Materials Literature
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Magnetoacoustic emission (MAE) has been measured from a Ni bar and a mild steel bar. The magnetizing field was produced by a c-core electromagnet, which was separated from the specimen surface by a nonmagnetic spacer layer (thickness la). In Ni, the MAE profile contains a single peak when la is small. As la increases,…
The observation of a magnetization reversal and a superparamagnetic behavior are reported for films of copper ferrite sputtered in an oxygen atmosphere. X-ray diffraction studies indicate the presence of 14-nm nanoscale crystals of CuFe2O4 in the films. Data on the temperature dependence of the film magnetization M fo…
The mixed series CoxFe1−xCr2S4 has been studied by x-ray, Mössbauer spectroscopy, and superconducting quantum-interference device (SQUID) magnetometry. The crystal structure is found to be a cubic spinel, and the lattice constant a0 decreases linearly with increasing cobalt concentration. Mössbauer spectra of CoxFe1−x…
In nuclear power plants, neutron embrittlement of pressure vessel steels has been one of the main concerns. The use of micromagnetic Barkhausen emissions is a promising method to monitor the variations in microstructural and subsurface stress states due to their influence on these emissions. Measurements of these emis…
Hysteresis loops in some magnetic systems are composed of small avalanches (manifesting themselves as Barkhausen pulses). Hysteresis loops in other first-order phase transitions (including some magnetic systems) often occur via one large avalanche. The transition between these two limiting cases is studied, by varying…
Heavily terbium-doped boron-silicate glasses (Tb3+10.4 at. %) with a Verdet constant (632.8 nm, room temperature) as large as −0.338 min/Oe cm, 38% larger than that of the famous FR-5 glasses, have been made. The wavelength and temperature dependencies of the Verdet constants of samples have been investigated in the r…
Fluorescence excitation vibronic spectra of aniline-M (M=He, Ne, Ar) van der Waals (vdW) complexes have been measured in the spectral region from 300 to 500 cm−1 above S1−S0 origin. Anomalous behavior of the vdW shifts are observed for two out-of-plane vibrational modes. The resulting vdW vibrational shifts for the ν1…
The magnetic properties of SmCo (2:17-type) magnets with high contents of Fe (v=Fe/3d≳0.34) and/or light rare earths (up to 0.4) were investigated. For magnets with compositions of Sm(FevCobalZr0.02Cu0.06{Ga}x)7.72, v=0.35, x=0–0.06, both iHc and (BH)max can be improved significantly by Ga doping, from 1.0 kOe and 5.4…
Crystalline Co spinel ferrite films were prepared by rf sputtering on glass substrates without buffer layer and annealed at temperatures from 400 to 600 °C for 2 h in air. (100) texture was obtained in these films. The anisotropy constant, magnetic hysteresis loops, and magneto-optical Faraday spectra of the films wer…
The solid-solution phase of hydrogen in hexagonal close-packed yttrium (\ensuremath{\alpha}-${\mathrm{YH}}_{\mathit{x}}$) is studied using the pseudopotential method within the local-density-functional approximation with a plane-wave basis. The binding energies associated with different interstitial sites are evaluate…
Rare-earth–cobalt alloys have been melt spun, yielding ribbons whose major phase was the hexagonal PrCo5 phase. Fully dense hot-pressed magnets with essentially isotropic magnetic properties have been formed by consolidating the ribbons at high temperatures and pressures. The hot-pressed precursor was then subjected t…
A micromagnetic formulation has been developed for modeling the effect of biaxial stress on magnetoelastic processes in polycrystalline steels. In particular, the formulation employs the Schneider–Cannell–Watts model and involves substitution of an effective stress equal to one of the deviatoric (i.e., distortional) n…
The transmittance of an anodic alumina film changes significantly with the refractive index of the guest material that is contained in columnar pores. We fabricated a channel waveguide with a Y junction in an alumina film by filling the pores with photocurable resins of suitable refractive indices.
Single layer films of FeTaN have been deposited by dc magnetron sputtering, and the relationships between the magnetostriction and film composition have been studied. A linear increase in magnetostriction with nitrogen content has been explained by the dependence of λ100 on nitrogen concentration. The form of this dep…
The hard magnetic properties of nitrided melt-spun Nd-Fe-Mo ribbons have been investigated as functions of composition, quench rate, and nitriding time. Ingots having the compositions Nd1Fe10Mo2, Nd1.15Fe10Mo2, Nd1.3Fe10Mo2, and Nd1.45Fe10Mo2 were melt spun over a range of quench rates specified by substrate wheel vel…
The hyper Rayleigh scattering (HRS) method was applied to determine the absolute value of second-order hyperpolarizabilities ((beta) ) of stilbazolium p-toluenesulfonates and related ionic species in methanol. In general, the (beta) values of stilbazolium derivatives become large with increasing wavelength of absorpti…
Relaxation of a stepped (111) diamond surface is studied using an accurate, total-energy tight-binding method. We determined that the bare surface will become ${\mathit{sp}}^{2}$ bonded near a step. This spontaneous graphitization is accompanied by a large increase in spacing between the surface layers. Band structure…
Scattering theory has been used to determine the effect of various defects on the scattering loss of As2S3 glass fibers. The scattering is related to the particle shape, size, relative refractive index, and wavelength of light. Bubbles possess the highest relative refractive index and therefore the highest scattering…
Crystalline barium ferrite films with in-plane magnetic anisotropy have been obtained by postdeposition annealing of amorphous sputtered films. The magnetic properties, the crystallographic texture, and the microstructure are very sensitive to the sputtering and postdeposition annealing conditions. It was found that b…
Mixed Li–Cd ferrites having the chemical formula Li0.5−x/2CdxFe2.5−x/2O4 (where x=0.2, 0.4, 0.6, 0.8, and 1.0) are prepared by the well-known double sintering ceramic technique. From x-ray diffraction studies lattice parameters are calculated and their variation with composition is explained on the basis of the tetrah…