Search Results (1,338)

Diamond has been extensively examined as an appealing material for use in quantum optics and quantum information processing owing to the existence of various classes of optically active defects, referred to as “color centers,” which can be engineered into its crystal structure. Among these defects, the negatively charged nitrogen-vacancy center (NV⁻) stands out as the most prominent type. Despite the progress made, the number of emitters characterized by reproducible fabrication processes within the desired spectral range at room temperature, with limited or no damage to the parent diamond lattice, remains restricted. Herein, we are proposing for the first time the creation of the FV⁻ center in diamond via low-energy implantation, which is particularly interesting as it possesses characteristic light absorption and magnetic properties similar to NV⁻ centers. The low-energy ion-implanted FV centers in diamond show more desirable optical emission properties at room temperature (RT). Additionally, as per DFT calculations, the flat bands near the Fermi energy indicate dominant electron–electron interactions, an important prerequisite for observing emergent behavior as seen in systems such as twisted bi-layer graphene. Consequently, as-developed new luminescent defects such as Fluorine Vacancy Centers (FV) with desirable spectral and quantum emission properties would be a significant breakthrough in diamond-based quantum materials. Full article

In recent years, diagnostic technologies that utilize noninvasively collected sweat have garnered significant interest. However, the concentration of components in sweat is lower than that in blood, making the introduction of a concentration step as a sample pretreatment crucial for achieving highly sensitive detection. In this study, we developed a PDMS-based microchannel filled with silica gel, a desiccant particle, to concentrate liquid samples at room temperature without requiring an external power source or heating. The evaluation of the basic characteristics of the fabricated microchannel confirmed that filling it with silica gel efficiently removed the solvent vapor from the liquid samples. In concentration tests using the fluorescent dye uranine as a model for sweat sugar, a maximum 1.4-fold concentration was achieved in DPBS solution and a 1.2-fold concentration in artificial sweat at room temperature. In contrast, no similar concentration effect was observed in microchannels without silica gel packing. The proposed silica-gel-packed PDMS microchannel features a simple structure and requires no external equipment, making it easily integrable with existing microfluidic devices as a sample pretreatment module. This method is considered useful as a passive and simple sample concentration technique for the analysis of low-molecular-weight components in sweat. Full article

Microparticle detection technology uses materials that can specifically recognize complex biostructures, such as antibodies and aptamers, as trapping agents. The development of antibody production technology and simplification of sensing signal output methods have facilitated commercialization of disposable biosensors, making rapid diagnosis possible. Although this contributed to the early resolution of pandemics, traditional biosensors face issues with sensitivity, durability, and rapid response times. We aimed to fabricate microspaces using metallic materials to further enhance durability of mold fabrication technologies, such as molecular imprinting. Low-damage metal deposition was performed on target protozoa and Norovirus-like particles (NoV-LPs) to produce thin metallic films that adhere to the material. The procedure for fitting the object into the bio structured space formed on the thin metal film took less than a minute, and sensitivity was 10 fg/mL for NoV-LPs. Furthermore, because it was a metal film, no decrease in reactivity was observed even when the same substrate was stored at room temperature and reused repeatedly after fabrication. These findings underscore the potential of integrating stable metallic structures with bio-recognition elements to significantly enhance robustness and reliability of environmental monitoring. This contributes to public health strategies aimed at early detection and containment of infectious diseases. Full article

This study introduces a synergistic drop-casting, sonication, and thermal treatment (DSTT) method for fabricating multi-walled carbon nanotube (MWCNT)-coated conductive cotton fabrics. The process produced uniform MWCNT networks with a minimum sheet resistance of 0.072 ± 0.004 kΩ/sq. at ~30 wt.% loading. Scanning electron microscopy confirmed an improved MWCNT network. Reproducibility was demonstrated for different fabric sizes, with resistance values remaining consistent within experimental errors. Stability tests showed only minor changes in sheet resistance after 16 weeks of ambient storage and periodic manual bending. Compared to conventional methods such as room-temperature drying, vacuum drying, and sonication alone, DSTT consistently performed better, yielding fabrics with lower resistance and more reliable conductivity. These results highlight DSTT as a reproducible and scalable method for producing conductive cotton fabrics suitable for smart textiles and wearable electronics. Full article

Laser cladding is an effective surface engineering technique to enhance the high-temperature performance of metallic materials. In this work, a Cr-Al-C composite coating was in situ fabricated on H13 steel by laser cladding to alleviate the performance degradation of H13 steel under severe thermomechanical conditions, particularly in high-temperature piercing applications. The phase composition, microstructure, microhardness, high-temperature oxidation behavior, and tribological performance of the coating were systematically investigated. The coating is mainly composed of a B2-ordered Fe-Cr-Al phase reinforced by uniformly dispersed M₃C₂/M₇C₃-type carbides, which provides a synergistic combination of oxidation protection and mechanical strengthening, offering a microstructural design that differs from conventional Cr-Al or Cr₃C₂-based laser-clad coatings. Cyclic oxidation tests conducted at 800–1000 °C revealed that the oxidation behavior of the coating followed parabolic kinetics, with oxidation rate constants significantly lower than those of the H13 substrate, attributed to the formation of a dense and adherent Al₂O₃/Cr₂O₃ composite protective scale acting as an effective diffusion barrier. Benefiting from the stable oxide layer and the thermally stable carbide-reinforced microstructure, the wear rate of Cr-Al-C coating is significantly reduced compared to H13 steel. At room temperature, the wear rate of the coating is 6.563 × 10⁻⁶ mm³/(N·m), about two orders of magnitude lower than 8.175 × 10⁻⁴ mm³/(N·m) for the substrate. When the temperature was increased to 1000 °C, the wear rate of the coating remained as low as 5.202 × 10⁻⁶ mm³/(N·m), corresponding to only 1.9% of that of the substrate. This work demonstrates that the Cr-Al-C laser-cladded coating can effectively improve the high-temperature oxidation resistance and wear resistance of steel materials under extreme service conditions. Full article

The present paper reports the preparation of a nanocomposite thin film consisting of calcium itaconate and graphene oxide (GO). The composite is a black powder consisting of individual shiny prismatic crystals at varying degrees of maturity. The crystal size distribution is quite narrow: from 3.6 to 6.2 μm in length and from 0.7 to 1.1 μm in width. Thin-film-based acetone sensor made of a nanocomposite was fabricated by spin coating of calcium itaconate–GO nanoparticles on glass plates. The thin-film acetone sensor was characterized using FTIR, XRD, SEM, TEM, and the low-temperature nitrogen sorption–desorption method. The sensor response time is 7.66 ± 0.07 s (s_r = 0.92%), and the relaxation time when blowing the surface with clean air or inert gas (nitrogen, argon) is 9.26 ± 0.12 s (s_r = 1.28%). The sensing mechanism of the sensor for detecting acetone at room temperature was also is proposed based on phenomenological understanding due to the absence of direct electronic/charge-transport evidence. Full article

Silicon carbide (SiC) ceramics are regarded as high-performance structural materials due to their excellent high-temperature strength, wear resistance, and thermal stability. However, their inherent high brittleness, low fracture toughness, and difficulty in densification have limited their wider application. To overcome these challenges, introducing a second phase and/or sintering aids is necessary. In this paper, SiC–AlN–VC multiphase ceramics were fabricated via spark plasma sintering at 1800 °C to 2100 °C. The interface, mechanical, and thermal properties were examined. It was found that the VC particles effectively pin the grain boundaries and suppress the abnormal growth of SiC grains. At temperatures exceeding 1800 °C, the N atoms released from the decomposition of AlN diffuse into the VC lattice, forming a V(C,N) solid solution that enhances both the toughness and strength of the ceramics. With increasing sintering temperature, the mechanical properties of the SiC multiphase ceramics first improve and then deteriorate. Ultimately, a nearly fully dense SiC multiphase ceramic is obtained. The maximum hardness, flexural strength, and fracture toughness of SAV20 are 28.7 GPa, 508 MPa, and 5.25 MPa·m^1/2, respectively. Furthermore, the room-temperature friction coefficient and wear rate are 0.41 and 3.41 × 10⁻⁵ mm³/(N·m), respectively, and the thermal conductivity is 58 W/(m·K). Full article

This paper presents a practical thermal control strategy to enhance the output performance of oxide-based all-solid-state batteries (ASSBs), which typically exhibit low ionic conductivity at room temperature. A lightweight polyimide (PI) film heater was designed, fabricated, and integrated into the cell stack to locally maintain the optimal operating temperature range (≈65–75 °C) for electrolyte activation. Unlike previous studies limited to liquid or sulfide-based batteries, this work demonstrates the direct integration and coupled numerical–experimental validation of a PI film heater within oxide-based ASSBs. The proposed design achieves high heating efficiency (~92%) with minimal thickness (<100 μm) and long-term stability, enabling reliable and scalable thermal management. Finite-element simulations and experimental verification confirmed that the proposed heater achieved rapid and uniform heating with less than a 10 °C temperature deviation between the cell and heater surfaces. These findings provide a foundation for smart battery management systems with distributed temperature sensing and feedback control, supporting the development of high-performance and reliable solid-state battery platforms. Full article

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes typically suffer from limited ionic conductivity at near-room temperature and often require inorganic reinforcement. Halide solid-state electrolytes such as Li₃InCl₆ (LIC) offer fast Li⁺ transport but are moisture-sensitive and typically require pressure-assisted densification. Here, we fabricate a flexible LIC–PEO composite electrolyte via slurry casting in acetonitrile with a small amount of LiPF₆ additive. The free-standing membrane delivers an ionic conductivity of 1.19 mS cm⁻¹ at 35 °C and an electrochemical stability window up to 5.15 V. Compared with pristine LIC, the composite shows improved moisture tolerance, and its conductivity can be recovered by mild heating after exposure. The electrolyte enables stable Li|LIC–PEO|Li cycling for >620 h and supports Li|LIC–PEO|NCM111 cells with capacity retentions of 84.2% after 300 cycles at 0.2 C and 80.6% after 150 cycles at 1.2 C (35 °C). Structural and surface analyses (XRD, SEM/EDX, XPS) elucidate the composite microstructure and interfacial chemistry. Full article

Fibre-reinforced polymer (FRP) composites are key materials used in the fabrication of lightweight and high-performance structures. Thus, a comprehensive understanding of material performance is required to ensure the safe and reliable operation of FRPs across a broad range of temperatures. For example, the application of FRPs in cryogenic environments, especially for lightweight cryogenic fuel storage, is gaining considerable attention. However, obtaining accurate tensile property measurements for FRPs can be challenging, as failure of the test specimen near the grips is common, even at room temperature. Under cryogenic conditions, the increased complexity of the experimental setup further reduces the accuracy and reproducibility of the tensile properties. This paper reviews standard test methods for tensile testing of FRPs and discusses the challenges of performing tensile tests in both room and cryogenic environments. Key experimental design considerations and directions for future research are identified to support the development of reliable tensile test methods that yield accurate and consistent measurements of FRP material properties. Full article

Owing to its narrow bandgap and excellent thermal stability, formamidinium–lead triiodide (FAPbI₃) is a promising perovskite for high-performance, wide-spectrum photodetectors. Here, we selected long-chain n-heptanoic acid as the passivating agent and introduced it onto the perovskite surface via post-treatment, thereby enabling the fabrication of high-quality α-FAPbI₃ perovskite films and photodetectors. It is found that the carboxylic acid group in the n-heptanoic acid molecule can effectively passivate crystal defects, greatly reduce the density of defect states in the perovskite film, and inhibit the non-radiative recombination of carriers. The α-FAPbI₃ perovskite phase was effectively stabilized. The responsivity of the photodetector optimized by n-heptanoic acid is as high as 0.47 A W⁻¹ at 740 nm. At the same time, the optimized device still maintains 95% of its initial performance after 552 h of storage in an air environment with a room temperature of 25 °C and a relative humidity of 25%. This method provides a reliable way to prepare a high-performance and stable α-FAPbI₃ photodetector. Full article

An IN738 alloy with a high Al and Ti contents induces a significant cracking tendency during laser powder bed fusion (LPBF) processing, leading to a mismatch between printability and mechanical properties. Modification of alloy compositions is an effective strategy to enhance the printability and mechanical properties of nickel-based superalloys via LPBF. In this study, the effects of adding 5 wt.%Co on the printability and mechanical properties of LPBF-fabricated IN738 were investigated by using three-dimensional high-resolution micro-computed tomography (micro-CT), electron backscatter diffraction (EBSD), and quasi-static room-temperature tensile tests. The results show that adding 5 wt.%Co can significantly reduce the defect rate and defect size of the LPBF-fabricated IN738 alloy, remarkably improve alloy densification, and optimize printability. Meanwhile, compared with the LPBF-fabricated IN738 alloy, the 5 wt.%Co-IN738 alloy exhibits an excellent balance of strength and ductility in horizontal and vertical directions, both LPBF-fabricated and heat-treated. These results are anticipated to offer valuable guidance for the development of LPBF-fabricated Ni-based superalloys that achieve a favorable balance between printability and mechanical properties. Full article

Traditional colloid SERS substrates are mostly based on metal nanoparticles (MNPs), which have complex and time-consuming fabrication processes, poor structural control, and are susceptible to oxidation. As a result, solid-state SERS substrates have emerged as an effective alternative. Here, we propose using two-step mild and hard anodization to fabricate ordered anodic aluminum oxide (AAO) substrates with high total pore circumference for SERS detection. Hybrid pulse anodization (HPA) enables the fabrication of AAO at room temperature using 40 V in the first step and 40, 110, and 120 V in the second step of anodization. The different voltages applied in the second step effectively control the pore diameter, thereby achieving various nanostructures. The enhancement mechanism primarily originates from the high total pore circumference of nanostructures, which generates abundant hot spots around the pore peripherals, thereby significantly amplifying the SERS signal. Sorbic acid is a common preservative widely used in food products and employed as a test substance on high regularity AAO substrates at concentrations of 1000 ppm to 10 ppb. The resulting SERS spectra exhibited distinct characteristic peaks at 1640–1645 cm⁻¹. The analytical enhancement factor is calculated as 1.02 × 10⁵ at the AAO substrate prepared by 110 V with the Si substrate as the reference. By appropriately tuning the process parameters, a limit of detection (LOD) as low as 10 ppb of sorbic acid was achieved. Full article

B₄C-HfB₂-SiC (BCHS) ceramic composites were fabricated by in situ reaction with B₄C and HfSi₂ mixed powders through spark plasma sintering in this work. Effects of sintering temperature and sintering additive (HfSi₂) content on the density, microstructure, and mechanical properties of the BCHS specimens were studied. The BCHS composite containing 15–30 vol.% HfSi₂ reached over 98% theoretical density in the temperature range of 1600–1750 °C under the pressure of 50 MPa. The Vickers hardness, fracture toughness, and room temperature flexural strength of BCHS sintered at 1650 °C with 25 vol.% HfSi₂ reached a maximum value of 31.3 GPa, 5.6 MPa·m^1/2, and 573.9 MPa, respectively. The flexural strength was not decreased at elevated temperatures, and the flexural strength at temperatures of 400 °C, 600 °C, and 800 °C was evaluated to be 540.7 MPa, 518.8 MPa, and 586.9 MPa, respectively. Dense B₄C-HfB₂-SiC composites were fabricated by the spark plasma sintering process. The introduction of HfSi₂ can significantly enhance the density and mechanical properties of B₄C ceramic. Full article

In this study, the influence of post-processing heat treatment on microstructure and mechanical properties of Ti-6Al-2Sn-4Zr-2Mo (Ti-6242) alloy fabricated by laser powder bed fusion (L-PBF) was investigated. The mechanical properties of the as-built and heat-treated samples with various temperatures (600–850 °C) were evaluated using a tensile test at room temperature. After heat treatments, both yield strength (YS) and ultimate tensile strength (UTS) gradually decreased, while the tensile elongation tended to increase as the heat treatment temperature increased. These variations were closely related to the microstructural evolution caused by heat treatment. Specifically, the decomposition of α′ martensite into the α + β lamellar structure and subsequent coarsening were promoted with increasing temperature, leading to stress relief and improved dislocation storage capability, which resulted in the variation in mechanical properties. Notably, although the mechanical strength was reduced after heat treatment with increasing temperatures, the lowest yield strength and ultimate tensile strength were measured as 1086.4 ± 16.5 and 1135.0 ± 15.0 MPa, respectively, which are comparable to or higher than those of conventionally processed Ti-6242. As a result, the post-processing heat treatment could be an effective approach to achieve desirable performance for targeted applications. Full article