Yu, WeiyangLuo, WenZhang, XiaoliWu, Yali...
6页查看更多>>摘要：Spin polarized van der Waals (vdW) heterostructures have attracted considerable interest owing to the spin splitting manipulation. In this paper, first-principles calculations are employed to explore the two-dimensional arsenene/CrI3 vdW heterostructure as a promising spin polarized material, as well as the spin polarization under strain and electronic field are investigated. The most stable stacking configuration and ferromagnetic (FM) property of the arsenene/CrI3 vdW heterostructure have been confirmed. The detailed calculations show that the Curie temperature (Tc) of the FM coupling CrI3 layer in the heterostructure can be enhanced up to 61 K, which is attributed to both superexchange interaction and proximity exchange effect. The electronic structures suggest that this heterostructure possess an intrinsic type-II band alignment and diluted magnetic semiconductor property. Interestingly, we found a transition from diluted magnetic semiconductor to half-metal and gradually to metal induced by the biaxial strains, and the extra electronic field can modulate the "maxican hat" of the valance band maximum (VBM) of arsenene. Our work provides not only application prospects of the arsenene/CrI3 vdW heterostructure nanodevices but also theoretical effective support for the research and development of the spin electronics and flexible electronics. (c) 2022 Elsevier B.V. All rights reserved.
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Elsevier
Gao, YanfenZhao, YixuanTan, CaiwangSong, Xiaoguo...
13页查看更多>>摘要：A porous FeCoNiCr high entropy alloy (HEA) coating was prepared on steel substrate via vacuum sintering. Wetting behavior of liquid Al-12Si alloy over coated and uncoated steel substrate was comparatively ana-lyzed. The results show that the liquid Al-12Si alloy droplets were quickly spread and infiltrated into the porous structures under the enhanced capillary force by the micro-channels in the porous coating. A complete wetting similar to 0 degrees contact angle (CA) was thus achieved; however, the CA was up to 41.2 degrees in the case of uncoated steel substrate. In the case of uncoated steel substrate, the interfacial microstructure consisted of theta-Al13Fe4, eta-Al5Fe2 and tau(1)-Al2Fe3Si3, while it changed to Cr-enriched FCC, AlFe-enriched BCC and AlNi-enriched B2 +Al-enriched BCC eutectic-like structure embedding in the HEA skeleton. The suppression of the formation of intermetallic compounds (IMCs) at the interface was mainly attributed to the sluggish diffusion and HEA effects of the porous coating. The altered interfacial metallurgical reactions and the enhanced capillary force were contributed to the improvement of wettability. This research provides a new method for improving the wettability and suppressing the interfacial IMCs in reactive metallic wetting systems. (c) 2022 Published by Elsevier B.V.
原文链接:- NSTL
- Elsevier
Corthay, ShaktiKutzhanov, Magzhan K.Matveev, Andrei T.Bondarev, Andrey, V...
11页查看更多>>摘要：Al/h-BN composites with high tensile and compressive strength at room and elevated temperatures, as well as enhanced ductility, were obtained by a combination of ball milling (BM) and spark plasma sintering (SPS) using Al and hexagonal BN nanopowders (0, 1, 2, 3, 4, 5, and 10 wt% of h-BN). The use of two types of nanopowders is intended to ensure uniform distribution of the reinforcing phase and improve Al-BN chemical interaction at the manufacturing stages by increasing the surface-to-volume ratio. Due to Al with h-BN interaction, the Al/h-BN composites were simultaneously strengthened by three types of nanoparticles: Al2O3, AlN(O) and h-BN, predominantly located along the Al grain boundaries. Compared to BM +SPS aluminum, the tensile strength of Al-2 wt%BN composite increased by 82% (25 degrees C), 64% (300 degrees C), and 65% (500 degrees C), and the compressive strength by 107-119% (25-500 degrees C) while maintaining high elongation to failure in tension (13.6%, 11.6% and 10.8%) and compression (12.6%, 13.1% and 8.1%) at 25 degrees C, 300 degrees C, and 500 degrees C, respectively. In terms of combination of tensile and compressive strength at room and elevated temperatures, the Al/h-BN materials are superior to many other Al-based composites. The high strength and relative elongation to fracture of the Al/h-BN composites can be explained by the formation of a heterogeneous microstructure consisting of pure Al grains surrounded by a metal-matrix composite material with fine metal grains and reinforcing ceramic nanoinclusions. The obtained results significantly expand the scope of Al/h-BN materials, since their strength at 500 degrees C is higher than that of pure Al at room temperature. (c) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Li, ShunQin, JianliangGao, TengjiaDu, Jingjing...
9页查看更多>>摘要：The design and fabrication of advanced carbon materials is highly important for potassium ion batteries. In this paper, Fe3C nanoparticles embedded in N-doped carbon nanotubes/porous carbon (Fe3C@N-CNPC) 3D materials were synthesized by pyrolysis of N-doped distilled grains in the presence of FeCl3/ZnCl2 activators. It was demonstrated that the FeCl3/ZnCl2 activators played an important role in the formation of Fe3C@ N-CNPC 3D materials. On the one hand, the activator endowed the carbonaceous materials with a high proportion of micropores and large surface area. On the other hand, Fe nanoparticles generated by decomposition of FeCl3 catalyzed the growth of intertwined carbon nanotubes on porous carbon, yielding Fe3C@N-CNPC 3D materials with abundant porous structure and a high degree of graphitization. The asprepared Fe3C@N-CNPC were used as anode materials for potassium ion batteries. Due to the synergistic effect of N-doping, superstructure, and large surface area, the Fe3C@N-CNPC based potassium ion batteries exhibited remarkable potassium storage capacity (273 mAh g-1 at 100 mA g-1) and excellent cycle stability (94% capacity retention at 100 mA g-1 after 570 cycles). This novel carbon material with low cost and ease preparation is of great significance for the application of potassium ion batteries. Meanwhile, our strategy also provides a reference idea for the resource utilization of the distilled grains waste. (c) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Yang, YuhangZhang, XianCheng, ZhuangWen, Zihui...
11页查看更多>>摘要：Silicon possesses high theoretical specific capacity but suffers from huge volume expansion and poor electrical conductivity during cycling, resulting in significantly reduced capacity and poor cycling stability. These issues could greatly be alleviated by the encapsulation of silicon nanoparticles in carbon materials. Therefore, a three-dimensional (3D) network Si@CTS precursor was prepared in this work through in-situ encapsulation of silicon nanoparticles in stable hydrogel formed by crosslinking chitosan with glutaraldehyde as a cross-linking agent. After freeze-drying followed by oxidation stabilization at 280 degrees C for 2 h under air and subsequent heat treatment at 800 degrees C for 2 h under Ar atmosphere, uniformly distributed 3D Si@C composites were obtained. The effects of added amounts of carbon nanotubes (CNTs) on the structures and electrochemical properties of the as-obtained composites were investigated. The results showed uniformly distributed silicon nanoparticles in the amorphous carbon layer owing to the freeze-drying and oxidation treatments conducive to maintaining the skeleton structure of the material. The amorphous carbon and appropriate CNTs effectively buffered the volume changes, as well as improved the ionic and electronic conductivity. Si@C/CNTs-10% showed better comprehensive electrochemical performances at CNTs added amount of about 10 wt%. The discharge specific capacities at 0.1 Amiddotg-1 after 150 cycles, as well as at 1.0 and 2.0 Amiddotg-1 after 1000 cycles were estimated to 943.1, 461.3, and 123.1 mAhmiddotg-1, respectively.(c) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Luo, WenhaoWu, CanfengLi, LiangjieJia, Tingting...
9页查看更多>>摘要：In this study, hexagonal boron nitride (h-BN) -polyetherimide (PEI) composites were prepared by a simple solution casting method, where the h-BN particles were aligned by an external magnetic field. Prior to the preparation of the composite samples, the h-BN platelets were firstly decorated by iron oxide nanoparticles (Fe3O4) to achieve the desired magnetic properties. Due to the alignment of h-BN particles, the composite exhibited greatly enhanced thermal conductivity along that direction. At a filler loading of 20 wt%, an enhancement of 166% was obtained, compared to that of the unaligned composite. Furthermore, the composite samples showed a low dielectric loss (~ 0.01) with the filling ratio below 20 wt% and a tensile modulus of up to 2.34 GPa. Bearing such thermal conductivity, electrical insulation properties, and mechanical properties, these composites with magnetically aligned h-BN particles show potentials for microelectronic packaging applications.(C) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Yang, Jin-MengWang, Ke-AnZhu, Hai-Bin
10页查看更多>>摘要：Rational design of advanced cobalt oxides/carbon nanocomposites toward electrocatalytic oxygen reduction has received increasing research attention largely due to the potential synergism between cobalt oxides and carbon support. An efficient CoO/Co-N-C hybrid electrocatalyst has been prepared by high-temperature pyrolysis of ZIF-8 (ZIF = Zeolitic Imidazolate Framework) involving cage-encapsulation of CoCl2 followed by KOH treatment. In the alkaline solution (0.1 M KOH), the optimal CoO/Co-N-C hybrid catalyst (namely C-Co (OH)(2)@ZIF-8-10%-100 0) delivers a half-wave potential (E-1/2) of 0.84 V (vs. RHE), and a high four-electron reduction selectivity. The control experiments reveal that the superb ORR activity with C-Co(OH)(2)@ZIF-8-10%-1000 is jointly contributed by strongly coupled CoO NPs and Co-Nx moieties. Compared to the Pt/C benchmark, C-Co(OH)(2)@ZIF-8-10%-100 0 exhibits comparable ORR performance but better methanol tolerance and electrochemical stability. Besides, the home-made zinc-air battery with C-Co(OH)(2)@ZIF-8-10%-1000 as the air-cathode catalyst displays an open-circuit voltage of 1.43 V and a maximal power density of 96 mW cm(-2). (c) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Huang, ZhenHe, XikouChen, KunWang, Xitao...
11页查看更多>>摘要：The solidification characteristics of C700R-1 alloy was investigated by DSC analysis, in-situ observation, quenching experiment and Thermo-Calc calculation. The segregation behavior during solidification was analyzed by Scanning Electron Microscope and Electron Probe Microanalysis. At the initial stage of solidification, the volume fraction of liquid experienced a steep decrease, accompanied by a rapid formation of dendrites. The residual liquid solidified slowly due to segregation at the final stage. Al, Ni, W and Co elements segregated in the dendrite stems, while Ti, Nb and Mo were enriched in the interdendritic, in which MC carbides also precipitated. At the end of solidification, the segregation of Mo and Cr is further aggravated, resulting in extremely low solidus and formation of eutectic region. The study on the solidification characteristics of C700R-1 alloy demonstrates that aggravation of segregation leads to deterioration of the solidification conditions.(c) 2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Sakaki, KoujiTerashita, NaoyoshiKim, HyunjeongTsunokake, Shigeru...
9页查看更多>>摘要：Hydrogenation properties of Mg2-xPrxNi4 (x = 1.0, 1.2 and 1.4) and their structural degradation (amorphization) upon hydrogenation have been investigated using in-situ X-ray diffraction. In Mg1.0Pr1.0Ni4, the crystalline phase was stable up to a temperature of 573 K under 3 MPa of hydrogen pressure and amorphization did not take place. Mg0.6Pr1.4Ni4 was directly transformed to an amorphous hydride, Mg0.6Pr1.4Ni4H~7.2, while Mg0.8Pr1.2Ni4 transformed to amorphous Mg0.8Pr1.2Ni4H~6 through the formation of Mg0.8Pr1.2Ni4H~4 having an orthorhombic structure. While reversible hydrogen absorption and desorption was observed in the first plateau region between Mg0.8Pr1.2Ni4 and Mg0.8Pr1.2Ni4H~4. First principles calculation indicate that the elastic modulus and bulk modulus decreased with increase of the Pr content and hydrogen content in Mg2-xPrxNi4 suggesting that decrease of bulk modulus induce amorphization upon hydrogen absorption. These results clearly indicate that the hydrogenation properties, the stability of crystalline hydride and amorphization behavior strongly depend on the chemical composition of Mg2-xPrxNi4 and their hydrogen content. (C)& nbsp;2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
Ye, GuoquanFang, LizhiZhou, XiongXia, Haiping...
9页查看更多>>摘要：Serial fluoro-oxide glass ceramics (GCs) containing 0.6 mol% Dy3+ and various Sm3+ from 0 mol% to 1.5 mol% co-doped novel KGd2F7 nanocrystals were firstly fabricated through high temperature melt-quenching method. Then the microscopic structure of the GCs was revealed by transmission electron microscopy (TEM). And the rare-earth ions (RE3+) of Dy3+ and Sm3+ were successfully doped in monoclinic-phase KGd2F7 nanocrystals, which can be verified by energy-dispersive X-ray spectroscopy (EDX) mappings. The photoluminescence spectra of the GCs were probed systematically utilizing 365 nm excitation light. The yellow (573 nm), green (486 nm), and red (648 nm) multiple emissions were observed in the co-doped GCs, and the intensity of red became stronger because of the higher Sm3+ doping concentrations. This contribution of multiple emissions is due to the co-absorption of both Dy3+ and Sm3+ for 365 nm and the presence of energy transfer (ET). Moreover, the ET between Dy3+ and Sm3+ was confirmed from the variations of emission spectra and measured decay curves of emissions. Furthermore, the maximum energy transfer efficiency (ETE) from Dy3+ to Sm3+ can reach ~60.34% and the internal quantum yield (QY) is computed to be around 31.82% upon excitation of 365 nm. The chromaticity coordinates (CIE (Commission Internationale de L'Eclairage)- 1931) of the GCs can be tuned effectively through changing activator con-centrations. Ideal white light emission is at the CIE (0.3357, 0.3342), which was achieved for 0.6 mol% Dy3+/ 0.9 mol% Sm3+ doped GCs sample. The results indicated that Dy3+/Sm3+ co-doped GCs with both high thermal and chemical-physical stabilities have strong potential application in white light-emitting diodes and fluorescent display devices. (C)& nbsp;2022 Elsevier B.V. All rights reserved.
原文链接:- NSTL
- Elsevier
