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51.
Fe-Ni-W alloys with 18 wt%, 35 wt% and 55 wt% tungsten have been obtained by electrodeposition from an ammoniacal citrate bath. The deposits are smooth, of nice appearance, and adhere well to iron and steel. The morphology and structure of Fe-Ni-W alloys were studied by SEM and XRD, respectively. The structure of the as-plated deposits changed from crystalline to amorphous with increasing tungsten content. The amorphous structure crystallized under heat treatment condition. The wear and corrosion resistance of the deposits were tested by MPX-2000 wear-tear equipment and neutral salt spray test (NSS), respectively. The alloys with 55 wt% tungsten, after heat treatment at proper temperatures, appear to have good wear resistance and hardness. The alloys with 18 wt% tungsten are very corrosion-resistant. 相似文献
52.
L. S. Geng E. Oset M. Döring 《The European Physical Journal A - Hadrons and Nuclei》2007,32(2):201-211
We evaluate theoretically the radiative decay widths into γΛ and γΣ
0 of the two poles of the Λ(1405) found in chiral unitary theories and we find quite different results for each of the two poles. We show that, depending
on which reaction is used to measure the Λ(1405) radiative decays, one gives more weight to one or the other pole, resulting in quite different shapes in the γΛ(Σ
0) invariant-mass distributions. Our results for the high-energy pole agree with those of the empirical determination of the
γΛ and γΣ
0 radiative widths (based on an isobar model fitting of the K-p atom data), which are sometimes referred to as “experimental data”. We have made a detailed study of the K
-
p→π
0
γΛ(Σ
0) and π
-
p→K
0
γΛ(Σ
0) reactions and have shown that they, indeed, lead to different shapes for the γΛ(Σ
0) invariant-mass distributions. 相似文献
53.
Santanu K. Maiti 《Solid State Communications》2007,142(7):398-403
We study electron transport through a moebius strip attached to two metallic electrodes by the use of a Green’s function technique. A parametric approach is used based on the tight-binding model to characterize the electron transport through such a bridge system and it is observed that the transport properties are significantly affected by (a) the transverse hopping strength between the two channels and (b) the strip-to-electrodes coupling strength. In this context we also describe the noise power of the current fluctuations, which provide key information about the electron correlation which is obtained by calculating the Fano factor (F). The knowledge of these current fluctuations gives important ideas for the fabrication of efficient molecular devices. 相似文献
54.
James S. Cooper 《Applied Surface Science》2007,254(3):662-668
An improved fuel cell cathode catalyst composition was pursued by fabricating and screening thin film combinatorial libraries. Results from the Pt-Ru, Pt-Co-Ti, Pt-Co-Cu and Pt-Co-Cr systems are reported. The discrete composition combinatorial libraries were fabricated by plasma sputtering through shadow masks. Each combinatorial library was tested by cyclic voltammetry in a multichannel electrochemical cell. Compositions were ranked based on the onset potential of the oxygen reduction reaction. Several compositions exhibited better onset potentials than pure Pt. The optimum composition from the Pt-Co-Ti system was Pt44Ti12Co44 but showed signs of corrosion after prolonged testing. A wide range of Pt-Co-Cu compositions also outperformed Pt initially, but ultimately failed due to poor corrosion resistance. Among all of the compositions that were screened, the best performance was demonstrated by Pt28Co36Cr36, with an onset potential 107 mV higher than pure Pt and no sign of corrosion. 相似文献
55.
W. Vervisch C. Mottet J. Goniakowski 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):311-314
Morphology and atomic structure of supported Pd clusters
on MgO(100) substrate are investigated theoretically using a
mixed approach: a semi-empirical potential for the metal bonding
within the cluster and a potential fitted to
ab initio calculations for
the metal-oxide interaction. We find that the clusters adopt a
truncated pyramidal morphology in agreement with experimental
results. The detailed study of the epitaxial relation as a
function of cluster size shows the existence of a critical size
around 3 nm where elastic strain due to the misfit between the
substrate and the deposit is released by the introduction of
interfacial dislocations. 相似文献
56.
A.Ya. Berdnikov Ya.A. Berdnikov A.N. Ivanov V.A. Ivanova V.F. Kosmach M.D. Scadron N.I. Troitskaya 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):341-347
Polarization properties of strange baryons produced in pp reactions, p + p↦p + Λ0 + K+ and p + p↦p + Σ0 + K+, near thresholds of the final states pΛ0K+ and pΣ0K+ are analysed relative to polarizations of colliding protons. The cross-sections for pp reactions are calculated within the
effective Lagrangian approach accounting for strong pp rescattering in the initial state of colliding protons with a dominant
contribution of the one-pion exchange and strong final-state interaction of daughter hadrons (Eur. Phys. J. A 9, 425 (2000)).
Received: 22 October 2001 / Accepted: 14 November 2001 相似文献
57.
N. Toshima Y. Shiraishi A. Shiotsuki D. Ikenaga Y. Wang 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,16(1):209-212
The catalytic properties of Pd-core/Pt-shell (inverted core/shell) structured bimetallic nanoclusters, synthesized by a successive
addition method using sacrificial hydrogen, were investigated for hydrogenation of methyl acrylate. Partial deposition of
Pt atoms on the surface of Pd nanoclusters can enhance the catalytic activity of the Pd atoms remaining in the surface of
the inverted core/shell structured Pd/Pt bimetallic nanoclusters.
Received 29 November 2000 相似文献
58.
Ming Wen Yanqiong LiJunmin Zhang Weiming GuanYuncang Li Cui’e WenPeter Hodgson 《Applied Surface Science》2011,257(11):4836-4843
In this work, porous titania was prepared on bulk Ti by chemical oxidation, and then nanostructured silver (Ag) was deposited on titania surface by ion beam sputtering. After annealing treatment, Ag/TiO2 composites were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results indicated that a nano-porous titania layer with mean pore size of 150 nm and thickness of 1 μm was formed by chemical oxidation at 80 °C for 45 min. There were three Ag species (Ag (0), Ag (1+), and Ag (2+)) on composites surface after annealing treatment, and metallic Ag content achieved maximum value with annealing temperature of 500 °C in air. Ag showed high thermal stability being partly attributed to the inhibiting the diffusion of Ag by the underlying porous titania. 相似文献
59.
We investigated superconducting AuIn2 by point-contact spectroscopy. Andreev reflexion was observed with nearly full excess current at contact sizes down to 0.15
nm. This implies, together with a large superconducting coherence length of 11 μm, almost ideal retroreflectivity. At the
onset of lateral confinement of the ballistic electrons the Andreev-derived spectra broaden dramatically due to inelastic
scattering at defects or the strain field near the contact. Lateral confinement does not suppress Andreev reflexion. 相似文献
60.
A series of I(V) characteristics and bias-dependent differential resistance dV/dI(V) curves of point contacts made between a single crystal of two-band superconductor MgB2 and Cu were measured in magnetic fields up to 9 T. The magnetic field dependences of the excess current in the I(V) curves were obtained and analyzed using Koshelev and Golubov's [Phys. Rev. Lett. 90, 177002 (2003)] theoretical results for the mixed state of a dirty two-band superconductor. Introducing a simple model for the excess current in the point contact in the mixed state, our data can be qualitatively described using the theoretical magnetic field dependence of the superconducting order parameter of the σ and π-bands and the averaged electronic density of states in MgB2. 相似文献