Ca0.15)(Zr0.1Ti0.9)O3-xBi(Mg0.5Ti0.5)O3 ceramics

Relaxor ferroelectrics are attracting an increasing interest in the application of pulse power systems due to their excellent energy storage performance. In this paper, the (1-x)(Ba_0·85Ca_0.15)(Zr_0·1Ti_0.9)O₃-xBi(Mg_0·5Ti_0.5)O₃ ((1-x)BCZT-xBMT, x ≤ 0.2) relaxor ceramics are prepared by the solid state method. The influence of BMT on the microstructure, dielectric and energy storage properties of the prepared ceramics is investigated. The XRD results show that the peak intensity of impurities (Bi₂O₃, TiO₂ and Ba₂Bi₄Ti₅O₁₈) is gradually stronger than that of BCZT phase with x increasing. Meanwhile, the grain size of (1-x)BCZT-xBMT ceramics gradually increases on account of the appearance of impurities Bi₂O₃. Influenced by the impurities and BMT, the dielectric constant of prepared ceramics gradually decreases with x increasing. A large W_rec value of 0.65 J/cm³ with an ultrahigh η value of 97.89% is achieved at x = 0.15 due to the high breakdown strength and slim P-E hysteresis loop. Meanwhile, the η is insensitive to the electric field. The ultrahigh η leads to lesser energy loss during the charge and discharge process. It makes the 0.85BCZT-0.15BMT ceramic more attractive in the application of pulse power systems.     

Achieving ultrafast discharge speed and excellent energy storage efficiency in environmentally friendly niobate-based glass ceramics

Environmentally friendly Na₂O–BaO–Nb₂O₅–SiO₂ glass ceramics (GCs) with different vanadium pentoxide (V₂O₅) contents were successfully synthesized using the conventional melt-quenching method and heat treatment. The microstructure and dielectric energy storage properties of the GCs could be related to the addition of V₂O₅. When 1 mol% of V₂O₅ was added_, the activation energy of crystallization decreased from 282 to 221 kJ/mol, and the GCs had the highest energy efficiency of 95.96% and breakdown strength of 1326 kV/cm. Moreover, the GCs could also achieve an ultrafast discharge time of 14 ns and an actual discharge energy density of 0.724 J/cm³. These results indicate that these environmentally friendly GCs can be used in energy storage devices.     

Electric fatigue in antiferroelectric Pb0.97La0.02(Zr0.55Sn0.33Ti0.12)O3 ceramics induced by bipolar cycling

Antiferroelectric lead zirconate titanate stannate (PZST) ceramics are promising materials for high-strain transducers and actuators. The degradation of the strain excited by an ac field remains largely unknown so far for this family of antiferroelectric ceramics. In this study, the bipolar electric fatigue of antiferroelectric Pb_0.97La_0.02(Zr_0.55Sn_0.33Ti_0.12)O₃ ceramics was investigated. Variations in the strain hysteresis loop and damage in the microstructure of the materials due to the electric cycling were monitored. Higher cycling field yielded a stronger fatigue effect. The material showed an increasingly asymmetric suppression of the strain hysteresis loop and diffuse AFE–FE phase transition with increasing cycle number. A damaged microstructure was observed on the polished surfaces of fatigued samples after acid etching. Electrochemical variations, the pinning of domains, randomly or preferentially orientated, due to the cycling are considered as the main fatigue mechanism of the material.     

Hierarchical domain structures in (Pb,La)(Zr,Sn, Ti)O3 antiferroelectric ceramics

(Pb, La)(Zr, Sn, Ti)O₃ (PLZST) ceramic is one of the most prospective antiferroelectric (AFE) materials for variety of functional applications including energy storage and converter. Systematic structural investigation of domain structures should be of fundamental importance for understanding the structure-property relationship in AFE ceramics. In this study, the hierarchical domain structures and modulated structures correlated to the compositional variation in (Pb_0.97La_0.02) (Zr_0.50Sn_xTi_0.50-x)O₃ (x = 0.375, 0.45 and 0.50) were observed and investigated in details by transmission electron microscopy. The PLZST ceramics show exclusively incommensurate modulated structures (IMS) whose modulation period changed from 9.37 to 6.15 and to 4.04 with increasing of the x value. The hierarchical domain structures include, in decreasing scales, AFE domains, incommensurate domains and nanodomains. The elementary domains in PLZST ceramics are pinstriped nanodomains which were formed based on IMS configuration but by frequent modulation of IMS periodicity and formation of faults. Nanodomains accumulated and then dissociated into incommensurate domains and AFE domains successively. The presently revealed structural characteristics in antiferroelectric PLZST may stimulate future researches on the evolution of IMS-based hierarchical domains under external physical fields, e.g. thermal or electrical, and their correlation to the physical performance.     

Achieving high energy storage performance of Pb(Lu1/2Nb1/2)O3 antiferroelectric ceramics via equivalent A-site engineering

Manipulating the critical switching field between antiferroelectric (AFE) state and ferroelectric (FE) is an important concept for tuning the energy storage performance of AFEs. As one of the lead-based AFE systems, Pb(Lu_1/2Nb_1/2)O₃ promises high potential in the miniaturization of pulsed power capacitors, but the extremely high critical switching field and low induced saturated polarization demonstrate severe drawbacks with respect to temperature stability and flexibility. Here, A-site Ba²⁺ doping engineering is used to effectively reduce the critical switching field and improve the saturated polarization in Ba_xPb_1-x(Lu_1/2Nb_1/2)O₃ (0.01 ≤ x ≤ 0.08, abbreviated as xBa-PLN) ceramics. We found the AFE-FE phase transition can be occurred at 80ºC with a high energy storage density of 4.03 J/cm³ for Ba_0.06Pb_0.94(Lu_1/2Nb_1/2)O₃ ceramic. Our results show that Ba²⁺ additions destroy the antiparallel structure of AFE phase, and finally reduce the critical switching field, demonstrating a potential alternative to modulate the energy storage performance of AFEs.     

Enhanced energy storage performances of Bi(Ni1/2Sb2/3)O3 added NaNbO3 relaxor ferroelectric ceramics

In the development of dielectric ceramic materials, the requirements of miniaturization and integration are becoming increasingly prominent. How to obtain greater capacitance in a smaller volume is one of the important pursuits. In this paper, lead-free (1-x)NaNbO₃-xBi(Ni_1/2Sb_2/3)O₃(xBNS) with high recoverable energy storage density (W_rec) and relatively high energy storage efficiency(η) were prepared by a solid state sintering method. Bi(Ni_1/2Sb_2/3)O₃ was introduced into the Sodium niobate ceramics(NN)-based ceramics to reduce the sintering temperature and increase the maximum breakdown field strength (E_b). Finally, 0.15BNS achieved a high E_b of 460 kV/cm, W_rec of 3.7 J/cm³ and η of 77%. In addition, the sample maintained excellent stability in the frequency range of 1–120 Hz. And the 0.15BNS ceramics also exhibited high power density (P_D = 36.4 MW/cm³), large current density (C_D = 520.8 A/cm²) and relatively fast charge-discharge rate (t_0.9 = 1050 ns). These results demonstrate the potential application value of xBNS ceramics in energy storage capacitors.     

Effects of annealing temperatures on energy storage performance of sol-gel derived (Ba0.95, Sr0.05) (Zr0.2, Ti0.8) O3 thin films

Dielectric polarization and breakdown strength of dielectrics generally show directly and inversely dependent upon their crystallization, respectively. Therefore, achieving the maximum energy storage density should be expected by controlling the crystallization. A serial of ferroelectric (Ba_0.95, Sr_0.05)(Zr_0.2, Ti_0.8)O₃ (BSZT) thin films were prepared by the sol-gel method. Effects of annealing temperatures on the microstructure, dielectric and energy storage performance of the films were investigated. The results indicate that BSZT thin films annealed at 600 °C for 30 min demonstrate the highest recoverable energy density and efficiency (50.5 J/cm³ and 91.9%). Such superior energy storage performance is attributed to an ultrahigh electric breakdown strength (6.65 MV/cm) induced by the dense amorphous-nanocrystalline microstructure. This work creates a new way for optimizing the energy storage performance of dielectric thin films via balancing their dielectric polarization and breakdown strength at appropriate heating processing temperature.     

Large barocaloric effect and pressure‐mediated electrocaloric effect in Pb0.99Nb0.02(Zr0.95Ti0.05)0.08O3 ceramics

Ferroelectric materials are being actively explored for next‐generation solid‐state cooling technology. Even though bulk materials possess an advantage in terms of overall heat extraction capacity, their performance is limited due to low adiabatic temperature change. In this regard, the present article explores enhanced cooling capacity of bulk polycrystalline Pb_0.99Nb_0.02(Zr_0.95Ti_0.05)_0.08O₃ (PNZT) through external‐field mediation and coupled caloric effects. Barocaloric (BC) and electrocaloric (EC) effects were indirectly estimated using polarization versus electric field (P‐E) loops (under varying pressure and temperature). It was observed that under applied pressure of 325 MPa, ΔT_EC could be improved from 1 K to 4.5 K. Similarly, a peak unbiased ΔT_BC of 1.5 K could be enhanced to 5.3 K under an electric field of 5 MV·m^?1. These figures correspond to an improvement of ~400% over the unbiased values. The results are indicative of the multicaloric cooling capacity of bulk ferroelectric materials.     

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.     

Ultrahigh electric breakdown strength,excellent dielectric energy storage density,and improved electrocaloric effect in Pb-free (1-x)Ba(Zr0.15Ti0.85)O3-xNaNbO3 ceramics

In this study, NaNbO₃ (NN) was introduced into Ba(Zr_0.15Ti_0.85)O₃ (BZT) to form a solid solution with relaxor ferroelectric characteristics. The dielectric breakdown strength (BDS) of the specimen with 6 mol.% NN reached 680 kV/cm, the corresponding recoverable energy storage density (W_rec) was 5.15 J/cm³, and the energy storage efficiency (η) was 77%. The dissolution of Na ⁺ ions at the A position and Nb⁵⁺ ions at the B position of the perovskite structure reduced the concentration of oxygen vacancies in the lattice and compensated for defects. The doped ceramics exhibited lower dielectric loss and better thermal stability: the W_rec value was 2 ± 1% J/cm³ at 30–120 °C. In particular, in the 0.02NN ceramics, a ΔT of 1.81 K was achieved at 130 kV/cm, and the operating temperature zone expanded with the increase in doping concentration. The introduction of NN resulted in BZT ceramics that possess excellent energy storage performance and electrocaloric effect properties.     

Ultrahigh storage density achieved with (1-x)KNN-xBZN ceramics

A series of (1-x)K_0.5Na_0.5NbO₃-xBa(Zn_1/3Nb_2/3)O₃ ((1-x)KNN-xBZN) nanostructural ceramics was successfully synthesised via solid-state reactions. These nanostructural ceramics exhibited high energy storage density compared with pure KNN ceramics. Further analysis of their dielectric/ferroelectric properties and structures revealed that the addition of BZN alloy disrupted the long-range order of the ferroelectric lattice of pure KNN and favoured the formation of ferroelectric islands and/or polar nano-regions. Consequently, the nanostructured ceramic with x = 0.05 exhibited ultrahigh energy storage density, W, of approximately 9.14 J/cm³ and recoverable energy storage density, W_rec, of approximately 4.87 J/cm³ under a fairly low applied electrical field (220 kV/cm). These values exceed the highest values ever reported for KNN-based bulk ceramics. In addition, both excellent fatigue endurance (10⁵ cycles) and temperature stability (Δε'/ε_100°C < 15 % in the range 30–390 °C) were realised with the 0.97KNN-0.03BZN ceramic. Their excellent energy storage properties render KNN-based ceramics potential candidates for application in pulsed-power systems.