Journal of Materials Science最新文献

This study investigates the effects of introducing 0–5 mol% NaNbO₃ (NN) seeds on the structural, microstructural, dielectric, ferroelectric, and piezoelectric properties of KNN-based lead-free piezoelectric ceramics. All samples with the final composition 0.96[0.95(K_0.52Na_0.48NbO₃) − 0.05LiSbO₃] − 0.04SrZrO₃–CuO (KNNLS–SZ–C) were sintered at 1060 °C for 6 h. X-ray diffraction analysis revealed a perovskite single phase for 0–5 mol% NN seed contents, with a multiphase coexistence of tetragonal, orthorhombic, and rhombohedral structures. As seed content increased from 0 to 3 mol%, the rhombohedral fraction increased while tetragonal and orthorhombic fractions decreased. SEM micrographs showed abnormal grain growth at 1–2 mol% seeds, transitioning to normal grain growth beyond 3 mol%. Optimal piezoelectric and electromechanical properties including d₃₃ = 323 pC/N, k_p = 0.39 were obtained at 3 mol% NN seed, attributed to the favorable multiphase structure fraction and moderate grain size. This work elucidates the interplay between NN seed addition, phase fraction distribution, and microstructural development in tuning the piezoelectric performance of these lead-free ceramics.

The development of efficient photocatalysts for renewable hydrogen production via water splitting is of paramount importance for sustainable energy generation. In this study, CoO/Co₃O₄ nanofibers were synthesized using an innovative water gas-assisted procedure and evaluated as photocatalysts for hydrogen generation from a methanol/water mixture under solar irradiation. The synthesized nanofibers exhibited superior photocatalytic activity compared to Co₃O₄ nanofibers and standard TiO₂ nanoparticles, with hydrogen production rates of 66.9, 25.3, and 15.9 mmol H₂/g_cat·s, respectively. Additionally, the CoO/Co₃O₄ nanofibers demonstrated an anomalous temperature dependence, with hydrogen production rates decreasing from 69.6 mmol H₂/g_cat·s at 20 °C to 17.76 mmol H₂/g_cat·s at 50 °C. This unexpected behavior was attributed to the exceptionally high photocatalytic activity of the nanofibers, where increasing temperature led to premature desorption of reactant molecules from the catalyst surface. These results highlight the potential of CoO/Co₃O₄ nanofibers as promising photocatalysts for efficient solar-driven hydrogen production and underscore the importance of temperature effects in optimizing photocatalytic systems for renewable energy applications.

Recovering precious metals (PMs) from diverse waste sources, including electronic waste (E-waste), mining residues, and industrial effluents, has become a critical focus due to their immense economic value and limited natural reserves. Nanoadsorbents, renowned for their high surface area, tunable surface properties, and exceptional physicochemical characteristics, have emerged as highly promising candidates for the efficient recovery of metals such as gold (Au), silver (Ag), platinum (Pt), and palladium (Pd). However, the full realization of their potential remains in its infancy, necessitating further research and significant advancements to optimize their efficiency. This review highlights two cutting-edge materials—porous carbons and metal–organic frameworks that stand out for their extraordinary surface areas, customizable properties, and selective adsorption capabilities, making them particularly suitable for PM recovery. Additionally, the review provides a critical evaluation of the advantages and limitations of these materials, offering a roadmap for selecting and enhancing adsorbents for PM recovery. We believe that this comprehensive analysis will drive innovation in material development, facilitating more efficient recovery of precious metals from waste streams.

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This study advances glass nanocomposite research by achieving exceptional Electromagnetic Interference (EMI) shielding while maintaining optical transparency. We employ femtosecond laser engraving and thermal vapor deposition to create precise periodic line patterns on fused quartz glass, which serve as a framework for the controlled deposition of silver (Ag) and gold (Au) nanoparticles through laser-ablated micro-channels. These nanocomposites effectively balance EMI shielding and optical transmittance, making them suitable for applications in electronics, aerospace, and telecommunications. Femtosecond laser ablation allows for meticulous glass surface modification. Using an XY motorized translation stage guided by a photoresist, we form line patterns with spacings of 200, 400, and 600 µ-meter, resulting in Shielding Effectiveness (SE) in the range of 10–37 dB. Notably, despite substantial modification, the glass nanocomposites retain optical transmittance comparable to clear glass, enhancing their utility in applications where visual clarity is essential, such as windows, displays, and security infrastructure. By integrating femtosecond laser ablation with controlled thermal deposition, we produce multifunctional glass nanocomposites that offer promising EMI shielding and optical transparency, paving the way for advanced materials in industries where both properties are critical.

The evolution of Al₃(Sc, Zr) and α-Al(Fe, Mn)Si dispersoids and their influence on the recrystallization behavior and mechanical properties of an Al–Mg–Sc alloy under various homogenization and annealing treatments were investigated by scanning electron microscopy, transmission electron microscopy and tensile testing. The results revealed that the one-step homogenization (OS, 350 °C/6 h) produces higher number density of Al₃(Sc, Zr) and α-Al(Fe,Mn)Si dispersoids compared with the three-stage homogenized alloy (THS8, 270 °C/6 h + 350 °C/6 h + 500 °C/8 h), significantly increasing the recrystallization resistance. The one-step homogenization produces evidently higher strength but lower elongation compared to the there-step homogenization when annealing at low temperature (350 ℃/1 h). However, when annealing at 550 °C/1 h, the one-step and three-step homogenized samples exhibit similar strength, suggesting the mechanical property difference can be eliminated by high temperature annealing. The evolution of Al₃(Sc, Zr) dispersoids during homogenization and annealing treatment plays a key role in determining the property differences of these samples. Although the OS and THS8 treatments produces distinct distributions of Al₃(Sc, Zr) dispersoids, the dispersoids can rapidly coarsen and produce similar dispersoid distributions after annealing at high temperature (550 °C), this difference can only be retained at low temperature annealing (350 °C). Besides, dislocation strengthening is also responsible for the property difference of these alloys. These results provide new information for designing new heat treatment process of Al–Mg–Sc–Zr alloys.

Thermal modification is a widely used technology for enhancing the dimensional stability and durability of wood. However, thermal degradation reactions in wood are complex and depend on the process conditions applied. Degradation products from thermal wood modification are expected to affect the wood chemistry and the wood–water interactions of the thermally modified wood. In this paper, we investigated the impact on wood chemistry and wood–water interactions of retaining or evaporating degradation products while thermally modifying beech and Scots pine in a closed thermal treatment process. Wood–water interactions were studied by LFNMR and DSC. Additionally, the presence of extractable degradation products was determined based on water and multi-solvent extraction, and pH measurements and ATR-FTIR analyses were performed to determine differences in wood chemistry. Light microscopy images of xylem cross-sections were taken to determine the lumen areas for interpretation of the LFNMR results. We found that thermal treatment with a cooling step at atmospheric pressure allowed some degradation products to evaporate, in the case of beech, resulting in a less hydrophobic end product. However, for Scots pine, evaporating degradation products during the thermal modification process did not have an effect on the pH and the amount of residual extractives, and as the impact on wood–water interactions was not in line with the findings on wood chemistry, the results are inconclusive. Our results demonstrate that degradation products can have an impact on the wood–water interactions of thermally modified wood in the cooling step and that the results are wood species dependent.

Laser cladding technology is an efficient method for repairing downhole drilling tools. The microstructural evolution and tribo-corrosion mechanism of Ni-WC laser-clad coating were investigated. The microstructural results indicate that the Ni-WC laser-clad coating is mainly composed of γ-Ni, WC, W₂C, M_xC_y (M = W, Ni, Cr, Fe, Mo), M₂₃C₆ (M = W, Ni, Cr, Fe, Mo), and eutectic phases (CrC / MoC). Cl⁻ exacerbates the corrosion of M_xC_y layer around WC particles by penetrating cracks, which further causes the shedding of the M_xC_y layer during wear. During tribo-corrosion, the Ni-WC laser-clad coating’s open-circuit potential shifts negatively with increasing loads. Meanwhile, E_corr shifted negatively and I_corr gradually increased, indicating more severe corrosion promoted by wear. The wear rate of coating is higher under open-circuit potential compared to that under pure mechanical wear, and mechanical wear is predominant in tribo-corrosion.

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Due to their affordable pricing and remarkable physicochemical properties, hard C materials have garnered significant attention in the field of sodium-ion batteries (SIBs). Nevertheless, the application of hard C as SIBs anodes is difficult owing to its poor stable cycle and rate performance, low electrode potential. In this study, we have developed B-doped hierarchical porous C composites using lignite as raw material. The incorporation of B atoms into C matrix can create a substantial number of reactive sites for Na⁺, and increase the interlayer spacing of C matrix, hence accelerating the process of Na⁺ de/intercalation. Consequently, when utilized as anodes for SIBs, B-doped hierarchical porous C composites exhibit a substantial reversible capacity of 359.1 mAh g⁻¹ after 400 cycles at 0.1 A g⁻¹, with a capacity retention up to 98.6%. Additionally, these composites demonstrate exceptional long-term stability, maintaining a capacity of 195.9 mAh g⁻¹ after 1000 cycles at a rate of 1.0 A g⁻¹.

In this study, niobium oxynitride nanoparticles were examined to determine the effect of particle size on oxygen reduction reaction (ORR) activity. To this end, catalyst precursors with niobium oxides dispersed on carbon supports were prepared using the irradiation or impregnation method. Polyacrylonitrile was added to each precursor, followed by heat treatment under an ammonia‐containing atmosphere to synthesize niobium oxynitride nanoparticles. The structures of the prepared catalysts were analyzed using transmission electron microscopy, X-ray diffraction, and X-ray absorption spectroscopy. The results indicated that two catalysts with the same crystal phase but different particle sizes were obtained. Comparing their ORR activities revealed that the effect of particle size on ORR activity was limited. Thus, it was inferred that controlling the microelectron conduction paths can help maximize the benefits of particle size reduction. In addition, niobium oxynitride nanoparticles with different structures were obtained by varying the heat-treatment temperatures, and the ORR activity of each prepared catalyst was evaluated. These findings suggest that forming graphitized carbon residues with high electrical conductivity and controlling nitrogen-doping in the oxide nanoparticles are crucial steps for enhancing the ORR activity of oxide-based catalysts. These findings offer valuable insights for developing material design strategies to improve oxide-based catalyst performance.

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MoS₂, with its abundant natural occurrence, low cost, tunable electronic properties and unique chemical stability, was an ideal catalyst for the hydrogen evolution reaction (HER) in water electrolysis processes. This work used natural molybdenite as the raw material and prepared few-layer MoS₂ nanosheets through electrochemical exfoliation and ultrasonic exfoliation, which enhanced their HER performance. Subsequently, by annealing MoS₂ in a reductive atmosphere at high temperatures to create a certain amount of sulfur vacancies, it was found that the number of sulfur vacancies in MoS₂ was positively correlated with its HER performance. The sample annealed at 900 °C exhibited the best HER performance, with the overpotential further reduced from 369 to 334 mV (@ j₀ = 10 mA/cm²). This work efficiently utilized natural molybdenite to prepare MoS₂ nanosheets and further enhanced their HER performance. This increased the added value of molybdenite and had significant implications for the development and comprehensive utilization of mineral resources.

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