Materials Literature
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A low concentration of substitutional impurities such as Ga or Si in R2Fe17 (R=rare earth) raises its Curie temperature. Self-consistent spin-polarized electronic-structure calculations are performed and exchange parameters (Jij) are derived from first-principles for pure Sm2Fe17 and Sm2Fe16A (A=Ga, Si). The changes i…
In Nd2Fe17−δCrδ (δ=0, 0.5, 1, 1.9), Cr substitutes for Fe atoms without changing the crystal structure. Neutron diffraction measurements show that for all values of δ, Cr preferentially substitutes for Fe in the 6 c site and randomly substitutes for Fe in the 18 f site. Cr substitution can be explained by considering…
A series of amorphous and partially crystalline giant magnetostrictive thin films of the composition (Tb0.3Dy0.7)39Fe61 has been prepared by dc magnetron sputtering. The sputtering conditions were the same for all samples apart from the substrate temperature TS, which varied between 330 and 510 °C. The crystalline sta…
Local-density approximation ab initio band-structure calculations have been carried out on the misfit compound (LaS)(SrS${)}_{0.2}$${\mathrm{CrS}}_{2}$. It appears that this phase can be regarded as an infinite two-dimensional intercalation compound. One electron is transferred from the LaS slab to the ${\mathrm{CrS}}…
Spin reorientation of Nd2Fe14B with different degree of grain sizes was detected by measuring the temperature dependence of the ac susceptibility. The studied materials include: (1) a spherical Nd2Fe14B single crystal that shows no coercivity. (2) Microcrystalline Nd2Fe14B obtained by induction-melting or by sintering…
Iron losses can account for a significant portion of the total loss in electrical machines. Nevertheless, although analytical and numerical techniques have been developed for predicting the iron loss density distribution and the total iron loss of various types of machine under any operating load condition, to date th…
A theory is presented to calculate the electron inelastic scattering cross section for a moving electron near the surface region at an arbitrary takeoff angle. The theory is based on using a bulk plasmon-pole approximation to derive the numerically computable expression of the electron self-energy in the random-phase…
At cryogenic temperatures magnetic properties of ferrites change significantly from their values at room temperature, which has been the main regime for most device applications. Recently, microwave ferrite devices with superconducting microstrip circuits have been demonstrated at a temperature of 77 K with virtually…
We have investigated how plastic deformation changes the yield stress and the magnetic properties of an ultralow carbon sheet steel. Plastic strains up to 10% nearly doubled the yield stress from 150 to 290 MPa (22–42 ksi), and the coercive field from 0.17 to 0.31 kA/m (2.1–3.9 Oe). The effects on other magnetic prope…
The sorption and transport of four aliphatic hydrocarbons into natural rubber crosslinked by different vulcanization systems [conventional (CV), efficient (EV), peroxide (DCP) and a mixed system consisting of sulfur and peroxide (mixed)] were investigated in the temperature interval of 28–60°C. Of the four systems, na…
Recent developments in rare earth intermetallic materials which may be suitable for bonded magnets are reviewed. These include isotropic coercive powder with a refined grain structure, isotropic single-phase powder showing remanence enhancement, exchange-coupled hard/soft nanostructures, anisotropic coercive powder, a…
In the crystal structure of hydrothermally synthesized sodium manganese fluoride orthophosphate, Na2{MnF[PO4]}, two kind of cis-MnO4F2 octahedra share common vertices to form (Mn2F2O8) chains parallel to the b axis of the monoclinic unit cell. In the a and c directions these chains are linked by PO4 tetrahedra to form…
The properties of Mn-substituted NiCuZn ferrites, (Ni0.2Cu0.2Zn0.6O)1.03(Fe2−xMnxO3)0.97 and (Ni0.2−xMnxCu0.2Zn0.6O)1.03(Fe2O3)0.97 sintered at a low temperature, were investigated in this study. When Mn was substituted for Fe ranging from 0 to 0.04 and for Ni ranging from 0 to 0.01, initial permeability and bulk dens…
From the investigation regarding the dependence of power loss and electrical resistivity at a temperature at which crystalline anisotropic energy becomes zero, eddy current loss and residual loss could be obtained separately. The increase in residual loss as exciting magnetic flux density, Bm, follows Bm2 at 1 MHz and…
Transport and contact properties of synthetic IIb- and intrinsic chemical vapor deposition (CVD) -diamond films are discussed. The samples have been investigated by time-of-flight and transient photoconductivity experiments using Cr/Au contacts. A hole depletion layer at the Cr/Au-IIb-diamond interface and an electron…
The effects of structural and oxygen site defects on the ferromagnetic phase transition and magnetotransport in doped lanthanum manganite films have been examined. Oxygen defects were introduced through a vacuum annealing process while structural defects were introduced using ion irradiation. The introduction of both…
Dynamic hysteresis loop shapes and magnetic power losses are studied in nonoriented Fe-Si laminations exhibiting significant excess losses. Measurements are carried out under controlled sinusoidal induction in the frequency range from 1 Hz to 1.6 kHz, at various peak inductions from 0.25 to 1.5 T. Excess losses are fo…
The time-dependent properties of arrays of elongated and mutually aligned iron particles in alumite (anodized aluminum oxide film) have been studied. At a constant particle diameter of 11 nm, the magnetic viscosity is nearly independent of the particle length (varied from 140 to 440 nm). The activation volume (1.1 to…
We report on surface structure analyses by quantitative low-energy electron diffraction for ultrathin films of 1.5 and 5 ML Co on Cu(111) and on the structural changes they undergo when additionally covered by 2--3 ML copper. The thin cobalt film is dominated by continuation of the fcc stacking dictated by the substra…
A simplified theory of magnetostriction, derived from micromagnetics, is presented. The theory is designed to provide a systematic, yet manageable, quantitative tool in the design of magnetostrictive actuators, by making the “calculation” of the overall response of magnetostrictive specimens subjected to applied magne…