Materials Literature
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This paper discusses the elevated temperature performance of Nd-Fe-B magnets containing 0–15 wt. % cobalt substitutions for iron and 0–10 wt. % dysprosium substitutions for neodymium. Test samples were prepared using conventional powder metallurgy techniques. Elevated temperature hysteresis loop and open-circuit measu…
The effects of cobalt substitution on the hard magnetic properties of melt-spun neodymium-iron-boron materials are reported. Samples having the starting composition Nd0.135[(CoxFe1−x)0.95B0.05 ]0.865 with x=0, 0.05, 0.10, 0.15, 0.20, 0.35, 0.50, 0.75, and 1 were prepared by melt-spinning over a range of substrate surf…
Samples of Nd2(Fe1−xNix)14B, 0≤x≤0.20, with good phase homogeneity have been made by heating under vacuum for 300 h. 57Fe Mössbauer parameters have been determined for all six different iron crystallographic sites at room temperature. The nickel atoms preferentially substitute for iron atoms on the 16k2 and 8j2 sites.…
The electric, dielectric permittivity, loss tangent, microwave power absorption, and hysteresis loop parameters were studied on a series of cobalt-substituted lithium titanium ferrites. The experimental results indicate that cobalt substitution affect all these parameters. The observed dispersion in conductivity and d…
Calculated thermomagnetization curves for MnFe2 O4 and NiFe2 O4 have been matched to reported experimental results. Since both Mn2+ and Ni2+ ions are also strongly exchange coupled to the Fe3+ ions, separate sets of molecular-field coefficients were determined for each of these interactions and then averaged into the…
R2Fe14−xGaxB (R=Pr and Nd) and PrCo5−xGax alloys were synthesized and examined by powder x-ray diffraction at room temperature and by magnetometry in the temperature range 4.2–1100 K. Lattice parameters, Curie temperature, spin-reorientation temperatures, anisotropy fields, and saturation magnetizations were determine…
We report the magnetic susceptibility as a function of temperature (4<T<200 K) and magnetic field (1000<H<7000 Oe) of EuTe/PbTe superlattices grown by molecular-beam epitaxy. Three superlattices were used, consisting of four EuTe monolayers alternating with four PbTe monolayers (EuTe${)}_{4}$/(PbTe${)}_{4}…
A particular mechanism for domain-wall nucleation in thin (350 Å) Permalloy films of typical geometry (7×140 μm) used for magnetoresistive (MR) sensors is studied in detail. A numerical micromagnetic model is described which can theoretically predict an observed domain-wall process (including domain-wall creation, des…
We have extended the matrix representation of the dynamical theory of x-ray diffraction to include Bragg planes that are oblique with respect to the surface of a crystal wafer. In place of the two independent 2\ifmmode\times\else\texttimes\fi{}2 matrices of the Abel\`es method for planes parallel to the surface, we us…
Mössbauer spectra of Zn0.2Fe2.3O4 particles at different temperatures have been obtained. They have been analyzed with five components, one due to the A-site Fe3+ ions, and the others due to the B-site Fe3+ and Fe2+ ions. Magnetic and electronic properties have been discussed with regard to zinc substitution and tempe…
Magnetic properties, such as domain patterns and anisotropy, were measured for negative magnetostrictive Co-Si-B amorphous wires exhibiting large Barkhausen discontinuities and the results are compared to those of Fe-Si-B wires with positive magnetostriction. The Co-based wire was found to have a bamboolike domain str…
The crystalline phase coexisting with the icosahedral quasicrystal (point group m3\ifmmode\bar\else\textasciimacron\fi{} 5\ifmmode\bar\else\textasciimacron\fi{}) in a rapidly solidified ${\mathrm{Al}}_{7}$Cr alloy was found to be the monoclinic ${\mathrm{Al}}_{45}$${\mathrm{Cr}}_{7}$ (2/m). A definite orientation rela…
Mixture equations relate the effective macroscopic electromagnetic properties (dielectric constant and magnetic permeability) of a composite material to the intrinsic microscopic electromagnetic properties of its constituents. The predictions of mixture equations in popular use generally agree with each other when par…
Indium tin oxide (ITO) films were prepared with relatively high deposition rate by rf magnetron sputtering under an applied external dc magnetic field. The films with resistivity as low as 2×10−4 Ω cm and average transmittance above 85% at wavelengths between 400 and 800 nm were able to form on the substrates at tempe…
The quantitative application of micromagnetic theory to barium ferrite particulate media is reported. The theory includes magnetostatic, anisotropic crystalline, and exchange interactions. It is found that neither packing, stacking, thermal fluctuations, nor curling can account for the discrepancy between the predicti…
SiO films evaporated under oblique incidences are well known to provide antisymmetric planar and symmetric tilted anchorings occurring as a function of the incidence angle. In the study of wetting of such substrates by nematics, we observe that the transition between these two types of anchoring is not discontinuous b…
Recent progress in preparing organic solids with ferromagnetic interactions between spins is reviewed. The three principal models are discussed together with relevant materials that have been prepared in Japan, at Columbia University, in Moscow, and at IBM, Almaden. These are compared with the molecular ferromagnets r…
The rare-earth–iron intermetallic compounds SmTiFex, with x ranging between 8 and 10, have been synthesized by an arc-melting technique. We found that they crystallize in the ThMn12-type tetragonal structure, I4/mmm. Unusual uniaxial magnetocrystalline anisotropies have been observed. The c axis is the easy magnetizat…
Single crystals of the compounds R2Fe14B some 1–4 mm in size have been grown for a study of the anisotropy of the magnetization curves. These curves for crystals with R=Tb, Dy, Ho, Er, and Tm were measured at the Service National des Champs Intenses, Grenoble, between 4.2 and 275 K, with fields of 0–18 T being applied…
We examine theoretically structural and electronic properties of thin ${\mathrm{Si}}_{\mathrm{n}}$${\mathrm{Ge}}_{\mathrm{n}}$ superlattices for n=1, 2, 4, and 6, grown on (001)-oriented substrates. The increased repeat distance along the growth direction leads to folding of conduction-band states to the \ensuremath{\…