Journal of Materials Science最新文献

In this research, mullite/cordierite (Mu/C) composite ceramics were synthesized using a novel low-temperature solgel technique, offering an energy-efficient approach to advanced ceramic fabrication. The precursors were prepared using Si(C₂H₅O)₄ and Al(NO₃)₃·9H₂O as sources for SiO₂ and Al₂O₃, respectively. The amorphous powder's formation and crystallization were confirmed by structural analysis using X-ray diffraction (XRD), and the sintered microstructure was discovered by scanning electron microscopy (SEM) following an hour of treatment at 1600 °C. Density measurements showed that increasing cordierite content reduced both apparent density and open porosity, influencing the material’s microstructural integrity. Complex impedance spectroscopy was utilized to examine electrical and dielectric behaviors over the frequency range of 100–10⁶ Hz and the temperature range of 40–400 °C. The findings demonstrated that the dielectric constant's real and imaginary parts rose with temperature but fell with frequency. The activation energies from the Arrhenius analysis backed up the change in the imaginary modulus and impedance peak with temperature, showing that the relaxation mechanism is not a simple Debye type. This study points out the strong electrical performance and adjustable transport behavior of Mu/C composites, making them great for real-world uses like high-temperature sensors, capacitors, and dielectric parts in tough conditions.

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Achieving a room temperature solid state gas sensor that allows the precise detection of CO₂ gas at ppm level is crucial for measuring higher levels indoor and outdoor places. The room temperature with fast-response CO₂ sensors based on vertically layered heterostructures continues to be a challenging frontier in sensor development. In this work, we have successfully developed a vertical device for CO₂ sensing in the range of 500–2000 ppm at 200 °C. The strategies for synthesizing stable MOF (UiO-66 (Zr)) on 2D MXene (Ti₃C₂T_x) layer have also been demonstrated. The sensing device was fabricated on ITO coated glass surface using a spin-coating method, with UV-ozone pretreatment to enhance substrate surface energy and improve adhesion. The structural and morphological characterization revealed the well-organized layered structure for UiO-66 (Zr)/Ti₃C₂T_x with a BET surface area of 1840 m², pore size in the range 3.5–4 nm, with pore volume 0.1398 (cm³/g), led to fast response and recovery times. The vertically with ITO/Au/Ti₃C₂T_x/UiO-66 (Zr)/Au configuration exhibited a higher gas response of ~ 36.67% at 200 °C and 2000 ppm with response and recovery times of ~ 1.0 min and 3.1 min, respectively. On the other hand, the Au/UiO-66 (Zr)/Au device showed a low gas response ~ 0.02% even at 450 °C and response/recovery times of 0.7/3.0 min. The device with pristine UiO-66 (Zr) have not shown a stable response even at 200 °C. We also evaluated the charge transport regime in Zr-based UiO-66 and UiO-66 (Zr) /Ti₃C₂T_x devices transitions from Poole–Frenkel conduction at lower temperatures to an Ohmic behavior at higher temperatures, which was strongly influenced by varying CO₂ concentration. These findings reveal that the temperature and concentration dependent conduction mechanisms are critical for optimizing vertical CO₂ sensors.

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In order to reduce climate change rate, sustainable energy sources have emerged as a promising solution. Nevertheless, such energy sources require the use of energy storage systems to match optimal performance. Within this context, the design and synthesis of materials, which can provide enhanced energy storage, stand as a major research field. Herein, we established an eco-friendly method to synthesize a coordination polymer (CP) based on benzene-1,4-diboronic acid (BDBA) and Co(II) atoms, entitled Co-BDBA, using only water in the whole synthetic process. Co-BDBA is a crystalline material comprising a mesoporous structure with specific surface area and a mean pore size of 104.9 m² g⁻¹ and 3.4 nm, respectively. Remarkably, Co-BDBA features enhanced electrical properties, compared to other reported CPs. Specifically, arguably due to a better orbital overlap in the coordinate bonds, Co-BDBA exhibits a band gap of 3.41 eV. Furthermore, Co-BDBA might transport charge carriers by a band-like mechanism. As a result of the enhanced electrical properties, Co-BDBA shows high electrochemical reversibility with a specific capacitance of 345 F g⁻¹ at 1 A g⁻¹ and superior capacitance retention of 109.7% after 2000 galvanostatic charge–discharge cycles. The voltammograms and the galvanostatic charge–discharge profiles indicate a pseudocapacitive behavior, where the energy storage kinetics is controlled by surface processes, i.e., a capacitive-controlled energy storage kinetics, contrary to the majority of coordination polymers previously reported, which, as best of our knowledge, storage kinetics is diffusion-controlled. Finally, capacitive-controlled energy storage kinetics was also confirmed by electrochemical impedance spectroscopy experiments.

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To address the growing threat of high-energy laser (HEL) attacks, this study focuses on developing phenolic resin-based composite coatings reinforced with various metallic and ceramic fillers. Among the formulations tested, the aluminum–molybdenum diboride (Al + MoB₂) composite coating exhibited the most promising laser ablation resistance. While pure aluminum displayed the highest reflectivity and alumina the lowest, the introduction of MoB₂ into the aluminum matrix significantly reduced reflectivity without compromising thermal performance. The Al + MoB₂ coating demonstrated the lowest backside temperature rise and minimal weight loss during laser exposure, indicating excellent thermal barrier characteristics and high resistance to material degradation. This superior performance is attributed to the high thermal stability and char-forming capability of MoB₂, which helps dissipate energy effectively while maintaining structural integrity. In contrast, the pure alumina coating, despite its low reflectivity, resulted in a higher backside temperature—likely due to its higher thermal conductivity and direct energy transfer. Overall, the Al + MoB₂ composite offers a favorable combination of reflectance control, thermal insulation, and durability, positioning it as a strong candidate for protective coatings against HEL threats in defense and aerospace applications.

Although perovskite crystals exhibit defect tolerance, the presence of crystal defects may still compromise their photodetection performance. In this paper, we study the solution growth of high-quality δ-CsPbI₃ single-crystalline fibers (SCFs), and highlight the impact of crystal quality on the enhancement of the photodetector performances. To achieve high-quality δ-CsPbI₃ SCFs, a seeded growth of δ-CsPbI₃ SCFs is carried out using an optimized HI-DMF growth protocol. In this protocol, fiber seeds picked in HI aqueous solution are seeded to grow in DMF solution. As a result, high-quality flexible δ-CsPbI₃ SCFs with a large length-to-width ratio are obtained. The photodetector fabricated with the high-quality SCF in an Ag/CsPbI₃/Ag architecture exhibits a low dark current, excellent device stability, a higher signal-to-noise ratio and a ninefold enhancement in photo-responsivity compared with the detector made using defective crystal. These findings establish a critical link between crystal perfection and advanced photodetector functionality, offering new avenues for high-performance X-ray detection technologies.

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CsPbI₃ single-crystalline fibers prepared by seeded growth exhibit high crystal quality, excellent flexibility and enhanced photodetection performance.

This study investigates the corrosion behavior and protective potential of anodic iron oxide films fabricated on low-carbon steel in an aqueous electrolyte. The film comprises FeOOH and Fe₂O₃, with inherent microcracks and pores attributed to stress accumulation and volumetric expansion during growth. Corrosion responses in 3.5 wt% NaCl, deionized water, and 5 wt% CuSO₄ solution were systematically evaluated via potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and copper sulfate spot tests. Results confirm the film’s physical barrier effect. It exhibited enhanced corrosion resistance in environments devoid of aggressive ions (deionized water) or containing SO₄²⁻ (CuSO₄ solution), evidenced by elevated low-frequency impedance modulus and prolonged discoloration times. However, in Cl⁻-containing solutions, protective efficacy was severely compromised by structural defects. Chloride ions rapidly penetrated cracks/pores, accumulating at the film/substrate interface to trigger pitting corrosion and electrochemical degradation. Low-frequency EIS behavior further revealed the influence of defects on electrochemical processes at the film/substrate interface. To validate defects as the critical factor in protection failure and explore mitigation pathways, a sealing treatment was applied. Sealing effectively filled defects, significantly improving corrosion resistance—enhanced impedance in NaCl and further prolonged discoloration times in CuSO₄. This confirms the pivotal role of defects and highlights the exceptional aggressivity of Cl⁻ toward defective films. Enhancing protection for these anodic iron oxide films hinges on suppressing defect formation or employing effective sealing, while avoiding high-Cl⁻ environments.

Ferrofluids, exhibiting the combined properties of liquids and magnetic responsiveness, have diverse potential applications in science and engineering. In this study, ferrofluids were synthesised using ∼ 10 nm iron oxide nanoparticles coated with citric acid and oleic acid, dispersed in polyvinyl alcohol (PVA) and kerosene, respectively. PVA-based ferrofluids were employed to prepare solid films by casting onto glass slides, while kerosene-based ferrofluids were used to form dynamic fluid films confined between two slides. Magnetic patterning in PVA films was achieved by drying under parallel and perpendicular magnetic fields using permanent magnets. Optical micrographs revealed chain-like structures indicative of field-induced alignment. Transmission of green laser light (532 nm) through parallelly patterned PVA films produced diffraction patterns resembling those from a series of wires. In situ magnetic patterning of kerosene-based ferrofluid films was studied under parallel magnetic fields using the same laser source. The diffraction patterns showed continuous lobes instead of sharp spots, attributed to the absence of perfectly periodic chain-like structures with uniform chain spacing. Magnetochromatic effects were observed as colour changes under white light illumination: perpendicularly patterned PVA films exhibited distinct colour modulation, while kerosene-based films showed a transition from yellow to red in CCD images. UV–Vis optical absorption measurements indicated that the magnetic field modifies the chromatic properties of ferrofluids, as demonstrated by a corresponding shift in their optical band gap. These observations confirm that ferrofluids can act as tunable optical gratings suitable for optical switches, filters, and sensors. Dielectric studies (100–1 MHz) of kerosene-based ferrofluids further revealed a decrease in dielectric constant and loss with increasing frequency, both influenced by applied magnetic fields, demonstrating the potential of these ferrofluids as magnetically tunable liquid dielectrics.

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In order to address the problems of antibiotic contamination in the aquatic environment, in this research, ZnSn(OH)₆/Cu₂O (ZHS/Cu₂O) composites were prepared by incorporating Cu₂O into ZnSn(OH)₆, in the process, Cu₂O nanoparticles were uniformly wrapped on the surface of ZHS cubes, and then in situ degradation of tetracycline hydrochloride (TC) was carried out under visible light. The optical, photovoltaic and photocatalytic properties of ZHS/Cu₂O composites could be modulated by varying the doping amount of Cu₂O in the material preparation. As expected, the optimal ZHS/Cu₂O-2 showed high photocatalytic performance after 90 min (the removal rate of TC was 93.4%), and clarified the promoting effect of water flow vibration on the photocatalytic degradation of the system. Based on the experimental results, we proposed the formation of p–n heterojunction on ZHS/Cu₂O and the transfer path of hole-electron pairs, and speculated the reaction mechanism of photocatalytic degradation of TC. This work provides a reasonable and simple strategy for the practical application of copper-based double hydroxide semiconductor catalytic materials in the field of antibiotics for environmental water treatment.

This study investigates how varying radio frequency (RF) plasma power influences nitrogen doping efficiency and mechanical bending performance in reduced graphene oxide (GO) and functionalized graphene oxide-poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (rGO-PEDOT:PSS) nanocomposites. This works also explained on how the conductive polymer matrix affects nitrogen doping stability and sensor performance under different plasma conditions. This is crucial for developing reliable, flexible sensors for wearable and rehabilitation technologies, where materials must endure repeated mechanical stress while maintaining electrical functionality. Structural and chemical analyses using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) revealed that nitrogen doping initiates at just 10 W, with optimal doping levels of 10.2% in NrGO and 13.4% in NrGO-PEDOT:PSS was achieved at 40 W. Notably, the presence of graphitic-N configurations in NrGO were sustained only up to 20 W, whereas NrGO-PEDOT:PSS maintained these configurations up to 80 W, demonstrating superior chemical and structural stability. The PEDOT:PSS matrix was found to encapsulate and protect the GO sheets during plasma exposure, shielding them from some of the detrimental effects of the plasma treatment, such as excessive oxygen removal or physical damage. Bending sensor tests confirmed that NrGO-PEDOT:PSS maintained stable performance up to 80 W, outperforming pristine NrGO. These findings highlight the synergetic benefits of combining GO with PEDOT:PSS, offering a promising route toward high-performance, flexible bending sensors for applications such as ankle rehabilitation sensors.

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The laminated heterogeneous microstructure consisting of alternating ultrafine-grained (UFG) and coarse-grained (CG) layers with pronounced Mn concentration gradients was successfully developed in the Fe-0.2C-8.5Mn-1.5Al lightweight medium-Mn steel via a combined hot-rolling, cold-rolling, tempering, and annealing route. Microstructural evolution and underlying strengthening mechanisms of the heterogeneous microstructure during plastic deformation were systematically elucidated, with particular attention to the pronounced hetero-deformation induced (HDI) strengthening and the superior work-hardening response. The T6A660 specimen demonstrated optimal mechanical properties, with an ultimate tensile strength of 1392.4 MPa, an elongation of 51.0%, and a product of strength and ductility reaching 71.01 GPa·%. Its work-hardening process can be divided into four deformation stages, with the third stage playing a decisive role in balancing strength and ductility. This stage is characterized by the most pronounced reduction in austenite fraction, where the intensified TRIP effect provides substantial work hardening, thereby delaying necking and enhancing the overall mechanical performance. In contrast, the T6A700 specimen experienced brittle fracture, primarily due to the reduced stability of austenite.