查看更多>>摘要：? 2022 Elsevier B.V.Flexible spintronics has recently sparked an upsurge due to the growing demand for miniaturization, high-speed, integration and energy-saving in portable and wearable devices. However, the stress/strain during the substrate deformation process is inevitable for flexible spintronic devices and may be available to assist the switching of the magnetization, accordingly. Therefore, combined with the previously discovered high energy efficient sunlight controlled magnetization switching, we propose a bending-insensitive photovoltaic flexible spintronic device constructed by PET/Ta/Permalloy/(PC71BM: PTB7-Th)/Pt heterostructure. The bent device achieved a 281 Oe of maximal ferromagnetic resonance (FMR) field shift by photoelectrons in a reversible manner under the sunlight soaking at room temperature. And the magnetic change as a function of the external light radiation was precisely determined. These findings provide a feasible way to combine the flexible substrate and photoelectrons for energy-saving and precise manipulation of magnetism in bendable spintronic devices.
查看更多>>摘要：? 2022 Elsevier B.V.(111)-oriented NixFe3?xOy thin films with varying Ni content (0.7 ≤ x ≤ 1.7) have been grown on c-plane (0001) α-Al2O3 substrates by ion beam sputtering. Epitaxial NixFe3?xOy thin films with spinel structure are obtained for x ≤ 1. For nickel content exceeding the value of the stoichiometric phase, i.e. NiFe2O4, a transition from an ordered spinel to a disordered rock-salt phase is identified, being the dominant one when x = 1.7. This result is confirmed by X-ray diffraction, Rutherford backscattering spectroscopy in channeling configuration, Raman spectroscopy, X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). We also report the first Raman spectra in NixFe3?xOy with mainly rock-salt structure. The evolution of the electrical and optical properties of the (111) NixFe3?xOy films as Ni content increases, supports the structural change. The electrical resistivity increases up to 103 ohm·cm, the direct and indirect band gaps also increase and only one direct band gap, instead of the two characteristic of the spinel structure, is present in the NixFe3?xOy film with x = 1.7.
查看更多>>摘要：? 2022 Elsevier B.V.The effect of CaTiO3 addition on the sintering behavior, microstructure, and magnetic and dielectric properties of NiCuZn/CaTiO3 composite dual-performance materials was investigated. The crystal and microstructure were characterized by X-ray diffraction and scanning electron microscopy. The magnetic and dielectric properties were obtained by vibrating sample magnetometry and impedance analysis. The CaTiO3 ceramic could coexist with the NiCuZn ferrite. The atom substitution occurred in the composite materials, and the increment in CaTiO3 content led to a gradual decline in grain size of NiCuZn ferrite. The saturation magnetization and permeability decreased gradually as CaTiO3 content increased, while the coercivity increased gradually. Meanwhile, the cut-off frequency and dielectric constant of the composite materials incremented, and all samples presented optimized performance with the increased sintering temperature. The NiCuZn/CaTiO3 composite duel-performance materials exhibited excellent dielectric and magnetic properties. All in all, the addition of CaTiO3 weakened the magnetic properties of the dual-performance material, while its dielectric properties were enhanced. These results would be useful for further study on NiCuZn/CaTiO3 composite dual-performance materials.
查看更多>>摘要：? 2022 Elsevier B.V.Metal sulfides are considered as promising anodes for lithium-ion batteries (LIBs) because of their high capacity. Among all of these metal sulfides, Tin(II) sulfide (SnS), possessing a unique 2D structure and with high lithium storage capacity, attract more attention as a promising anode for LIBs. However, serious volume change, sluggish kinetics, and low electric conductivity during the charging/discharging process, lead to poor rate capability and fast capacity fading. Herein, a ZnS/SnS@C yolk-shell microspheres (ZSS@NC) is synthesized through a facile hydrothermal process coupled with a PPy coating and sulfidation-in-microsphere strategy. The built-in electric field generated from ZnS/SnS heterostructure benefits the rapid transport of Li-ion and enhances the electric conductivity. Meanwhile, the N-doped carbon further improves the electronic conductivity and provides a robust support architecture, which can mitigate the volume variation of ZnS/SnS during the lithiation/delithiation process. Therefore, the ZnS/SnS@NC delivers high capacity (775.5 mA h g?1 at 200 mA g?1 after 200 cycles), outstanding rate performance (395.8 mA h g?1 at 5 A g?1), and superior long-term cycling performance (571.2 mA h g?1 at 1 A g?1 after 1000 cycles).
查看更多>>摘要：? 2022 Elsevier B.V.The spheroidization behavior of γ′ phase and dynamic recrystallization (DRX) mechanisms of a novel HIPed powder metallurgy (P/M) superalloy deformed at high temperatures (1080?1170 ℃) and different strain rates (1–0.001 s?1) are investigated. The results show that the spheroidization behavior of γ' phase and DRX mechanisms are greatly influenced by deformation condition. The coarse γ′Ⅰ phase promotes the DRX process, while the fine spherical γ'Ⅲ phase results in the formation of sub-grain boundaries. Thus, the grains are refined. During hot deformation, some coarse γ′Ⅰ and γ′ⅠⅠ phases transform into the fine spherical γ'Ⅲ phases, while some initial γ'Ⅲ phases gradually diminish. Besides, the spheroidization rates of γ′Ⅰ, γ′Ⅱ and γ'Ⅲ phases increase with the increase of strain rate. The low DRX volume fraction and refined grains with the average size of 2.27 μm are obtained at 1110 ℃/1 s?1. It is attributed to the fact that the DRX nucleation is obviously enhanced and the pinning effects of spherical γ′Ⅲ phases on dislocations accelerate the formation of sub-grains. In addition, the discontinuous DRX is the main DRX mechanism of this novel P/M superalloy.
查看更多>>摘要：? 2022 Elsevier B.V.The diffusion behaviors and the mechanical properties of Zr-X (X[dbnd]Nb, Ta, Hf) systems have been systematically investigated at the annealing temperature range of 950–1200 °C. Based on the Sauer-Freise method and the Hall method, the interdiffusion coefficients of the Zr-rich alloys were evaluated, and the impurity diffusion coefficients on the Zr-rich side have been extracted by using the Darken equation. The presently obtained interdiffusion coefficients and impurity diffusion coefficients are all in good agreement with experimental data in the literature. According to the Arrhenius regression, the diffusion activation energies of the three systems have been calculated. It can be concluded that the diffusion activation energies of the Zr-Ta system are the largest value. Finally, the hardness and Young's modulus of the Zr-X have been obtained by using the nanoindentation test. The present results can help the materials design, research and development for the Zr-based alloys.
查看更多>>摘要：? 2022 Elsevier B.V.A new kind of porous 6061 aluminum alloy composite material was successfully fabricated using self-made high-strength silicon-containing ceramic hollow spheres as reinforcement. For comparison, another composite with commercial alumina hollow spheres was produced. All of these porous composite materials were produced by sintering at 650 ℃ for 2 h. Their microstructures display that the aluminum alloy reacts with the self-made ceramic hollow spheres, forming a thin transition layer containing MgO and Al2O3. Moreover, it was analyzed that the influence of the different classes of ceramic hollow spheres on the properties of porous composites, including the compressive strength, specific strength and energy absorption performance. The results indicate that the self-made silicon-containing ceramic hollow sphere can help to hinder the plastic deformation of the aluminum alloy metal matrix, which makes the sample display a short yield platform where the stress remains relatively stable. As a comparison, there is no yield platform where the stress remains relatively stable in the sample with commercial alumina hollow spheres under compression. Due to the formed transition layer, the sample with the self-made ceramic hollow sphere has a significantly higher compressive strength, specific strength and energy absorption performance. Compared with the porous magnesium alloy composite, the compressive behavior of porous composite is subject to that of the metal matrix to a great extent, and the content of Mg in the matrix determines the resultants and the level of the interface reaction. In addition, the compressive strength, specific strength, and energy absorption capacity of the porous aluminum alloy composite are all significantly higher than those of the porous magnesium alloy composite.
查看更多>>摘要：? 2022 Elsevier B.V.Using an arc heat source, the filling ratio of Ti6Al4V and Inconel 625 wires was controlled to manufacture a TiNi gradient material using wire arc additive manufacturing (WAAM). The effects of wire filling ratio on the microstructure of the deposition layer were studied through X-ray diffraction (XRD), scanning electron microscope (SEM), and differential scanning colorimetry (DSC). The mechanical performance was evaluated using compression, Vickers hardness, and surface wear testing. The results show that increasing the ratio of Inconel 625 filling wire can form Ti2Ni and TiNi strengthening phases in the deposition layer. The Ti2Ni and TiNi phases are evenly distributed over the region owing to the stirring of the molten pool by the arc, which improves the compression and surface wear performance of the WAAM parts. When the Inconel 625 wire filling ratio is 35%, the Vickers hardness reaches 600 HV and the compression strength increases to 2.15 GPa. However, excessive Ti2Ni phase will reduce toughness. As an Inconel 625 wire filling ratio lower than 35% can achieve a well-performing structure, five kinds of wire filling ratios were chosen to fabricate different gradient materials, and the microstructure, elemental distribution, phase composition, and mechanical properties were analyzed thoroughly.
查看更多>>摘要：? 2022 Elsevier B.V.One-dimensional (1D) nanostructures have attracted extensive attention in electrochemical hydrogen evolution reaction (HER) because of their specific electronic structures and morphology effect. Here, a photochemical approach was developed to prepare 1D wormlike heterostructured nanorods (HSNRs) for improving the electrocatalytic HER performance. The optimized electronic structure has been demonstrated by the radial and axial electron transfer channels for plasmon oscillation. The increased active sites have been confirmed by the increased electrochemically active surface area. The normalized Pt mass activity of Au5Pt1 HSNRs was 23.9 and 10.9 times of that of commercial 20 wt% Pt/C and Au/Pt NPs catalysts at - 0.05 V, respectively. The charge transfer resistance and Tafel slope of Au5Pt1 HSNRs were the smallest among different samples. The excellent catalytic performances of Au5Pt1 HSNRs catalyst can be attributed to the special electronic structure and morphology effect of Au/Pt HSNRs.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, the thermoelectric properties of TiS2-xmol%SnSe (x = 0, 0.5, 1 and 2) composites prepared with liquid-assisted shear exfoliation (LASE) process were investigated. Results show that the carrier mobility of composites can be improved owing to the enhanced texturing degree via LASE process, and the carrier concentration can be increased together with SnSe addition due to charge transfer. Therefore, high power factors optimally to ~16.4 μW cm?1 K?2 can be obtained, which is almost 67% and 40% higher than that of the pristine and the LASE TiS2, respectively. Unexpectedly, lattice thermal conductivity was increased probably due to the enhanced heterophase electrostatic force between TiS2 and SnSe phase induced by charge transfer. As a result of compromise, a modest ZT maximum of ~0.48 at 673 K was obtained for TiS2-1 mol%SnSe.
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