Materials Literature
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Dynamics of amorphous cis-1,4-polybutadiene was studied by incoherent inelastic and quasielastic neutron scattering below 10 meV in a wide temperature range covering the glass transition temperature Tg. The spectra at low temperatures below Tg show a broad excitation peak at about 2–3 meV, which is the so-called low-e…
New isotropic vector Preisach-type models of hysteresis are introduced. These new models contain additional unknown functions. This presents the opportunity to incorporate more experimental data in the identification process than in the case of previously suggested vector Preisach models, thus leading to more accurate…
The magnetic properties of materials containing rare earth ions coupled to the stable organic radicals nitronyl nitroxides are reported. When the rare earth ions are nonmagnetic, like yttrium(III) and europium(III), the materials behave as one-dimensional antiferromagnets, the coupling between the radicals being deter…
Abstract It has been found that three possible mechanisms can contribute to the improvement in fibre/resin adhesion when high‐modulus polyethylene fibres are subjected to oxygen gas plasma treatment. These mechanisms are surface oxidation, cross‐linking and surface etching. In this paper it is attempted to estimate th…
High-resolution photoemission studies of oxidation of the Al(111) surface have been performed. The appearance of a component at lower binding energy than the metallic bulk Al emission in the Al 2p spectrum at oxygen exposures above \ensuremath{\sim}50 langmuir (1 L = ${10}^{\mathrm{\ensuremath{-}}6}$ Torr s) is argued…
Abstract Surface contamination is one of the most insidious factors affecting adhesive bond performance and, hence, reliability of bonded structures. Sources of contamination are widespread and include primary materials, secondary materials, equipment, human operators, adjacent processes and the atmosphere. A successf…
Recent work by Bertotti [IEEE Trans. Magn. MAG-24, 621 (1988)] and others has shown that it is possible to model the micromagnetic Barkhausen discontinuities at the coercive point using a two-parameter stochastic model. However, the present formulation of the model is restricted to limited regions of the hysteresis cu…
57Fe Mössbauer spectroscopic measurements have been made at 296 K on single crystals of MFe12O19 (M=Ba, Sr, Pb) oriented parallel and perpendicular to the c axis, permitting the establishment of the systematics of the static and dynamical aspects of the hyperfine interactions, and their relationship to crystal/chemica…
Theoretical results obtained with first-principles total-energy calculations are reported for potassium adsorption on the graphite (0001) surface. The structural parameters, the chemisorption energies, and the electronic properties of the K-graphite system are studied at two representative coverages, i.e., in the tria…
We studied the finite-size effect on the first-order metal-insulator phase transition and the accompanying tetragonal-to-monoclinic structural transition of ${\mathrm{VO}}_{2}$ films. The ${\mathrm{VO}}_{2}$ films were epitaxially grown by a metal-organic-chemical-vapor-deposition technique on the (101) growth plane o…
In contrast to most ferromagnetic materials, the low-temperature phase of MnBi exhibits an increased coercivity, Hc, with temperature. μ0Hc has a value of 0.2 T at room temperature, and rises dramatically to a maximum value of 1.9 T at 550 K. In the temperature region near its maximum value, Hc is much larger than tha…
The aim of the present work is to attempt to make a number of different glasses, based on tellurite as the principal former, which contain substantial quantities of zinc oxide up to 40 mol % ZnO. To study the longitudinal elastic properties, measurements have been made of the velocity of the longitudinal ultrasonic wa…
Free-standing, stable, single-sized, and highly pure ZnS nanosize particles or quantum dots are synthesized using a chemical route. The dimension of the quantum dots as estimated from x-ray diffraction was about 7 and 15 Å. The optical band gap for these particles was 5.2 and 4.8 eV, respectively, as compared with the…
The best starting materials for die-upset magnets are moderately overquenched melt-spun ribbons of Nd-Fe-B alloys with ∼20 at. % more rare earth than stoichiometric Nd2Fe14B. Remanence increases with increasing die-upset (DU) level, reaching a maximum of 13.5 kG at 70% DU for ternary Nd-Fe-B magnets, beyond which crac…
ZnO (zinc oxide) thin films have been prepared by using rf magnetron sputtering on a SiO2/Si substrate. The crystallographic properties and optical properties were investigated. It is shown that the ZnO films exhibit strong c-axis orientation. The standard deviation of the c axis was obtained less than 1°. The optical…
Dynamic vibrational first and second hyperpolarizabilities, applicable to a number of nonlinear optical processes, have been calculated for H2O, CO2, and NH3 at a typical laser frequency. As a percentage of their electronic counterparts, they range from being very small to being on the order of 20–30 %. The static val…
The use of dispersion techniques for development of microwave absorbers is a convenient way of realization of coatings with good attenuation characteristics in the 1- to 20-GHz range. Particularly, elastomer mixing is a very good technique for dispersion and individualization of each grain up to 60% volume. A first ge…
A series of the toroidal cage forms of graphitic carbon is proposed. They have local topological structures of positive Gaussian curvature (for instance ${\mathrm{C}}_{60}$) and of negative Gaussian curvature. The toroidal forms consist of fivefold, sixfold, and sevenfold carbon rings. The cohesive energies of the tor…
Fe100−xCox and Fe100−xNix powders were prepared by mechanical alloying of the elements in a planetary ball mill. They were investigated with respect to phase formation and magnetic properties using x-ray diffraction and measurements of the saturation magnetization and the coercivity. In both systems, disordered solid…
Oxygen K-edge electron-energy-loss spectra have been recorded for several transition-metal oxides (NiO, MnO, ${\mathrm{MnO}}_{2}$, ${\mathrm{TiO}}_{2}$, ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{Mn}}_{2}$${\mathrm{O}}_{3}$) of different crystal structures. The origin of the distinct features which can be identi…