Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
After reviewing the main aspects of Barkhausen effect (BE) phenomenology and the principal theoretical models proposed for its interpretation, a new experimental and theoretical approach is presented. It is shown that definite progress in the comprehension of BE phenomenology is achieved by restricting BE experiments…
Starting from elemental powders, hard-magnetic Nd-Fe-B can be produced by mechanical alloying and a solid-state reaction. Due to the short reaction time at relatively low temperatures (typically 30 min at 700 °C), the magnetically isotropic particles are microcrystalline and show a high coercivity. These powders can b…
A model is proposed for interstitial diffusion in a disordered alloy. Diffusion is described in terms of single-jump processes with an activation energy and a prefactor depending on the chemical and physical structure of the initial and final sites. Site-dependent activation energies, prefactors, selective blocking fa…
A novel magnetostriction measurement tool is developed for a thin soft-magnetic film on a nonmagnetostrictive substrate. The sensitivity is at least an order of magnitude better than prior art, and is adequate to measure a magnetostriction coefficient as small as 10−7–10−8 for a film as thin as 30 nm on a glass wafer…
A novel icosahedral alloy, ${\mathrm{Al}}_{65}$${\mathrm{Cu}}_{20}$${\mathrm{Fe}}_{15}$, produced in both a thermodynamically metastable and stable phase, has been studied with $^{57}\mathrm{Fe}$ M\"ossbauer spectroscopy, x-ray diffraction, and differential thermal analysis. It was found that the M\"ossbauer spectrum…
Intermetallic compounds of the type RE(TM1−xMx)12 with RE=Y, Er; TM=Fe, Co; M=Si, Ti, V of the ThMn12 tetragonal crystal structure have been studied by the singular point detection technique and high-resolution neutron powder diffraction in order to (a) evaluate both the rare-earth and transition-metal sublattice cont…
Results are reported from angle-integrated, angle-resolved, and resonant photoemission measurements on cleaved MnO single crystals using synchrotron radiation. Normal-emission spectra from a cleaved (100) surface indicate that the relative dispersion of Mn 3d states in the valence band is less than \ifmmode\pm\else\te…
The primary structure of the ribonuclease inhibitor from pig liver has been determined by amino acid sequence analysis. The N alpha-acetylated polypeptide chain of 456 amino acids consists of 15 homologous leucine-rich repeats, characterized by leucyl residues at constant positions. Two types of alternating repeats oc…
Enhanced magnetically isotropic properties are observed in melt-spun flakes of the Nd2Fe14B(Si) type. The magnetic enhancement, referred to as HIREM, includes a remanent magnetization equal to 8–9.3 kG (with saturation magnetization measured between 15.2 and 15.7 kG), and an energy product up to 19 MGOe. Both of these…
A recently developed density-functional method for calculating elastic moduli of crystals is generalized to include phason elasticity in incommensurate crystals. The theory is applied to hypothetical icoshedral quasicrystals based on interactions embodied in the pair correlation functions of a dense-random-packing mod…
Effects of the spin reorientation in Nd2Fe14B below Ts =135 K on the hard magnetic properties of melt-spun Nd-Fe-B ribbons are reported. As the ribbons are cooled from room temperature, the shape of the second quadrant demagnetization curve is maintained down to 150 K, with an intrinsic coercivity Hci which increases…
Extensive x-ray diffraction (XRD) and magnetic measurements were done on Nd15 Fe77 B8 magnet alloy green compacts after cold isostatic pressing following a pulsed 2-T field (CIP) and die-pressing under a static 1.2-T perpendicular field (DP1) or parallel field (DP2), and on those after sintering. An alignment factor F…
Dielectric properties of the {N(CH 3 ) 4 } 2 ZnI 4 crystal were studied between room temperature and 4.2 K. Two phase transitions were seen from dielectric constant anomalies at T 1 =254 K and T c =210 K on cooling. Ferroelectric hysteresis loops were observed along the c -direction below T c with a low frequency appl…
The ferromagnetic anisotropy of resistivity Δρ/ρ0=(ρ∥−ρ⊥)/ρ0 depends strongly on the nature of the dominant electron scattering centers, and is usually larger for impurity scattering than for phonon scattering. This explains why Δρ/ρ0 decreases with increasing temperature T in crystalline transition-metal alloys. Park…
Vibrational contributions to the molecular polarizability and hyperpolarizabilities are calculated for OH, OH+, and OH− for an electric field directed along the bond axis. It was found that vibrational averaging of the polarizability works reasonably well for OH and OH−, but fails for OH+ , giving a result 16% to low.…
Measurements of magnetostriction λ, magnetic Barkhausen effect (MBE), and magnetic induction B have been made as a function of magnetic field H in a number of specimens of Tb0.3Dy0.7Fe1.9 prepared recently at Ames Laboratory. These results showed marked variations in properties from specimen to specimen. For example,…
It is a very serious problem for an implantable artificial heart to receive energy from outside the body. A new implantable transformer with a plain weave structure was proposed by using amorphous magnetic fibers. The transformer has the following features: (i) a thin, planar shape; (ii) high flexibility; and (iii) lo…
The formation of the tetragonal compounds R2Fe14C (Nd2Fe14B structure) was studied as a function of the R component. At high temperatures the tetragonal R2Fe14C phase transforms mainly into a rhombohedral phase of the type of R2Fe17Cx in which the C atoms occupy an interstitial position. The transformation temperature…
The frequency, field, and temperature dependencies of core loss in rapidly quenched Fe-6.5 wt. %Si ribbons are reported. The annealed material exhibits (001)〈uv0〉 fiber texture, resulting in isotropic properties in plane; equivalent losses and B-H loops are seen in tape-wound toroids and in annuli punched from ribbon.…
Structure and magnetic properties of the rapidly quenched SmTiFe11 alloy ribbons fabricated under various quenching rates were systematically examined. Phase transformation from an equilibrium ThMn12-type structure (tetragonal) to a metastable TbCu7-type disordered structure (hexagonal) was found for the ribbons fabri…