Materials Literature
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We report a systematic analysis of the crystal-field spectra of four fluoride compounds containing tetravalent actinide ions. The first part of this work [J. Chem. Phys. 95, 7194 (1991)] provided interpretation of the absorption spectra of UF4, NpF4, and PuF4. To extend our analysis to heavier elements of the series,…
Electron microscopy and initial magnetization studies at elevated temperatures were performed on two die-upset rare-earth magnets with bulk compositions Nd13.75Fe80.25B6 and Pr13.75Fe80.25B6. In both compositions the intergranular phase is amorphous and occurs primarily on those surfaces parallel to the tetragonal 2-1…
The effect of changing stress on the magnetization of ferromagnetic materials leads to behavior in which the magnetization may increase, or decrease, when exposed to the same stress under the same external conditions. A simple empirical law seems to govern the behavior when the magnetization begins from a major hyster…
Abstract New strategies for the synthesis of perfectly alternating segmented polyimide‐polydimethyl siloxane copolymers were developed by utilizing a transimidization method. Imide oligomers endcapped with 2‐aminopyrimidine were reacted with aminopropyl terminated (dimethyl siloxane) oligomers to afford perfectly alte…
Electronically conductive polymers can be synthesized within the pores of microporous membranes to yield microscopic tubules of the polymer. We have investigated the temperature dependence of resistance of thin films prepared from microtubules composed of polyaniline and polypyrrole. All resistance data obtained follo…
Magnetization and magnetostriction in amorphous binary TbFe and DyFe and amorphous and polycrystalline, ternary (TbxDy1−x)yFe100−y thin films have been investigated. The measurements reflect the compositional dependence of the easy direction of magnetization in the films. In plane magnetostrictions of over 300×10−6 we…
The inverted hysteresis loop is claimed to be possible, in an exchange-coupled bilayer, when a magnetically soft material is affected by the demagnetizing field of the hard material. These demagnetizing fields are caused by the charge on the surfaces, neglected in all the theories that assume a strictly one-dimensiona…
We report on soft-x-ray photoelectron spectroscopy (SXPS) of a ${\mathrm{TiO}}_{2}$(110) surface during deposition of Fe in the monolayer regime. At low fractional monolayer coverages, the adsorbed Fe atoms are oxidized and Ti cations at the interface become reduced due to Fe adsorption. SXPS from shallow core levels…
By means of a Green-function, volume-integral-equation approach we study numerically the scattering of a surface plasmon polariton at a planar vacuum-metal interface by dielectric and metallic defects that are either embedded in the metal substrate or are situated in the vacuum region on the substrate. We calculate th…
Controversy about the magnetic properties of α″-Fe16N2 thin films makes it desirable to examine bulk material. In the original preparation and crystal structure determination of α″ in 1951, N-austenite (γ) prepared by nitriding α-iron powder at 700–750 °C was quenched to give N-martensite (α′) which then gave α+α″ on…
Using both primary- and tertiary-structure comparisons, we have established new structural similarities shared by reductases, epimerases and dehydrogenases not previously known to be related. Despite the low sequence identity (down to 10%), short consensus segments are identified. We show that the sequence, the active…
The half-metallic ferromagnetic compounds due to the absence of states at EF for minority spin electrons, as predicted by band theory, should exhibit unique features in their transport properties. Transport measurements conducted as a function of T and H for NiMnSb and PtMnSb thin films show interesting behavior. In H…
A study of the adsorption of sulfur on the GaAs(100) surface after in situ thermal desorption of a protective As capping layer is presented. The sulfur flux was generated by the decomposition of silver sulfide in an UHV-compatible electrochemical cell. Use of As-capped samples provided a means to study the interaction…
We present a theoretical study of the effect of longitudinal-optical phonons and surface-optical phonons on the electronic states of conduction electrons and donorlike excitons in a spherical semiconductor quantum dot. The effect of the quantum confinement is described by an infinitely deep potential well in the frame…
Time dependence of magnetization in ferromagnetic materials was first described towards the end of the 19th century. Subsequently, two types of mechanisms responsible for time dependent behavior were identified and became known as ‘‘diffusion’’ and ‘‘fluctuation’’ after-effect or viscosity. The former depends on therm…
Spherical and monodisperse Co20Ni80 particles were prepared, in the micrometer and submicrometer size range, by the polyol process. X-ray diffraction showed crystalline particles with a fcc structure. From electron probe microanalysis a fairly homogeneous distribution of both elements within each particle was observed…
We have studied the crystallization, crystal structure, microstructure and magnetic properties of R-Fe-B (R=Nd,Pr,Dy,Tb) based melt-spun ribbons consisting of a mixture of R2Fe14B and α-Fe phases. All the samples crystallize first to α-Fe and a metastable phase (Y3Fe62B14 for R=Nd,Pr,Dy and TbCu7 for R=Tb) before they…
Changes in the impedance, ≊600%/Oe, at axial fields less than 1 Oe have been observed in the presence of a 90 kHz, few mA current through a soft, nearly zero magnetostrictive wire. In this 125 μm diameter CoFeSiB amorphous wire we observe a total change of 160% at the maxima of the impedance in dc fields less than 2 O…
Conflicting reports of large magnetoresistive and magnetoinductive effects in amorphous FeCoSiB wires and ribbons prompted the impedance measurements reported here. The spectra (0≤f≤3.2 MHz) were obtained at room temperature using a commercial impedance analyzer both as functions of axial magnetic field (−140<H…
Stabilizing the 1-12 phase with cerium was possible using a special heat treatment. The structural and magnetic properties of Ce(Fe,M)12 and their nitrides, for M=Ti, V, Cr, Mo, etc., were investigated using x-ray-diffraction and magnetic measurements. The effects of interstitial nitrogen atoms on lattice parameters,…