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。
This corrosion study was performed to determine the reaction kinetics of Nd-Fe-B type magnets in oxidizing environments. Thus the oxidation model developed provides basic information for the development of oxidation-resistant magnets. The oxidation of Nd-Fe-B magnets was studied at temperatures between 20 and 150 °C.…
Reflectivity and Raman measurements of magnetite at 300, 130, 80, and 6 K are presented. The four infrared-active phonon modes and the five Raman modes exhibit fine structures below the Verwey transition (120 K), which are clearly detected for what may be the first time. A phenomenological analysis of the phonon spect…
A model is presented for the stress-dependent effective field, which when used in conjunction with the Jiles–Atherton theory, qualitatively accounts for (1) the change in slope and shape of the hysteresis curves with uniaxial stress and (2) the convexity of the curves depicting remanent and peak magnetization as a fun…
Magnetically isotropic Nd15Fe77B8 powder is prepared by mechanical alloying and a solid-state reaction from the elemental powders. Due to the extremely short reaction time (for example, 10 min at 700 °C) the magnetically isotropic particles have a very fine microstructure comparable to rapidly quenched samples, show a…
In rare earth (R)–transition metal (M) compounds, large R-M magnetic interactions can occur, which give rise to higher values of the ordering temperature (TC,TN) for compounds with magnetic R elements than for compounds with R nonmagnetic, i.e., La, Lu, Y. Due to the localized character of the 4f shell, these R-M inte…
The temperature dependence of the coercivity (HcI)of Nd15(Fe1−xCox)77B8 and (Nd1−xDyx)15Fe77B8 sintered magnets and that of the saturation magnetization (Ms) and the anisotropy field (HA) of Nd2(Fe1−xCox)14B and (Nd1−xDyx)2Fe14B single crystals have been observed in the temperature range between 295 and 800 K. The dep…
Dendritic growth of crystals in two dimensions is analyzed by a Green's-function method. A one-sided diffusional model is treated in quasistationary approximation. Anisotropy is found necessary for dendritic growth. We find scaling with anisotropy to be in agreement with recent results for needle crystals in the symme…
Submicron (<0.25 μm) wide lines of iron have been deposited by low-energy (0.5–3.0 keV) electron beam induced decomposition of iron pentacarbonyl. Selective area thermal decomposition of iron pentacarbonyl has also been demonstrated. It was found that under certain conditions, the thermal decomposition only occ…
First-principles, total-energy electronic structure calculations have been used to study the effects of charge transfer in graphite intercalation compounds. Together with an in situ diffraction study on graphite undergoing intercalation with sulphuric acid, the results strongly support the idea of a universal relation…
A linear electro-optic effect in a cholesteric liquid crystal is described and attributed to the flexoelectric effect. An electric field applied perpendicular to the helix axis rotates the director about an axis parallel to the field. This produces a periodic splay-bend pattern in the helix, which couples flexoelectri…
The density functional theory of freezing is extended to the crystallisation of multicomponent systems into substitutional solid solutions. The formalism is applied to the case of binary mixtures of hard spheres. As the ratio of diameters alpha = sigma 1 / sigma 2 is lowered, the fluid-solid phase diagram evolves from…
EPR spectra at 9.1 and 30 GHz are reported for the iso-electronic ions Gd 3+ and Eu 2+ in glasses of composition 0.50 ZrF 4 , 0.20 BaF 2 , 0.055 AlF 3 , 0.045 LaF 3 and 0.10 NaF or LiF. The spectra are similar to the 'U' spectra familiar in many oxide glasses, indicating very low and disordered site symmetries with a…
The structural phase transition in GeTe has been investigated by neutron diffraction in the temperature range 295-716 K. Accurate positional and thermal parameters have been obtained as a function of temperature both in the rhombohedral hR2 phase(binary analogue of grey arsenic structure A7) and in the cubic CF8 phase…
Abstract The hydrogenation and dehydrogenation of cyclohexene has been studied in temperature-programmed and isothermal modes over oxide-supported Pt surfaces. The ratio of the rates of dehydrogenation: hydrogenation measured experimentally does not appear to correlate with that expected from standard thermodynamic fr…
Abstract A new R-matrix theory of electron-atom and electron-molecule scattering at intermediate energies is described. In this theory both the outer valence electron of the target atom or molecule and the scattered electron are expanded in terms of a continuum R-matrix basis. This enables target eigenstates as well…
A new variant of the usual x-ray standing-wave experiment, scanning the Bragg reflection in energy at normal incidence, is shown to be applicable to metal crystals without special precautions being taken to ensure high crystalline perfection. The structure of the Cu(111)(\ensuremath{\surd}3 \ifmmode\times\else\texttim…
The primary structure of human uromodulin, a 616-amino acid, 85-kilodalton glycoprotein with in vitro immunosuppressive properties, was determined through isolation and characterization of complementary DNA and genomic clones. The amino acid sequence encoded by one of the exons of the uromodulin gene has homology to t…
Nonuniform flux distributions in amorphous toroidal cores can result in anomalous eddy current losses. Amorphous toroidal cores were excited (by a sinusoidal magnetic flux) and the resulting core losses and local flux distributions measured. Though the overall core flux was sinusoidal, the local flux distribution was…
The wear rate of cast iron and the corrosion potential (Ecorr) and current (Icorr) were measured in sulphuric acid in order to study the mechanism of corrosive wear of cast iron. The corrosive wear rate of cast iron was found to reach a maximum at around 35 wt. percent sulphuric acid concentration and increase with lo…
Abstract In this study the apparent rate constant model was used to determine the mechanism of termination and other rate constants for free radical copolymerizations that are chemically controlled with no penultimate effect. The data required were the number average molecular weight and the conversion obtained at var…