The inherent trade-off between the piezoelectric coefficient (d(33)) and Curie temperature (T-C) poses a significant challenge for the practical application of potassium sodium niobate (KNN)-based lead-free piezoceramics. Conventional methods to enhance d(33) typically require high dopant concentrations, which inevitably severely degrade T-C. Herein, we propose a novel low-concentration doping strategy that aims to maximize d(33) while minimizing the sacrifice of T-C. By introducing a trace amount (1.2 mol.%) of AgSbO3 into the 0.96K(0.48)Na(0.52)Nb(0.96)Sb(0.04)O(3)-0.04Bi(0.5)Na(0.5)ZrO(3) matrix, the d(33) was significantly boosted from 487 pC/N to 605 pC/N (an enhancement of similar to 24 %), while the T-C maintained a high value of 215 degrees C (a decrease of <15 % from 251 degrees C). This remarkable performance is attributed to the highly efficient A/B-site synergistic doping effect of AgSbO3, which optimizes the phase boundary composition and refines the domain structure, thereby facilitating polarization switching. The resulting piezoceramic demonstrates a combination of d(33) and T-C that is competitive with commercial PZT-5H. This work not only presents a high-performance lead-free candidate but also provides a general design strategy for overcoming performance trade-offs in functional materials using high-efficiency, low-concentration modifiers

Lead-free Bi0.5Na0.5TiO3-based ceramics have attracted significant research interest due to their promising ferroelectric and piezoelectric properties. However, in practical applications, thermal stability of these properties is equally important. Therefore, the compositions away from the morphotropic phase boundary (MPB) such as 0.85Bi0.5Na0.5TiO3–0.15BaTiO3 (BNT–15BT), although exhibiting slightly worse piezoelectric properties than the MPB composition like BNT–7BT, are highly favored by manufacturers because of their better thermal stability. However, BNT–xBT solid solutions with high BT content usually show secondary phase after calcination. In this study, Ti non-stoichiometric 0.85Bi0.5Na0.5Ti1−xO3–0.15BaTi1−xO3 (BNBT1−x) ceramics were prepared. It is found that an appropriate Ti deficiency (x = 0.04) successfully eliminates secondary phases, whereas an even greater Ti deficiency will result in a new secondary phase. Our systematic survey on how the properties, especially depolarization temperature and electrical conductivity, vary with the Ti deficiency emphasizes the cruciality of careful batching procedures to a reliable manufacturing of similar BNT compositions. In this study, Ti non-stoichiometric (Bi0.5Na0.5)0.85Ba0.15Ti1−xO3 (BNBT1−x) ceramics were prepared. It is found that an appropriate Ti deficiency (x = 0.04) successfully eliminates secondary phases, whereas an even greater Ti deficiency will result in a new secondary phase. Our systematic survey on how the properties, especially depolarization temperature and electrical conductivity, vary with the Ti deficiency emphasizes the cruciality of careful batching procedures to a reliable manufacturing of similar BNT compositions.

Advanced electronics and power systems urgently demand polymer nanocomposites with exceptional high-temperature capacitive performance. To achieve this goal, incorporated fillers must simultaneously enhance polarization and suppress loss of the nanocomposites at elevated temperatures. Herein, core-shell structured (Bi0.2Na0.2Ba0.2Sr0.2Ca0.2)TiO3@Al2O3 (BNBSCT@A) high-entropy ferroelectric fillers featuring inhomogeneous polarization configuration are designed. Multiphase polar nanoregions and random oxygen octahedral tilt in BNBSCT can effectively enhance dielectric constant (εr), refine electric displacement-electric field loops, reduce remnant electric displacement and delay polarization saturation of the nanocomposite. Meanwhile, suitable εr and high thermal conductivity of Al2O3 shell enable homogenous distribution of the external electric field and rapid dissipation of the generated Joule heating, thereby suppressing conduction loss and enhancing breakdown strength. Consequently, encouragingly, the BNBSCT@A/polyetherimide (B@A/PEI) nanocomposite displays an outstanding discharged energy density (Udis) of 8.7 J cm−3 and high efficiency (η) of 90.4% at 150 °C, surpassing most of reported dielectric nanocomposites with η>90%. Additionally, by employing polyetherimide-riptycene (PEI-TE) polymers with dense physical crosslinking networks as the matrix to further suppress electrical and electromechanical breakdown, the B@A/PEI-TE nanocomposites achieve an impressive Udis of 5.9 J cm−3 along with a high η of 90.6% at 200 °C.

Achieving high recoverable energy density (Wrec) with near-unity efficiency (η) in lead-free dielectrics remains a major challenge for advanced pulse power capacitors, given their central role in emerging pulsed power systems and high-voltage electronics. Here, we show that targeted engineering of dynamic dipole behavior provides an effective route to remarkable energy storage performance. Guided by phase-field simulations, we design (Bi0.5Na0.5)TiO3 (BNT)-based multilayer ceramic capacitors that transform a continuous network of strongly correlated dipoles into discrete nano-domains. Within each nano-domain, dipoles retain strong local cooperativity, which maintains high polarization while markedly suppressing hysteresis losses. As a result, the optimized multilayer ceramic capacitors (MLCCs) achieve a recoverable energy density of 16.2 J cm-3, an η of 98.5%, and a record-high figure of merit (WF) of 1080 at 650 kV cm-1. This moderate operating field also produces an ultrahigh energy storage strength (ξ) of 249 J kV-1 m-2, highlighting the efficiency of the dipole-regulation strategy. These findings demonstrate that weakly correlated and dynamic dipoles can be harnessed to advance high-performance, lead-free energy storage devices and offer a viable design principle for next-generation capacitive technologies.

ABSTRACT Dielectric energy storage capacitors play a pivotal role in pulsed power systems. Herein, we demonstrate a breakthrough in dielectric energy storage by engineering ​local polarization units in high‐entropy multilayer ceramic capacitors (MLCCs). By incorporating equimolar Ba 2 + /Sr 2 + dual cations, we precisely smoothen the phase transition and stabilize a nanoscale phase‐coexistence state in an NBT‐based matrix, which simultaneously retain robust local polar units while disrupting long‐range domain order. This unique configuration, validated by atomic‐resolution HAADF‐STEM and phase‐field simulations, enables a high reversible polarization and breakdown strength. The optimized MLCCs achieve an ultrahigh recoverable energy density of 18.2 J cm −3 with 91% efficiency, coupled with exceptional thermal stability and fatigue resistance. This work establishes a general design paradigm for high‐entropy dielectrics for energy storage by controlling local polarization configurations.

Sodium niobate-based antiferroelectric ceramics are widely regarded as one of the most promising lead-free materials for application in energy storage capacitors. Nonetheless, the large residual polarization and comparatively low breakdown field strength limited their energy storage performance (ESP). In this work, we have designed and synthesized a new ceramic system with the composition of 0.95(0.90NaNbO(3)-0.10((1-x)Bi(Mg2/3Nb1/3)O-3-xBa(Mg1/3Nb2/3)O-3))-0.05SrTiO(3) (NN-BiMN-xBaMN-ST) through partial replacement of 0.95(0.9NaNbO(3)-0.10Bi(Mg2/3Nb1/3)O-3)-0.05SrTiO(3) (NN-BiMN-ST) at A/B site. The structural modification effectively broke the long-range ordered state and ameliorated relaxation behavior. Additionally, grain was refined and grain boundary resistivity was enhanced in certain compositions, particularly at x = 0.2, which demonstrated the highest barrier for oxygen vacancy transition and thus reduced oxygen vacancy concentration. The synergy of these two endows NN-BiMN-0.2BaMN-ST composition with superior comprehensive ESP (W-rec = 4.49 J/cm(3), eta = 86.51 %, the fluctuation of W-rec < 2 % within 1-300 Hz and the fluctuation of W-rec < 17 % over 25-175 degrees C, P-D = 118.12 MW/cm(3), C-D = 1073.78 A/cm(2), t(0.9) = 32.5 ns), predetermining their remarkable application potential in wide-temperature pulsed power capacitors.

High-temperature capacitive energy storage is critical for next-generation electronics and power systems, yet it is hindered by the severe performance degradation of polymer dielectrics at elevated temperatures. Conventional strategies using high-permittivity ceramic fillers often exacerbate leakage conduction, leading to failure above 100°C. Here, we demonstrate a paradigm shift through a dual-functional interfacial design exemplified by calcium fluoride (CaF2) nanoparticles in a polyetherimide (PEI) matrix. A comparative study with strontium and barium fluorides (SrF2, BaF2) was conducted to underscore the uniqueness of this approach. Contrary to the conventional filler role, fluorides exhibit unique interfacial activities: F- anions effectively neutralize protonated amine groups to mitigate mobile ions, while M2+ cations coordinate with carbonyl groups to create deep energy traps. This synergy redistributes charge and counterintuitively enhances breakdown strength and insulation at 150°C. Consequently, the optimal PEI/2CaF2 nanocomposite achieves an exceptional discharge energy density of 6.54 J cm-3 at 150°C, which markedly outperforms composites with SrF2 or BaF2, as well as most reported polymer composites. This work unveils the previously overlooked multifunctional role of fluorides and provides a novel materials design strategy for high-performance dielectric polymers under extreme conditions.

Potassium-sodium niobate (KNN)-based lead-free piezoelectrics are promising environmentally benign alternatives to lead-based ceramics, yet their performance is often limited by high polarization-reversal energy barriers. Here, a simple and effective A/B-site synergistic doping strategy using NaSbO3 (NS) and Bi0.5Na0.5ZrO3 (BNZ) is proposed to construct a stable new phase boundary (NPB) in KNN. Rietveld refinement confirms that the optimum composition (x = 0.035) exhibits rhombohedral-orthorhombic-tetragonal (R-O-T) triple-phase coexistence at room temperature. This NPB state considerably reduces the polarization-reversal barrier and is accompanied by maximized grain size (similar to 6.68 mu m). As a result, the ceramic shows significantly enhanced electrical properties: a high piezoelectric coefficient d(33) = 456 pC/N, a planar electromechanical coupling coefficient k(p) = 52.2%, and a greatly increased dielectric constant (epsilon(r) approximate to 2542) with low loss. The improvement stems from the multi-orientation polarization paths and low-energy-barrier reversal enabled by the NPB, further aided by facilitated domain-wall motion due to larger grains. This work not only presents a high-performance KNN composition but also offers a straightforward doping approach to controllably design NPBs for advanced lead-free piezoelectrics.

The urgent need for sustainable and green energy storage has intensified the demand for high-performance, lead-free dielectric capacitors that couple high power density with ultra-fast charge-discharge characteristics. Herein, a novel lead-free relaxor antiferroelectric ceramic, (1-x)[0.9NaNbO3-0.1BiFeO3]-xBi(Mg2/3Nb1/3)O3 (NN-BF-BMN), was designed by incorporating BMN as a third component to the NN-BF matrix. This synergistic approach of BMN incorporation demonstrates inducing relaxor antiferroelectric characteristics, enhancing polarization response and enabling superior energy storage performance. Resultantly, the 0.9(NN-BF)-0.1BMN bulk ceramic achieves an excellent recoverable energy density (Wrec) of 7.3 J/cm3 and a high efficiency (η) of 86.6% under an electric field (Eb) of 720 kV/cm. The optimized composition with x = 0.10 was further selected for multilayer ceramic capacitors (MLCCs) fabrication via tape casting. The MLCCs revealed a breakthrough in energy storage performance, exhibiting an ultrahigh Wrec of 12.2 J/cm3 with an outstanding η of 89.6% at a high Eb of 920 kV/cm along with thermal stability across the broader temperature range from 30 to 150 °C with little variation in Wrec (<7.1%) and η (<5.7%). Furthermore, a robust discharge time (t0.9 = 19.2 ns), and ultra-high current density (CD = 1598.7 A/cm2) along with substantial power density (PD = 263.8 MW/cm3) represent a promising lead-free environmentally friendly candidate​ for next-generation advanced pulsed power applications.

Electrocaloric (EC) cooling is a promising alternative to conventional vapor-compression refrigeration by virtue of its potential for miniaturization, its high energy efficiency, cost-effectiveness, and environmental benignity. However, the practical application of lead-free EC ceramic materials is hindered by the challenge of simultaneously realizing a large adiabatic temperature change (Delta T) and a broad operating temperature span (T-span). In this work, Sm3+ was doped into the A-sites of a Ba0.9Sr0.1Ti0.93Sn0.07O3 ceramic system to modify its ferroelectric polarization and relaxor behavior. The (Ba0.9Sr0.1)(0.995)Sm0.005Ti0.93Sn0.07O3 ceramic exhibits a Delta T of 3.8 K at an electric field of 200 kV cm(-1) near room temperature, accompanied by a wide T-span of 78 degrees C. A decrease in oxygen-vacancy concentration with increasing Sm3+ doping content significantly improves the dielectric breakdown strength of the ceramics. The enhanced breakdown strength effectively boosts spontaneous polarization, thus enabling excellent room-temperature electrocaloric performance. This work provides a facile and effective compositional regulation strategy for optimizing the electrocaloric properties of BaTiO3-based ceramics for solid-state cooling applications.

BaTiO3 (BT)-based lead-free piezoceramics face limitations in high-temperature applications due to their low Curie temperature (TC). Here, we propose a novel strategy to enhance TC by generating localized compressive stress through a secondary Ba2TiSi2O8 (BST) phase. In BT-xBST (0 mol% <= x <= 30 mol%) ceramics, TC increases by 36 degrees C to 158 degrees C at x = 25 mol%, which one of the highest reported values for BT-based systems. GPA analysis of STEM images confirms compressive strain at BST-BT interfaces, significantly exceeding intragranular stress. Phase-field simulations quantitatively validate this mechanism, showing an 18 degrees C TC increase under compressive stress, consistent with experiments. We attribute the enhancement to suppressed lattice expansion during the tetragonal-to-cubic transition, which raises the energy barrier for phase transformation. This stress engineering approach offers a generalizable route to design high-TC piezoceramics beyond doping paradigms. (c) 2026 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

The structural, microstructural, ferroelectric, dielectric, and impedance properties of (0.7BiFeO3–(0.3–x)BaTiO3)–xBa(Ti0.2Zr0.2Sn0.2Hf0.2Mn0.2)O3 (BF-(0.3-x)BT-xBTZSHM) ceramics (0 ≤ x ≤ 0.30) were systematically investigated. All compositions exhibit a single-phase perovskite structure, while the X-ray diffraction peaks gradually shift toward lower diffraction angles with increasing x, indicating lattice expansion induced by multi-component B-site substitution. Scanning electron microscopy observations reveal progressive grain refinement with increasing high-entropy content. Polarization–electric field (P–E) hysteresis loops show relatively large remanent polarization (Pr) and coercive field (Ec) at low x, whereas the loops become slimmer with increasing x, accompanied by decreases in both maximum polarization (Pmax) and Pr. Dielectric measurements indicate that the sharp ferroelectric–paraelectric transition observed at x = 0 gradually evolves into a diffuse phase transition with pronounced frequency dispersion as x increases. Impedance spectroscopy reveals multiple electrical responses associated with grains and grain boundaries, while the activation energy for electrical conduction decreases with increasing x. These results suggest that the incorporation of the complex Ba(Ti0.2Zr0.2Sn0.2Hf0.2Mn0.2)O3 component enhances polar disorder and weakens long-range ferroelectric ordering in the BiFeO3–BaTiO3 system.

Dielectric capacitors are critical components in pulsed power and advanced electronic systems; however, most lead-free bulk ceramic dielectrics suffer from an intrinsically low recoverable energy density (Wrec) due to limited breakdown strength (BDS) and pronounced ferroelectric hysteresis. To overcome these limitations, an entropy engineering strategy is proposed by introducing a high-entropy perovskite oxide, Ba (Ti0.2Zr0.2Sn0.2Hf0.2Nb0.1Sc0.1)O3 (BTHE), into the 0.7BiFeO3-0.3BaTiO3 (BF-BT) ferroelectric matrix, forming a series of BF-BT-xBTHE lead-free high-entropy ferroelectric ceramics. Structural analyses reveal that multi-component substitution at the B-site induces severe lattice distortion and enhanced pseudo-cubic phase characteristics, leading to pronounced relaxor ferroelectric behavior and significant grain refinement. As a result, both polarization hysteresis and electrical conduction are effectively suppressed, leading to a remarkable enhancement in BDS. An ultrahigh BDS of 840 kV cm-1 is achieved, giving rise to a superior Wrecof 10.55 J cm-3 in bulk ceramics. Furthermore, statistical analysis and phase-field simulations indicate that entropy-induced microstructural heterogeneity effectively disperses local electric fields and delays dielectric breakdown. This work demonstrates that entropy engineering offers a powerful and generalizable approach to simultaneously enhancing BDS and energy-storage performance in lead-free ferroelectric ceramics.

Purpose This study aims to investigate the effect of microwave hybrid heating (MHH) reflow on the corrosion immersion and mechanical reliability of SAC305/Cu solder. SAC305/Cu solder joints were reflowed by MHH using controlled processing durations.Design/methodology/approach Corrosion behavior was evaluated through 3.5 Wt.% NaCl immersion for up to 28 days. Structural phase evolution, interfacial morphology and elemental distribution were analyzed. Metallic ion dissolution was quantified to evaluate corrosion-induced ion release behavior, and Vickers hardness measurements were conducted to assess mechanical integrity.Findings Uniform scalloped Cu6Sn5 intermetallic layers with stable ss-Sn matrix were formed by MHH reflow method. Immersion exposure induced progressive pitting corrosion dominated by Cl--assisted ss-Sn dissolution. Oxide phases (SnO, SnO2) and complex Sn3O(OH)2Cl2 formed, contributing to partial passivation. Immersion corrosion was more severe at solder edges, whereas pitting dominated at peak regions. High initial dissolution of the Cu element was observed, followed by stabilization attributed to the formation of a protective oxide layer. A noticeable reduction in hardness (9.43%) was observed after 28 days, reflecting corrosion-induced degradation of the ss-Sn matrix.Originality/value This work provides a comprehensive correlation between MHH-induced microstructure, electrochemical degradation mechanisms and mechanical reliability of SAC305/Cu solder joints in saline environments.

Dielectric energy storage materials play a pivotal role in pulsed power systems. In this work, ternary, quaternary, and quinary BiMeO₃-doped BaTiO3 ceramics were systematically constructed, and the influence of B-site diversification on the microstructure, polarization mechanism, and energy storage performance was investigated. The results indicate that increasing configurational entropy modifies the local random fields and polarization response of the system, while simultaneously overriding the dominant contribution to polarization from individual elements, leading to an averaged and stabilized polarization response. Finally, through multi-scale comparative analysis, a quinary composition exhibiting both excellent room-temperature energy storage performance (Wrec = 6.7 J cm−3, η = 94

The novelty of this study, compared to our previous sol-gel coating works, lies in the use of solar panel glass substrates and the comprehensive characterization carried out, including mineralogical, morphological, thermal, and mechanical analyses. The first step in the process is to prepare a sol, which is a colloidal solution consisting of solid particles uniformly dispersed within a liquid medium. Sols utilized within the present study were prepared through hydrolysis and polishing of Titanium and Boron Alkoxides, respectively, within Alcohol. To create the thin film on a glass, each sol was placed onto a glass by the dipping method with the aid of a dip coater, and the coated glasses were allowed to air dry. The characteristics of the surfaces of the processed glasses were determined through cross-sectional testing (XRD), pencil hardness tests, scanning electron microscopy (SEM) and contact angle (CA). The untreated glass surface exhibits a water contact angle of 59.20°, reflecting its inherently hydrophilic character. The contact angle significantly decreases to 10.46°, 17.14°, and 5.34%, respectively. Glasses with TiO2 and B2O3 addressing display increased scratch resistance but decreased CA versus uncoated counterparts.

Ultra-low permittivity (epsilon(r):4-5) Mg2Al4-x(Ge0.5Mg0.5)(x)Si5O18 (0.12 <= x <= 0.28) and Mg2Al4-y(Mn0.5Mg0.5)(y)Si5O18 (0.1 <= y <= 0.3) cordierite ceramics were fabricated by solid-state reaction method. The improvement in [(Si4Al2)O-18] hexahedral ring roundness significantly enhances the quality factor through the substitution of complex ionic pairs of Ge0.5Mg0.5/Mn0.5Mg0.5 for Al lattice sites in the [(Si4Al2)O-18] hexahedral ring of these cordierite ceramics. Excellent microwave dielectric performances of Mg2Al3.8(Ge0.5Mg0.5)(0.2)Si5O18 and Mg2Al3.8(Mn0.5Mg0.5)(0.2)Si5O18 ceramics sintered at 1400 degrees C were demonstrated using the Hakki-Coleman resonant method with epsilon(r) = 4.676, Qxf = 186, 503 GHz@13.659 GHz and 199,476 GHz @ 27.434 GHz, tau(f) = -20.02 ppm/degrees C and epsilon(r) = 4.807, Qxf = 101,420 GHz@13.662 GHz and 143,005 GHz @ 27.366 GHz, tau(f) = -26.44 ppm/degrees C, respectively. These results present the potential application of high-quality cordierite in future B5G/6 G millimeter and terahertz communication frequency bands.

Achieving high recoverable energy storage density (W-rec) and efficiency (eta) in relaxor ferroelectric (RFE) ceramics with fatigue resistance and fast charge-discharge behavior remains a significant challenge. In this work, we report a novel lead-free RFE ceramic system, KTaO3 (KT)-modified Ba0.6Sr0.4TiO3 (BST), that exhibits excellent energy storage performance and fatigue-resistance (temperature, frequency, and cyclic poling) stability. The optimum composition, 0.92BST-0.08 KT, demonstrates a high W-rec of 3.91 J cm(-3), an outstanding eta of >87 %, an excellent power density (P-D) of 108.79 MW cm(-3), and an ultra-fast discharge time (t(0.9)) of 18.7 ns. The enhanced energy storage properties are attributed to the synergistic effects of the relaxor ferroelectric behavior, high breakdown strength, and optimized microstructure induced by KT doping. The multiscale modulation strategy employed in this work provides valuable insights into designing high-performance RFE ceramics for energy storage applications.

The development of dielectric ceramics that simultaneously achieve high energy density and ultra-broad temperature stability remains a fundamental challenge for advanced electrostatic capacitors. Here, we report a high-entropy engineering strategy that transforms conventional relaxor ferroelectric BT-Bi(Mg0.5Zr0.5)O3 into entropy-stabilized BT-H through a dual-phase cationic disorder modulation. By maximizing configurational entropy, this approach induces atomic-scale lattice heterogeneity with reduced size of polar units, and establishes temperature-adaptive multiphase coexistence structure, effectively decoupling polarization configuration from thermal fluctuations. Consequently, the optimized BT-H ceramics exhibit extraordinary recoverable energy density (Wrec) of 8.9 J cm-3, near ideal conversion efficiency (η) of ~ 97.8 % and superior temperature stability of ΔWrec ~±9 % and Δη ~ ±4.8% over a ultrawide operational range (-85-220 °C). This work validates the entropy-mediated cocktail effect, demonstrating that leveraging high-entropy materials to design capacitors with superior integrated energy storage performance is an advanced and viable strategy.

Bismuth ferrite-barium titanate (BF-BT) piezoelectric ceramics typically suffer from high leakage current and dielectric loss, which impede full domain polarization and weaken their piezoelectric response. To address these limitations, BF-BT ceramics were doped with varying amounts of ZrO2 and systematically assessed its effects on phase composition, microstructure, and electromechanical properties. Rietveld refinement of X-ray diffraction (XRD) data shows that the undoped ceramic primarily consist of rhombohedral (R3c) and cubic (Pmm) phases, with the R3c phase accounting for 35.83 %, increasing Zr content steadily raises the R3c fraction. Scanning electron microscopy (SEM) microstructural analysis reveals that average grain size grows with Zr doping, reaches a peak at 0.3 wt% Zr, then decreases at higher levels. Importantly, Zr doping boosts the resistivity at 400 degrees C from 1.3 x 10(2) to 7.4 x 10(4) Omega cm and markedly enhances electrical homogeneity. At 0.3 wt% Zr, the ceramics achieve a peak piezoelectric coefficient (d(33) similar to 204 pC/N) while retaining a relatively high Curie temperature (T-c = 443 degrees C). These findings demonstrate that high-valence Zr4+ doping is an effective strategy to suppress leakage current and improve piezoelectric performance in BF-BT piezoelectric ceramics.