Search results for "Metals"
showing 10 items of 2013 documents
Influence of Nb-doping on the local structure and thermoelectric properties of transparent TiO2:Nb thin films
2020
The experiment at HASYLAB/DESY was performed within the project I-20180036 EC. The research leading to this result has been supported by the project CALIPSOplus under the Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020. Filipe Correia is grateful to the Fundação para a Ciência e Tecnologia (FCT, Portugal) for the Ph.D. Grant SFRH/BD/111720/2015 . Joana Ribeiro is grateful to the Project WinPSC - POCI-01-0247-FEDER-017796, for the research grant, co-funded by the European Regional Development Fund (ERDF) , through the Operational Programme for Competitiveness and Internationalisation (COMPETE 2020), under the PORTUGAL 2020 Partnership Agreement…
Local structure relaxation in nanocrystalline Ni1−xO thin films
2014
Abstract Non-stoichiometric nickel oxide (Ni 1 − x O) thin films were prepared by DC magnetron sputtering technique in mixed Ar/O 2 atmosphere and studied by synchrotron radiation Ni K-edge x-ray absorption spectroscopy, x-ray diffraction and scanning electron microscopy. The use of advanced modelling technique, combining classical molecular dynamics with ab initio multiple-scattering extended x-ray absorption fine structure calculations, allowed us to describe the structure relaxation and dynamics in nanocrystallites and to estimate their size and the concentration of nickel vacancies.
Terahertz spectroscopy for all-optical spintronic characterization of the spin-Hall-effect metals Pt, W and Cu80Ir20
2018
Identifying materials with an efficient spin-to-charge conversion is crucial for future spintronic applications. In this respect, the spin Hall effect is a central mechanism as it allows for the interconversion of spin and charge currents. Spintronic material research aims at maximizing its efficiency, quantified by the spin Hall angle and the spin-current relaxation length . We develop an all-optical contact-free method with large sample throughput that allows us to extract and . Employing terahertz spectroscopy and an analytical model, magnetic metallic heterostructures involving Pt, W and Cu80Ir20 are characterized in terms of their optical and spintronic properties. The validity of our …
Wavelet and fractal approach to surface roughness characterization after finish turning of different workpiece materials
2009
In this paper, the surface profiles generated in longitudinal turning operations were characterized using continuous wavelet transform (CWT) and normalized fractal dimension Dn. In the comparative analysis, some characteristic roughness profiles after the turning of different workpiece materials, such as C45 medium carbon steel, nodular cast iron and hardened (55 HRC) high-strength alloy steel were selected. For wavelet characterization, both Morlet and ‘Mexican hat’ analyzing wavelets, which allow the assessment of extrema and frequency distribution, were utilized. The results of the CWT as a function of profile and momentary wavelet length are presented. It is concluded that CWT can be us…
Defect characterization in Al welded joints by non-contact Lamb wave technique
2006
Abstract The use of air-coupled sensors to detect flaws in Al welded joints and the advantage of Lamb wave for their characterization has been proved. Ultrasonic waves were generated by a pulsed laser and by contact angle-beam transducer, and received by an air-coupled capacitive transducer. Laser-based configuration was used to quickly locate the defect, whereas the angle-beam contact probe configuration to characterize it thanks to the dispersive behavior of Lamb waves. Guided waves allow inspection of the complete thickness with only one scan, permitting to detect and to size both internal and surface defects; their high flexibility in the measurement is due to the various parameters cha…
Non-destructive technique to detect local buried defects in metal sample by scanning microwave microscopy
2012
International audience; Based on the skin effect, our recent developments using scanning microwave microscopy lead to propose a non-destructive method to detect located buried defect in metal samples like stainless steel. A 3D tomography is possible by taking advantage of microwave measurement, using a vector network analyzer in bandwidth frequencies, and the nanometer resolution positioning capabilities with atomic force microscopy. At each used frequency, an incident electromagnetic wave is sent to the sample and the reflected wave gives information on a specific depth layer in the material. With diagnostic tools of nanotechnologies (SEM. AFM, etc.), different stainless steel samples (fro…
Hybrid electrochemical/electrochromic Cu(II) ion sensor prototype based on PANI/ITO-electrode
2017
Abstract Conducting polymer polyaniline (PANI) based electrochromic films were electrochemically synthesized on indium tin oxide (ITO) covered glass electrodes and their electrochromic performances were investigated by spectroscopic methods before and after the incubation in Cu(II) ion containing aqueous solution. Chemical structure of synthesized PANI layer was evaluated by FTIR. The electrochromic performance of PANI film was determined by measuring of spectroscopic signals before and after the incubation of PANI film coated electrode in Cu(II) ion containing solution. During the change of potential, which was applied to PANI-modified electrode, the colour of PANI thin film turned from gr…
Benzene monitoring by micro-machined sensors with SnO2 layer obtained by using micro-droplet deposition technique
2011
International audience; SnO2 thin layers were deposited by the way of the micro-droplet technique. The sensor substrate consisted of a thin membrane developed on oxidised silicon wafer. The sensing layers were deposited by means of the micro-droplet technique into thin layers of about 100 nm. Such devices were tested for benzene detection. The obtained results showed a very high sensitivity for this chemical compound since 500 ppb were detected. The results presented in this paper were not focused on the reactional mechanism of benzene detection but rather on the development of a cheap and sensitive sensor using sol-gel and micro-droplet processes. Since these layers were elaborated using s…
Silica nanoparticle core structure examined by the E?Si? center 29Si strong hyperfine interaction
2015
Abstract β-Ray irradiation up to 1.2 GGy was employed to induce E′Si γ defects and to study the structure of silica nanoparticles with diameters from 7 up to 20 nm. Defect concentration and their 29 Si strong hyperfine doublet were investigated through electron paramagnetic resonance measurements. Our data indicate that stable defects are located in the nanoparticle core. Furthermore, the E′Si γ hyperfine interaction evidences that the core structure is denser than bulk silica and independent from the particle size. Finally, we put in evidence that the core structure is stable and unaffected by the irradiation in the investigated dose range maintaining the specific features of nanoparticles.
A nanostructured sensor of hydrogen peroxide
2017
Abstract A nanostructured electrochemical sensor of hydrogen peroxide was fabricated growing self-standing Pd nanowires (Pd NWs) into polycarbonate (PC) membranes through a simple metal galvanic deposition. Conditions of deposition were adjusted in order to attain 2–5 μm long Pd wires. Characterization of Pd-NWs was performed by scanning electrode microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Properties of the nanostructured sensor were studied by cyclic voltammetry and chronoamperometry in phosphate buffer—ethanol solution. Addition of pure ethanol to the test solution was essential in order to increase wettability of the nanostructures. Sensing features were comp…