Journal of Materials Science最新文献

This work explores the effects of Y or Nd interactions with Mn substitutions in the new (Y, Nd)BaCuFe_1−xMn_xO_5+δ compounds with x = 0.00, 0.03, 0.10, and 0.25 (RE- x) focusing on their structural, morphological, and magnetic properties. Rietveld refinement of X-ray diffraction (XRD) patterns showed that the (Y, Nd)³⁺ and Fe³⁺ ions predominantly crystallize in a tetragonal structure (P4mm), with variations in tetragonal bond distances dependent on the Mn ion substitution degree. Scanning electron microscopy technique (SEM) revealed polycrystalline morphology with grain shapes that change with cation substitution, consistent with the synthesis method. Energy-dispersive X-ray spectroscopy (EDS) technique confirmed the materials stoichiometry, while attenuated total reflectance-infrared (ATR-IR) spectroscopy demonstrated the increased anisotropy in metal–oxygen interaction along different crystallographic directions when Y is replaced by Nd. Magnetization curves obtained in the zero-field cold/field cold (ZFC–FC) modes as a function of temperature 50 K up to 400 K show some of the expected characteristics of the magnetic phase transition at temperatures between 176 and 330 K for the Y-based systems, and an increase in the antiferromagnetic (AFM) transition temperature with Mn substitution. The Nd-based systems reveal a paramagnetic (PM) behavior that could be attributed to the dominance exerted by the magnetic moments of the Nd ions.

Understanding and predicting phase transitions in high-entropy alloys (HEAs) are pivotal for alloy design and performance optimization. This study aims to utilize artificial feature parameters for the predictive modeling of phase transitions in HEAs. Four elementary algorithms and four ensemble algorithms were employed for model selection. An innovative classification approach was introduced, classifying HEAs into eight distinct structural categories: IMS, AM, FCC + IM, BCC + IM, FCC, SS, BCC, and IM. To enhance feature selection, a three-phase feature screening method was devised, resulting in the identification of seven highly representative features from an initial pool of 64. These selected features were then used for model training. A comparative analysis was conducted against feature sets obtained from six peer-reviewed publications to validate the efficacy of the chosen features. In addition, various oversampling techniques were incorporated to further optimize model performance. Upon examination, factors such as electronegativity differences, heat of vaporization, and melting point temperatures play a decisive role in distinguishing alloy phase structures. Interactions between important characteristics exhibit significant differential impacts on phase structures.

Multi-axial forging (MAF) is a severe plastic deformation technique in which a large plastic strain is imparted by multi-axial compression to achieve a high level of grain refinement. In this study, the microstructural changes due to multi-axial forging of AA6082/B₄C nanocomposite and their effect on mechanical properties have been studied. The samples of AA6082/B₄C composite have been subjected to three cycles of multi-axial forging at room temperature, imparting a true strain of 0.3 in each cycle. The microstructure after multi-axial forging showed a bimodal grain structure composed of ultrafine and coarse grains with average grain size reducing from 154 to 52 μm. MAF also improved the distribution of B₄C nanoparticles with increase in the number of cycles. The mechanical properties of the composite after MAF have been correlated with dislocation density and evolution of secondary phases using microstructural analysis. Crystallographic texture evolution during MAF of the composite revealed change in the intensity of some texture components which is consistent with the observed variation in the yield strength. The strength of the composite improved by 135% after three cycles of MAF when compared to the initial as-cast condition but the failure strain in uniaxial compression decreased by 23%.

Two-dimensional materials (2DMS) have emerged as key potential materials for electronic, spintronics, photocatalytic, and energy storage device applications, due to their outstanding intrinsic properties. Additionally, ion irradiation, a technique in which energetic beams of charged particles are exposed on materials, enhances the formation of atomic defects toward changing the materials’ properties significantly even for superior performances over their conventional counterparts. Monolayer MoS₂ has shown several potential applications as semiconductor with an intrinsic direct band gap. In this study, we have grown monolayer MoS₂ on sapphire substrate via. thermal chemical vapor deposition approach and homogenously irradiated with 100 keV helium ions (1 × 10¹³–1 × 10¹⁶ ions cm⁻² fluence) and argon ions (1 × 10¹³–1 × 10¹⁴ ions cm⁻² fluence) at room temperature to study the effects of ion beam irradiation specifically on surface morphology, structure, optical, and chemical compositions. Both the micro-Raman and photoluminescence studies confirmed the sequential reduction in sulfur atomic concentration due to preferential sputtering and infusion of associated defects, which provide additional nucleation sites due to sulfur vacancies. Consequently, we observed evolutions of MoS₂ nano-island on monolayer MoS₂ edges due to well controlled low-energy ion irradiation. The study not only leveraging the better understanding and gain of knowledge on the effects of low-energy ion exposers on monolayer MoS₂ but also opening a gateway for generating MoS₂ nanostructures having potential applications in 2D electronics, spintronics (once integrated with magnetic impurities), and photocatalytic applications.

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The effects of plasma nitriding (PN) on the tribological and corrosion properties of TC6 titanium alloy were studied using X-ray diffraction, microhardness testing, scanning electron microscopy, a friction wear testing machine, and an electrochemical workstation. The results reveal that following PN treatment, a 5-μm-thick nitrided layer and diffusion layer formed on the surface of the TC6 titanium alloy. The surface hardness of the PN sample reached 1321.1 HV_0.5, representing a 2.77-fold increase, while the wear scar volume decreased by approximately 99%, significantly enhancing wear resistance. Additionally, corrosion resistance showed marked improvement.

Fluorescent anti-counterfeiting paper was a very important kind of special paper, which played an important role in people’s life, such as paper money. In this work, fluorescent anti-counterfeiting paper was prepared by using lead-metal–organic framework (Pb-BTC) that was in situ formed on the surface of pulp fibers (PFs) with lead ions and pyromellitic acid (H₄BTC), which served as template to in situ anchoring of CH₃NH₃PbBr₃ (MAPbBr₃) to achieve the controllable synthesis of MAPbBr₃ and reduce aggregate fluorescence quenching. The CH₃NH₃Br (MABr) as the anti-counterfeiting ink was applied on Pb-BTC@PFs to achieve security writing. MAPbBr₃ forming writing was invisible under sunlight but displayed green fluorescence under 365 nm ultraviolet lamp excitation. The writing with green fluorescence could be extinguished by water and reconstructed by forming new MAPbBr₃. The Pb-BTC@PFs was as the precursor to product fluorescent anti-counterfeiting paper (MAPbBr₃@Pb-BTC@PFs) reacted with MABr in ethanol solution, so that the green fluorescence of it was opened under 365 nm ultraviolet lamp. When it was exposed to polar solution, MAPbBr₃ structure collapsed. Since Pb-BTC was stably in paper and was not easy to lose in polar solution, it could be reused several times on the premise that the paper structure was not damaged, which demonstrated an advantage over using perovskite alone in paper. Consequently, the current study not only provided a new idea for controllable anchoring perovskite on support materials, but also offered a new method for producing fluorescent anti-counterfeiting paper.

The tunable optical properties and exceptional electromagnetic field enhancement of nanostar-based plasmonic nanoparticles make them highly promising for a wide array of biomedical applications. However, a great challenge for their widespread use is the time-sensitive nature of the various processes in the nanostar synthesis workflow, which could lead to imprecise control of their homogeneity and high batch-to-batch variability. To address these challenges, we have developed an automated synthesis system with AI capability to reproducibly synthesize large quantities of nanostar particles. This platform uses key synthesis parameters such as reagent volume and reagent addition timing to systematically evaluate how these factors determine the optical properties and SERS enhancement of gold nanostars and bimetallic nanostars. We developed and trained different machine learning (ML) models using nanoparticle characterization data to predict absorbance features and SERS enhancement from synthesis parameters. We compared the performance of five different machine learning models, including artificial neural networks, support vector regression, and several tree-based models, including random forest, extreme gradient boost, and categorical boost. A grid matrix was fed into the final trained models to create a look-up table to synthesize gold nanostars with an absorbance maximum at specific wavelengths, culminating in the reproducible synthesis of desired nanostar platforms with a peak absorbance wavelength of less than 1.2% difference compared to the target peak absorbance. This machine learning-integrated automated nanostar synthesis platform paves the way for more consistent and scalable production to enable the next phase of investigation for nanostar-based technologies and expand the scope of their current biomedical applications.

The physical applications of negative Poisson’s ratio structures of insufficient bearing capacity were limited. The topologies of high stiffness negative Poisson’s ratio (T-SNPR) were designed, and the bearing and energy absorption performance of their three-dimensional structures (S-SNPR) were analyzed using the finite element method. Furthermore, the experimental results of the second SNPR structure (S-SNPR-2) specimen produced by wire electro discharge machining (WEDM) were identical to the numerical results, and the error values of force and energy absorption were 8.9% and 14.9%, respectively. The SNPR-2 obtained the higher EA value of 83 kJ, SEA value of 2.3 kJ kg⁻¹, and bearing force value of 1050 kN, as well as the more extensive compress stroke strain value of 0.18 than S-SNPR-1. Under compression and high-velocity impact, the S-SNPR-2 structure with a relative density value of 0.57 obtained better bearing, energy absorption, and impact resistance capacities. Under low- and medium-velocity impact, the S-SNPR-2 structure with a relative density value of 0.52 obtained better bearing and impact resistance characteristics, and the S-SNPR-2 structure with a relative density value of 0.57 had better energy absorption performance. The S-SNPR-2 proposed in this paper has a good application prospect as an energy-absorbing component in coal mining supporting equipment.

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Impregnating phase change materials (PCMs) into cellulose aerogels has been recognized as an effective approach to mitigating the liquid leakage issues because of the superior surface tension and capillary force. However, these phase change aerogels suffer from inadequate mechanical properties, making them susceptible to breakage and deformation under external forces. To address this challenge, this study explores the effects of varying waterborne polyurethane (WPU) concentrations on the mechanical and thermal properties of polyethylene glycol (PEG)/cellulose nanofibril (CNF)/WPU phase change foams, successfully fabricating a series of PEG/CNF/WPU phase change foams. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mechanical testing, and leakage rate tests were employed to systematically evaluate the morphology, crystalline structure, chemical composition, mechanical properties, and thermal characteristics of these foams with different WPU additions. The results revealed that the PEG/CNF/WPU phase change foam containing 9 g WPU achieved a phase change enthalpy of 134.81 J·g⁻¹, accompanied by outstanding compressive strength, compressive yield stress, and compressive modulus. Notably, the leakage rate after a 30-day leakage test was only 8.09%.

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This study aimed to explore the impact of annealing temperature on the nucleation and subsequent growth of nanocrystalline α-Fe grains in a high saturation magnetization soft magnetic Fe_84.8Si_0.5B_9.4P_3.5Cu_0.8C_1.0 alloy. Thus, we conducted multiprobe analyses of the isothermal crystallization process within 633–733 K. Transmission electron microscopy and atom probe tomography observations of the samples isothermally annealed at 733 and 633 K revealed distinct differences in their microstructures. In case of the higher isothermal temperature, larger Cu clusters were observed, whereas the α-Fe grains were finer. In contrast, in case of the lower isothermal temperature, the Cu clusters were smaller, and the α-Fe grains were coarser. Time-resolved synchrotron radiation X-ray diffraction measurements confirmed the sporadic nucleation mechanism, highlighting the significant effect of isothermal temperature on the formation of α-Fe grains. To achieve an optimal microstructure for lower coercivity, the Cu clustering and α-Fe nanocrystallization must be controlled by annealing at higher temperatures for shorter durations.

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