Materials Literature
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We present a treatment of the scattering of electromagnetic waves at rough dielectric surfaces using both the Rayleigh hypothesis and the extinction theorem. An explicit expression relating s- and p-polarized components of the field in the dielectric with the incident field is given. A Dyson equation is then derived f…
A structure model of an icosahedral Al-Mn quasicrystal is proposed based on the structure-factor calculation and the x-ray and neutron powder-diffraction patterns of rapidly solidified Al-Mn alloys. The model has a local atomic arrangement similar to that of the cubic \ensuremath{\alpha}--Al-Mn-Si and has icosahedral…
A series of NMR experiments has been conducted on $^{1}\mathrm{H}$ in the metallic glass a-${\mathrm{Zr}}_{3}$${\mathrm{RhH}}_{3.5}$ to establish the temperature dependence of the mean H-atom jump rate. Temperature and frequency dependence of the $^{1}\mathrm{H}$ spin-lattice relaxation rates and, at three temperature…
A simple model used previously by the authors to explain stress variation of magnetic hysteresis is now employed to explain the effect of stress on the amplitudes of the first- and third-order harmonics of the magnetic induction signal resulting from application of an ac magnetic field of low frequency to a steel spec…
We study surface orientation of nematic 5 CB on obliquely SiO evaporated glass plates, at grazing incidence. For SiO thickness comparable with nematic molecular length, we observe a twofold degenerate oblique orientation, which allows a continuous transition between the well-known planar and oblique orientations. This…
Reactive sticking coefficients (RSCs) were measured for silane and disilane on polycrystalline silicon for a wide range of temperature and flux (pressure) conditions. The data were obtained from deposition-rate measurements using molecular beam scattering and a very low-pressure cold-wall reactor. The RSCs have nonlin…
The hard magnetic properties of Fe-Mm-B alloys have been studied in melt-spun ribbons and sintered magnets. The as-spun ribbons were magnetically soft and high coercive fields (Hc∼7 kOe) were obtained after a heat treatment at about 700 °C. This caused crystallization of the sample into the Mm2Fe14B phase. The magneti…
Permeability relates the magnetic field intensity in a magnetic material to the resulting flux density. The initial part of the permeability extending from dc fields to the radio-frequency fields of a few hundred megahertz is due to domain wall displacement. A spin resonance occurs due to the presence of an anisotropy…
We apply spin-density functional theory (SDF) to describe noncollinear magnetism; i.e., self-consistent energy-band calculations based on the local approximation to SDF theory are presented in which the magnetization associated with different atoms in a unit cell is allowed to point along different, noncollinear direc…
The parameter dependence of vacancy and self-interstitial formation energies has been studied with an analytic nearest-neighbor atomistic model based on the embedded-atom method. The model was designed for fcc copper, but the results should not depend on either the structure or the element. Exponentially decreasing fu…
Nickel zinc ferrites have been very widely used in the high-frequency applications. In our present study we have prepared Ni1−x Znx Fe2O4 (0≤x≤1) using novel hydrazinium metal hydrazinecarboxylate precursors. High densities (∼99%) have been obtained for all the ferrites sintered at relatively low temperatures, 1100 °C…
Formation of grain oriented Nd-Fe-B magnets from melt-spun ribbons by hot deformation has been studied using electron microscopy. It is shown that deformation and alignment of Nd2Fe14B magnets result from a combination of plastic deformation, grain boundary migration, and grain boundary sliding. Due to a limited numbe…
Measurements of the effect of uniaxial stress on the frequency of the k≊0 optical phonons in heat-treated benzene-derived graphite fibers have been performed using first-order Raman scattering. Application of uniaxial stress along the fiber axis is found to cause polarization-dependent splittings and shifts of the Ram…
The validity of nucleation and domain wall pinning models has been examined in R-Fe-B magnets by correlating the hard magnetic properties with the microstructure and magnetic domain structure. The nucleation model can be used to explain the magnetic properties of R-Fe-B magnets at low temperatures, but it fails at hig…
A long standing problem in numerical statistical mechanics has been the incorporation of the long range, many-body hydrodynamic forces between particles in suspension. In this paper I describe a general computational method for calculating the forces and torques exerted by slowly moving spheres suspended in an incompr…
This paper describes a type of vibrating-sample magnetometer capable of sensitivity exceeding 10−8 emu. The instrument is 1000 times more sensitive than a conventional VSM with comparable working space, and is much quicker to use than a SQUID magnetometer, which generates point-by-point data. The magnetic sample is mo…
The structures and the magnetic properties of some novel ternary compounds were studied. These compounds have the approximate composition RFe10T2, where T represents Cr, V, Ti, Mo, W, or Si. The structure of all these compounds can be derived from the tetragonal ThMn12 structure type, but the crystallographic position…
Density-functional calculations using the full-potential linearized augmented-plane-wave (FLAPW) film method have been used to compute the effective potential for electrons at different surfaces of Al, Ni, Cu, Ag, and W. In each case, the average of the potential parallel to the surface is reproduced well by a simple…
The dynamics of an electron in a one-dimensional tight-binding model with incommensurate sinusoidal modulation (Harper's model) is studied numerically. The width of a wavepacket of an electron put on a single site at the time t =0 exhibits such asymptotic time evolution as \(\sqrt{\langle\varDelta x^{2}\rangle}\sim t^…
Large ‘‘jumps’’ in the magnetostriction have been observed in twinned single crystals of Tb0.3Dy0.7Fe1.9 (Terfenol-D) for magnetic fields parallel to the crystalline [112̄] direction. The interpretation of these large magnetostriction discontinuities is based upon a model of twinned dendritic Terfenol-D in which the m…