Materials Literature
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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…
A thin amorphous Ba–Fe–O film was deposited as an underlayer for the growth of c-axis oriented hexagonal barium ferrite (BaM) films using a facing targets sputtering system. This underlayer facilitates the crystallization and improves the crystallinity for hexagonal M phase. BaM films with c-axis orientation can be pr…
Charge transport in polyaniline protonated fully with methane sulphonic acid (MSA) and polyaniline (MSA)-polyurethane [PANI(MSA)-PU] blend has been investigated through measurements of temperature (T) and electric field (E) dependence of conductivity (\ensuremath{\sigma}), temperature dependence of thermoelectric powe…
Double-exchange ferromagnets with their associated large magnetoresistance have recently been considered as candidates in magnetic storage applications. We review materials aspects of one compound family, La1−xCaxMnO3. There exist two distinct low temperature regimes; (i) ferromagnetic and metallic (x<0.5) and…
Active powders of Ni–Zn ferrite were synthesized by soft chemical approaches and were extensively characterized using x-ray diffraction, scanning electron micrographs, vibrating sample magnetometer, resistivity, and permeability/loss factor techniques. The variation in the sintering conditions established a useful mic…