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Preliminary Characterization of Glass/Alumina Composite Using Laser Powder Bed Fusion (L-PBF) Additive Manufacturing
摘要： Powder bed fusion (PBF) additive manufacturing (AM) is currently used to produce high-efficiency, high-density, and high-performance products for a variety of applications. However, existing AM methods are applicable only to metal materials and not to high-melting-point ceramics. Here, we develop a composite material for PBF AM by adding Al2O3 to a glass material using laser melting. Al2O3 and a black pigment are added to a synthesized glass frit for improving the composite strength and increased laser-light absorption, respectively. Our sample analysis shows that the glass melts to form a composite when the mixture is laser-irradiated. To improve the sintering density, we heat-treat the sample at 750°C to synthesize a high-density glass frit composite. As per our X-ray diffraction (XRD) analysis to confirm the reactivity of the glass frit and Al2O3, we find that no reactions occur between glass and crystalline Al2O3. Moreover, we obtain a high sample density of ≥95% of the theoretical density. We also evaluate the composite’s mechanical properties as a function of the Al2O3 content. Our approach facilitates the manufacturing of ceramic 3D structures using glass materials through PBF AM and affords the benefits of reduced process cost, improved performance, newer functionalities, and increased value addition.
关键词： density,powder bed fusion,additive manufacturing,mechanical property,3D printing,glass/alumina composite
更新于2025-09-23 15:21:01
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Investigation of the structural and electronic properties of InP1-xSbx alloy for mid-infrared optoelectronic applications: A TB-mBJ DFT study
摘要： The structural and electronic properties of InP1(cid:1)xSbx supercell structure at different percent of Sb incorporation have been studied under the Density Functional Theory formalism employing WIEN2K package. From the total energy calculations, the supercell lattice structures have been optimized. The structural properties have been calculated from the equation of state which suggests the supercell structures to be signi?cantly stable with a higher degree of compressive ?exibility (speci?cally, at lower percent of Sb incorporation). The contribution of the partial and total DOS (Density of States) of constituent elements to total DOS of the supercell structure has been investigated. The relativistic effects have been assimilated into the band structure calculation, along various high symmetry k directions for each supercell structure. The values obtained for band gap (both, direct and indirect), spin-orbit splitting energy and bowing coef?cient have been observed to vary signi?cantly as a function of Sb mole fraction. Moreover, a relationship has been established between band gap (both, direct and indirect) values and spin-orbit splitting energy with Sb mole fraction. The in?uence of SOC (spin-orbit coupling) effect on the parameters concerning electronic properties has also been analyzed. The effective mass values for conduction and valence sub-bands (heavy hole, light hole and spin orbit split-off hole) near the Brillouin zone has been calculated at different percent of Sb incorporation in InP1(cid:1)xSbx supercell structure. The interpretation of these results obtained suggests InP1(cid:1)xSbx material to be competent for mid-infrared optoelectronic applications.
关键词： III-V semiconductor,Electronic band structure,DOS,DFT calculation,Effective mass calculation,Structural and electronic property
更新于2025-09-23 15:21:01
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Influence of pore size of Ti substrate on structural and capacitive properties of Ti/boron doped diamond electrode
摘要： This work is aimed at understanding the influence of pore size of titanium (Ti) substrate on the capacitive properties of boron doped diamond (BDD) electrode. BDD films were deposited on Ti substrates with five different pore sizes - 2.5, 5.0, 20.0, 30.0, 50.0 mm - using hot filament chemical vapor deposition (HFCVD). The pore size of substrate was found to cause significant variations in surface structure and capacitive properties of the Ti/BDD electrodes. The optimum pore size that resulted in best surface structure and capacitive properties was found to be 30.0 mm. The Ti30.0/BDD electrode was found to possess higher sp2-C bonds content, sp3-C bond with doped boron atom, more closely interlaced grains and bigger specific surface area than other electrodes. The maximum capacitance obtained for Ti30.0/BDD electrode was 53.3 mF cm-2, with minimum impedance value Rct of 4.8 U. The minimum capacitance of 1.07 mF cm-2 was obtained for the Ti50/BDD electrode, and the maximum impedance value Rct of 290 U was obtained by the Ti20.0/BDD electrode. Furthermore, the Ti30/BDD electrode possessed a favorable electrochemical stability of capacitance retention of 89.3% after 2070 cycles. A mechanism by which pore size affects the capacitance properties of the Ti/BDD electrode is proposed and discussed in this paper.
关键词： Capacitive property,Porous titanium substrate,Boron doped diamond,Surface structure
更新于2025-09-23 15:21:01
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Grain refinement in laser manufactured Al-based composites with TiB2 ceramic
摘要： Al-based composites reinforced with TiB2 ceramics (1 wt.%, 2 wt.% and 5 wt.%) have been manufactured through selective laser melting (SLM). The results show that the densification, microstructure and mechanical properties of the SLM-processed composites are sensitive to the ceramic particle fraction. The average grain size of the composites decreased from ～6.32 μm with increasing TiB2 fraction from 1 to 5 wt.% respectively. Fine equiaxed grains with narrow size distribution were obtained for composites with relatively high amount of TiB2 particles. The effects of TiB2 ceramic fraction on grain refinement and strengthening mechanisms of SLM-processed composites were discussed. Al-based composite with 2 wt.% TiB2 ceramic was determined to be optimum, especially in the view of manufacturing quality, grain refinement and mechanical properties. The composites at an optimum fraction of 2 wt.% TiB2 exhibited high microhardness of ～127 HV0.2, tensile strength of ～444 MPa, yield strength of ～283 MPa and elongation of ～4.2% owing to collective effects of dispersion and grain refinement strengthening as well as high degree of densification. This study can readily offer reference values for laser additive manufacturing of other metal matrix composites to obtain a good compromise of strength and ductility by tuning reinforcement fraction.
关键词： Selective laser melting (SLM),Mechanical property,Al-based composites,Grain refinement,TiB2 ceramic
更新于2025-09-23 15:21:01
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Focusing properties of spirally polarized sinh Gaussian beam
摘要： The tight focusing properties of spirally polarized sinh-Gaussian beam is investigated numerically by vector diffraction theory. Results show that the optical intensity in focal region of spirally polarized sinh Gaussian beam can be altered considerably by the beam order, relative waist width and the spiral parameter that indicates the polarization spiral degree of the spirally polarized sinh Gaussian beam. Many novel focal patterns including flattop profile, focal hole axially separated focal spots and focal spot with long focal depth are evolved considerably for the suitable beam parameters. We expect such a tunable focal patterns are useful for optical manipulation of micro particles.
关键词： Vector diffraction theory,spirally polarized sinh Gaussian beam,Focusing property
更新于2025-09-23 15:21:01
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Fluorescent Platforms Based on Organic Molecules for Chemical and Biological Detection
摘要： Fluorescent platforms based on organic molecules have attracted great attention in the field of chemical and biological detection because of their high detection efficiency and sensitivity. Strategies in fluorescent platform design with controlled luminescence properties based on F?rster resonance energy transfer, excimer/exciplex formation, and metal-enhanced fluorescence mechanisms are reviewed herein. Attention is focused on the photophysical processes of fluorescent molecules in their interactions with other components as well as with the target. Color- and intensity-tunable luminescence from energy or electron transfer and the electronic structures of fluorescent molecules are discussed. On the basis of the photophysical properties of fluorescent molecules, their responsive fluorescence signals, which reflect specific inter- and intra-molecular interactions, are particularly effective for chemical and biological detection.
关键词： detection,fluorescent platform,fluorescent molecules,photophysical property,tunable luminescence
更新于2025-09-23 15:21:01
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Graphene induced sensitivity enhancement of thin-film coated long period fiber grating
摘要： In this work, the tuning property and sensitivity enhancement of the long period fiber grating (LPFG) coated with the higher refractive index film are demonstrated theoretically by integrating a monolayer graphene. The general variation rule of the mode characteristics and the resonance with the chemical potential of the graphene are explored. The polarization-independent transmission and sensing characteristics are obtained even though the optical property of the graphene is polarization-dependent. The results reveal that the sensing characteristics are significantly dependent on the tunable state of the graphene, which can be used to greatly optimize the sensing performance. By this approach, an ultrahigh sensitivity up to 28 337.5 nm/RIU is achieved, which is 2:57 times higher than that of the conventional LPFG without graphene. The sensitivity can be further optimized by integrating few-layer graphene. This tunable property at a wide range makes the graphene integrated LPFG devices without destroying the fiber integrity ideal for wide applications, such as biochemical sensing and optical modulation.
关键词： graphene,long period fiber grating,optical modulation,sensitivity enhancement,tunable property
更新于2025-09-23 15:21:01
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Highly coherent 1.5-8.3μm broadband supercontinuum generation in tapered As-S chalcogenide fibers
摘要： We reported a highly coherent broadband supercontinuum (SC) generation in As-S chalcogenide tapered fibers pumped at 3.75 μm. The fiber preforms based on As-S glasses with a core/cladding diameter ratio of 1:25 were fabricated via isolated stacked extrusion. The waist diameters of tapered fibers can be changed by controlling the parameter of homemade tapering platform to realize all-normal dispersion (ANDi) characteristic. A broadband SC generation spanning from 1.5 to 8.3 μm was obtained in a 15-cm-long tapered fiber with waist core diameter of 4.8 μm. And high coherence property of the generated SC spectrum was investigated and verified by the simulation. The effect of different waist core diameters on SC spectra coherence properties was also investigated by numerical simulation.
关键词： coherence property,tapered fiber,supercontinuum generation,Chalcogenide glass
更新于2025-09-23 15:21:01
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Thermoluminescence of single wall carbon nanotubes synthesized by hydrogen-arc-discharge method
摘要： Single Wall Carbon Nanotubes (SWNT) synthesized by the hydrogen-arc-discharge method were tested as thermoluminescent (TL) material and found to be highly resistant to gamma radiation. Gamma irradiation of the as-prepared material with doses between 1 and 20 kGy induced changes on the morphology of the SWNT, such as nanoloops, as observed by Scanning Electron Microscopy. From X-ray diffraction, the as-prepared material shows content of various forms of carbon, including nanotubes, hexagonal carbon (graphite), and rhombohedral carbon too. The full width at half maximum (FWHM) of diffraction peaks remain practically unchanged after irradiation. The glow curves show a single TL peak centered at about 449 K. Because the complex structure of the glow curves, it seems that the TL signal could be produced by a trap distribution instead of a single level of traps. To dilucidate the mechanism responsible of glow curves and the value of activation energy of traps, kinetic parameters like Eeff, ?E, and s of experimental the glow curves have been analyzed using computerized glow curve deconvolution (CGCD) considering a continuous distribution of trapping levels, peak shape and initial rise methods, as well as heuristic equations. The measured TL dosimetric properties may be summarized as follows: (a) moderate reproducibility of the TL signal (coefficient of variation 24.87%); (b) main peak activation energy of 1.206 eV; (c) threshold dose of ~1 kGy; (d) TL-sensitivity of ~7.0x10-4; (e) human bone equivalence, i.e., high-Z material, Zeff =15 and, (f) wide linear range of TL dose-response in the range 0.170–2.5 kGy.
关键词： Radiation effects,kinetic property,thermoluminescence,carbon nanotubes,dosimetric material
更新于2025-09-23 15:21:01
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Grain size dependence of tensile properties in nanocrystalline diamond
摘要： Nanocrystalline diamond (NCD) is a promising material due to its extraordinary mechanical properties, however, the research on the dependence of mechanical properties on the grain size (d) of NCD is still limited. In this paper, the mechanical behavior of 3D NCD with various d is investigated using molecular dynamics (MD) simulations. It was found that the mechanical properties of NCD are sensitive to d. The Young's modulus (E) increases with the increase of d due to the increasing fraction of grain interiors (GIs), while the failure strain (εf) decreases with the increase of d due to the decreasing fraction of grain boundaries (GBs). It was also found that the failure strength (σf) decreases with the increase of d, which could be attributed to that for larger d the stress concentration in the GBs is severer, which may make cracks initiate more easily. Similar to εf and σf, the deformation work density was found to increase with the decrease of d, indicating the enhancement of toughness of NCD when d is small. For the samples of different d, the nucleation and propagation of both transgranular and intergranular cracks are the main failure mechanisms, which is consistent with experimental observations.
关键词： Molecular dynamics simulation,Mechanical property,Nanocrystalline diamond,Tension,Grain size
更新于2025-09-23 15:21:01