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Abstract The antiferroelectric-ferroelectric phase transition is a basic principle that holds promise for antiferroelectric ceramics in high capacitance density nonlinear capacitors. So far, the property optimization based on antiferroelectric-ferroelectric transition is solely undertaken by chemical composition tailoring. Alternately, here we propose a phase transition engineering tactic by applying pulsed electric stimulus near the critical electric field, which finally results in ~54.3% enhancement and quick stabilization of capacitance density in Pb0.97La0.02(Zr0.35Sn0.55Ti0.10)O3 antiferroelectric ceramics. Ex-situ and in-situ structural characterizations show that electric stimuli can induce the charming successive structural evolution, including domain evolution from multidomain to monodomain state, and modulation period change from 7.49 to 7.73. Structure-property correlation indicates that the antiferroelectric-ferroelectric phase transition engineering mainly stems from the unexpected irreversible recovery of the modulated structures. The present findings would deepen the understanding of the structural phase transition and provoke composition-independent post-treatment property innovation in the incommensurate antiferroelectric materials and devices.

Zirconate-based dielectric ceramics are potential materials for base metal electrode multilayer ceramic capacitors (BME-MLCCs) due to their exceptional chemical and thermal stability, as well as excellent dielectric properties. In this work, (Sr0.7Ca0.3)1.02(Zr0.95−xTi0.05Mnx)O3+δ (SCZTM, 0 ≤ x ≤ 0.05) ceramics with two coexisting phases were prepared using a solid-state reaction method in a reducing atmosphere. This study investigates the impact of Mn doping on sintering temperature, microstructure, and electrical properties of SCZTM ceramics. Mn doping can reduce the sintering temperature from 1450 to 1300 °C. The impact of Mn doping on the structure and phonon vibration is minimal, resulting in a negligible effect on the intrinsic loss. The valence states of Mn ions and defects were characterized by X-ray photoelectron spectroscopy (XPS) and thermally stimulated depolarization current (TSDC) analysis. The results demonstrate the significant role of Mn doping in nonintrinsic loss. Due to the decrease in the concentration of oxygen vacancies (VO⋅⋅), SCZTM (x = 0.01) ceramics exhibit attractive properties: resistivity (ρ) = 8.93×1014 Ω·cm, dielectric constant (εr) = 36.16, dielectric loss (tanδ) = 2.43×10–4, temperature dependence of dielectric constant (τε) = 15.44 ppm/°C (@−55–200 °C, 1 MHz), Q×f = 30,257 GHz (@6.12 GHz), and temperature coefficient of resonant frequency (τf) = –9.9 ppm/°C. SCZTM (x = 0.01) ceramic powders were used to successfully fabricate Ni-based multilayer ceramic capacitors (MLCCs) with a high insulation resistance of IR ≥ 39.6 TΩ, an ultralow dielectric loss of tanδ = 0.2×10–4, and a wide operating temperature range (temperature coefficient of capacitance (Tcc) = 10.88 ppm/°C, @−55–200 °C, 1 MHz). SCZTM ceramics exhibit properties that make them suitable for use as BME-MLCC materials with potential market applications.

AgNbO3 (AN) and modified AgNbO3 have been extensively investigated as promising lead-free antiferroelectric (AFE) energy storage materials. Previous studies have focused mainly on the use of an ion dopant at the A/B site to obtain a stabilized AFE phase; however, simultaneous improvements in the recoverable energy storage density (Wrec) and efficiency (η) are still difficult to realize. Herein, we innovatively constructed a AgNbO3–NaNbO3–(Sr0.7Bi0.2)TiO3 (AN–NN–SBT) ternary solid solution to achieve a relaxor AFE in AgNbO3-based materials. The coexistence of antiferroelectric (M3) and paraelectric (O) phases in 0.8(0.7AgNbO3–0.3NaNbO3)–0.2(Sr0.7Bi0.2)TiO3 confirms the successful realization of a relaxor AFE, attributed to multiple ion occupation at the A/B sites. Consequently, a high Wrec of 7.53 J·cm−3 and η of 74.0% are acquired, together with superior stability against various temperatures, frequencies, and cycling numbers. Furthermore, a high power density (298.7 MW·cm−3) and fast discharge speed (41.4 ns) are also demonstrated for the AgNbO3-based relaxor AFE. This work presents a promising energy storage AgNbO3-based ternary solid solution and proposes a novel strategy for AgNbO3-based energy storage via the design of relaxor AFE materials.

Bismuth sodium titanate (BNT)-based piezoelectric materials are the most promising candidates for lead-free actuator applications. With the request for integration and size miniaturization of devices, it is urgent to develop thin films for microdevices to be compatible with semiconductor processes. Through composition engineering, BNT-based thin films were fabricated on silicon substrates, with ultra-high strain response and negligible hysteresis in strain curves. The DC-dependent and temperature-dependent dielectric properties were collected to investigate the relaxor state of thin films. The structure and polarization transition and evolution as a function of electric field and time were analyzed based on the electric characterization, in-situ Raman measurements, and dynamics PFM. The reversible phase transition and polarization order-disorder transformation are the most significant features for reaching a large strain of >1.6% in BNT-based thin films.

Abstract Dielectric ceramic capacitors with ultrahigh power densities are fundamental to modern electrical devices. Nonetheless, the poor energy density confined to the low breakdown strength is a long-standing bottleneck in developing desirable dielectric materials for practical applications. In this instance, we present a high-entropy tungsten bronze-type relaxor ferroelectric achieved through an equimolar-ratio element design, which realizes a giant recoverable energy density of 11.0 J·cm−3 and a high efficiency of 81.9%. Moreover, the atomic-scale microstructural study confirms that the excellent comprehensive energy storage performance is attributed to the increased atomic-scale compositional heterogeneity from high configuration entropy, which modulates the relaxor features as well as induces lattice distortion, resulting in reduced polarization hysteresis and enhanced breakdown endurance. This study provides evidence that developing high-entropy relaxor ferroelectric material via equimolar-ratio element design is an effective strategy for achieving ultrahigh energy storage characteristics. Our results also uncover the immense potential of tetragonal tungsten bronze-type materials for advanced energy storage applications.

Abstract PbZrO3 has been broadly considered as a prototypical antiferroelectric material for high-power energy storage. A recent theoretical study suggests that the ground state of PbZrO3 is threefold-modulated ferrielectric, which challenges the generally accepted antiferroelectric configuration. However, such a novel ferrielectric phase was predicted only to be accessible at low temperatures. Here, we successfully achieve the room-temperature construction of the strongly competing ferrielectric and antiferroelectric state by strain-mediated phase separation in PbZrO3/SrTiO3 thin film. We demonstrate that the phase separation occurs spontaneously in quasi-periodic stripe-like patterns under a compressive misfit strain and can be tailored by varying the film thickness. The ferrielectric phase strikingly exhibitsa threefold modulation period with a nearly up-up-down configuration, which could be stabilized and manipulated by the formation and evolution of interfacial defects under applied strain. The present results construct a fertile ground for further exploring the physical properties and applications based on the novel ferrielectric phase.

Multilayer ceramic capacitors (MLCCs) play a crucial role in pulsed power applications because of their rapid charge/discharge capabilities. However, the combination of high energy density and high efficiency is the main challenge in practical applications. This study presents barium titanate-based (BaTiO3-) lead-free relaxor ferroelectric (RFE) MLCCs formulated with 0.84BaTiO3–0.16Bi(Mg0.2Ni0.2Zn0.2Zr0.2Nb0.2)O3 (0.84BT–0.16BMNZZN) and platinum inner electrodes via a tape-casting method. The introduction of the high-entropy component BMNZZN effectively enhances the relaxation behavior and local nanodomains while promoting grain refinement, resulting in a comprehensive improvement in insulation performance and energy storage performance. As a result, MLCCs exhibit excellent recoverable energy density (Wrec = 15.7 J∙cm−3) and ultrahigh efficiency (η) of 96.4% (@1614 kV∙cm−1), simultaneously showing good temperature stability over a range of −120‒100 °C (Wrec ≈ 8.9 J∙cm−3 with a variation of less than ±4.85%, @1078 kV∙cm−1) and excellent fatigue resistance (Wrec ≈ 9.2 J∙cm−3 with a variation of less than ±0.82% over 107 cycles, and η greater than 95%, @1078 kV∙cm−1). These findings indicate that BT–BMNZZN RFE MLCCs offer a viable solution for high-power energy storage capacitors.

In this article, hot-pressed PZT ceramics were used as a sensitive element material and made into a pyroelectric chip. Three current mode sensors were fabricated using a pyroelectric chip of different thicknesses (80 μm, 40 μm, and 30 μm). The voltage responsivity of sensors reached the order of magnitude of 105. The size effect resulting from varying the thickness was studied. The results indicate that as the thickness decreases, the performance significantly increases. When the modulation frequency is 10 Hz, the specific detectivity of the sensor with a 30 μm PZT ceramic pyroelectric chip reaches 5.3 × 108 cm·Hz1/2/W.

The external pressure is one of the essential parameters for regulating the structure and energy conversion properties of antiferroelectric AgNbO3. For pure AgNbO3, however, there has been still a blank of its real lattice structure under the stress field. Here, high-pressure lattice structures and phase transitions of AgNbO3 have been explored by spectroscopic experiments and theoretical models. A successive phase transition process from Pbcm to C2221 to P21 has been observed at the pressure range of 0–30 GPa, associated with displacive-type characterized by soft-mode kinetics. Note that the paraelectric phase cannot be achieved under high-pressure at room temperature. Significantly, the competition of long-range Coulomb force, short-range interatomic interaction, and covalent interaction in AgNbO3 lattice were demonstrated under the stress field. The present work can provide fundamental guidelines to reveal the high-pressure phase transitions of AgNbO3, which will open up possibilities for the designing device with functional properties at extremes.

In recent years, the development of environmentally friendly, lead-free ferroelectric films with prominent electrostrictive effects have been a key area of focus due to their potential applications in micro-actuators, sensors, and transducers for advanced microelectromechanical systems (MEMS). This work investigated the enhanced electrostrictive effect in lead-free sodium bismuth titanate-based relaxor ferroelectric films. The films, composed of (Bi0.5Na0.5)0.8−xBaxSr0.2TiO3 (BNBST, x = 0.02, 0.06, and 0.11), with thickness around 1 μm, were prepared using a sol-gel method on Pt/TiO2/SiO2/Si substrates. By varying the Ba2+ content, the crystal structure, morphology, and electrical properties, including dielectric, ferroelectric, strain, and electromechanical performance, were investigated. The films exhibited a single pseudocubic structure without preferred orientation. A remarkable strain response (S > 0.24%) was obtained in the films (x = 0.02, 0.06) with the coexistence of nonergodic and ergodic relaxor phases. Further, in the x = 0.11 thick films with an ergodic relaxor state, an ultrahigh electrostrictive coefficient Q of 0.32 m4/C2 was achieved. These findings highlight the potential of BNBST films as high-performance, environmentally friendly electrostrictive films for advanced microelectromechanical systems (MEMS) and electronic devices.

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

Ferroelectric/antiferroelectric phase boundary is both technologically and scientifically important. Here, the authors reveal the structure of intermediate phase involved in classical Pb(Zr1-xTix)O3.

Abstract The recently discovered ductile/plastic inorganic semiconductors pave a new avenue toward flexible thermoelectrics. However, the power factors of current ductile/plastic inorganic semiconductors are usually low (below 5 µW cm−1 K−2) as compared with classic brittle inorganic thermoelectric materials, which greatly limit the electrical output power for flexible thermoelectrics. Here, large plasticity and high power factor in bulk two‐dimensional van der Waals (2D vdW) single‐crystalline SnSe2 are reported. SnSe2 crystals exhibit large plastic strains at room temperature and they can be morphed into various shapes without cracking, which is well captured by the inherent large deformability factor. As a semiconductor, the electrical transport properties of SnSe2 can be readily tuned in a wide range by doping a tiny amount of halogen elements. A high power factor of 10.8 µW cm−1 K−2 at 375 K along the in‐plane direction is achieved in plastic single‐crystalline Br‐doped SnSe2, which is the highest value among the reported flexible inorganic and organic thermoelectric materials. Combining the good plasticity, excellent power factors, as well as low‐cost and nontoxic elements, bulk 2D vdW single‐crystalline SnSe2 shows great promise to achieve high power density for flexible thermoelectrics.

Glass-free MgO-based microwave dielectric ceramics (1-x) wt% (0.98 MgO-0.02 Al2O3)-x wt% LiF (x = 0.5, 1, 2, 3, 4) were synthesized where LiF and Al2O3 were utilized as sintering additive and reinforcement phase in MgO matrix respectively. It was found that ion substitution is apt to occur between LiF and MgO, leading to the formation of oxygen vacancies and MgF2. Nevertheless, different from ordinary liquid-phase sintering, morphologies of ceramics were distinctly altered with grains changing from polyhedron to sphere-like shape and densities underwent obvious decrease when excessive amount of LiF was introduced and we call it excessive liquid-phase sintering. Grain boundary weakening caused by this circumstance would exert an adverse effect on physical properties. Moreover, LiF addition dramatically reduced dielectric breakdown strength and altered the dielectric breakdown behavior of MgO-based ceramics, which is dominated by electrical breakdown mechanism. Combination of good properties were achieved in 1 wt% LiF modified MgO-based ceramics sintered at 950 °C which exhibited superior microwave properties (εr = 9.56, tanδ = 9.2 × 10−5, Qf = 124,600 GHz), high flexural strength (184.5 MPa), high thermal conductivity (21.3 W/(m⋅K)), high coefficient of thermal expansion (∼12 ppm/°C) and moderate electrical properties (Eb = 35.9 kV/mm, ρ = 4.9 × 1012 Ω cm).

The lead-free 0.96NaNbO3-0.04CaSnO3 ceramics with rare-earth dopants (La, Sm and Lu) (NCLn100x) were prepared and characterized. It is found that a certain amount of La substitution stabilizes the antiferroelectric (AFE) phase but alleviates the lattice distortion in the fresh samples. Re-entrant-like characteristics are observed in the temperature – dielectric constant curves with the room temperature P phase gradually replaced by a possible R phase. Relaxor-like hysteresis loops with suppressed hysteresis loss and remanent polarization were obtained at high La content, achieving a relatively high Wre of 2.1 J/cm3 at a low electric field (250 kV/cm). The relaxation behaviors of the ferroelectric (FE) domain measured by piezoresponse force microscopy suggest an even long characteristic relaxation time of field-induced FE phase, which is different from the situations of other AFE perovskites. Via an explanatory defected diatomic chain model, we propose that a much larger mass of substitutive ion than the origin one helps to induce low-frequency localized mode, which is believed to be in favor of the formation of polar nano-regions and hence strengthens the dynamic stability of FE phase during electric field loading. Our research provides a further understanding of the tuning strategy for enhancing the antiferroelectricity of the NaNbO3-based system.

The large family PbZrO3-based solid solutions are usually considered as antiferroelectric materials with specific antiparallel polarization configuration. Here, the authors demonstrate the PbZrO3-based material has ferrielectric dipoles ordering and configure a clear structure-property relationship.

In the practical application of capacitors, especially in pulsed application, recoverable energy is a key parameter, which represents the ability to store energy. However, many existing evaluation methods for energy storage calculation have not been systematically implemented and comprehensively understood. In this work, four methods were applied to calculate the energy storage in linear, ferroelectric, and antiferroelectric capacitors. All methods were valid when the linear capacitor was examined. In terms of the ferroelectric capacitor, the method of equivalent parameter using DC-bias capacitance was infeasible under the high voltage owing to a massive decrease in field-dependent capacitance. As for the antiferroelectric capacitor with noticeable hysteresis, the maximum of energy storage was obtained by the method of integration of hysteresis loop, while the lower one was obtained in the fast discharge condition by the method of integration of UI (product of voltage and current). In summary, for different materials, both test conditions and calculation methods should be considered to get accurate energy storage, which best fits the working conditions.

PbZr0.35Ti0.65O3 (PZT), PbZrO3 (PZO), and PZT/PZO ferroelectric/antiferroelectric multilayer films were prepared on a Pt/Ti/SiO2/Si substrate using the sol–gel method. Microstructures and physical properties such as the polarization behaviors, leakage current, dielectric features, and energy-storage characteristics of the three films were systematically explored. All electric field-dependent phase transitions, from sharp to diffused, can be tuned by layer structure, indicated by the polarization, shift current, and dielectric properties. The leakage current behaviors suggested that the layer structure could modulate the current mechanism, including space-charge-limited bulk conduction for single layer films and Schottky emission for multilayer thin films. The electric breakdown strength of a PZT/PZO multilayer structure can be further enhanced to 1760 kV/cm, which is higher than PZT (1162 kV/cm) and PZO (1373 kV/cm) films. A recoverable energy-storage density of 21.1 J/cm3 was received in PZT/PZO multilayers due to its high electric breakdown strength. Our results demonstrate that a multilayer structure is an effective method for enhancing energy-storage capacitors.

The pulse discharge properties of lead lanthanum zirconate stannate titanate (PLZST) antiferroelectric (AFE) ceramics, ferroelectric (FE) dielectrics, and linear dielectrics were compared in this paper. It is found that as the voltage increases, those three types of dielectrics display three different voltage-dependent regularities: the peak current (Imax) of linear dielectrics increases linearly with increasing voltage; the Imax of FE dielectrics rises up with a gradually declined increase rate; the Imax of PLZST AFE ceramics presents a three-stage growth and during the third stage, the regularity is similar with that of FE dielectrics. Furthermore, three advantages of PLZST AFE ceramics for pulse discharge can be determined: a large increase rate of Imax due the field-forced AFE-FE phase transition, a great enhanced power density and a relatively short discharge period time. These results would pave the way for understanding and utilizing AFE ceramics in pulse power application.

The dielectric and energy-storage properties of Pb0.99Nb0.02[(Zr0.60Sn0.40)0.95Ti0.05]0.98O3 (PNZST) bulk ceramics near the antiferroelectric (AFE)-ferroelectric (FE) phase boundary are investigated as a function of temperature. Three characteristic temperatures T0, TC, T2 are obtained from the dielectric temperature spectrum. At different temperature regions (below T0, between T0 and TC, and above TC), three types of hysteresis loops are observed as square double loop, slim loop and linear loop, respectively. The switching fields and recoverable energy density all first increase and then decrease with increasing temperature, and reach their peak values at ∼T0. These results provide a convenient method to optimize the working temperature of antiferroelectric electronic devices through testing the temperature dependent dielectric properties of antiferroelectric ceramics.