Modification of magnetic anisotropy in metallic glasses using high-energy ion beam irradiation

Heavy ion irradiation in the electronic stopping power region induces macroscopic dimensional change in metallic glasses and introduces magnetic anisotropy in some magnetic materials. The present work is on the irradiation study of ferromagnetic metallic glasses, where both dimensional change and modification of magnetic anisotropy are expected. Magnetic anisotropy was measured using Mössbauer spectroscopy of virgin and irradiated Fe₄₀Ni₄₀B₂₀ and Fe₄₀Ni₃₈Mo₄B₁₈ metallic glass ribbons. 90 MeV ¹²⁷I beam was used for the irradiations. Irradiation doses were 5×10¹³ and 7.5×10¹³ ions/cm². The relative intensity ratios D ₂₃ of the second and third lines of the Mössbauer spectra were measured to determine the magnetic anisotropy. The virgin samples of both the materials display in-plane magnetic anisotropy, i.e., the spins are oriented parallel to the ribbon plane. Irradiation is found to cause reduction in magnetic anisotropy. Near-complete randomization of magnetic moments is observed at high irradiation doses. Correlation is found between the residual stresses introduced by ion irradiation and the change in magnetic anisotropy.     

Numerical modeling of gas flow around oscillating compressor blades

The problem of gas flow around a plane cascade of oscillating blades is numerically solved using the ANSYS CFX package. The blade surface displacement is taken into account using a movable grid generated before the beginning of the calculations at each time step. The calculated and experimental data are compared. The calculated results are used for determining the blade stability against flutter.     

Statistical and dynamic intensities of atomic spectral lines in plasma

Based on the quasi-classical approach, we solve the problem of a radiative cascade between Rydberg states in the space of parabolic quantum numbers that correspond to atom (or ion) quantization in a plasma microfield. We consider the level population source associated with the dielectronic recombination of electrons on ions with the cores in an external electric field. We determine the populations of states and the intensities of transitions between levels with a small change in principal quantum number. These “dynamic” intensities are compared with the “ statistical” intensities that correspond to an equidistribution in Stark sublevels. An appreciable discrepancy was found between the two types of intensities in plasma of low density that corresponds to the dominance of radiative transitions over collisional transitions.     

Convenient preparation and full characterization of a synthetically useful salt of the dithianitronium cation, SNSSbF6, from readily available starting materials

The synthetically useful SNSSbF6 is prepared, in good yield, from the reactions of S3N2Cl2 or S3N3Cl3 with stoichiometric amounts of AgSbF6 and S8 in liquid SO2. SNSSbF6 crystallizes monoclinic in space group C2/m (a = 9.740(2) A, b = 6.644(2) A, c = 5.334(1) A, beta = 90.58(2) degrees , Z = 2). The crystal structure was determined by standard methods and refined to R1 = 0.019 and wR2 = 0.048. The structure consists of discrete linear centrosymmetric SNS+ cations [S-N = 1.4871(10) A] and almost octahedral SbF6- anions, with weak cation-anion interactions. The lattice energy of SNSSbF6 was determined from the volume-based method as 525 +/- 32 KJ mol(-1) and the heat of formation of SNSSbF(6(s)) has been estimated as -1566 +/- 24 KJ mol(-1). The FT-IR, Raman, and (14)N NMR spectra are reported, as well as an in situ study of the reaction of S3N2Cl2 with AsF5 in SO2 solution.     

Heavy-flavor production in <Emphasis Type="Italic">pp</Emphasis> and heavy-ion collisions in QCD up-to-LHC energies

Charm production in pp collisions is considered in the framework of perturbative QCD. The values of two parameters, the charm quark mass m _c and the QCD scale μ², are determined from the comparison of the theoretical calculations with experimental data. The RHIC data on charm and beauty production are compared with the k _T -factorization approach predictions and with standard NLO QCD. The calculated results underestimate the STAR Collaboration data. The role of possible nuclear effects is discussed. The predictions for LHC energies are also given.     

Dielectric relaxation in layered oxides of the Aurivillius phase family

Two new polycrystalline layered oxides Bi_2.33Ca_0.17Nb_1.33W_0.17O_7.5 and Bi_2.25Ca_0.25Nb_1.25W_0.25O_7.5, in which the number of perovskite layers is equal to 1.5, have been synthesized. It has been revealed using X-ray powder diffraction analysis that both compounds have a single-phase composition and exhibit a structure of Aurivillius phases with orthorhombic unit cells corresponding to space group Cmm2. The analysis of the temperature dependences of the permittivity in the frequency range from 1 kHz to 1 MHz has demonstrated that these compounds are characterized by relaxor properties. This manifests itself in the frequency dispersion of the ferroelectric-paraelectric transition temperature and high values of the diffusivity parameter: γ = 1.75 and 1.82.