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Utilizing a high‐entropy strategy, we propose a novel approach for synthesizing (Na0.4K0.1Bi0.5)TiO3 (NKBT)‐based ceramics endowed with exceptional dielectric stability at elevated temperatures. The high‐entropy effect induces a random tilt in the oxygen octahedra of NKBT ceramics, leading to a broad dielectric response characterized by diffuse phase transitions. By weakening the dielectric abnormal peak at Ts of BNT, the dielectric stability of high‐entropy NKBT ceramics is significantly enhanced. Notably, at 100 kHz, the temperature stability range of (Na0.4K0.1Bi0.5)(Ti0.65Zr0.1Sn0.15Hf0.1)O3, synthesized through the traditional solid reaction method, reaches an impressive 311°C, surpassing undoped NKBT by 257%. This significant enhancement underscores the feasibility of our high‐entropy strategy in improving dielectric performance. Our work demonstrates a straightforward and cost‐effective method for significantly improving the dielectric temperature stability of NKBT ceramics. [ABSTRACT FROM AUTHOR]

Realizing ultrahigh recoverable energy-storage density (Wrec) alongside giant efficiency (η) remains a significant challenge for the advancement of dielectrics in next-generation pulse power energy-storage (ES) devices. In this study, we introduce an entropy engineering approach, manipulating local polar fluctuations and tailoring microstructure evolution through a high-entropy design strategy, to effectively regulate the ES performance of lead-free (Bi0.5Na0.5)TiO3 (BNT)-based dielectrics. By intricately designing a high-entropy matrix, (Bi0.375Na0.3Sr0.25K0.075)TiO3 (BNSKT), and enhancing configurational entropy with the Bi(Mg0.5Sn0.5)O3 (BMS) end member, we developed multi-cation substituted BNT relaxor ceramics based on a viscous polymer process (VPP) method. Our findings reveal that modulating atomic configurational entropy yields favorable and stable microstructural characteristics, contributing to an improved breakdown electric field (E-field), reduced hysteresis and delayed polarization saturation. The VPP-synthesized high-entropy 0.85BNSKT-0.15BMS (BNT-H15VPP) ceramics achieved a significant ES density Wrec of 11.24 J cm−3, η of 88.3%, and responsivity (ξ, defined as Wrec/E) of 184 J kV−1 cm−2 under 610 kV cm−1. Additionally, pulse charging/discharging measurements indicated a large discharge energy density (Wdis) of 6.6 J cm−3, a short discharge time of 2.2 μs, and remarkable temperature stability over 20–120 °C. This work underscores the feasibility of the high-entropy strategy for designing robust dielectric ceramics, heralding promising advancements in advanced ES capacitors with comprehensive ES performance. [ABSTRACT FROM AUTHOR]

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(1−x)Pb(Mg1/3Nb2/3)‐xPbTiO3 (PMN‐xPT) ceramics with x ranging from 0.1 to 0.3 were synthesized by solid‐state reaction method. X‐ray diffraction, dielectric and ferroelectric property characterizations were systematically investigated. As x rises, the PMN‐xPT transitions from a cubic to a rhombohedral phase, resulting in an enhancement in ferroelectricity. Our findings show that the electrostrain and longitudinal electrostrictive coefficient Q33 both increase and then decrease within a critical region located between the depolarization temperature TFR and Tm (corresponding to the maximum permittivity), demonstrating strong temperature‐dependent characteristics. In x = 0.2, the maximum Q33 of 0.0361 m4/C2 is obtained, and a phase diagram of studied system is built. Our findings not only shed light on the phase evolution in this system but also reveal a strong temperature‐dependent electrostrictive effect that can be used to improve electrostrains in PMN‐based solid solutions if the critical region can be regulated to a suitable temperature region using engineering strategies. [ABSTRACT FROM AUTHOR]

Despite the fact that relaxor ferroelectrics (RFEs) have been extensively researched because of their various advantages, there are still barriers to simultaneously increasing their energy storage density (Wrec) and efficiency (η). By substituting Bi(Mg0.5Sn0.5)O3 (BMS) and optimizing the formation process, this study follows a stepwise optimization route to achieve comprehensive exceptional energy storage performance (ESP) in Na0.5Bi0.5TiO3-Sr0.85Bi0.1TiO3 (NBT-SBT)-based ceramics. On the premise of constructing a Sr2+–Sr2+ ion pair at the A-site to ensure a large polarization, the introduction of Mg2+ and Sn4+ ions at the B-site further induces a local disordered field and promotes polar nanoregions. Following that, the viscous polymer process (VPP) used to synthesize NBT-SBT-BMS ceramics can thin the thickness, reduce defects, and boost compactness, hence improving the polarization difference (ΔP) and breakdown strength (Eb). Using the stepwise optimization route, we were able to attain a high ΔP of 64.6 μC cm−2 and an Eb of 440 kV cm−1 in 0.92(0.65NBT-0.35SBT)-0.08BMS-VPP ceramics. More crucially, an ultrahigh Wrec of 7.5 J cm−3 and a high η of 85% are simultaneously achieved, together with excellent temperature adaptability between 20 and 120 °C. Our superb ESP exceeds the majority of previously reported NBT-based ceramics, confirming the applicability of this stepwise optimization route to other similar high-performance dielectric ceramic designs. [ABSTRACT FROM AUTHOR]

In pulse power systems, multilayer ceramic capacitors (MLCCs) encounter significant challenges due to the heightened loading electric field (E), which can lead to fatigue damage and ultrasonic concussion caused by electrostrictive strain. To address these issues, an innovative strategy focused on achieving an ultra-weak polarization-strain coupling effect is proposed, which effectively reduces strain in MLCCs. Remarkably, an ultra-low electrostrictive coefficient (Q 33 ) of 0.012 m 4 C -2 is achieved in the composition 0.55(Bi 0.5 Na 0.5 )TiO 3 -0.45Pb(Mg 1/3 Nb 2/3 )O 3 , resulting in a significantly reduced strain of 0.118% at 330 kV cm -1 . At the atomic scale, the local structural heterogeneity leads to an expanded and loose lattice structure, providing ample space for large ionic displacement polarization instead of lattice stretching when subjected to the applied E. This unique behavior not only promotes energy storage performance (ESP) but also accounts for the observed ultra-low Q 33 and strain. Consequently, the MLCC device exhibits an impressive energy storage density of 14.6 J cm -3 and an ultrahigh efficiency of 93% at 720 kV cm -1 . Furthermore, the superior ESP of the MLCC demonstrates excellent fatigue resistance and temperature stability, making it a promising solution for practical applications. Overall, this pivotal strategy offers a cost-effective solution for state-of-the-art MLCCs with ultra-low strain-vibration in pulse power systems., (© 2024 Wiley‐VCH GmbH.)

Lead-free relaxor ferroelectric ceramics with outstanding energy-storage (ES) density ( W rec ) and high ES efficiency ( η ) are crucial for advanced pulse-power capacitors. This study introduces a strategic approach to maximizing the polarization difference (Δ P ) by inducing a transition from the ferroelectric phase to the ergodic relaxor (ER) phase. By employing this strategy, a series of ceramics, (1 - x )(Bi 0.5 Na 0.4 K 0.1 )TiO 3 - x (Sr 0.85 La 0.1 )(Zr 0.5 Ti 0.5 )O 3 (BNKT- x SLZT), with varying SLZT content ( x = 0.05, 0.10, 0.15, and 0.20), were designed. The addition of SLZT enhances cationic disorder, induces vacancies at A sites, and disrupts long-range ferroelectric order, facilitating the formation of polar nanoregions and enhancing relaxor ferroelectric behavior. Furthermore, a viscous polymer process (VPP) technology is employed to optimize the ceramics' structure, aiming to increase the breakdown strength ( E b ) and enhance Δ P . Ultimately, enhanced ES performance is demonstrated in BNKT-0.15SLZT VPP , achieving a remarkable W rec of 6.85 J/cm 3 and η of 84% under 470 kV/cm. This composition demonstrates excellent stability with minimal variations in W rec (3.0%) and η (4.4%) over the temperature range of 20-110 °C. Additionally, BNKT-0.15SLZT VPP exhibits exceptional pulse charge-discharge properties, featuring a high discharge density of 3.72 J/cm 3 , a large power density of 164.2 MW/cm 3 , and a short discharge time ( t 0.9 ) of 193 ns under 300 kV/cm. The study validates the practicality of BNKT-0.15SLZT VPP for pulse capacitors and underscores the potential to enhance ES performance through A-site donor doping and VPP technology. This work provides a comprehensive understanding of the interplay among composition, structure, and ES properties in lead-free relaxor dielectric ceramics, laying the groundwork for innovative advancements in the field.