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Fe3Al powders with different order degrees were fabricated by a high-energy ball milling process and ordering transformation process. The order degree of the Fe3Al powders with plate structures can be tuned by the calcination temperature. It is found that the order degree of the obtained Fe3Al powders affects the magnetic properties. When the sample is calcined at 500 °C, the obtained Fe3Al contains the most DO3 superlattice structure with an order degree of 40.2%, thus exhibiting the best magnetic properties. Moreover, the best impedance matching ratio and attenuation constant are also achieved, leading to the best electromagnetic wave absorption performance. When the thickness is 1.35 mm, the effective absorption bandwidth with RL ≤ − 10 dB is as wide as 7.2 GHz. [ABSTRACT FROM AUTHOR]

B4C@CNT nanowires were synthesized on the carbon fiber fabric (CFs) surface to form CFs-B4C-CNT hybrid materials via thermal growth method for improving the microwave absorption performance. The microwave absorption property of the CFs-B4C-CNT hybrid materials were studied in the frequency range of 8.2–12.4 GHz. The results exhibited that B4C@CNT nanowires were decorated on CFs surface successfully. The minimum reflection loss (RLmin) value of 2 wt% CFs-B4C-CNT hybrid material was − 19.7 dB at 8.2 GHz with a layer thickness of 2.9 mm. And the maximum effective absorption bandwidth (RL < − 10 dB) was obtained over the frequency range of 8.4–12.1 GHz with a layer thickness of 2.5 mm. Furthermore, the microwave absorption mechanism of the CFs-B4C-CNT hybrid materials were discussed. This work demonstrated that CFs-B4C-CNT hybrid materials possessed high potential as microwave absorbers with good microwave absorption performance, which provided a new idea for the development of nano-hybrid materials to improve electromagnetic microwave absorption performance. [ABSTRACT FROM AUTHOR]

CoSe2 nanostructure was regarded as an excellent electrocatalyst for hydrogen evolution reaction by water splitting owing to its particular electronic configuration. Herein, Ni atoms doped in CoSe2 nanowire arrays was fabricated on carbon fiber paper substrate by two-step hydrothermal routes and subsequent heat treatment. Both common transient analysis, steady-state analysis, and TOF and EIS measurements confirmed that Ni doping effect could significantly enhance the HER performance of CoSe2 in 0.5 M H2SO4 electrolyte. Density functional theory calculation showed that Ni doping effect in CoSe2 lattice can decrease the electronic density of Se p-orbital around the Fermi level. The ΔGH* in Se site of Ni-doped CoSe2 was decreased to 0.196 eV from 0.356 eV (pure CoSe2) because the empty orbital of Se sites could strengthen the adsorption of H atoms. Finally, Ni doping effect provides an effective method for improved HER activity of CoSe2 electrocatalyst. [ABSTRACT FROM AUTHOR]

A simple method was reported to fabricate a three-dimensional (3D) porous carbon through freeze drying followed by organic calcination. When the porous carbon is used as a matrix, the obtained SnO2/C composite with SnO2 nanoparticles (less than 8 nm) chemically bonded on the carbon surface by Sn–O-C exhibits more excellent electrochemical performance than bare SnO2. The SnO2/C electrode delivers a high initial reversible capacity of 854 mAh g−1 at 200 mA g−1 and remains at 287 mAh g−1 even after 100 cycles. Furthermore, with increasing current rate, the SnO2/C still restores a high capacity of 394 mAh g−1 at a higher current density of 2000 mA g−1, indicating its better rate capability than SnO2 (82 mAh g−1). The superior Li+ storage performance of SnO2/C can be resulted from the designed structure of composite as well as the 3D porous carbon. On one hand, the 3D porous carbon confining SnO2 nanoparticles in their localized regions by chemical bonding can buffer the volume expansion and shrinkage. On the other hand, the rich channels of 3D porous carbon can bring more paths for charge transfer, thus resulting in superior rate and cycling performance of SnO2/C composite. [ABSTRACT FROM AUTHOR]

(YGd)OS:0.08Yb/0.02Er powders doped with different concentrations of Gd (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 and 1.0) were prepared by flux method. The effects of Gd doping amount on the phase composition, the crystal structure, the luminescent intensity, the emission color, phonon energy and forbidden bandwidth of YOS:Yb/Er were investigated by XRD, UPL, CIE, RAMAN and R%, respectively. (YGd)OS:Yb/Er powders doped with different concentrations of Gd were all pure oxysulfide phase. Upconversion luminescent intensity of (YGd)OS:Yb/Er was the maximum. Green and red emission intensity of YOS:Yb/Er was increased by three times with doping 10 mol% Gd ions. The emission color was basically yellow. Gd ions optimized the crystal structure of YOS, changed the crystal field of Er and Yb ions, and improved the upconversion luminescent properties. [ABSTRACT FROM AUTHOR]

This paper modified the preparation of SmBO by the conventional solid state method, by using LiCO as flux, to reduce the preparation temperature and improve particle quality. Characterization methods mainly used the X-ray diffraction analysis, scanning electron microscopy, light reflectivity and thermogravimetry-differential scanning calorimetry analysis. The results showed that: the usage of LiCO flux effectively reduced the calcination temperature of the solid state reaction to 600 °C, and it improved the particle properties of SmBO, making particle size more uniform and weakening agglomeration. The materials could absorb 1.06 and 1.54 μm near infrared light simultaneously so it could be used as a composite absorbent. Furthermore, the mechanism of LiCO flux was discussed. [ABSTRACT FROM AUTHOR]

Porous silicon nitride (SiN) ceramics were fabricated by compression molding and slip casting methods using petroleum coke as pore forming agent, and YO-AlO as sintering additives. Microstructure, mechanical properties and gas permeability of porous SiN ceramics were investigated. The mechanical properties and microstructure of porous SiN ceramics prepared by compression molding were better than those which were prepared by slip casting method, whereas slip casting method is suitable for the preparation of porous SiN ceramics with higher porosity and excellent gas permeability. [ABSTRACT FROM AUTHOR]

Green bodies of porous SiN ceramics were shaped by extrusion technique using different organic additives as binder during extrusion molding. Different porosity, microstructures and mechanical properties after the extrusion, drying, debinding and sintering stages were investigated. The solid slurry content of 70-75% and extrusion pressure of 0.5-1.0 MPa had played a decisive role in the smooth realization of extrusion molding. The porous SiN ceramics were obtained with excellent properties using 4% hydroxypropyl methyl cellulose (HPMC) as binder and polyethylene glycol (PEG) of molecular weight, 1000, as plasticizer with a density of 1.91 g cm, porosity of 41.70%, three-point bending strength of 166.53 ± 20 MPa, fracture toughness of 2.45 ± 0.2 MPa m and Weibull modulus (m) of 20.75. [ABSTRACT FROM AUTHOR]

Porous Si3N4 ceramics were successfully synthesized using cheaper talc and clay as sintering additives by pressureless sintering technology and the microstructure and mechanical properties of the ceramics were also investigated. The results indicated that the ceramics consisted of elongated β-Si3N4 and small Si2N2O grains. Fibrous β-Si3N4 grains developed in the porous microstructure, and the grain morphology and size were affected by different sintering conditions. Adding 20% talc and clay sintered at 1700°C for 2 h, the porous Si3N4 ceramics were obtained with excellent properties. The final mechanical properties of the Si3N4 ceramics were as follows: porosity, P0 = 45·39%; density, ρ = 1·663·g·cm-3; flexural strength, σb (average) = 131·59 MPa; Weibull modulus, m = 16·20. [ABSTRACT FROM AUTHOR]