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Journal of Alloys and Compounds
Elsevier Science S.A.
Journal of Alloys and Compounds

Elsevier Science S.A.

0925-8388

Journal of Alloys and Compounds/Journal Journal of Alloys and CompoundsSCIISTPEI
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    (163127)Evolution of core-shell structure induced by Yttrium in Nd-LaCe-Fe-B multi-main-phase magnets

    Sining FanZhixiang WangZhehuan Jin
    7页
    查看更多>>摘要：The effects of Y and LaCe substitution in Nd-Fe-B multi-main-phase (MMP) magnets were investigated by co-mixing with the binary or ternary components. The microstructure and magnetic properties showed some differences after Y and LaCe-substitution. The coercivity was increased for the LaCe-substituted MMP magnets with two-types shell structures due to the stronger magnetic isolation between adjacent grains. Y-substituted MMP magnets with one-type shell structure exhibited a relatively lower coercivity due to the deterioration of anisotropy owing to the La/Ce/Y enrichment in the core-shell structure. The La element preferred to migrate to the grain boundary regions in the LaCe-substituted MMP magnets, while it was trapped in the 2:14:1 shell by the inducement of Y in the Y-substituted MMP magnets. This work provides new insights into the fabrication of La/Ce/Y magnets with high performance.
      原文链接:
    • NSTL
    • Elsevier

    (162912)Effects of Fe addition on the microstructures and mechanical properties of as-extruded Zn-0.2Mg alloys

    Dongfang LouMingda ZhangJinze Lv
    10页
    查看更多>>摘要：Zn-0.2Mg-(0, 0.05, 0.2, 0.4 wt%)Fe alloy rods were produced by indirectly extruding the as-cast ingots at 200 °C. The addition of minor Fe significantly improved the ductility of as extruded Zn-0.2Mg alloy without scarifying the strength. As 0.05 wt% Fe was added, the yield strength, ultimate tensile strength and elongation were increased from 216 MPa, 228 MPa and 1.85% for Zn-0.2Mg alloy to 240 MPa, 258 MPa and 42% for Zn-0.2Mg-0.05Fe. Texture variation from basal texture to non-basal texture alongside the grain refinement contributed the great improvement of ductility and slight increase of strength, respectively. As Fe content increased from 0.05 wt% to 0.4 wt%, the volume fraction and size of the second phases changed, leading to the reduction in elongation by 50% yet maintaining the yield strength and ultimate tensile strength.
      原文链接:
    • NSTL
    • Elsevier

    (162966)Synthesis and investigation of structural, morphological, and magnetic properties of the manganese doped cobalt-zinc spinel ferrite

    Hamnesh MahajanSachin Kumar GodaraA.K. Srivastava
    10页
    查看更多>>摘要：The current work involves the synthesis of Mn_xCo_(0.5-x)Zn_(0.5)Fe_2O_4 (x = 0.0, 0.1, 0.2, 0.3, and 0.4) by adopting sol-gel auto combustion technique. For all the samples, the single-phase spinel structure with cubic symmetry was assured by the XRD studies. The crystallite size lies in the nanoscale range of 35.4-43.6 nm as estimated by utilizing Debye-Scherrer formula. FTIR spectroscopy affirms the formation of spinel structure due to the appearance of characteristic vibrational bands near 400 and 600 cm"1 which corresponds to the octahedral and tetrahedral sites respectively. FESEM micrographs reveal the presence of non-uniform grain growth which was agglomerated, inhomogenous in size and shape, and having porous morphology. VSM study exhibits soft ferromagnetic nature due to the low coercivity value. There is a decrement in the saturation magnetization with increasing Mn~(2+) concentration which is due to the decrease in the crystallite size and non-magnetic nature of the Mn~(2+).
      原文链接:
    • NSTL
    • Elsevier

    (163117)Heterovalent substituted BaFe_(12-x)Sn_xO_(19) (0.1 ≤ x ≤1.2) M-type hexaferrite: Chemical composition, phase separation, magnetic properties and electrodynamics features

    M.A.DarwishV.A. TurchenkoA.T. Morchenko
    10页
    查看更多>>摘要：Hexaferrites are usually used in devices for frequencies of 8-75 GHz. In this work, it is shown that Sn-substituted hexaferrite can be used for electromagnetic shielding and at lower frequencies (for example, in the L-band and S-band) as absorbing materials. The paper defines a solid-state reaction technique for preparing BaFe_(12-x)Sn_xO_(19) (0.1 ≤ x ≤1.2). The samples are characterized by XRD, SEM, VSM, and VNA. The study shows that increasing the Sn-substitution leads to weakening the interaction between the magnetic sublattices. So, in general, the saturation magnetization (M_s) decreases. Low saturation magnetization at high coercivity values gives a high anisotropy field, which provides significant absorption and matching impedance. The sample with substitution of x = 1.2 is the most absorbing sample (more than 99.99% of the incident energy absorbed for 10 mm thickness). The investigated samples have the potential to be useful absorption materials for shielding production (materials that absorb electromagnetic radiation)
      原文链接:
    • NSTL
    • Elsevier

    (162801)Preparation and photoelectric properties of Bi doped ZnO nanoarrays

    Jinsong SunJinxing CaoXiaohong Jiang
    8页
    查看更多>>摘要：ZnO has a large band gap, which affects its photoelectric catalytic performance to a certain extent. In this paper, Bi-doped ZnO nanoarray was successfully prepared by electrochemical deposition to improve the photoelectrochemical performance of ZnO as a photoanode. XRD results show the prepared Bi-doped ZnO is a typical hexagonal wurtzite crystal, and the SEM results also proved this point. The prepared Bi-doped ZnO presents a neat nano-array, and the doping of Bi also reduces the diameter of the nanorods from the original 500-350 nm. The results of XPS show that Bi is successfully doped into the ZnO nanoarrays, and it exists in the form of Bi_2O_3. Subsequently, the prepared Bi-doped ZnO was analyzed by fluorescence spectroscopy and photoelectrochemical properties, and it was found that when the doping concentration was 5%, the fluorescence intensity was the lowest, and at this time the carrier recombination rate corresponding was the lowest, the photoelectric catalytic effect was the best.
      原文链接:
    • NSTL
    • Elsevier

    (162881)Metal hydride - Graphene composites for hydrogen based energy storage

    Boris P. TarasovArtem A. ArbuzovAlexey A. Volodin
    9页
    查看更多>>摘要：The paper presents a review of the authors' studies of advanced functional composites of graphene based materials with metals, alloys, intermetallic compounds and their hydrides, and on the creation on their basis of hydrogen-storage materials for a compact and safe hydrogen storage, electrode materials for nickel-metal hydride batteries, highly efficient catalysts for the hydrogenation of metals and organic compounds as well as their integration into the hydrogen energy systems for the backup electric power and for the H-based energy storage.
      原文链接:
    • NSTL
    • Elsevier

    (162794)Modulation of luminescence thermometry in Nd~(3+)-Yb~(3+) co-activated phosphors via engineering host matrix

    Fengkai ShangChunhai HuWei Xu
    10页
    查看更多>>摘要：Luminescence thermometry based on the rare earth (RE) doped materials has displayed promising applications in various fields due to its fast response and high spatial resolution. However, the achievement of sensitive and accurate temperature sensing over a wide temperature scope is still a great challenge for this thermal sensing technology. Herein, excited by 980 nm laser, the inverse thermal responses of the near-infrared emissions in Nd~(3+)-Yb~(3+) codoped phosphors, which was attributed to the phonon-assisted energy transfer between RE ions, were employed for ratiometric thermometry within the temperature range of 303-773 K. The modification of thermometric capability for the NIR luminescence was proposed through engineering the aluminate host matrix with SiO_2. The influence of SiO_2 on the luminescence behaviors of Nd~(3+) and Yb~(3+) was systematically investigated through the X-ray diffraction patterns, Fourier-transform infrared spectra, Judd-Ofelt theory calculation, as well as luminescence decay profiles. The results demonstrated that the luminescence and the subsequent thermal sensing properties of Nd~(3+)-Yb~(3+) ion pair were strongly dependent on the host. As the host structure varied from aluminate to aluminosilicate, the spontaneous radiative transition and the energy transfer for RE ions were clearly improved, whereas the multiphonon nonradiative relaxations were weakened. The Nd~(3+)-Yb~(3+) codoped aluminosilicate phosphors synthesised by adding 100 mol% SiO_2 exhibited much high sensitivity (0.7-4.6% K~(-1)) at temperatures ranging from 303 to 773 K, accompanied with a measurement uncertainty of about 0.1 K. This work provides an effective guidance for developing high-performance luminescence-based ratiometric thermometers.
      原文链接:
    • NSTL
    • Elsevier

    (163102)Achieving high strength and superior ductility in Al-Si alloy by cold rolling and friction stir processing

    Mehdi SoleymanpourHamed Jamshidi AvalRoohollah Jamaati
    15页
    查看更多>>摘要：In the current work, the influence of heat treatment, rolling, and friction stir processing (FSP) on the microstructure, hardness, tensile behavior, and fracture mechanism of hypoeutectic Al-Si alloy were investigated. The FSP led to a reduction in the aspect ratio and increased the size and sphericity of particles. Also, fine silicon and Fe-rich particles were uniformly distributed in the matrix. With increasing the rotational speed, the size and aspect ratio of particles was decreased, and their sphericity was increased. The best morphology of Si particles (size of 2.23 urn, aspect ratio of 1.91, and sphericity of 0.682) had been obtained at the rotational speed of 800 rpm. The microhardness profiles of the FSPed samples were roughly homogeneous. After the cold rolling, the yield strength (YS), ultimate tensile strength (UTS), and energy absorption (EA) were enhanced to 288.7 MPa, 296.0 MPa, and 18.5 J/cm~3, however, the total elongation (TE) was reduced to 6%. Interestingly, the YS, UTS, TE, and EA of all FSPed samples were much higher than that of the initial material. The 800-120 sample had the best tensile properties with YS, UTS, TE, and EA of 116.7 MPa, 235 MPa, 27.2%, and 57.9 J/cm~3, representing 162%, 43%, 263%, and 395% improvement, respectively. The results of the fractography exhibited that the preferential cracks propagated perpendicularly to the loading direction along the Al/Si and Al/Fe-rich interfaces in the initial and heat-treated samples. In contrast, the crack planes of the rolled and FSPed samples were oriented around 45° with respect to the loading direction. The fracture of the initial, heat-treated, and rolled samples was dominated by cleavage mode. In contrast, the FSPed samples revealed a full ductile fracture.
      原文链接:
    • NSTL
    • Elsevier

    (162807)Designing intimate porous Al_2O_3 decorated 2D CdO nano-heterojunction as enhanced white light driven photocatalyst and antibacterial agent

    B. JananiAsad SyedLija L. Raju
    10页
    查看更多>>摘要：The mesoporous network of γ-Al_2O_3 ceramic support was coupled with the two dimensional (2D) hexagonal CdO nanoplates by ultrasonic assisted method. The fabricated photocatalyst was analyzed for its structural, morphological and optoelectrical properties by employing X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), photoluminescence, electron spin resonance (ESR) analysis and electrochemical impedance spectroscopy (EIS). The X-ray powder diffraction (XRD) result supports the good crystallinity of the fabricated nanohybrid with co-existence of pure phases of γ-Al_2O_3 and CdO nanoparticles (NPs). The nanohybrid was tailored to narrow down the bandgap to visible-light region. The bandgap energy obtained by UV-visible diffuse reflectance spectroscopy (DRS) for CdO/Al_2O_3 nano-composite (NCs) was 2.95 eV. The Brunauer-Emmett-Teller (BET) surface area analysis shows porosity of material with high surface area. During photocatalysis, e" from CdO migrates to defect levels of A1_2O_3 that facilitated charge separation. The kinetic rate of degradation of methylene blue (MB) by NCs was 3.5 and 14 times higher than CdO and A1_2O_3 respectively. The performance was optimized and it showed good reusability. In addition, the multiple applications of the CdO/Al_2O_3 were evaluated by testing the bactericidal activity. The nanohybrid posed high growth inhibition activity towards both gram positive and negative bacterial strains. The maximum colour removal (97.3%) and high mineralization (87%) was verified by UV-visible and total organic carbon (TOC) measurements. This promotes the nanohybrid to act as a better candidate for environmental remediation and disinfectant applications.
      原文链接:
    • NSTL
    • Elsevier

    (162898)Contribution to Al-Pd-Co system: Structural studies of epsilon phase and proposal of partial isothermal section at 1035 °C

    Libor DuriskaPeter SvecIvona Cernickova
    12页
    查看更多>>摘要：The aim of this work was to propose the experimental partial isothermal section of the Al-Pd-Co phase diagram at 1035 °C and to study the structure of quasicrystalline approximant ε_n. Scanning electron microscopy including energy dispersive X-ray spectroscopy, X-ray diffraction and scanning transmission electron microscopy were used in the investigation. Calculation of atomic structures was performed using Monte Carlo simulation minimising Empirical Oscillating Pair Potentials energy. Besides the proposed partial isothermal section at 1035 °C, homogeneity ranges of phases ε_n, U, F, V,δ, and W were schematically projected. Various modifications of ε_n were observed and/or identified in the investigated alloys. The structures of ε_(22) and ε_(34) were experimentally observed in the Al-Pd-Co system for the first time. Furthermore, their atomic structure models were created. Last but not least, it was experimentally documented that the regular arrangement of tiles in ε_n structures can be interrupted by structural defects. The obtained results form a comprehensive picture of the individual structural modifications of the ε_n phase.
      原文链接:
    • NSTL
    • Elsevier