Search results for "Nitrogen"
showing 10 items of 1200 documents
Influence of Nitrogen Doping on Device Operation for TiO 2 -Based Solid-State Dye-Sensitized Solar Cells: Photo-Physics from Materials to Devices
2016
International audience; Solid-state dye-sensitized solar cells (ssDSSC) constitute a major approach to photovoltaic energy conversion with efficiencies over 8% reported thanks to the rational design of efficient porous metal oxide electrodes, organic chromophores, and hole transporters. Among the various strategies used to push the performance ahead, doping of the nanocrystalline titanium dioxide (TiO 2) electrode is regularly proposed to extend the photo-activity of the materials into the visible range. However, although various beneficial effects for device performance have been observed in the literature, they remain strongly dependent on the method used for the production of the metal o…
Glovebox atmosphere detritiation process using gas separation membranes.
2003
Abstract The use of gas separation membranes in atmospheric detritiation systems has been studied. The main advantage of this new process is to reduce the number and/or the size of the equipment in comparison to conventional tritium removal systems. Owing to the constraints linked to tritium handling, the separation performances of several commercial hollow fiber organic membranes have been analyzed, under various operating conditions, with hydrogen/nitrogen or deuterium/nitrogen mixtures. The experiments are performed with small quantities of hydrogen or deuterium (5000 ppm). The experimental results allow to evaluate the separation efficiency of these membranes and to determine the approp…
Performance Analysis of Ammonia in Solid Oxide Fuel Cells
2021
The transition of the marine propulsion system towards alternative fuels is mandatory to offset carbon emission. Among the alternative fuels, ammonia is carbon-free and can be produced in sustainable ways. Ammonia has 17.8% hydrogen (wt %) and is easily liquified at 25°C and 8 bar pressure. The two-stroke internal combustion engines currently used in the marine sector reach efficiencies of about 50% but generate substantial polluting emissions. Solid oxide fuel cells generate electricity with efficiencies greater than 50 % and can use ammonia as fuel. In this work, a single-cell SOFC was characterised using in-situ ammonia decomposition reaction (Int-ADR) and compared with ex-situ ammonia …
Factors Controlling the Energy of Nitrogen Monolayer Coverage onHigh Surface Area Catalyst Oxide Carriers
2011
Factors affecting the strength of nitrogen physisorption at monolayer coverage on different catalytic oxide carriers (e.g., ZnO, MgO, Al2O3, ZrO2, TiO2, and SiO2) have been addressed. Isotherm elaboration by the two-parameter BET equation provides C-constant values (80–200) inversely related to the polarizing power (PP) of the oxide adsorbent irrespective of the surface area exposure. The energy of monolayer formation depends on the extent of charge-delocalization characterizing the surface cation-oxygen bond, which determines the acid–base character of the oxide and strength of van der Waals interactions with adsorbate molecules. Density functional theory (DFT) calculations on MgO and TiO2…
Adsorption of CO and N 2 molecules at the surface of solid water. A grand canonical Monte Carlo study
2020
International audience; The adsorption of carbon monoxide and nitrogen molecules at the surface of four forms of solid water is investigated by means of grand canonical Monte Carlo simulations. The trapping ability of crystalline Ih and low-density amorphous ices, along with clathrate hy-drates of structures I and II, are compared at temperatures relevant for astrophysics. It is shown that, when considering a gas phase that contains mixtures of carbon monoxide and nitrogen, the trapping of carbon monoxide is favored with respect to that of nitrogen at the surface of all solids, irrespective of the temperature. The results of the calculations also indicate that some amounts of molecules can …
Efficiency of an on-line isotope separator system employing cooled and NaCl-loaded He-jet methods
1976
Abstract A pure helium-jet at liquid nitrogen temperature coupled to a Nielsen type ion source, and a NaCl-loaded helium-jet coupled to a hollow-cathode ion source have been investigated as means to connect a cyclotron target chamber on-line to a mass separator. Technical details and performances of some critical parts of the system are described. Total separation efficiencies measured under various experimental conditions for several nuclides vary between 0.01 and 1.0%.
Zero-field magnetometry based on nitrogen-vacancy ensembles in diamond
2018
Ensembles of nitrogen-vacancy (NV) centers in diamonds are widely utilized for magnetometry, magnetic-field imaging and magnetic-resonance detection. They have not been used for magnetometry at zero ambient field because Zeeman sublevels lose first-order sensitivity to magnetic fields as they are mixed due to crystal strain or electric fields. In this work, we realize a zero-field (ZF) magnetometer using polarization-selective microwave excitation in a 12C-enriched HPHT crystal sample. We employ circularly polarized microwaves to address specific transitions in the optically detected magnetic resonance and perform magnetometry with a noise floor of 250 pT/Hz^(1/2). This technique opens the …
Surface magnetic structure investigation of a nanolaminated Mn$_2$GaC thin film using a magnetic field microscope based on Nitrogen-Vacancy centers
2021
This work presents a magnetic field imaging method based on color centers in diamond crystal applied to a thin film of a nanolaminated Mn$_2$GaC MAX phase. Magnetic properties of the surface related structures have been described around the first order transition at 214 K by performing measurements in the temperature range between 200 K and 235 K with the surface features fading out by increasing temperature above the transition temperature. The results presented here demonstrate how Nitrogen-Vacancy center based magnetic microscopy can supplement the traditionally used set of experimental techniques, giving additional information of microscopic scale magnetic field features, and allowing t…
Characterization of microscopic ferromagnetic defects in thin films using magnetic microscope based on Nitrogen-Vacancy centres
2020
In this work we present results acquired by applying magnetic field imaging technique based on Nitrogen-Vacancy centres in diamond crystal for characterization of magnetic thin films defects. We used the constructed wide-field magnetic microscope for measurements of two kinds of magnetic defects in thin films. One family of defects under study was a result of non-optimal thin film growth conditions. The magnetic field maps of several regions of the thin films created under very similar conditions to previously published research revealed microscopic impurity islands of ferromagnetic defects, that potentially could disturb the magnetic properties of the surface. The second part of the measur…
Ceramic/metal nanocomposites by lyophilization: Processing and HRTEM study
2012
5 páginas, 8 figuras, 1 tabla.-- El pdf del artículo es el manuscrito de autor.