[en] Density functional theory (DFT) calculations were performed to study the hydrogen adsorption over Ni₂-B (1 2 0) surface. The hydrogen adsorption energy was studied for both on-top and hollow sites. Adsorption energies calculated for all the sites were negative exhibiting their exothermic nature as well as stability. It was also deduced that the on top sites of both Ni and B were not stable sites. It was observed that though both threefold hollow sites as well as bridge sites were stable sites, the bridge site was more favored for hydrogen adsorption over threefold hollow site. The bridge site connecting Ni and B proved to be the most stable configuration for atomic hydrogen adsorption on Ni₂B (1 2 0) surface with bond length of 1.69 Å and 1.32 Å for Ni-H bond and B-H bond, respectively, and an adsorption energy of -0.30 eV. (author)

[en] In the present work the sign of Hsub(int) was measured for Ni₃[Fe(CN)₆]₂. The polycrystalline absorber was placed in an external longitudinal magnetic field of a superconducting solenoid. The temperature of the sample, 4.2K, was sufficiently below the Curie point Tsub(c)=19.5K and the magnitude of Hsub(ext) used was strong enough to orient the magnetic domains, also stronger than any possible induced fields. The Moessbauer experimental spectra are presented amounts to 265+-10 kOe, in agreement with earlier data. The observed expansion of the Zeeman pattern in the external field signifies the positive sign of Hsub(int)

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[en] Evolution of the vortex lattice, the rhombus-square transition included, for LuNi₂B₂C in the field along the c crystal axis, is tracked by the decoration technique pushed up to the record high (for this method) field of 1480 Oe. Decoration images are analyzed with the help of the Fourier transform, which indicates disordered structures in small fields of a few Oe. In fields H<200 Oe the coexisting domains of different structures are observed. A technique based on the Fourier transform is employed to see the domains separately. The transition to the square lattice is recorded near 900 Oe. The results are in agreement with predictions of the nonlocal London theory

No abstract available

[en] We introduced a novel technique to fabricate a Microlattice-cored miniature sandwich panel with an ultralow density. This sandwich panel was made of a monolithic Ni-P foil without any bonding between the core and the faces. As a preliminary study, the mechanical properties were evaluated under compression in two different loading directions, and the effects of the face sheets added on the top and bottom were investigated in comparison to the conventional Microlattice without the face sheets. Under the out-of-plane compression, almost no difference was evident between the conventional Microlattice and the Microlattice sandwich in their compressive behaviors, because of the high friction with the compression platens. However, under the in-plane compression, the addition of the face sheets to the conventional Microlattice significantly increased the strength and stiffness, when the wall thickness was higher than a certain limit. Otherwise, the reinforcing effect became much less significant, because the very thin face sheets were easily buckled across the entire area even at the beginning of the loading.

[en] The crystal structure data of HoNi₄B are given including the XRD data, atomic coordinates and thermal displacement parameters

[en] A sample of nearly stoichiometric fcc nickel hydride in the form of polycrystalline plates with strong texture was studied by inelastic neutron scattering (INS) in two different orientations, with the [100] axis of the texture parallel and at an angle of 45 to the direction of neutron momentum transfer. The INS spectra were measured at 5 K with energy transfers ω ranging from 26 to 380 meV. In the region of the second and third band of optical hydrogen vibrations, they showed a significant directional dependence. A similar anisotropy was recently observed in the INS spectrum of fcc palladium hydride, and the now available data for NiH and PdH are discussed together. (orig.)

[en] Recently, there is an increasing interest in magnetic nano wires because of their unusual properties compared to the bulk materials. To understand the complexity of nano wire arrays and to improve their potential in various applications more studies are still needed, for example, to understand completely the effect of geometrical factors, i.e. aspect ratio, areal density etc., on magnetic properties of these arrays. In this work, arrays of nickel nano wires with aspect ratio is proportional to 1200 and diameter ranging between 25-100 nm were fabricated by electrodeposition in etched ion track templates. Samples with areal density from 1 X 10/sup 6/ cm/sup -2/ to 1 X 10/ sup 8/ cm/sup -2/ were prepared. Measurements of magnetic hysteresis loops were performed at room temperature with SQUID magnetometer and magnetic properties of arrays of different diameters and aspect ratios were compared. Coercivity of the wires showed strong dependence on aspect ratio, diameter and microstructure. Room temperature coercivity of the wires showed a maximum at is proportional to 40 nm diameter and arrays with high density of nano wires showed lower coercivity. The results were discussed by taking into account anisotropies originating from the shape, crystalline structure and magnetostatic interactions among the wires and by previous experimental observations in literature. (Orig./A.B.)