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11.
Luca Pasquini Elsa Callini Matteo Brighi Federico Boscherini Amelia Montone Torben R. Jensen Chiara Maurizio Marco Vittori Antisari Ennio Bonetti 《Journal of nanoparticle research》2011,13(11):5727-5737
We report on the hydrogen storage behaviour of Mg nanoparticles (NPs) (size range 100 nm–1 μm) with metal-oxide core–shell
morphology synthesized by inert gas condensation and decorated by transition metal (TM) (Pd or Ti) clusters via in situ vacuum
deposition. The structure and morphology of the as-prepared and hydrogenated NPs is studied by electron microscopy, X-ray
diffraction including in situ experiments and X-ray absorption spectroscopy, in order to investigate the relationships with
the hydrogen storage kinetics measured by the volumetric Sieverts method. With both Pd and Ti, the decoration deeply improves
the hydrogen sorption properties: previously inert NPs exhibit complete hydrogenation with fast transformation kinetics, good
stability and reversible gravimetric capacity that can attain 6 wt%. In the case of Pd-decoration, the occurrence of Mg–Pd
alloying is observed at high temperatures and in dependence of the hydrogen pressure conditions. These structural transformations
modify both the kinetics and thermodynamics of hydride formation, while Ti-decoration has an effect only on the kinetics.
The experimental results are discussed in relation with key issues such as the amount of decoration, the heat of mixing between
TM and Mg and the binding energy between TM and hydrogen. 相似文献
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Plasticized nanocomposite polymer electrolytes (PNCPEs) based on poly(vinyl alcohol) (PVA)–MI (M=Na, K, Ag) dispersed with nanofillers Al2O3 and plasticized with poly(ethylene glycol) (PEG) have been prepared by solution cast technique. The structural properties of the samples have been characterized using various experimental techniques such as XRD, DSC, FTIR and B-G spectroscopy. The ionic conductivity and dielectric constant of the samples have been estimated using a LCZ meter in a wide temperature range, i.e. from 30 to 170 °C. It has been observed that the presence of water molecules in polymer electrolytes significantly affects the mobility of ionic species. The temperature dependent ionic conductivity shows the Arrhenius type behavior separated in three distinct regions. The ionic transference number for all PNCPE samples is found to be ≈1, which strongly suggests their ionic nature. 相似文献
14.
Laser Physics - A two-component bosonic mixture loaded in a two-dimensional optical lattice is analyzed. By means of Mean-Field techniques and Worm algorithm Monte Carlo simulations, we study the... 相似文献
15.
Evgeny Pozhidaev Sofia Torgova Maxim Minchenko Cesar Augusto Refosco Yednak Elio Miraldi 《Liquid crystals》2013,40(8):1067-1081
A chiral ferroelectric smectic C* liquid crystal (FLC) with the helix pitch p 0?=?330 nm was developed to avoid any scattering of visible light when the helix is not unwound over a certain limit. Planar cells with different FLC layer thickness (16 and 44 μm) have been assembled with helix axis parallel to the glass plates and aligned along the rubbing direction. The ellipticity of the light passing through the cells vs. the electric field was investigated, and a method for evaluating the electrically controlled birefringence via ellipticity measurements has been established. We have found that the FLC cell is an optical retardation layer driven by the electric field, the effective birefringence being proportional to the square electric field. The physical origin of the electrically controlled phase shift of the light passing through the FLC layer has been analysed. 相似文献
16.
S. Mignoni M. D. Fontana M. Bazzan M. V. Ciampolillo A. M. Zaltron N. Argiolas C. Sada 《Applied physics. B, Lasers and optics》2010,101(3):541-546
The photorefractive properties of LiNbO3 are closely related to the defect structure which strongly depends on the conditions of sample preparation. By means of micro-Raman
scattering measurements we investigate the influence of the thermal treatment in the preparation of Fe-diffused waveguides.
We underline the role of intrinsic defects and discuss the mechanism of incorporation of iron in the lattice. We especially
emphasize the specific role of three phonon modes which are able to separately probe the Li, Nb or O sublattice. 相似文献
17.
F. Pegoraro S. V. Bulanov 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(2):399-405
The stability of a thin plasma foil accelerated to relativistic velocities by the radiation pressure of an ultra high intensity electromagnetic pulse is investigated. The effects of the onset of a Rayleigh-Taylor-like instability are discussed in the context of the ion acceleration process during the interaction of the laser pulse with the plasma. It is stressed that the experimental study of this advanced laser plasma interaction regime will be accessible within the framework of the ELI experiment and will be of relevance for our understanding of high energy astrophysical phenomena. 相似文献
18.
Well-ordered clean InAs(1 1 1) A and B surfaces have been prepared using HCl-isopropanol solutions and characterized using low-energy electron diffraction and photoemission spectroscopy. The as-treated surfaces are covered by a layer containing arsenic and small amounts of InClx. Annealing induces desorption of the overlayer and reveals (2 × 2) and (1 × 1) structures on the A and B surfaces, respectively. For both surfaces, the surface components of the In 4d and As 3d reveal a charge transfer from the electropositive surface indium to the electronegative surface arsenic. The major advantage of this preparation method over conventional thermal cleaning is a significant reduction in the annealing temperature (≈250 °C) thereby avoiding anion evaporation. 相似文献
19.
Renato S. Gonnelli Mauro Tortello Dario Daghero Giovanni Alberto Ummarino Valeri A. Stepanov Jun S. Kim 《Central European Journal of Physics》2009,7(2):251-256
Point-contact Andreev-reflection (PCAR) experiments were performed in the Fe-1111 layered superconductor LaFeAsO0.9F0.1 with resistive T
c
on
∼ 27 K. The observation of two pairs of peaks in the low-temperature Andreev-reflection spectra clearly indicates the presence
of two order parameters. The behavior of the two gaps as a function of temperature, obtained by fitting the conductance curves
by means of the generalized two-band Blonder-Tinkham-Klapwijk model, shows some anomalies. A theoretical analysis performed
within the two-band Eliashberg theory with a generic electron-boson coupling can reproduce the low-temperature value of the
two gaps but generally fails in giving a satisfactory fit of their overall temperature dependence, indicating the rich and
complex physics of these newly discovered superconductors.
相似文献
20.
We have developed an apparatus for nanostructure fabrication based on direct deposition of laser-manipulated cesium vapors onto pyrolitic graphite. Key features of our apparatus are production and manipulation of a longitudinally cooled atom beam, which allows for straightforward operation in the moderate to low flux density conditions. Both unstructured and structured low surface coverage depositions have been carried out and samples carefully analyzed at the atom scale by in situ tunneling microscopy. Results represent a step forward to the realization of a novel technology for space-controlled deposition of few, eventually single, atoms. 相似文献