Ferromagnetic and spin-wave resonance in Co/Pd/CoNi multilayer films

It has been found that the magnitude and sign of exchange interaction between Co(5 nm) and CoNi(5 nm) ferromagnetic layers through Pd depend on magnetization orientation of ferromagnetic layers. If magnetization is oriented in a layer plane, exchange interaction can be both ferromagnetic and antiferromagnetic. If magnetization orientation is orthogonal to a layer plane, the exchange constant is always positive at d_Pd<d _c and equals zero at d_Pd>d _c (d _c is the characteristic length).     

Exponentially convergent lattice sums

For any oblique incidence and arbitrarily high order, lattice sums for one-dimensional gratings can be expressed in terms of exponentially convergent series. The scattering Green's function can be efficiently evaluated also in the grating plane. Numerical implementation of the method is 200 times faster than for the previous best result.     

Seeking and investigating isospin-two narrow dibaryon resonances in neutron-proton interactions at P n =5.20±0.13 Gev/c

The results are presented that are obtained from searches for and an investigation of isospin-two narrow resonances in the effective-mass spectrum of ppπ⁺ combinations originating from the reaction np → ppπ⁺π^?π^? induced by P _n =5.20±0.13 GeV/c neutrons. Data subjected to our analysis come from the 1-m hydrogen bubble chamber installed at the Laboratory for High Energies, Joint Institute for Nuclear Research (Dubna), and exposed to a beam of quasimonochromatic neutrons. Narrow structures in the effective-mass spectrum of ppπ⁺ combinations are found at 2175, 2221, 2321, 2398, 2471, 2525, 2596, and 2709 MeV/c ². The experimental widths of the resonances are determined primarily by the instrumental resolution. The branching fractions for various channels through which the 2596-MeV/c ² resonance decays are determined to be (83±23)% for the Δ ₃₃ ⁺⁺ p channel, (10±3)% for the (BB) ₂₀₉₅ ⁺⁺ π⁺ channel, and (7 _?7 ⁺¹⁵ for the ppπ⁺ channel; here, (BB) ₂₀₉₅ ⁺⁺ is a dibaryon in the two-proton system with a mass around 2095 MeV/c ². A qualitative analysis of the spins of the 2596-and 2709-MeV/c ² resonances is performed.     

Structural study of highly dispersed cerium dioxides

Cerium dioxide samples of different dispersivity, obtained by different methods, have been investigated by X-ray diffraction (XRD) analysis, full-profile analysis of diffraction patterns, calculation of radial distribution function (RDF) of electron density, and extended X-ray absorption fine-structure (EXAFS) spectroscopy. According to the XRD data, the samples studied can be identified in the fluorite structure with conventional unit-cell parameters. However, the local structure of highly dispersed samples, determined by the RDF and EXAFS methods, changes: the coordination spheres for the Ce-O distances are represented by two distances.     

Comparison of engineering methods of loss prediction in thin ferromagnetic laminations

The loss predictive methods based on the static and dynamic components of power loss are compared with the methods where the total loss is subdivided into hysteresis, classical and excess components. It is explained why the simplest two-component methods can be preferable. An approach to the characterization of a given steel is outlined.     

Influence of the texture and acid-base properties of the alumina-containing support on the formation of Co(Ni)-Mo catalysts for deep hydrodesulfurization of the diesel fraction

The influence of the texture of γ-Al₂O₃ on the formation of Co(Ni)-Mo catalysts for hydrodesulfurization of the diesel fraction is studied. As shown by low-temperature N₂ adsorption, X-ray diffraction, IR spectroscopy of adsorbed molecules, and high resolution electron microscopy (HREM), use of a support with a larger specific surface and a lower total concentration of terminal OH groups makes it possible to prepare more active catalysts. The electron density radial distribution method shows that the finely dispersed cobaltcontaining catalyst in its initial state contains CoMoO₄, Al₂(MoO₄)₃, and CoAl₂O₄, the last two phases being present in trace amounts. After the reaction, this catalyst contains cobalt-doped molybdenum sulfide. According to HREM data, the active phase of the cobalt-containing catalyst consists of layered sulfide association species Co_1.3Mo₂S_3.3, which differ in composition from the bulk phase CoMo₂S₄. It is assumed that, out of the 1.3 cobalt atoms in Co_1.3Mo₂S_3.3 0.3 Co occurs at the edges of the association species and 1.0 Co is intercalated into their interlayer space, and 0.7 S at the boundary between the association species and the Al₂O₃ phase is replaced by the corresponding amount of oxygen.     

Synthesis and investigations of mixed-ligand lanthanide complexes with N,N′-dipyrrolidine-N′′-trichloracetylphosphortriamide,dimethyl-N-trichloracetylamidophosphate, 1,10-phenanthroline and 2,2′-bipyrimidine

Coordination compounds with general formula [Ln(L¹)₃phen], where Ln = Nd, Eu, Er, Yb, HL¹ = N,N′-dipyrrolidine-N′′-trichloracetylphosphortriamide, phen = 1,10-phenanthroline; [Ln(L¹)₃bpm], where Ln = La, Nd, Eu, Gd, Er, Y, bpm = 2,2′-bipyrimidine and [{Ln(L²)₃}₂(μ-bpm)], where Ln = La, Nd, Eu, Gd, Er, Y, HL² = dimethyl-N-trichloracetylamidophosphate have been synthesized and characterized by means of IR and UV–Vis spectroscopy. Crystal structures of [Nd(L¹)₃phen] (1), [Nd(L¹)₃bpm] (2) and [{Nd(L²)₃}₂(μ-bpm)] (3) have been determined. It was found, that in the deprotonated form the phosphoryl ligands (L¹)^? and (L²)^? are coordinated to the neodymium atoms in a bidentate manner via the oxygen atoms of the phosphoryl and the carbonyl groups with formation of six-membered metallocycles. In the case of compounds 1 and 2 the 1,10-phenanthroline (or 2,2′-bipyrimidine) molecules are coordinated to the metals in a bidentate manner via the nitrogen atoms. In contrast 2,2′-bipyrimidine acts in the bidentate-bridge mode forming binuclear complex 3. Variable-temperature magnetic susceptibility measurements of 3 and [{Gd(L²)₃}₂(μ-bpm)] (4) reveal a weak antiferromagnetic interaction between the two magnetic centres, whereas in the case of [{Eu(L²)₃}₂(μ-bpm)] (5) the presence of spin–orbit coupling leads to a deviation from the Curie and Curie–Weiss laws.     

Possibilities of powder X-ray diffraction methods in determining structural characteristics of carbon materials

The possibilities of using powder X-ray diffraction methods in the study of carbon materials are discussed. To determine the phase composition of the crystalline materials the X-ray phase analysis is employed; the real structure is established by the harmonic analysis of diffraction profiles; the structural features and phase composition of the nanomaterials are found by the radial electron density distribution function.     

Construction of the model radial distribution curves with regard to the features of X-ray diffraction experiment

A method to construct model radial distribution functions (RDFs) from the already known structural data is described. The method includes the procedures to calculate termination ripples that always appear on the experimental RDF because of the bounds of the integration limits in the Fourier transformation of the X-ray scattering curve. The introduction of this procedure increases the accuracy of the comparative RDF method used to elucidate the phase composition of nanodispersed materials and to determine the features of the local structure of the phases as compared to their well crystallized analogues. Cerium dioxide samples with different dispersion exemplify the applicability of this method to determine the features of the local structure.     

1H NMR Study of Zeolite Water Structure and Broensted Acid Centers in Chabazite

The disordered structure of absorbed water in a highly porous zeolite chabazite Ca₂[Al₄Si₈O₂₄]·nH₂O (2 ≤ n ≤ 12.8) is studied from motionally narrowed ¹H nuclear magnetic resonance spectra at room temperature. Concentration phase transitions were observed at n ≈ 8.3 and n ≈ 10.2. The transitions are accompanied by displacement of Ca²⁺ ions and variation of the Broensted acid centers at inner surface of zeolite pores.