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High-performance dielectric capacitor materials are required for the miniaturization of electronic devices. To this end, (1- x)(0.65BiFeO 3 -0.35BaTiO 3)- x La(Mg 2/3 Ta 1/3)O 3 (BFBT- x LMT, x = 0, 0.06,0.10, 0.14 and 0.18) ceramics were fabricated by a solid-state method. The experimental results indicate that LMT doping can well improve the energy storage density (W rec) and efficiency (η) of BFBT ceramics. Especially, the optimal energy storage performance (ESP) (W rec =4.92 J/cm3, η = 85%) was obtained in BFBT-0.14LMT ceramics under 390 kV/cm. The enhancement of ESP of BFBT-0.14LMT ceramics can be ascribed to the decreased hysteresis of polarization (P) - electric field (E) loops resulting from the aggravation of the composition and charge disorder in the system, and the improved breakdown strength (E b) which is related to the reduced grain size, the widened band gap (E g) and the decreased oxygen vacancy concentration. Additionally, the thermal stability of ESP of BFBT-0.14LMT ceramics is also enhanced compared with pure BFBT ceramics. Meanwhile, BFBT-0.14LMT ceramics exhibit a fast discharge rate (t 0.9 = 152 ns) under 180 kV/cm. These results indicate that BFBT-0.14LMT ceramics could be a promising dielectric capacitor material. In general, our study reveals that LMT is good dopant to enhance the E b and ESP of BF-based ceramics. • High W rec of 4.92 J/cm3 and large η of 85% are achieved in BFBT-0.14LMT ceramics. • LMT doping significantly enhances the E b of BFBT ceramics. • The energy storge performances show good thermal stability (30–150 ℃). [ABSTRACT FROM AUTHOR]

Long-afterglow phosphor SrAl 2 O 4 : 0.01Eu 2+ , 0.01Dy 3+ (SAO) requires a high sintering temperature of 1400 °C even when boric acid is added as flux via a solid-state reaction. The aluminum source NaAlO 2 behaved as a good mineralizer in the designed hydrothermal process to achieve a large surface-to-thickness ratio of SAO. The flower-like shape of hydrothermally prepared hSAO without B 2 O 3 after annealing at 1100 °C/4 h transformed into a rod-like plate phosphor with nano-thickness. Such a small rod-like plate exhibited higher photoluminescence (PL) intensity than large-grained B 2 O 3 -added bSAO prepared via a solid-state reaction. The annealed hSAOs inherited the morphology of the as-hydrothermally prepared aluminates. A nano-thick sheet of annealed aSAO containing B 2 O 3 further enhanced the PL significantly and indicated a blue shift independent of the grain size. Furthermore, the nano-thick sheet of phosphors exhibited the same afterglow as the conventional tens-of-micrometers-sized phosphors. Fourier-transform infrared spectroscopy and X-ray diffraction results showed that the B O 4 bond may substitute Al O 4 in the structure and the B O 3 bond is in a flux outside the annealed aSAO and bSAO grains. The molten flux formed a thin layer on the surface of the SAO particles to be a core-shell of the SAO-B 2 O 3 structure, behaving as a diffusion-assistant medium and environmental protection layer against acid and humidity. [ABSTRACT FROM AUTHOR]

SiO 2 nanoparticles have been introduced into epoxy-modified silicone resin (ESR) via two routes including direct addition (DA) and in-situ growth (ISG). Growth mechanism of the SiO 2 nanoparticles has been revealed where chemical bonding forms between the SiO 2 and the epoxy, ester and hydroxyl groups of the ESR during ISG. The obtained hybrid resins have been used as the matrix in the fabrication of Fe soft magnetic composites (SMCs). Effects of the SiO 2 incorporation method and its content on the magnetic, electrical and mechanical properties of the SMCs have been investigated. Optimized performance of the SMC with large effective permeability (107.9), reduced core loss (1220 mW/cm 3 ) and enhanced mechanical strength (2.95 MPa) can be achieved by introduction of 34 wt% SiO 2 nanoparticles into the ESR via ISG. The formation of chemical bonding between the SiO 2 nanoparticles and the ESR also gives rise to improved thermal stability for complete stress relaxation of the SMCs. [ABSTRACT FROM AUTHOR]

Soft magnetic composites (SMCs) containing Fe powders embedded in insulating matrix have been fabricated via alkaline bluing as a new method. Effects of reaction time on the magnetic properties of the SMCs have been investigated. Mechanism of the oxidation process has also been revealed, which involves initial oxidation of Fe into Fe 2+ (Na 2 FeO 2 ) and Fe 3+ (Na 2 Fe 2 O 4 ) by NaNO 2 and NaNO 3 followed by hydrolysis of Fe 2+ and Fe 3+ into Fe 3 O 4 . Hydrolysis of the excessive Fe 3+ leads to the formation of Fe 2 O 3 which reduced the effective permeability of the SMCs. To form pure Fe 3 O 4 coating, the reaction process has been improved to suppress the Fe 3+ hydrolysis. The obtained ferromagnetic Fe 3 O 4 coating effectively reduces magnetic dilution, while its high electrical resistivity allows satisfactory insulation between the Fe powders, giving rise to simultaneous high effective permeability (97.7) and low core loss (771.3 mW/cm 3 ) of the SMC. [ABSTRACT FROM AUTHOR]

In this paper, the impact of cooling rate on solidification microstructures of Al 75 Bi 9 Sn 16 alloy was studied for obtaining Al Bi Sn core-shell organizations by SEM under normal casting conditions. The results show that the core-shell structure is composed of Sn Bi-rich core and Al-rich shell and outermost thin layer of Sn Bi phase when Al 75 Bi 9 Sn 16 alloy melt is cast in a copper mold; when Al 75 Bi 9 Sn 16 alloy melt is cast in sand mold, alloy does not form the typical core-shell structure. [ABSTRACT FROM AUTHOR]

Fe soft magnetic composites (SMCs) containing Fe powders embedded in Fe 3 O 4 /epoxy-modified silicone resin (ESR) matrix have been fabricated via thermal oxidation of Fe powders with H 2 O under alkalic conditions, prior to mixing with ESR. The ferromagnetic Fe 3 O 4 coating effectively reduces magnetic dilution, while high electrical resistivity of both Fe 3 O 4 and ESR provides satisfactory insulation of the SMCs, giving rise to simultaneous high permeability and low core loss. Evolution of the Fe 3 O 4 /ESR matrix during the annealing process has been investigated, which is correlated to changes in the magnetic properties of the SMCs. The ESR starts to decompose at around 382 °C, leaving reducing groups which then convert the Fe 3 O 4 coating into Fe with increased annealing temperature to 466 °C. Further raised annealing temperature to 570 °C leads to the reduction of Fe 3 O 4 into FeO. Such evolution provides in-sight information on choosing appropriate annealing conditions to avoid decomposition of the Fe 3 O 4 /ESR matrix and can be expanded to other Fe-based SMCs. [ABSTRACT FROM AUTHOR]

Fe 73.5 Cu 1 Nb 3 Si 15.5 B 7 amorphous alloy was fabricated into nanocrystalline soft magnetic composites (SMCs). Crystallization process and the evolution of stress relaxation of the SMCs during annealing have been investigated and their effects on the magnetic properties are revealed. Crystallization of the amorphous alloy is accomplished by increment of nucleation sites with the annealing temperature ranged from 500 °C to 600 °C. Stress induced by milling and compaction relieves with increased annealing temperature and complete relaxation can be achieved at around 575 °C. Coupling of small grains (9.1 nm–12.8 nm) and stress relaxation ensures the FeCuNbSiB SMCs of relatively low coercivity, high permeability and low loss. Further raised annealing temperature above 600 °C leads to dominating growth and coalescence of the existing α-Fe(Si) grains and the precipitation of the Fe 23 B 6 phase, which deteriorates the magnetic properties. Optimized soft magnetic properties of the SMCs such as small coercivity (4.5 Oe), large effective permeability (115) and low total core loss (200 mW/cm 3 measured when B m = 0.1 T and f = 50 kHz) can be achieved by post-annealing at 575 °C. [ABSTRACT FROM AUTHOR]

Phosphate layers were prepared as the insulation coating for Fe and FeSiAl soft magnetic composites (SMCs) and mechanisms of the phosphating process have been investigated. Effects of high-temperature annealing on the phosphate coating and the magnetic properties of the SMCs have also been revealed. For Fe SMCs, the insulating coating mainly consists of iron phosphate after surface passivation. It degrades into iron phosphide after annealing at relatively high temperatures (600 °C), leading to decreased electrical resistivity and increased eddy current for deteriorated magnetic properties of Fe SMCs. For the FeSiAl SMCs, the phosphate coating mainly contains Al(PO 3 ) 3 , which converts into oxides such as Al 2 O 3 and P 2 O 5 after annealing. These oxides possess high electrical resistivity, and continue to serve as the insulation coating for the composites. Consequently, the resistivity of the FeSiAl SMCs increases with the annealing temperature, which is beneficial to decrease the eddy current loss for enhanced magnetic performance. [ABSTRACT FROM AUTHOR]

Concerning the practical applications, dielectric capacitors with simultaneously high recoverable energy density (W rec) and large energy storage efficiency (η) under a low electric field is imperative and challenging. Herein, a strategy of complex ions substitution is proposed to achieve the goal. The (1- x)(0.75Na 0.5 Bi 0.5 TiO 3 -0.25SrTiO 3)- x La(Mg 2/3 Ta 1/3)O 3 (NBST- x LMT) ceramics were fabricated through a solid-state reaction method. A significantly enhanced breakdown electric field (E b) of 246.03 kV/cm is obtained in NBST-0.06LMT ceramics due to the refined average grain size (AGS), the enhanced band gap width and the inhibited oxygen vacancies by LMT doping. Furthermore, a high W rec of 3.18 J/cm3and large η of 86% are concurrently achieved in NBST-0.06LMT ceramics under a relatively low electric field of 246 kV/cm. Meanwhile, the variations of (W rec , η) under 170 kV/cm are less than 10% from 30 ℃ to 200 ℃, indicating an excellent thermal stability. Besides, the ceramics show a fast discharge rate of 155 ns by a charge-discharge measuring. In general, our results demonstrate the strategy of complex ions substitution is an effective way to achieve high energy storage performance under a relatively low electric field in NBT-based ceramics. [Display omitted] • Complex ions (La3+, Mg2+ and Ta5+) substitution was proposed to achieve high energy storage performance. • An enhanced Eb (246.03 kV/cm) was realized in NBST ceramics. • A high Wrec of 3.18 J/cm3and large η of 86% were concurrently obtained under 246 kV/cm. • The (Wrec, η) exhibits excellent thermal stability from 30 ℃ to 200 ℃. [ABSTRACT FROM AUTHOR]

Highlights: [•] Three microwave (MW) processes achieved high PL efficiency of nanophosphor. [•] The EG solvent provided homogeneous nucleation and activator homogenization. [•] Pseudo-oxide crystal may form during microwave heating in EG+KOH system. [•] Low MW power 100W economically reduced post-heating temperature to 600°C. [•] Residual hydroxyl/carbonyl groups on nanophosphors may be as chemical grafting. [ABSTRACT FROM AUTHOR]

A simple and facile method has been provided to develop novel core-heteroshell electromagnetic (EM) wave absorbers via selenylation of FeNi 3 nanoparticles. Core-heteroshell composites containing multiple phases including the FeNi 3 , NiFe 2 O 4 and NiSe x can been obtained with increased surface gradient of Se with the growth mechanisms revealed. Not only synergistic effects of magnetic and dielectric attenuation have been introduced, the multiple components also give rise to tunable impedance and enhanced interfacial polarization for improved EM wave absorbing performance. Such effective one-step route may be extendable to achieve core-heteroshell structure with multiple components for applications in other fields including energy, catalysis and sensing. • Core-heteroshell composites achieved via facile one-step selenylation of FeNi 3 nanoparticles. • Growth mechanisms revealed for the core-heteroshell structure. • Tunable impedance and enhanced interfacial polarization via multiple components. • Synergetic dielectric and magnetic attenuation for enhanced wave absorption. [ABSTRACT FROM AUTHOR]

FeCoAlON films were fabricated by reactive pulsed laser deposition. The microstructure and electromagnetic properties have been investigated as a function of N 2 pressure, which was varied from 0 to 5 mtorr. All the FeCoAlON films contains ultrafine FeCo nanoparticles isolated by nonmagnetic insulating layers. Those insulating layers ensure high electrical resistivity of the films and will be transformed from Al 2 O 3 into AlN with increasing N 2 pressure. The oxidation of Fe and Co can be effectively suppressed by introducing N 2 . The Fe tends to form amorphous iron nitrides at higher N 2 pressures, leading to different magnetic response. Optimized electromagnetic properties can be achieved under 3 mtorr of N 2 , showing great potential in noise suppression application at high frequencies. Further increased N 2 pressure to 5 mtorr leads to shrunken FeCo nanoparticles and thickened insulating layers due to the formation of nonmagnetic iron nitrides, giving rise to superparamagnetic response of the FeCoAlON thin film. Consequently, appropriate N 2 pressure plays an essential role in inducing favorable microstructure and phase composition for enhanced electromagnetic performance. [ABSTRACT FROM AUTHOR]

• Hierarchical SiO 2 @MoSe 2 @FeNi 3 designed for electromagnetic wave absorption • Impacts of evolution from core-shell to yolk-shell and hollow structure revealed • Enhanced absorption with RL of − 45.25 dB and EAB of 6.80 GHz at 1.4 mm achieved • Insights on the absorption tuned via compositional and microstructural design [Display omitted] In the design of advanced electromagnetic wave absorbing materials, composition and microstructure are critical to affect interactions between the incident waves with the absorbers. Here hierarchical SiO 2 @MoSe 2 @FeNi 3 has been developed and impacts of evolution from core-shell, yolk-shell to hollow structures on the absorption performance has been investigated. Combination of the magnetic FeNi 3 and the dielectric MoSe 2 and SiO 2 gives rise to synergistic and effective dissipation of the incident waves, whereas the impedance can be tuned by the size of the void during the microstructural evolution. Among the designed hierarchical SiO 2 @MoSe 2 @FeNi 3 , the yolk-shell composite exhibits enhanced absorption with a minimum reflection loss of − 45.25 dB over a wide effective absorption bandwidth of 6.80 GHz at a thickness of 1.4 mm due to optimal attenuation and impedance matching. [ABSTRACT FROM AUTHOR]

The FeNi 3 , MoSe 2 and MoSe 2 @FeNi 3 hollow nano-spheres synthesized by wet chemical method are used for the first time to improve the hydrogen storage properties of the MgH 2. The results show that they all possess excellent catalytic activity in the hydrogen desorption/sorption reactions of MgH 2. Because of the synergistic catalytic effect of MoSe 2 and FeNi 3 , the MoSe 2 @FeNi 3 has the most outstanding catalytic effect. In detail, the onset dehydrogenation temperature of MgH 2 is reduced from 310 °C to 194 °C, and its maximum dehydrogenation rate is increased by 19.8 times by the introduction of 10 wt% MoSe 2 @FeNi 3. Furthermore, the 10 wt% MoSe 2 @FeNi 3 -doped MgH 2 sample, 5.8 wt% H 2 can be absorbed in 0.5 min at 150 °C. However, the un-doped MgH 2 sample hardly absorbs hydrogen under the same conditions. The onset hydrogen absorption temperature of the composite is only 73 °C. More importantly, it has an excellent cycling stability. These improvements are because the in situ formed MgSe, Mo, Mg 2 Ni and Fe can serve as active species, and they as well as their homogeneous distribution on MgH 2 matrix can remain stable during dehydrogenation/hydrogenation. In addition, the presence of Mg 2 Ni can convert MgH 2 to an easier pathway of hydrogen absorption/desorption. These help to facilitate the hydrogen storage performance of MgH 2. • The MoSe 2 @FeNi 3 hollow nano-spheres can improve hydrogen storage properties of MgH 2. • The onset dehydriding temperature of the MgH 2 −10 wt% MoSe 2 @FeNi 3 is only 194 °C. • Dehydrogenated the composite can absorb 5.8 wt% of H 2 in 30 s at 150 °C and 5 MPa H 2. • Hydrogen storage capacity and kinetics of the composite can stay stable in 10 cycles. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries have been regarded as one of next promising alternatives for large scale energy storage originated from its resource abundance, low cost and environmental benignity. Sodium vanadium phosphates (Na 3 V 2 (PO 4) 3) owing to its robust structure, three-dimensional diffusion channels, and satisfactory energy density have been extensively studied. Herein, Na 3 V 2 (PO 4) 3 samples have been prepared by solid state method and post heat treatment employing two kinds of sodium source (Na 2 CO 3 and NaOH). Furthermore, the related solid-state reaction mechanism and corresponding electrochemical properties have been investigated in detail. It turned out that sodium source has important effect on the crystal structure and morphology, which would influence the (de)insertion reaction of sodium-ion during cycling process. Na 3 V 2 (PO 4) 3 synthesized at 750 °C with Na 2 CO 3 shows better electrochemical performance. And the original capacity is 114.8 mA h g−1 at 0.1C with following capacities of 104.6, 95.2 and 71.6 mA h g−1 at 5, 10 and 20 C delivered, respectively. Moreover, a reversible capacity of 92.5 mA h g−1 at 5 C after 300 cycles could be achieved realizing a high capacity retention of 93.5%. The results indicate that it is vital to select the suitable sodium source to prepare Na 3 V 2 (PO 4) 3 with favorable performance. • Na 3 V 2 (PO 4) 3 samples were prepared with different sodium sources of NaOH and Na 2 CO 3. • The NVP sample with Na 2 CO 3 shows smaller particles and more stable crystal structure. • The synthesis processes were investigated in detail. [ABSTRACT FROM AUTHOR]