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A two-step design is developed to realize multi-objective synergistic optimizations including high activity/ultrafine PNRs and ultrasmall grain size with compact grain boundaries, showing huge application potential in advanced pulsed power devices.

The light rare earth Pr/Ce-contained (Tb0.2Pr0.8)1–xCexFe1.93 (0 ≤ x ≤ 1.0) intermetallics were arc melted and magnetoelastic properties were investigated. The compounds of x ≥ 0.40 are found to stabilize at ambient pressure in a single Laves phase with MgCu2-type C15 structure, which is attributed to the strong Ce 4f bonding. The mixed-valence behavior, with a support of the deviation from the linear Vegard’s law for both lattice parameter a and saturation magnetization MS, is observed at room temperature. The easy magnetization direction (EMD) was determined by the analysis of XRD on both magnetically aligned samples and the (440) splitting, that is, EMD lies toward axis for x ≤ 0.50 rotating to for x = 0.60, accompanied with the structural distortion from rhombohedral to orthorhombic. The substitution of Ce for Tb/Pr is conductive to the reduction of magnetocrystalline anisotropy, giving rise to an improvement of the low-field magnetostriction. The excellent magnetoelastic properties can be tailored by the Ce introduction, e.g., the spontaneous magnetostriction coefficient λ111 as large as 1150 × 10−6 for x = 0.40, and the low-field induced magnetostriction achieving a high value of λa = 180 × 10−6 at 80 kA/m for x = 0.60. The excellent magnetoelastic properties and the combination in high Pr-content with low cost, suggest promising prospects in applications.

As microelectronic devices move toward integration and miniaturization, the thin film capacitors with high energy density and charge/discharge efficiency have attracted immense interests in modern electrical energy storage systems. Despite morphotropic phase boundary (Na0.8K0.2)0.5Bi0.5TiO3-based lead-free materials with outstanding ferroelectric and piezoelectric properties, while large ferroelectric hysteresis with high remanent polarization (Pr) hinder to improve energy storage capability. Here, novel lead-free relaxor-ferroelectric (RFE) thin film capacitors with high energy density are successfully prepared in (1-x) (Na0.8K0.2)0.5Bi0.5TiO3-xBa0.3Sr0.7TiO3 [(1-x)NKBT-xBST] systems. Introducing BST into the NKBT systems is expected to reduce remanent polarization (Pr) on account of coupling reestablishment of the polar nano-regions (PNRs) and improving the relaxation behavior. As a result, 0.6NKBT-0.4BST thin film exhibits high energy density (Wrec ∼ 54.79 J/cm3) together with satisfactory efficiency (η ∼ 76.42%) at 3846 kV/cm. The stable energy storage performances are achieved within the scope of operating temperatures (20–200 °C) and fatigue cycles (1-107 cycles). This work furnishes a new technological way for the design of high energy-density thin film capacitors.

Dielectric capacitors with ultrahigh power densities and fast charging/discharging rates are of vital relevance in advanced electronic markets. Nevertheless, a tradeoff always exists between breakdown strength and polarization, which are two essential elements determining the energy storage density. Herein, a novel trilayered architecture composite film, which combines outer layers of two-dimensional (2D) BNNS/poly(vinylidene fluoride

Newly one-dimensional hydroxyapatite nanowires are synthesized and applied in P(VDF–HFP) nanocomposites for energy storage application. Excellent Ud of ∼27.6 J cm−3 accompanied with high η of ∼72.9% at Eb of 650 MV m−1 are achieved.

Considering the significant threat of heat to electronic equipment and the heat dissipation problems existing in powerful systems, thermal management materials are in high demand. In conjunction with the increasing desire of dissipating heat and stabilizing temperature, high thermal conductivity and phase change latent heat are attracting more attention when designing thermal management material. This work proposes a strategy to combine phase change matrix and thermally conductive filler using freeze casting. The highest thermal conductivity reaches 23.1 W m-1 K-1 accompanied by 62 J g-1 phase change latent heat. Meanwhile, replacing ice with organic phase change material in freeze casting can result in an aligned structure. This discovery will pave a novel way for introducing thermal latent heat without abandoning the aligned structure.

Sandwich-structured polymer nanocomposites exhibit remarkable capacitive energy storage performance, including high energy density, great charge–discharge efficiency and excellent dielectric stability at elevated temperatures.

A high-performance lead-free relaxor ferroelectric ceramic capacitor designed by a multiscale optimization strategy for energy storage applications.

Simultaneous achievement of high thermal transportation performance and superior mechanical properties in a same thermal management composite film.

Novel 2D BNNs/cyanoethyl cellulose composite films exhibit a large Ud of 23.5 J cm−3 along with a high η of 83.6% at 680 MV m−1.

The need for high-performance capacitors that possess superb discharged energy density and efficiency is continually increasing. Relaxor ferroelectric 0.94(0.65Na0·5Bi0·5TiO3-0.35Sr0·7Bi0·2TiO3)-0.06K0·5Na0·5NbO3 ((NBT-SBT)-KNN) ceramics with different MnO2-doping concentrations are prepared in this study. An outstanding discharged energy density (Wrec = 3.25 J/cm3) and efficiency (η = 93.8%) are concurrently acquired under 280 kV/cm for these doped ceramics. The ceramics also exhibit extraordinary thermal (30–200 °C), frequency-dependent (1–200 Hz) and fatigue stability (104 st). Additionally, the (NBT-SBT)-KNN-0.08 mol.% MnO2 ceramic displays a large power density (42 MW/cm3) and an ultrafast discharge speed (98 ns). This contribution offers powerful support for the use of energy storage ceramics in practical applications.

Conventionally, interface effects between polymers and fillers are essential for determining the breakdown strength and energy storage density of polymer-based dielectric composites. In this study, we found that interface effects between different fillers have similar behavior. BN and BaTiO3 fiber composite fillers with three different interface bonding strengths were successfully achieved by controlling composite processes (BT-fiber/BN

Lead-free ceramic capacitors play an important role in electrical energy storage devices because of their ultrafast charge/discharge rates and high power density. However, simultaneously obtaining large energy storage capability, high efficiency and superior temperature stability has been a huge challenge for practical applications of ceramic capacitors. Here, the relaxor ferroelectric (1-x)[0.8Bi0.5Na0.5TiO3-0.2Ba(Zr0.3Ti0.7)O3]-xSr0.7La0.2TiO3 ((1-x)(BNT-BZT)-xSLT) ceramics are prepared through solid-state reaction method to obtain excellent comprehensive energy storage performances. Particularly, high recoverable energy density (Wrec ∼ 2.6 J/cm3) as well as superior efficiency (η ∼ 92.2 %) can be achieved simultaneously under 210 kV/cm with composition of x = 0.3. Meanwhile, the corresponding ceramic shows excellent temperature (20−140 °C), frequency (1−200 Hz) and cycle stabilities (106 st). Additionally, the 0.7(BNT-BZT)-0.3SLT ceramic also displays high power density (PD ∼ 38.8 MW/cm3) and extremely short discharge time (τ0.9 ∼ 0.11 μs). Therefore, this study provides a useful guideline for designing novel BNT-based ceramics with superior comprehensive energy storage performances.

Morphotropic phase (MPB) eco-friendly ferroelectric 0.94Bi0.5Na0.5TiO3- 0.06BaTiO3 (NBT-BT) ceramics exhibits superior piezoelectric performances. However, the large remnant polarization (Pr) and low breakdown strength (Eb) of NBT-BT systems hinders application in energy storage capacitors. Herein, the Bi(Zn1/3Nb2/3)O3 (BZN) is selected to partially replace the NBT-BT ceramics to break ferroelectric long-range order domains achieving higher energy storage properties. Highly recoverable energy storage density (Wrec ~ 3 J/cm3) and efficiency (η ~ 75%) are acquired in (NBT-BT)-0.06BZN ceramics under a low applied electric field of 210 kV/cm. Furthermore, superior temperature stability (20–120 °C), and frequency (1–1000 Hz) stability, and fatigue endurance (105 st) are also gained. These advantages further suggest that the (NBT-BT)-0.06BZN ceramics exhibit great promise in pulsed power markets.

The magnetostrictive materials are widely applied as modern smart materials converting electrical to mechanical energy. Here, the pseudobinary Sm0.88Nd0.12Fex compounds, free of both (expensive) heavy rare earths and B/Co stabilizer, have been prepared with mechanical alloying and subsequent solid-state sintering process. An amorphous phase can be formed by high-energy ball milling, followed by the formation of single-phase Sm0.88Nd0.12Fe1.80 alloy at an annealing temperature of 690 °C. A high anisotropic magnetostriction λa as large as 1280 ppm for the as-sintered alloy is obtained at an external field of 12 kOe. The oriented pseudo 1-3 type particulate composite is fabricated by embedding and aligning the as-sintered alloy particles in an epoxy matrix under an oriented magnetic field. The composite with a volume faction of 30% shows large magnetostriction (λa ~895 ppm at 12 kOe). In particular, λa and the longitudinal magnetostriction λ|| at a low field (3 kOe) reaches a value as high as 630 and 450 ppm, respectively, 78% and 84% larger than that of its as-sintered polycrystalline alloy although Vp is only 30%. Ultimately, it is anticipated that this work will open a new design paradigm to develop Sm-based materials with negative-magnetostriction performance.

Ferroelectric thin films capacitors have been potentially applied in advanced electronics and electric power systems because of their high power densities and fast charge–discharge responses. However, continuous operation of the ferroelectric thin film capacitors under elevated temperatures and high electric fields still remains a huge challenge. Herein, we report eco-friendly BiFeO3-modified Bi3.15Nd0.85Ti2.8Zr0.2O12 (BNTZ) free-lead ferroelectric thin films for high-temperature capacitor applications that simultaneously possess high-energy storage density (Wreco), efficiency (η), and temperature-dependent stability. The BNTZ–0.09BFO thin film shows a first-class-level Wreco (∼124 J cm−3) along with high η (∼81.9%), which surpasses almost all the Pb-contained and Pb-free perovskite ferroelectrics. Of particular importance is that excellent fatigue endurance for long-term stability (109 cycles) and thermal stability (−100 °C to 200 °C) could be achieved. This work represents a new design paradigm to exploit advanced dielectric capacitor materials for high-temperature electronics and energy storage devices.

High-performance electrostatic capacitors are in urgent demand owing to the rapid development of higher power electronic applications. However, developing polymer-based composite films with both a high breakdown strength (Eb) and dielectric constant (er) is still a huge challenge. Here, hierarchically structured SrTiO3@SrTiO3 nanofibers (ST@ST NFs), in which crystalline SrTiO3 nanoparticles are embedded into the amorphous SrTiO3 nanofibers, are incorporated into the poly(vinylidene fluoride-co-hexafluoropropene) (P(VDF-HFP)) matrix to form a multiscale internal/external interface to break the paradox of a high er with decreased Eb, and that in turn gives rise to a remarkably improved energy storage capability. The percolation of the SrTiO3–SrTiO3 interfaces could promote interfacial polarization, resulting in a substantially increased er of the polymer nanocomposites at a rather low concentration of nanofillers. More importantly, the improved Eb of 630 MV m−1 is also achieved through the multiscale internal/external interface. These very favorable values give rise to an ultrahigh discharged energy density (Ud) of ∼25.26 J cm−3, which is 283% of the value of the pure P(VDF-HFP) film. A record enhancement ratio of Ud is achieved in this work among the previously reported results to the best of our knowledge. This approach provides a new dimension of interface engineering to adjust and improve the energy storage properties of polymer nanocomposites.

The texture-oriented TbxDy0.7−xPr0.3(Fe0.9B0.1)1.93/epoxy particulate composites are fabricated with a magnetic field of 640 kA/m. The -oriented 1–3 type (x ≤ 0.16) and -oriented composites (x ≥ 0.22) are obtained. The composite exhibits a negative ΔE effect of elastic modulus (E3) with trivial eddy-current losses at frequency up to 50 kHz. The 1–3 type composite with a particle volume fraction Vf ~ 0.30 displays an enhanced magnetoelastic performance, that is, the dynamic piezomagnetic coefficient d33 ~ 2.2 nm/A at Hbias ~ 80 kA/m, which is 150% higher than that of its 0–3 type one and approaches 92% of its monolithic polycrystalline alloy. This enhanced effect can be attributed to its easy magnetization direction (EMD) lying towards axis as well as the formation of -texture-oriented structure. This facile approach will open a new way to prepare magnetoelastic composites for high-frequency applications.

Thermal stability of capacitors with both superior recoverable energy density (Wrec) and efficiency (η) have recently attracted great research interest for application in the pulse power systems. Here, high-quality lead-free relaxor-ferroelectric (RFE) (1-x)Bi0.5Na0.5TiO3-x(Na0.73Bi0.09)NbO3 [(1-x)BNT–xNBN, x = 0.10–0.18 ] ceramics are fabricated through solid-state reaction method. The NBN substitution of NBT ceramics could improve effecitively breakdown strength (BDS), energy storage performances, and the thermal stability. Especially, excellent recoverable energy density (Wrec ~ 2.41 J/cm3) and efficiency (η ~ 81.6%) could be achieved synchronously in 0.84BNT–0.14NBN ceramic. Moreover, the good thermal stability (20 °C ~ 140 °C), frequency stability (1–1000 Hz), and fatigue endurance (104 cycles) are also obtained in the composition of x = 0.14 ceramic. Particularly, corresponding ceramic shows high current density (~ 817 A/cm2), discharge energy density (~ 0.729 J/cm3), extremely short discharge rate (

In today's global traditional energy shortage environment, developing renewable and environmental-friendly energy has become a trend. In this work, the (1-x)Na0.5Bi0.5TiO3-xSr0.7Bi0.2TiO3 ((1-x)NBT-xSBT, x=0.2, 0.3, 0.4, and 0.5) relaxor ferroelectric thin films are grown on Pt/Si/SiO2 substrate via the sol-gel method. The structure, dielectric properties, energy density, thermal stability, frequency stability, and fatigue endurance for long-term stability of the (1-x)NBT-xSBT thin films are studied systematically. The experimental results demonstrate that the NBT-0.5SBT thin film exhibits an excellent discharge energy density (Wrec ~35.014 J/cm3) and efficiency (η ~73.8%) under 3200 kV/cm at room temperature (RT). More importantly, the corresponding thin film display superior the thermal stability (20–140 °C), frequency stability (102–104 Hz), and fatigue endurance for long-term stability (104 st). Therefore, this contribution will provide a convenient and efficient way for preparing high-performance dielectric capacitors for application in power pulse systems.

Electrostatic capacitors, though presenting faster rate capability and higher power density, are hindered in applications because of their low energy density. Accordingly, many efforts in electrostatic capacitors, for electronics and electrical power systems, have mainly concentrated on the development of dielectric materials with high-energy density (

Poly(lactic acid)-based (PLA) films with biodegradability and ease of processing are promising dielectrics for application in electrostatic capacitors. Nevertheless, the relative low energy storage capability of the PLA film greatly hampers the development of its further application. Herein, a biodegradable polymer of stereocomplex crystals of poly(lactic acid) is prepared utilizing a solution blending method of the co-blended poly-L-lactic acid (PLLA) and poly-D-lactic acid (PDLA) in a 1:1 ratio. The stereocomplex crystals could prominently improve insulation and mechanical properties of PLLA/PDLA blend films, thus achieving an outstanding energy density ( Ud ∼ 13.7 J/cm3) accompanied with high efficiency ( η ∼ 92.8%) at a breakdown electric field of 750 MV/m. Additionally, the PLLA/PDLA blend film also exhibit good high-temperature performance and reliability. This work provides a reasonable tailoring strategy for biodegradable polymer dielectrics and demonstrates a great potential of biodegradable polymers for practical applications in environmentally friendly power electronics and electrical systems.

Polycrystalline alloys of (Pr0.5Nd0.5)1−xCexFe1.93 (0 ≤ x ≤ 1.0) are arc melted and investigated for structural, magnetic, and magnetoelastic properties. The light rare earth Ce presents a mixed-valence behavior and helps form a single C15 Laves phase for the composition of x ≥ 0.40. Both the lattice parameter a and the saturation magnetization MS of the Laves phase decrease with increasing Ce content, and the dependence of a on the Ce concentration deviates the linear Vegard law. The easy direction of magnetization (EMD) at room temperature is detected toward axis by performing X-ray diffraction on magnetic-field–aligned powders. The Ce introduction into (Pr,Nd)Fe2 system can reduce the magnetocrystalline anisotropy, resulting in an enhancement of the magnetostriction at low magnetic fields. The good magnetoelastic properties, that is, a low anisotropy and a high low-field anisotropic magnetostriction λa ~ 165 ppm at 1 kOe, can be obtained for the free-heavy rare earth (Pr0.5Nd0.5)0.6Ce0.4Fe1.93 alloy, and may make it a promising candidate for applications.

The development of lead-free bulk ceramics with high recoverable energy density (Wrec) and high efficiency plays a major role in meeting the requirements for miniaturization and integration of advanced pulsed power capacitors. In this study, composition-dependent phase structures and ferroelectric properties of lead-free relaxor ferroelectric ceramics (1 − x)(0.84Bi0.5Na0.5TiO3–0.16K0.5Bi0.5TiO3)–x(Bi0.2Sr0.7TiO3) [(1 − x)(BNT–KBT)–xSBT, x = 0–0.45] are investigated. The introduction of SBT into the morphotropic phase boundary (MPB) BNT–BKT system constructs the relaxor ferroelectrics according to the order–disorder theory, leading to an improved energy storage performance. Results show that an ultrahigh recoverable energy density of 4.06 J cm−3 and a high energy-storage efficiency of 87.3% under an electric field of 350 kV cm−1 are achieved concomitantly, together with a superior high temperature stability (30–160 °C) and strong fatigue endurance (104 cycles). In particular, the corresponding ceramic exhibits an ultrafast discharge rate (τ0.9 = 127 ns) and a high level of discharge energy density (Udis = 1.29 J cm−3). Our study provides the groundwork for an effective way to design high-performance ceramics for application in next generation energy storage capacitors.

High-temperature electrostatic capacitors are in urgent demand owing to the rapid development of advanced power electronic applications. However, obtaining polymer films with excellent discharge energy density and efficiency is still a huge challenge under harsh environmental conditions. Here, novel Ag nanodot/polyimide (Ag-ND/PI) nanocomposite films are designed and prepared through an in situ method. The energy storage capability and thermal stability of the PI matrix are significantly improved via loading a small amount of Ag-NDs, owing to the Coulomb-blockade effect and high thermal conductivity. Particularly, a high discharge energy density (Ud) of 5.16 J cm−3 at 600 MV m−1 is achieved for nanocomposite films with an ultralow filler content of 0.1 vol% Ag-NDs at room temperature, which is 260% higher than that of the pristine PI (2.02 J cm−3 at 450 MV m−1). Concurrently, the corresponding nanocomposite films exhibit an excellent high-temperature Ud of 2.56 J cm−3, together with efficiency exceeding 80% at a temperature of 150 °C at 400 MV m−1. Therefore, this research unveils a new method towards high-performance polymer capacitors for high-temperature applications.

The magnetostrictive alloys with composition Tb0.4Nd0.6(Fe0.8Co0.2)x (1.50 ≤ × ≤ 1.90) are synthesized using the solid-state mechanical alloying (MA) method followed by sintering. The phase component, structure, thermal stability, and magnetoelastic properties are investigated as functions of composition, milling process, and annealing temperature. An amorphous phase companied by free alpha-iron is formed by MA in a high-energy ball mill, which crystallizes into MgCu2-type and PuNi3-type structures with different annealing temperatures. A single Laves phase for the high Nd-content Tb0.4Nd0.6(Fe0.8Co0.2)1.60 is formed at optimal conditions for heat treating at 700 °C for 30 min. A large linear anisotropic magnetostriction λa (=λ||–λ⊥) as high as 560 ppm at 12 kOe is obtained for the sintered alloy, which may make it a promising magnetostrictive material. Meanwhile, this work may help to open up a new way to search for Laves phase magnetostrictive materials containing Nd.

Electromagnetic wave absorbing materials have been widely applied in the wireless communication, electronic devices, and radar technology. In this work, metal-organic frameworks derived nanoporous Fe3O4 @ carbon (Fe3O4@NPC) composites were successfully obtained by a simple method. Electromagnetic wave absorbing performances were significantly enhanced due to the optimal impedance matching and strong attenuation via the synergy between the dielectric loss and the magnetic loss. As a result, the Fe3O4@NPC composites exhibited excellent electromagnetic wave absorbing properties, in which a strong reflection loss (RL) of −65.5 dB at 9.8 GHz as well as a wide absorbing bandwidth of 4.5 GHz (RL

Electrostatic capacitors with a high dielectric constant and breakdown strength are desired for dielectrics to achieve a higher discharged energy density. Here, we propose that an artificial polymer nanocomposite combining a novel hybrid structure of one-dimensional Ag@BaTiO3@polydopamine@Ag nanofibers (1D ABPAs) as fillers and poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] as the matrix demonstrated a remarkably comprehensive performance. A large displacement (9.84 μC cm−2 at 480 MV m−1) was observed so as to obtain a high discharged energy density (∼17.25 J cm−3) of the composite films with 3 vol% 1D ABPAs, which was 2.22-times that of pristine P(VDF-HFP) (∼7.74 J cm−3). This discharged energy density is among the highest under an equivalent electric field strength reported so far. The corresponding composite films exhibited a superior charge/discharge speed of 139 ns and excellent reliability in energy storage performance by consecutive cycling. This work could provide an effective way to design and improve the performance of polymer-based nanocomposites for capacitive energy-storage applications.