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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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    (162865)An experimental and theoretical investigation on structure-property correlation of Cu_2Mn_1Al_(1-x)Ga_x full-Heusler alloy

    Shashank Shekhar MishraAnurag BajpaiThakur Prasad Yadav
    17页
    查看更多>>摘要：The present study reports the evolution of microstructure and magnetic properties of Cu_2MnAl_(1-x)Gax Heusler alloys. The L2_1 phase, which remained stable up to a Ga substitution of x = 0.3, transformed into mixed phases, i.e., hexagonal close packed (HCP) and complex cubic structure (CCS) on further addition of Ga. The non-monotonic increase in the lattice constant indicates that some amount of Ga retains its monovalent state. The magnetic phase showed a transition from ferromagnetic to paramagnetic state with increasing Ga concentration. The re-entrant temperature (T_R) decreased from 8.2 K to 5.2 K as Ga content increased from 5 at% to 10 at%. The strength of magnetic exchange-coupling also reduced with an increase in Ga content. Gaussian process regression (GPR) was used to estimate the lattice parameter using the ionic radii and Pauling electronegativity of the constituents. The modeling approach showed high accuracy and stability, providing new insights into future alloy development.
      原文链接:
    • NSTL
    • Elsevier

    (162764)Effects of Sc alloying on the evolution of solidification microstructure and formation of W phase in as-cast 2519 aluminum alloys

    Jin QinMingyang MaPan Tan
    10页
    查看更多>>摘要：In this study, the effect of Sc content on the phase transformation of the 2519 alloy during solidification is investigated through microstructure characterization and thermodynamic calculations. The results show that the grain size of the 0.3-0.4Sc alloy is reduced by 70% (approximately 28.9 um) to achieve maximum refinement in the as-cast 2519(Sc) Al alloy. The phase diagram calculation shows that the sequence of intermetallic formation during the solidification of 2519(Sc) Al alloy is as follows: Al_3Sc, W phase, θ. The primary Al_3Sc particles appear at the center of the a-Al grains and evidently acted as heterogeneous nucleating agents. Transmission electron microscopy shows that the nano-sized bean-like Al_3Sc phase precipitated from the saturated solid solution. Moreover, the phase transition analysis of the 0.3-0.4SC alloy during solidification shows that the formation of the W phase underwent two different types of reactions: the peritectic-eutectic reaction (L + Al_3Sc → aAl + W) and eutectic reaction (L → aAl + W, L→ aAl + θ + W). The W phase formation mechanism of these two reactions is revealed through experiments. Simultaneously, W phases with different morphologies are observed in the 0.3-0.4Sc alloy, i.e., the W phase of the spherical-shell structure is formed by the peritectic-eutectic reaction, and the long strip W phase (~6 um in size) is precipitated by the eutectic reaction.
      原文链接:
    • NSTL
    • Elsevier

    (163092)Correlation between magnetic and crystal structural sublattices in palladium-doped FeRh alloys: Analysis of the metamagnetic phase transition driving forces

    Aleksei S. KomlevDmitriy Y. KarpenkovRadel R. Gimaev
    11页
    查看更多>>摘要：FeRh alloys doped with the third element exhibit a change in the lattice and magnetic subsystems, which are manifested in antiferromagnetic- ferromagnetic (AFM-FM) first-order phase transition temperature, the shrinkage of the temperate hysteresis under transition, and the reduction of the saturation magnetization. All aforementioned parameters are crucial for practical applications. To control them it is quite important to determine the driving forces of the metamagnetic transition and its origins. In this manuscript ab initio calculations and experimental studies results are presented, which demonstrate the correlation between the structural and magnetic properties of the Fe_(50)Rh_(50-x)Pd_x alloys. The qualitative analysis of the metamagnetic phase transition driving forces in palladium-doped FeRh alloys was performed to determine their contribution to the evolution of magnetic and lattice subsystems. In addition, the impact of the impurities phases together with its magnetic behavior on the AFM-FM phase transition was considered.
      原文链接:
    • NSTL
    • Elsevier

    (162891)Hydrothermal growth of Sb_2S_3 thin films on molybdenum for solar cell applications: Effect of post-deposition annealing

    Pravin S. PawarRaju NandiKrishnaRao Eswar Neerugatti
    10页
    查看更多>>摘要：The binary chalcogenide material antimony sulfide (Sb_2S_3) has attracted significant attention as a potential absorber material for photovoltaics (PVs) owing to its suitable bandgap of -1.7 eV and other unique properties. However, only a few substrate-configured Sb_2S_3 thin-film solar cells (TFSCs) have been reported, and they demonstrated an extremely low power conversion efficiency (PCE, η < 2.5%) owing to the unfavorable (hk0) orientation of Sb_2S_3. In most studies, Sb_2S_3 absorber layers were grown through physical vapor deposition or high-vacuum methods. By contrast, we used a facile hydrothermal approach to deposit Sb_2S_3 thin films on molybdenum and investigated the effect of post-deposition annealing on the structure, orientation, and morphology of Sb_2S_3 thin films. Annealing at temperatures ranging from 0° to 350°C transformed the Sb_2S_3 thin films from nearly amorphous to polycrystalline with large, horizontally aligned plate-like grains. All the annealed Sb_2S_3 thin films were confirmed to have a preferred orientation along the (hkO) crystal direction. The fabricated substrate-configured TFSCs with SLG/Mo/Sb_2S_3/CdS/i-ZnO/Al-doped ZnO/Al configuration exhibited the highest PCE of -1.0%. Further, over 95% of this initial efficiency was maintained after 90 days. We also addressed the underlying reasons for the low efficiency of Sb_2S_3 TFSCs to provide a pathway for improving the device performance in the future.
      原文链接:
    • NSTL
    • Elsevier

    (162811)Distortion control of (l-x)Ba(Hf,Ti)O_3-x(Ba,Ca)TiO_3 piezoelectric ceramics to improved piezoelectric properties and related Curie temperature

    Jin Su BaekJung-Hyuk Koh
    6页
    查看更多>>摘要：In this paper, we have studied the correlation between the Curie temperature and tolerance factor of the (1-x)BHT-xBCT system. In a perovskite system, the distortion between the lattice parameters, a and c, can be used to investigate the tolerance factor. By changing the (Ba,Ca)TiO_3 ratio in the (l-x)BHT-xBCT system, the distortion of the lattice parameter can be varied. The tolerance factor is also related to the distortion values of perovskite systems. Therefore, the Curie temperature of (l-x)BHT-xBCT ceramics can be controlled by the tolerance factor. To confirm this assumption, we fabricated and analyzed (1 -x)BHT-xBCT ceramics for x = 0.3, 0.4, 0.5, 0.6, and 0.7, sintered at the various temperature range from 1400° to 1600 °C. We confirmed that the highest piezoelectric property, d_(33) of 540 pC/N was observed in the polymorphic phase transition (PPT) region when x = 0.5, for all sintering temperature conditions.
      原文链接:
    • NSTL
    • Elsevier

    (162778)Ce-doped ZIF-67 derived Co_3O_4 nanoparticles supported by carbon nanofibers: A synergistic strategy towards bifunctional oxygen electrocatalysis and Zn-Air batteries

    Xingwei SunTong XuWeiyan Sun
    9页
    查看更多>>摘要：Enhancing the activity of Co-based electrocatalysts can be generally achieved by increasing the active center conductivity even fabricating hybrid materials for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) process. Herein, we developed a bifunctional oxygen electrocatalyst for Zn-air batteries (ZABs). The Ce-doped Co_3O_4 nanoparticles embedded on carbon nanofibers complex catalyst (Ce@Co_3O_4/ CNFs) was synthesized via the incorporation of the electrospinning technology and in-situ growth process. The Ce@Co_3O_4/CNFs exhibited the comparable performance to Pt/C and RuO_2 in the alkaline environment with a half-wave potential of 0.810 V and overpotential of 380 mV(@ 10 mA cm~(-2)) for the ORR and OER, respectively. Moreover, an all-solid-state rechargeable ZABs with Ce@Co_3O_4/CNFs cathode was also assembled, which shows a relatively narrow discharge-charge voltage gap and a good cycle performance. These results provide a novel approach in developing Co-based dual functional electrocatalysts to enable the energy applications.
      原文链接:
    • NSTL
    • Elsevier

    (162987)Synergetic enhancing cycling stability of Li-S battery by hollow SrTiO_3 microspheres wrapped by reduced graphene oxide

    Zehua LeiHui LiuXuanmeng He
    10页
    查看更多>>摘要：LiPSs shuttle effect and cycling decay are still considered the main bottlenecks towards the practical application of Li-S batteries as commercial batteries. In the paper, we designed hollow SrTiO_3 microspheres wrapped by reduced graphene oxide (SrTiO_3@rGO) as efficient sulfur host materials with the aim of suppressing LiPSs shuttle and improving cycling stability of Li-S batteries. The hollow SrTiO_3 microspheres wrapped by rGO, with appropriate binding energy to LiPSs, provide balancing surface adsorption and diffusion of LiPSs on nonconductive SrTiO_3 and then promote its conversion on the interface, thus inhibiting the shuttle effect and greatly minimizing the active material irreversible loss in charge/discharge process. Meanwhile, the conductive rGO tightly wrapped on the surface of SrTiO_3 offers an interconnected conductive network to support the fast electron/ion transfer. Profit from these merits, the SrTiO_3 @rGO as sulfur host manifested superior cycling stability with a meager capacity decay rate of 0.0398% per cycle after 500 cycles at 0.2 C and an ultralow decay rate of 0.024% per cycle after 600 cycles at 1 C The superior cycling stability suggested the hollow SrTiO_3 @rGO was a potential candidate for the cathode of high-performance Li-S battery.
      原文链接:
    • NSTL
    • Elsevier

    (162960)On simultaneous enhancement in local yield strength and plasticity of short-term annealed bulk metallic glasses

    Priyanka SainiR. Lakshmi Narayan
    7页
    查看更多>>摘要：The variations in local yield strength and plasticity of a Zr-based bulk metallic glass at different Active temperatures (T_f are studied. To probe the size and distribution of microscopic carriers of plasticity, spherical-tip nanoindentation and microindentation are employed. With nanoindentation, events signifying the departure from Hertzian elastic contact, which manifest as pop-ins in the load-displacement response and correspond to incipient plasticity, are recorded and analyzed. Results indicate that with increasing T_f, the incipient plastic event and the number of subsequent pop-ins increases. Using statistical analysis of the scatter in strength, the activation parameters for shear transformation zones (STZs) in all specimens are determined. By considering the linear accumulation of STZs to form a shear band, the increase in shear yield strength along with plasticity, with increasing T_f, is explained.
      原文链接:
    • NSTL
    • Elsevier

    (162906)Magnetic and dielectric properties of NiCuZn ferrite with optimized Cu content and sintered by a two-step process

    Xinran JiTengqian ChenChang Shen
    8页
    查看更多>>摘要：Nickel-copper-zinc (NiCuZn) ferrites with high permeability and low magnetic loss have high application potential in high-frequency electronics. In this work, NiCuZn ferrite samples with different Cu contents were prepared by a two-step sintering method. First, the optimal temperatures of the two-step sintering method (1025/925 °C) were confirmed, thereafter the influence of the Cu content on the crystal structure, microstructure, magnetic and dielectric properties of NiCuZn ferrite were studied in detail. Structural characterization showed that an increase in Cu content promoted grain growth and resulted in NiCuZn ferrites with a denser microstructure and decreased porosity. However, a second phase of CuO formed once the content of Cu (x value) reached 0.16. The magnetic hysteresis loops revealed that the saturation magnetization increased as x increased and the highest value of 57.3 emu/g was obtained at x = 0.14. The dielectric property measurement showed that increasing the Cu content could improve the dielectric constant and reduce the dielectric loss. The permeability measurements showed an increase in permeability with Cu content from x = 0.10 to x = 0.14 and a decrease when x = 0.16. Consequently, a NiCuZn ferrite with an appropriate microstructure and with high permeability (μ'=855), low magnetic loss (tanδ_μ = 0.02), and high saturation magnetization (57.3 emu/g) could be obtained at a Cu content of x = 0.14 and sintering temperatures of 1025/925 °C in the two-step sintering method. This NiCuZn ferrite provides new guidance for developing RF frequency multilayer inductors.
      原文链接:
    • NSTL
    • Elsevier

    (162761)Terahertz-infrared dielectric properties of lead-aluminum double-cation substituted single-crystalline barium hexaferrite

    Asmaa AhmedAnatoly S. ProkhorovVladimir Anzin
    14页
    查看更多>>摘要：Hexaferrite materials are highly demanded to develop and manufacture electronic devices operating at radio- and microwave frequencies. In the light of the prospects for their use in the forthcoming terahertz electronics, here, we present our results on the terahertz and infrared dielectric response of a typical representative of hexaferrites family, lead-substituted M-type barium hexaferrite doped with aluminum, Ba_(0.2)Pb_(0.8)Al_xFe_(12-x)O_(19), x(Al) = 0.0, 3.0, and 3.3. We studied uniquely large and high-quality single crystals of the compounds prepared by spontaneous crystallization growth technique. Our aim was to explore the effect of aluminum substitution on the dielectric response of the compounds. Systematic and detailed investigations of the dependences of terahertz-infrared (frequencies 8-8000 cm"1) spectra of complex dielectric permittivity on the temperature, 4-300 K, and on the chemical composition, x(Al) = 0.0,1.2,3.0, and 3.3, were performed for two principal polarizations of the electric field E-vector of the probing radiation relative to the crystallographic c-axis, namely E||c and E⊥c. Furthermore, infrared phonon resonances are recorded and discussed. In contrast to undoped BaFe_(12)O_(19), no softening of the lowest frequency A_(2u) phonon is observed, indicating suppression of a displacive phase transition in substituted compounds. A number of resonance absorption bands are discovered at terahertz frequencies and assigned to transitions between energy levels of the fine-structured ground state of Fe~(2+) (~5E) ions. The temperature and aluminum-doping dependences of the resonances are analyzed with an account taken of disorder introduced by aluminum. Basing on dielectric data and detailed X-ray experiments, we find that for all concentrations of Al~(3+) ions, x (Al) = 0.0,1.2,3.0, and 3.3, they mainly occupy the 2a and 12k octahedral site positions and that the degree of substitution of iron in tetrahedral positions is not substantial. Along with fundamental findings, the obtained data on broad-band dielectric properties of Ba_(0.2)Pb_(0.8)Al_xFe_(12-x)O_(19) crystals provides the information that can be used for development and manufacture of electronic devices with operating frequencies lying in the terahertz spectral band.
      原文链接:
    • NSTL
    • Elsevier