Rare Metals最新文献

Lithium–sulfur batteries (LSBs) have attracted widespread attention due to their high theoretical energy density. However, the dissolution of long-chain polysulfides into the electrolyte (the “shuttle effect”) leads to rapid capacity decay. Therefore, finding suitable materials to mitigate the shuttle effect of polysulfides is crucial for enhancing the electrochemical performance of lithium–sulfur batteries. In this study, LSBs’ separator is modified with Ni₃V₂O₈ nanoparticles@carboxylated carbon nanotubes (Ni₃V₂O₈@CNTs) composite. There are abundant oxygen vacancies in Ni₃V₂O₈@CNTs composite which plays a synergistic effect on shuttle effect. The Ni₃V₂O₈ can tightly anchor soluble polysulfides through oxygen vacancies, while the CNTs not only facilitate the transport of ions and electrons but also weaken the migration of polysulfides, limiting shuttle effect. As a result, the cycling stability of LSBs using Ni₃V₂O₈@CNTs-modified separator has been significantly improved (with a capacity decay rate of only 0.0334% after 1500 cycles at 4.0C). This study proposes a strategy to design modified separator for high-performance LSBs.

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The mutual coupling of structure and magnetism is crucial for Heusler alloys. In this paper, Ni₅₀Mn₃₄Sb_16−xGa_x (0 ≤ x ≤ 16) alloys were prepared by arc melting. Based on the test results of structure and magnetism, the magnetic-structural phase diagram of Ni₅₀Mn₃₄Sb_16−xGa_x (0 ≤ x ≤ 16) was drawn. The structure changes from cubic to monoclinic and finally to tetragonal as the x increases at room temperature. Its phase diagram shows a morphotropic phase boundary (MPB) starting from a tricritical triple point (around the Ni₅₀Mn₃₄Sb₅Ga₁₁ alloy) of a cubic paramagnetic phase, ferromagnetic monoclinic, and antiferromagnetic tetragonal phases. And Ni₅₀Mn₃₄Sb₅Ga₁₁ alloy has experienced five different phase states: paramagnetic austenite → ferromagnetic austenite → antiferromagnetic martensite → ferromagnetic martensite → spin glass as the temperature decreased. Further study of the alloys’ magnetostrictive properties near the MPB showed that as x increases, a negative strain initially appears, followed by a W-type that crosses negative and positive strains, and then a positive strain. This is caused by the inconsistency in the speed and degree of magnetic domain walls response with monoclinic and tetragonal coexisting structures. This indicates that coupling between structure and magnetism is critical to the properties of materials. This work provides valuable insights into the magnetostrictive behavior and structural evolution of Heusler alloys, particularly in the context of MPB systems, and offers guidance for the design and optimization of material properties through controlled magnetic-structural interactions.Kindly check and confirm the edit made in the title.The edit made in the title has been confirmed to be accurate.

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A new approach was introduced by combining laser powder bed fusion and hot isostatic pressing processes to create a Ti6Al4V-Ti composite alloy structured similar to nacre, merging Ti6Al4V with pure Ti. Titanium alloys are known to be sensitive to fluoride ions commonly found in dental products like rinses, toothpaste, and mouthwashes, impacting their corrosion resistance. Therefore, the aim of this research is to investigate how fluoride ions affect the corrosion characteristics of the Ti6Al4V-Ti composite and to evaluate the unique dissolution behaviors observed in the Ti6Al4V and pure Ti zones. The findings from electrochemical tests reveal that adding fluoride ions decreases the composite's corrosion resistance, yet fluoride concentrations of 0.01 and 0.05 M still exhibit passive behavior. However, at a fluoride concentration of 0.1 M, there is a significant degradation of the passive film, presenting a porous structure. Additionally, the observation from atomic force microscope demonstrated Ti6Al4V zone shows a preference for dissolution compared to the Ti zone, particularly evident at fluoride ion concentrations of 0.1 M. This study is expected to provide valuable insights to deepen the understanding of Ti6Al4V-Ti composites' suitability for dental applications.

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Co-precipitation strengthening of the L1₂ nano-particles along with hard intermetallic phases, including L2₁, B2, σ and η, demonstrates significant potential for the development of advanced CoCrFeNi high-entropy alloys (HEAs) with favorable strength-ductility balances. Understanding the alloying effect of Al and Ti on the formation and stability of these intermetallic phases in the CoCrFeNi HEAs is crucial for efficiently exploring the multi-component space for future alloy designs. In the present work, stepwise compositionally graded CoCrFeNi–AlTi HEAs comprising 35 different compositions were fabricated using high-throughput additive manufacturing (AM) and analyzed through a suite of localized characterization techniques. Our analysis confirmed the existence of two primary solid solution phases, face-centered cubic (FCC) and body-centered cubic (BCC), as well as four distinct intermetallic phases, which include L1₂, L2₁, σ and η. By overlapping the zero phase fraction (ZPF) lines of these phases, the pseudo-ternary phase diagram of the multi-component CoCrFeNi–AlTi system at 800 °C was determined, demonstrating good agreement with the literature results. Furthermore, the composition-dependent microstructural evolution and Vickers hardness (HV) were also established, providing numerous opportunities to design CoCrFeNi–AlTi HEAs with superior microstructure stability and balanced strength-ductility properties for structural applications at elevated temperatures.

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The complicated structure of electronic devices makes the conventional annealing method, which involves placing the entire device in a furnace, insufficient for achieving the desired quality. This issue is currently addressed through the use of pulsed laser annealing, where a specific target layer is heated, preventing the overheating of other layers or the substrate. However, this method is only applicable to a very limited range of materials and requires very expensive, powerful pulsed laser sources. Herein, a novel approach for the selective local thermal treatment of thin films is proposed; in this method, short, powerful current pulses are applied to the target conductive layer. The application of two current pulses with a length of 1.5 s induced the crystallization of a 160-nm thick indium tin oxide (ITO) film, resulting in a sheet resistance of 8.68 Ω·sq⁻¹, an average visible light transmittance of 86.69%, and a figure of merit (FoM) of 293.61. This FoM is an order of magnitude higher than that of the as-prepared ITO film, and to the best of our knowledge, is among the highest reported values for the polycrystalline ITO films. Simulations have shown that even faster and more localized crystallization could be achieved by increasing the power of pulsed current. This novel annealing method is applicable to most semi-conductive or metallic thin films and requires only a relatively inexpensive pulsed current source, making it potentially more attractive than pulsed laser annealing.

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Transition metal selenides (TMSs) are effective pre-electrocatalysts and are commonly used in electrochemical processes. During the electrocatalytic oxygen evolution reaction (OER), metal cations in TMSs are in-situ reconstructed and converted into high-valence metal oxyhydroxides. However, a limited understanding of the effects of electro-oxidation and anion leaching has resulted in insufficient theoretical guidance for the rational design of efficient catalysts. Herein, FeSe@NiSe nanorods were fabricated for the OER using a facile hydrothermal selenization method supported on FeNi foam. In-situ Raman spectroscopy and multiple characterization techniques were employed to elucidate the mechanism of FeSe@NiSe surface evolution. Metal cations on the catalyst surface were reconstructed and converted into OER-active species Fe/NiOOH at low potential. As the applied potential increased, electro-oxidation and leaching of Se occurred, resulting in SeO₄²⁻ adsorption on the catalyst surface, which further enhanced catalytic activity. As a result, the reconstructed FeSe@NiSe/iron-nickel foam (INF) exhibited exceptional catalytic activity for OER, achieving an ultralow overpotential of 283 mV at a current density of 100 mA·cm⁻². Notably, the bifunctional FeSe@NiSe/INF electrode facilitated overall water splitting, affording a current density of 10 mA·cm⁻² only at 1.53 V, even superior to the noble RuO₂(+)||Pt/C(−). This work offers valuable insights into the surface evolution and electrocatalytic mechanisms of TMSs.

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Typical p-n junctions have emerged as a promising strategy for contending with charge carrier recombination in solar conversion. However, the photo-corrosion and unsuitable energy band positions still hinder their practical application for hydrogen production from water in photoelectrochemical systems. Here, an in-situ photo-oxidation method is proposed for achieving self-adapting activation of BiVO₄-based photoanodes with surface-encapsulated CuGaS₂ particles by the ZnO layer. The self-adapting activation demotes the energy band positions of CuGaS₂, establishing an S-scheme structure with BiVO₄, resulting in an efficient p-n junction photoanode. The optimal sample exhibits enhanced photocurrent and an onset potential cathodically shifted by ~ 300 mV compared with BiVO₄, which is attributed to significantly enhanced charge transport and transfer efficiencies. As expected, it attains the highest photocurrent value of 5.87 mA·cm⁻², aided by a hole scavenger at 1.23 V versus a reversible hydrogen electrode, which significantly surpasses that of BiVO₄ (4.32 mA·cm⁻²).

Recently, stimuli-responsive nanocarriers capable of precision drug release have garnered significant attention in the field of drug delivery. Here, an in-situ dynamic covalent self-assembled (DCS) strategy was utilized to develop a co-delivery system. This assembly was based on a thiol-disulfide-exchange reaction, producing disulfide macrocycles in an oxidizing aerial environment. These macrocycles encapsulated the anti-cancer drug (paclitaxel, PTX) on the surface of gold nanoparticles, which served as photothermal therapy agents during the self-assembly. In the DCS process, the kinetic control over the concentration of each building unit within the reaction system led to the formation of a stable co-delivery nanosystem with optimal drug-loading efficiency. Notably, the high glutathione (GSH) concentrations in tumor cells caused the disulfide macrocycles in nanostructures to break, resulting in drug release. The stimuli-responsive performances of the prepared nanosystems were determined by observing the molecular structures and drug release. The results revealed that the self-assembled nanosystem exhibited GSH-triggered drug release and good photothermal conversion capability under near-infrared light. Moreover, the in vitro and in vivo results revealed that conjugating the targeting molecule of cRGD with co-delivery nanosystem enhanced its biocompatibility, chemo-photothermal anti-cancer effect. Overall, our findings indicated that in-situ DCS strategy enhanced the control over drug loading during the construction of the co-delivery system, paving a way for the development of more functional carriers in nanomedicine.

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Iron disulfide (FeS₂) has been widely used in thermal batteries because of its high theoretical specific capacity and voltage plateau. However, low thermal decomposition temperature, poor conductivity and inferior actual specific capacity limit its wide applications. Herein, we report a gold-doped FeS₂ (FeS₂-Au), which not only reduces the band gap of the FeS₂ crystals but also enriches the electron transport path of FeS₂ by the formation of Au nanoparticles. First-principles calculation shows that the diffusion energy barrier of lithium-ion is reduced after the Au-doped FeS₂. In addition, Au increases the electron cloud density around sulfur atoms, which helps to enhance the stability of Fe-S covalent bonds and thus results in better thermal stability of FeS₂. When the Au content is 130 μg·g⁻¹ (FeS₂-Au₄), the thermal decomposition temperature (TG_5%) of FeS₂-Au is 72.2 °C higher than that of pristine FeS₂. At a discharge temperature of 500 °C, a current density of 200 mA·cm⁻² and a cutoff voltage of 1.4 V, FeS₂-Au₄ demonstrates superior specific capacity and high specific energy compared to FeS₂. More precisely, the specific capacity of FeS₂-Au₄ attains a value of 379 mAh·g⁻¹, with a corresponding specific energy of 714 Wh·kg⁻¹. In contrast, the discharge specific capacity and specific energy of FeS₂ are lower, amounting to 348 mAh·g⁻¹ and 656 Wh·kg⁻¹, respectively. This study offers a novel approach to enhancing the electrochemical performance of FeS₂ in high-temperature molten salt electrochemical systems (thermal batteries), thereby laying a solid foundation for its potential practical application.

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The photovoltaic properties of indium–gallium–zinc oxide (IGZO) thin film utilized in electronic information applications depend on the quality and performance of the corresponding target. In this study, high-energy ball milling was combined with atmospheric sintering to achieve precise control over the phase composition and microstructure of In₂Ga₂ZnO₇ ceramic targets. This was achieved by controlling the sintering process and performing thermodynamic calculations to analyze the phase transition process. Further, the electronic structure simulation results of the relevant phases were analyzed, and crystal structure models were constructed. According to the density functional theory calculations, the enthalpy of formation of In₂Ga₂ZnO₇ was found to be the largest, followed by those of InGaZnO₄ and ZnGa₂O₄, which indicates that the In₂Ga₂ZnO₇ phase exhibits the highest thermal stability. The relationship of the enthalpy of formation corresponds to two distinct reactions of the IGZO powders. The ZnGa₂O₄ phase is initially formed and remains stable for an extended period. This is followed by the rapid formation and subsequent disappearance of the InGaZnO₄ phase within a narrow temperature range. Finally, a single In₂Ga₂ZnO₇ phase is formed. The target sintered at 1500 °C exhibits a narrow band gap and the lowest porosity, which results in the highest relative density (99.52%) and the lowest resistivity (3.4 mΩ·cm). These experimental findings can provide guidelines for controlling the phase and microstructural characteristics of In₂Ga₂ZnO₇ targets with the aim of producing IGZO targets with excellent properties, including homogeneous composition, high density, and low resistance in the field of flat displays.

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