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Influence of Heat Treatments on Microstructure and Mechanical Properties of Ti–26Nb Alloy Elaborated In Situ by Laser Additive Manufacturing with Ti and Nb Mixed Powder
摘要： In the present work, a Ti–26Nb alloy was elaborated in situ by laser additive manufacturing (LAM) with Ti and Nb mixed powders. The alloys were annealed at temperatures ranging from 650 °C to 925 °C, and the effects of the annealing temperature on the microstructure and mechanical properties were investigated. It has been found that the microstructure of the as-deposited alloy obtained in the present conditions is characterized by columnar prior β grains with a relatively strong <001> fiber texture in the build direction. The as-deposited alloy exhibits extremely high strength, and its ultimate tensile strength and yield strength are about 799 MPa and 768 MPa, respectively. The annealing temperature has significant effects on the microstructure and mechanical properties of the alloys. Annealing treatment can promote the dissolution of unmelted Nb particles and eliminate the micro-segregation of Nb at the elliptical-shaped grain boundaries, while increasing the grain size of the alloy. With an increase in annealing temperature, the strength of the alloy decreases but the ductility increases. The alloy annealed at 850 °C exhibits a balance of strength and ductility.
关键词： microstructure,Ti–Nb alloy,mechanical properties,in situ alloying,laser additive manufacturing,heat treatment
更新于2025-09-19 17:15:36
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Hierarchical WO3/ZnWO4 1D fibrous heterostructures with tunable in-situ growth of WO3 nanoparticles on surface for efficient low concentration HCHO detection
摘要： Hierarchical WO3/ZnWO4 1D fibrous heterostructures with tunable in-situ growth of WO3 nanoparticles on surface have been fabricated by the original one-step electrospinning technology combined with subsequent calcination process. Phase composition and morphology can be transformed from bead-like WO3 fibers to hierarchical WO3/ZnWO4 1D composites with the introduction of ZIF-8 into the precursor solution, which was mainly attributed to the combination of nucleation competition and crystal planes matching mechanisms during heat treatment. Compared with pure WO3 and WO3/ZnWO4-10%, WO3/ZnWO4-5% displayed the highest specific surface area value evaluated to be 268.57, indicating the prominent enhanced absorption behavior for targeted organic species. It is found that WO3/ZnWO4-5% composites have a response about 44.5 for 5 ppm HCHO, which was almost 8 times higher than that of sensor based on pure WO3 nanofibers at the optimal operating temperature. Meanwhile, the fast response/recovery time (12/14 s) and excellent stability characteristics (recycling, long-term, and humidity stability) towards HCHO can be also observed for WO3/ZnWO4-5% samples. The enhanced gas-sensing mechanism based on WO3/ZnWO4 composites can be ascribed to the synergistic effect of effective heterojunctions, large specific surface area, multiple reaction sites, and unique surface/interface electron transmission. The design and construction of hierarchical WO3/ZnWO4 1D materials attest to the significant potential of their use as novel gas sensors for detecting low concentration HCHO.
关键词： electrospinning,gas sensors,in-situ growth,HCHO,WO3/ZnWO4 heterostructures
更新于2025-09-19 17:15:36
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European Microscopy Congress 2016: Proceedings || An in-situ Low Energy Argon Ion Source for Local Surface Modification
摘要： A new in-situ low energy ion source for surface modification of a sample surface has been designed. The source is based on the principle of low energy ion bombardment from a beam of ions such as Ar+, N+, or He+ can be used for a local modification of the sample surface. Typical energies are in the range 10 - 100 eV, covering the interaction types from chemical reaction to ion etching and to ion implantation. The source is based on the following principle: electrons from a filament are accelerated towards a grid by a potential difference between the filament and the grid. The electrons enter a gas-filled region between the grid and the sample, where they ionize the gas. The ions are then accelerated towards the sample by a potential difference between the grid and the sample. The source produces a static beam of ions with a selectable energy of 10-100 eV and a full width half maximum (FWHM) of 7.1 um. This corresponds to a central ion current density of 0.019 nA/um2 at 100 eV, which is very similar to the current density at 100 eV of a regular ICP source. In this way, the sample area that is affected by the low energy ions can be more or less defined by the applied bias voltage. The first application can be polishing the top surface of a TMD laminate produced by CVD, or improvement of and LPE surface prepared by ICP. An example of the interaction with the beam is shown in Figure 1, where a native oxide on Si has been removed in 25 seconds, using 100 eV Ar+ ions.
关键词： Ar+,surface modification,low energy ion source,chemical reaction,FWHM,native oxide removal,ion etching,ICP,current density,static beam,N+,ion bombardment,TMD,He+,LPE,ion implantation,in-situ,gas ionization,filament,grid,CVD
更新于2025-09-19 17:15:36
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Wearable piezoelectric nanogenerators based on reduced graphene oxide and in situ polarization-enhanced PVDF-TrFE films
摘要： PVDF-TrFE-based wearable nanogenerators were designed and fabricated with enhanced performances via reduced graphene oxides (rGO) and in situ electric polarization. Our laboratory-made polarization system may complete the in situ poling of PVDF-TrFE films in 5 min without heating, which has the advantages of high production efficiency, excellent piezoelectric performances, and favorable uniformity, compared to traditional poling approaches. The addition of rGO into PVDF-TrFE significantly improved the crystallinity of the b-phase PVDF-TrFE and enhanced the formation of hydrogen bonds via interaction of dipoles between rGO and PVDF-TrFE. This further improved the energy-harvesting performances of these piezoelectric nanogenerators with 1.6 times of the open-circuit voltage and 2 times of the power density than that of pure PVDF-TrFE-based devices. The high production efficiency and excellent piezoelectric performances of in situ polarized rGO/PVDF-TrFE make them of great potential for self-powered, wearable/portable devices.
关键词： Electronic materials,Reduced graphene oxide,PVDF-TrFE,Wearable piezoelectric nanogenerators,In situ polarization
更新于2025-09-19 17:15:36
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Electronic surface, optical and electrical properties of p – GaN activated via in-situ MOCVD and ex-situ thermal annealing in InGaN/GaN LED
摘要： Electronic surface properties, optical and electrical characteristics of p-type Mg-doped Gallium Nitride (p-GaN) activated under different thermal annealing condition were investigated. In this work, p-GaN samples were subjected to in-situ and ex-situ thermal annealing process at 650°C in Nitrogen (N2) rich condition. In-situ annealing process took place in Metal Oxide Chemical Vapor Deposition (MOCVD) chamber while ex-situ annealing process was carried out in the conventional oven. X-Ray and Ultraviolet Photoemission Spectroscopy (XPS/UPS) were used to observe the energy alignment of the p-GaN surface. From PES spectra, the sample subjected to in-situ thermal annealing shown to exhibit lower surface bend bending of 0.28 eV as compared to ex-situ thermal annealing activation with 0.45 eV band bending. This result is in agreement with specific contact resistance measurement that shows in-situ sample exhibits lower resistance resulted in better carrier injection from metal to p-GaN. Photoluminescence (PL) spectra elucidates that in-situ sample has a good surface quality with less nitrogen related vacancies (VN) formed on the p-GaN surface. All these results are further proved with the higher output power from LED with in-situ annealing. At 20 mA, in-situ sample shown an increment of ~14% light output power compared to ex-situ sample. Results obtained in this work suggest that the thermal activation condition for p-GaN activation process plays an active role on the surface quality as well as the energy alignment of the film surface and shows the potential of in-situ p-GaN activation for tunnel junction structure.
关键词： ex-situ,p-GaN,in-situ,thermal annealing,LED
更新于2025-09-19 17:13:59
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Thermally Stable Aua??BaTiO <sub/>3</sub> Nanoscale Hybrid Metamaterial for High-Temperature Plasmonic Applications
摘要： The thermal stability of the Au?BaTiO3 nanocomposite thin film as a hybrid metamaterial deposited by a one-step pulsed laser deposition (PLD) method has been investigated via both ex situ annealing followed by TEM analysis and an in situ heating study in TEM. For the ex situ annealing study, the XRD analysis shows good crystallinity for both as-deposited and annealed films after being annealed at 600 °C for different time periods (i.e. 1, 3, 6, and 30 hours). The optical measurements including transmittance/reflectance, ellipsometry, and Raman spectroscopy demonstrate excellent optical properties of the hybrid metamaterial films by exhibiting the static localized surface plasmon resonance (LSPR) peak and hyperbolic dispersion in the visible to near-infrared regime. Both TEM results of the ex situ annealed samples and in situ heating TEM results reveal no obvious microstructure change after the extensive high-temperature annealing and suggest the high thermal stability of the Au?oxide hybrid materials for their future high-temperature plasmonic applications.
关键词： crystallinity,localized surface plasmon resonance,in situ,hyperbolic dispersion,hybrid metamaterial,thermal stability,ex situ
更新于2025-09-19 17:13:59
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Laser machined ultrathin microscale platinum thermometers on transparent oxide substrates
摘要： Ultrathin microscale platinum resistive thermometers are of key value to transient temperature measurements. Neither transparent oxide substrates nor femtosecond laser patterning have been investigated for the fabrication of Pt thin film thermometers. Here, we have fabricated a laser machined, 50 μm wide and 50 nm thick, serpentine, Pt thin film sensor capable of sensing temperatures up to 650 oC. It is anticipated that this sensor can be used for fast, high spatial resolution temperature probing for laser processing applications.
关键词： Platinum,temperature sensor,thin film,in-situ,laser machining
更新于2025-09-19 17:13:59
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Trace level toxic ammonia gas sensing of single-walled carbon nanotubes wrapped polyaniline nanofibers
摘要： This paper presents a two-step enhancement and a comprehensive analysis of single-walled carbon nanotubes (SWCNTs) wrapped polyaniline nanofiber (NPANI) ammonia (NH3) gas sensor at room temperature. SWCNT-PANI composites are successfully synthesized using an efficient and cost-effective rapid in situ chemical polymerization method. The structural morphology and modification of the samples are characterized using field-emission scanning electron microscopy and HRTEM. FTIR and Raman spectroscopic studies are also performed to gain a better insight into the chemical environmental interaction in the as-prepared nanocomposite. The analysis confirms the successful formation of the nanocomposite. The observed NH3 gas-sensing response at 10 ppm of SWCNT, f-SWCNT (functionalised SWCNT), and SWCNT-PANI composite sensors are 5%–6%, 18%–20%, and 24%–25%, respectively. The SWCNT-PANI composite sensors have shown higher repeatability, selectivity, long-term stability, and fast response-recovery characteristics as compared to f-SWCNTs and pristine SWCNT sensors. Concentration and temperature dependent gas-sensing studies are also analyzed. The sensor response also shows a linear relationship with NH3 gas concentration and an inverse relationship with increasing temperature.
关键词： Raman spectroscopy,rapid in situ chemical polymerization,ammonia gas sensor,polyaniline nanofiber,field-emission scanning electron microscopy,FTIR,HRTEM,room temperature,single-walled carbon nanotubes
更新于2025-09-19 17:13:59
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Optical Pooled Screens in Human Cells
摘要： A screening approach that combines high-content imaging with in situ sequencing can identify genes that affect spatially and temporally defined phenotypes like morphology and subcellular localization, expanding the list of scientific questions that can be asked with genetic tools.
关键词： genetic perturbations,in situ sequencing,high-content imaging,optical pooled screens,cellular phenotypes
更新于2025-09-19 17:13:59
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Light-induced Polymer Response Through Thermoplasmonics Transduction in Highly Monodisperse Core-Shell-Brush Nanosystems
摘要： Smart nanosystems that transduce external stimuli to physical changes are an inspiring challenge in current materials chemistry. Hybrid organic-inorganic materials attract great attention due to the combination of building blocks responsive to specific external solicitations. In this work, we present a sequential method for obtaining an integrated core-shell-brush nanosystem that transduces light irradiation into a particle size change through a thermoplasmonic effect. We first synthetize hybrid monodisperse systems made up of functionalized silica colloids covered with controllable thermo-responsive Poly(N-isopropylacrylamide), PNIPAm, brushes, produced through radical photopolymerization. This methodology was successfully transferred to Au@SiO2 nanoparticles, leading to a core-shell-brush architecture, in which the Au core acts as a nano-source of heat; the silica layer, in turn, adapts the metal and polymer interfacial chemistries and can also host a fluorescent dye for bioimaging. Upon green LED irradiation, a light-to-heat conversion process leads to the shrinkage of the external polymer layer, as proven by in situ DLS. Our results demonstrate that modular hybrid nanosystems can be designed and produced with photo-thermo-physical transduction. These remote-controlled nanosystems present prospective applications in smart carriers, responsive bioscaffolds or soft robotics.
关键词： photothermal effect,hybrid materials,in-situ DLS,UV-photo induced polymerization,core-shell-brush colloids,Smart nanosystems
更新于2025-09-19 17:13:59