Search results for "engineering.material"
showing 10 items of 2352 documents
Optimal ferromagnetically-coated carbon nanotube tips for ultra-high resolution magnetic force microscopy
2013
Using single-walled carbon nanotubes homogeneously coated with ferromagnetic metal as ultra-high resolution magnetic force microscopy probes, we investigate the key image formation parameters and their dependence on coating thickness. The crucial step of introducing molecular beam epitaxy for deposition of the magnetic coating allows highly controlled fabrication of tips with small magnetic volume, while retaining high magnetic anisotropy and prolonged lifetime characteristics. Calculating the interaction between the tips and a magnetic sample, including hitherto neglected thermal noise effects, we show that optimal imaging is achieved for a finite, intermediate-thickness magnetic coating, …
Ni alloy nanowires as high efficiency electrode materials for alkaline electrolysers
2021
Abstract The fabrication and characterization of nickel-alloy electrodes for alkaline electrolysers is reported. Three different alloys (Ni–Co, Ni–Zn and Ni–W) at different composition were studied in order to determine the optimum condition. Nanostructured electrodes were obtained by template electrodeposition into a nanoporous membrane, starting from aqueous solution containing the two elements of the alloy at different concentrations. Composition of alloys can be tuned by electrolyte composition and also depends on the difference of the redox potential of elements and on the presence of complexing agents in deposition bath. Electrochemical and electrocatalytic tests, aimed at establishin…
Fabrication and characterization of ZnO/Zn2TiO4/ZnAl2O4 composite films by using magnetron sputtering with ceramic targets
2022
Abstract Transparent conducting oxides (TCO), including ZnO/Zn2TiO4/ZnAl2O4 composite films, are of considerable importance in optoelectronic applications. We fabricated composite film assisted with DC magnetron sputtering using ceramic target material (ZnO, TiO2, and Al2O3 powders mixture). The influence of processing gases composition (0–50% O2–Ar) on film characteristics, including structural, optical, and electronic properties, is assessed. All films contain hexagonal wurtzite ZnO structure and ZnAl2O4, Zn2TiO4 spinel phases, with (002), (100), and (101) as dominant orientation by increasing oxygen contents. The transmittance of deposited films is above 81% (except for 50% oxygen), and …
Large area perovskite light-emitting diodes by gas-assisted crystallization:
2019
Halide perovskites have been gaining considerable attention recently for use in light-emitting applications, due to their bandgap tunability, color purity and low cost fabrication methods. However, current fabrication techniques limit the processing to small-area devices. Here, we show that a facile N 2 gas-quenching technique can be used to make methylammonium lead bromide-based perovskite light-emitting diodes (PeLEDs) with a peak luminance of 6600 cd m −2 and a current efficiency of 7.0 cd A −1 . We use this strategy to upscale PeLEDs to large-area substrates (230 cm 2 ) by developing a protocol for slot-die coating combined with gas-quenching. The resulting large area devices (9 device…
Periodic nanoscale patterning of polyelectrolytes over square centimeter areas using block copolymer templates
2016
© The Royal Society of Chemistry 2016. Nano-patterned materials are beneficial for applications such as solar cells, opto-electronics, and sensing owing to their periodic structure and high interfacial area. Here, we present a non-lithographic approach for assembling polyelectrolytes into periodic nanoscale patterns over cm2-scale areas. Chemically modified block copolymer thin films featuring alternating charged and neutral domains are used as patterned substrates for electrostatic self-assembly. In-depth characterization of the deposition process using spectroscopy and microscopy techniques, including the state-of-the-art scanning transmission X-ray microscopy (STXM), reveals both the sel…
Exfoliation of Alpha-Germanium: A Covalent Diamond-Like Structure
2021
2D materials have opened a new field in materials science with outstanding scientific and technological impact. A largely explored route for the preparation of 2D materials is the exfoliation of layered crystals with weak forces between their layers. However, its application to covalent crystals remains elusive. Herein, a further step is taken by introducing the exfoliation of germanium, a narrow-bandgap semiconductor presenting a 3D diamond-like structure with strong covalent bonds. Pure α-germanium is exfoliated following a simple one-step procedure assisted by wet ball-milling, allowing gram-scale fabrication of high-quality layers with large lateral dimensions and nanometer thicknesses.…
Multi-scale structural analysis of xyloglucan colloidal dispersions and hydro-alcoholic gels
2020
Xyloglucans are highly branched, hydroxyl rich polyglucans that for their abundance in nature, biocompatibility, film forming and gelation ability may take a prominent role in the design and fabrication of biomedical devices, including in situ forming scaffolds for tissue engineering, wound dressings and epidermal sensors. The understanding and exploitation of their self-assembly behavior is key for the device performance optimization. A multi-scale analysis, conducted combining small-angle X-ray scattering, both static and dynamic light scattering at large and small angles, and rheological measurements, provides a description of the supramolecular organization of this biopolymer, from the …
Rapid One-Step Fabrication of Graphene Oxide-Decorated Polycaprolactone Three-Dimensional Templates for Water Treatment
2020
Coating of flexible substrates is crucial to prepare versatile, multifunctional materials. However, exploration of effective fabrication approaches is still a challenging issue, because the pathways generally proposed require time-consuming, multistep protocols. Here, we developed a one-pot process for decorating either pearl necklace-like or fibrous fluffy-like structures of polycaprolactone (PCL) with graphene oxide (GO) skin. PCL solutions were dry jet-wet electrosprayed or electrospun into a stirred liquid collector constituted by ethanol-containing GO nanoparticles. The stirred liquid collector enables the formation of 3D-structures, whose microarchitecture can be designed by controlli…
Tunable coaxial cavity resonator for linear and nonlinear microwave characterization of superconducting wires
2011
We discuss experimental results obtained using a tunable cylindrical coaxial cavity constituted by an outer Cu cylinder and an inner Pb-BSCCO wire. We have used this device for investigating the microwave response of the superconducting wire, both in the linear and nonlinear regimes. In particular, by tuning the different modes of the cavity to make them resonant at exactly harmonic frequencies, we have detected the power emitted by the superconducting inner wire at the second- and third-harmonic frequency of the driving field. The results obtained in the nonlinear regime, whether for the microwave surface impedance or the harmonic emission, are qualitatively accounted for considering inter…
Phase evolution in hot forging of dual phase titanium alloys: Experiments and numerical analysis
2014
Abstract Modern aeronautical and aerospace industries must face the demanding challenge of reducing operational consumption and production costs coming from materials and labor. Current trend of engineering is oriented to meet both requirements increasing the use of materials characterized by high specific resistance as titanium alloys. Hot forging can be used to reduce the production costs of titanium components: forging in closed dies of billets or semi-finished forms, at different temperatures above or below the β-transus temperature, allows the production of complex shapes with limited amount of edge trim removal and machining rework after forging. Unfortunately, as far as Ti–6Al–4V tit…