bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Conduction-Diffusion Theory of Semiconductor Junctions
Authors: Chang Y. F. 
Published: January 2005

This is a mathematical analysis of the conduction-diffusion equation, which governs the carrier motions in semiconductor materials. The model used for the junction devices is based on the Fletcher—Harrick injection relations at junctions and on the vanRoosbroeck conduction—diffusion equation in bulk regions. The exact solution of this analysis is obtained by numerical computation using the Automatic Taylor Series (ATS) method. Besides the numerical solution, there is a closed-form exact solution for zero recombination; this is the Gunn solution.
The limitations of this analysis are those imposed on the Fletcher—Harrick and vanRoosbroeck developments. They are the abrupt-junction condition, and the quasineutrality condition. Satisfaction of the first condition depends on device fabrication. This analysis does not include the effects found in diffused junctions. Satisfaction of the quasineutrality condition depends on the internal electric fields in the devices. This analysis examines these electric fields and keeps watch over its own validity.
The characteristics of semiconductor junction devices are analyzed by the conduction—diffusion theory with mathematical uniformity and exactitude. Application of this theory to the p—n and n—n+ junctions yields these results. The characteristics of p—n junctions analyzed here basically agree with the results of previous researchers. The n—n+ junction exhibits a current-saturation effect in the forward bias direction. This is due to a limitation on the injected carrier concentration in this device. The p—n—n+ and n+—n—n+ junctions are analyzed to eliminate metal contacts to the base region, because the quasineutrality condition is violated near these contacts. The three-layer devices have basically the same characteristics as the two-layer diodes. In p—i—n junction devices with long base regions, the quasineutrality condition is violated in the middle of the base region. In such cases, the solutions of Lampert and Rose and of Baron are more appropriate.
Structure of Martensite
Authors: Ron M. , Kidron A. , Schechter H. , Niedzwiedz S. 
Published: January 2005

X-ray measurements cannot give a complete microscopic interpretation of the structure of carbon—iron martensite because of the broad diffuse diffraction lines. They show that the iron martensite has a body-centered tetragonal lattice on the average, but cannot give an exact picture of the distortion centers around the carbon atoms.
Several samples of martensite were studied by means of the Mössbauer effect to separate the octahedra occupied by carbon atoms from the rest of the lattice. The iron atoms around each octahedron gave two extra different hyperfine fields, with an isomer shift relative to Armco iron. The strength of the new fields coupled with the intensity ratio of the absorption lines leads to the interpretation that the distortion around a carbon atom is local, and that most of the crystal has an almost bcc structure, probably with a small strain field centered at the carbon atom.
Reflection and Refraction of Electromagnetic Waves by a Moving Dielectric Medium
Authors: Pyati V. P. 
Published: January 2005

The problem of reflection and refraction of a plane electromagnetic wave by a semi-infinite dielectric medium moving uniformly parallel to its surface is analyzed. The scope of this paper is wider than earlier ones in that the orientation of the plane of incidence is arbitrary.
Certain interesting features are revealed. First, Snell's law is modified. Secondly, the resultant reflected and transmitted E and H vectors are not parallel (or antiparallel) to the incident E and H. Furthermore, when the incident wave is polarized with its electric field parallel to the plane of incidence, there is no angle of incidence (Brewster's angle) for which the reflected wave vanishes. An exception to these results occurs when the plane of incidence is parallel to the velocity. In this case, there is a strong resemblance to the nonmoving case.
Effect of Grip Stresses on Dislocation Configuration after Plastic Deformation
Authors: MacCrone R. K. 
Published: January 2005

Berg—Barrett x-ray micrographs of strained single crystals of aluminum have revealed that the macroscopic dislocation configuration is inhomogeneous. Two kinds of inhomogeneity are recognised: short-range inhomogeneity in any one ``small'' area due to dislocation subboundary formation and long-range inhomogeneity in which both subboundary type and density depend upon the position along the specimen gauge length and also on the position within the cross-sectional area.
The experimental results are interpreted in terms of the effects of grip stresses on dislocation motion.
Ionizing Space-Charge Waves in Gases
Authors: Winn William P. 
Published: January 2005

Luminous waves have been produced along the positive column of a glow discharge in N2 by applying a fast-risetime step voltage to an electrode at one end of the column. Such waves have been identified as a primary mechanism in the buildup of ionization in many kinds of electrical breakdown in gases. Voltage-sensing probes and a photomultiplier were used to observe how the waves were affected by the electron density in the positive column of the glow discharge. The most noticeable effect was that the velocity increased from 1×109 cm/sec at zero density to around 7×109 cm/sec at a density of 3×109 /cm3. The velocity also depended upon the magnitude of the voltage pulse, pressure, and the diameter of the coaxial shielding surrounding the glow-discharge tube. The shape of the wavefront also depended on the electron density, but it was more strongly affected by the pressure.
There were three striking differences between positive waves (those produced by a positive step voltage) and negative waves: (1) The velocities of positive waves depended more strongly on the initial electron density. (2) The wavefront of positive waves had a more complicated shape than that of negative waves. (3) Negative waves had to be initiated from a special electrode.
The electron density resulting from the ionizing waves has been calculated.
Location of Inert Gas Atoms in KCl, CaF2, and UO2 Crystals by H+ and He2+ ``Channeling'' Studies
Authors: Matzke Hj. , Davies J. A. 
Published: January 2005

The α-particle emission rate of 222Rn, embedded in single crystals of KCl, CaF2, and UO2 at a concentration of 10−4−10−3 at. %, exhibits no detectable anisotropy—thereby proving that the radon atoms do not occupy single lattice vacancies and also, in the case of the fluorite structures, CaF2 and UO2, that they do not occupy the big interstitial holes either.
The α-emission rate of the short-lived daughter isotopes (218Po and 214Po) also exhibits no anisotropy in the KCl, and CaF2 experiments. In UO2, however, the polonium α-peaks are attenuated markedly within 0.8°±0.2° of the 〈100〉 direction, indicating that the Po atoms are located along the 〈100〉 lattice row.
Similarly, wide-angle Rutherford scattering of protons has been used to show that Xe, embedded in KCl at a concentration of 0.2 at. %, does not occupy single lattice vacancies.
Dislocation Velocities in Nickel Single Crystals
Authors: Rohde Richard W. , Pitt Charles H. 
Published: January 2005

The velocities of dislocations moving in nickel single crystals were measured at various temperatures as a function of stress. The data were found to fit an equation obtained from reaction-rate theory.
The activated volume varied approximately linearly with temperature and was independent of the applied stress over the rather limited range of stresses investigated.
The enthalpy of activation was also independent of stress but changed abruptly with temperature from 1200 cal/mole at approximately 130°K to 2500 cal/mole at higher temperatures. This change is explained by a change in the Peierls stress, which is associated with a sudden increase in dislocation density at higher temperatures. The dislocations were believed to be emitted from sources which are thermally activated.
The Formation of Uniaxial Anisotropy in Nickel by Plastic Deformation
Authors: Krause R. F. , Cullity B. D. 
Published: January 2005

Previous plastic elongation, or compression, of polycrystalline nickel was found to produce a uniaxial anisotropy. The easy axis of magnetization was parallel to the direction of previous elongation and at right angles to the direction of previous compression. The maximum value of the uniaxial anisotropy energy constant Ku was about −2 700 erg/cm3 after 2.5% elongation.
The observed anisotropy is shown to be due to a particular distribution of residual microstress, in which most of the volume of the specimen is in residual compression, balanced by a small volume in tension, after plastic elongation. These stresses, although balanced, introduce magnetoelastic effects which do not cancel in a nonsaturated specimen and which thereby cause the observed anisotropy. Evidence for the assumed stress distribution was obtained by x-ray diffraction.
Computer Simulation of the Magnetic Dipole Interaction Problem
Authors: Moskowitz Ronald , Della Torre Edward 
Published: January 2005

Interacting systems of a large number of hysteretic bistable magnetic particles have been studied by direct calculation using digital computers. In this paper, we discuss calculations made on oriented dipole moments in a regular cubic array periodically extended parallel to the dipole axes in order to avoid demagnetization effects. Distributions of critical fields and moments are assigned to the array. The switching fields of the particles are modified by the interaction field. After the interaction fields are computed, the array is relaxed for the current applied field which may be cycled in any desired variation. The relaxation process is in order of decreasing particle vulnerability. The average interaction field has been found to be a linear function of the magnetization in agreement with the theoretical predictions of Della Torre. Distribution functions, n(Hi), have been determined. In addition a type of breakdown phenomena in these arrays suggested by Barker has been observed.
In application to fine particle systems as used in magnetic recording tapes, effects such as variation in particle orientation and nonuniform dispersions may be simply introduced into a subprogram of the simulation. In a similar fashion the model can be generalized to different types of interactions and applied to other magnetic and dielectric cooperative phenomena.
New Figure of Merit for Ceramic Permanent Magnet Material Intended for dc Motor Applications
Authors: Ireland J. R. 
Published: January 2005

In evaluating ceramic magnet materials as to suitability for permanent magnet motor use, it has been found that the normally accepted criterions, energy product, is of very little value.
A new figure of merit is proposed, which is BrHx. Br is the residual induction of the material, and Hx is defined as the H coordinate of a point on the intrinsic demagnetization curve, whose B coordinate is 0.8Br. For an imaginary motor with zero air gap, equations are developed to show an inverse proportionality between BrHx and the total volume of magnet material required to meet a given motor performance curve. For real motors, which contain air gaps, the figure of merit becomes; Br[Hx−0.8Br/(Pc +1)], where Pc is the permeance coefficient at which the magnet is operating. Since Pc does not vary widely in typical motors, and since this second figure of merit is not extremely sensitive to the value of Pc in typical ceramic magnet materials, an average value can be assigned to each material for comparison purposes. This second quantity is designated BrHa.
A tabulation of both figures of merit, and other data, is given for the materials designated by the Magnetic Materials Producers Association as Ceramic 2–6, inclusive.
Effect of Impurities on the Microwave Properties of Yttrium Iron Garnet
Authors: Sparks Marshall 
Published: January 2005

Simplified physical models are given for the giant anisotropy theory, the longitudinal relaxation theory, and the rapidly relaxing impurity (i.e., transverse relaxation) theory for the ferromagnetic resonance linewidth ΔH, and field for resonance Hres. A classification of the types of temperature T and frequency ω dependence of ΔH and Hres which may result from the longitudinal relaxation mechanism is given. Recent experiments on giant anisotropy peaks in ΔH and Hres and on maxima in ΔH and Hres vs T are interpreted with reference to this classification. By observing both ΔH and Hres, it is possible to distinguish between the transverse and longitudinal mechanisms even when ΔHis proportional to ω above and below the maximum of ΔH vs T.
A new interpretation is given for observed linewidths at the angles for the giant anisotropy effect, and the possibility of having a longitudinal relaxation mechanism without maxima—such as T−1 sech2(ℏωn/2kBT) —in ΔH and −Hres from the population factor is discussed.
Open-Shell Hartree—Fock Molecular Orbital Theory of Transition Metal Ion Complexes: KNiF3
Authors: Ellis D. E. , Freeman A. J. , Ros P. 
Published: January 2005

In order to investigate the magnetic properties of transition metal salts, we have developed the open shell single determinant Hartree—Fock SCF molecular orbital method for transition metal ion complexes. This cluster approach removes many of the shortcomings of earlier treatments1 and, in principle, provides a framework for obtaining fairly accurate and meaningful results within the single determinant approximation. These wave functions thus provide a realistic basis set for configuration interaction calculations of superexchange and other properties. By choosing a special one-center basis set for the cluster, we are able to compute all matrix elements of the molecular Hamiltonian accurately including the effects of the crystal field external to the cluster. Furthermore, the computation is sufficiently fast so that we may include all electrons of the molecular cluster while allowing considerable variational freedom in all representations.
Detailed self-consistent field calculations have been made using, as example, KNiF3, the antiferromagnetic Perovskite treated extensively by previous workers.1 By considering a NiF64− cluster in its crystalline environment, the crystal field splitting parameter 10 Dq is found to be in fairly good agreement with experiment, but sensitive to a number of factors. The resulting molecular orbitals are compared with those obtained by earlier LCAO calculations. While the radial distributions are quite reasonable, the limitations imposed on these first calculations with this one-center method are apparent; the restriction to low angular momentum in the basis sets used leads to a poor description of ligand core orbitals.
Spin densities throughout the cluster have been computed; neutron magnetic form factors have been calculated for comparison with experiment. In agreement with earlier work2 based on a single parameter LCAO scheme, we find that the cluster spin density gives a large peak in the form factor near zero scattering angles compared with the Ni2+ free ion result. This peak is seen to arise from the eg spin density on the ligand sites; the spin density from all the remaining molecular orbitals, unpaired by exchange polarization, is found to be small (≈2%).
The limitations imposed by the restricted basis set used have led us to consider a triatomic system, Ni2F, as the cluster for the calculation of F19 hyperfine interactions. While the calculated isotropic hyperfine term was found to be too large relative to experiment, the computed anisotropic hyperfine interaction agreed (surprisingly) well.
A full report will be submitted to the Physical Review.
Exchange Energy, Stress, and Momentum in a Rigid Ferrimagnet
Authors: Morgenthaler Frederic R. 
Published: January 2005

A self-consistent formulation of the exchange energy density, effective exchange field, and Poynting vector is carried out, for a general ferrimagnet, in terms of the spin and orbital angular momentum densities. When there is more than one magnetic lattice or when the gyromagnetic ratios are tensor quantities, this formulation leads to an exchange energy density and Poynting vector that differ from those commonly employed. The associated boundary conditions at a surface of passive discontinuity are also discussed; power flow considerations lead to the conclusion that one of these is a dynamic boundary condition.
With the help of the correspondence principle and a quasi particle interpretation of spin waves, a small-signal energy density, momentum density, and stress tensor are postulated for a ferromagnet. The associated small-signal force density (postulated to equal the divergence of the stress tensor minus the time rate of change of the momentum density) is found to be the negative of the force density that accelerates the envelope of the spin wave packet and is interpreted as a reaction force density acting upon the lattice. A prediction is made that a magnon incident upon a surface of discontinuity such as a material—air interface, will exert an exchange-radiation pressure on it.
The Solubility of Sulfur in Silicon Iron
Authors: Grenoble H. E. 
Published: January 2005

An earlier determination of the solubility of sulfur in silicon iron by Ainslie and Seybolt appears to be somewhat high for a material prepared in the manner of cold-rolled oriented steel strip. Accordingly, a redetermination has been made with materials having this particular processing.
The solubility was obtained using an equilibration method with the reference potential of sulfur provided by powdered ferrous sulfide or by a high-sulfur silicon iron. For the primary recrystallized structure the solubility is found to be 0.015% at 900°C and increases to 0.025% at 1100°C. For a large-grain structure the solubility at 900°C is significantly lower, indicating that there is a grain size effect upon solubility. This effect diminishes with increasing temperature.
Magnetic Materials for Space Power Systems
Authors: Beiler A. C. 
Published: January 2005

Deep space missions will require megawatts of electric power. Nuclear-electric systems, reliable for 50 000 h, will need materials to operate up to 1600°F in vacuum. They must withstand liquid alkali metals or their vapors and nuclear or cosmic radiation. Magnetic materials must meet high electrical efficiency requirements under severe environmental conditions and in some cases, stringent mechanical requirements.
Many types of electrical equipment, e.g., inverters and other devices in the manned quarters, will not be required to withstand such severe environments, but must still operate with the highest efficiency and reliability. Materials for such uses and the basis of their selection are reviewed.
The components and their environmental and operating requirements are reviewed. The status of available magnetic materials and the basis of their selection to satisfy these requirements for the two principal temperature ranges, 800°–1100°F and 1100°–1600°F, are presented. Weak areas and gaps are identified. The major gap is in materials for high-speed rotors in the highest temperature range.
The various metallurgical approaches applied to this problem and the necessary magnetic and physical compromises are presented.
The three approaches now being investigated are: (1) improved martenistic alloys; (2) improved precipitation strengthened Co alloys; (3) new dispersion strengthened Co and Fe-Co alloys. Encouraging preliminary results are presented.
Production and Properties of Grain-Oriented Commercially Pure Iron
Authors: Kohler D. M. 
Published: January 2005

Flat-rolled commercially pure iron such as Armco magnetic ingot iron has been found useful in applications requiring high-flux density. The existing commercial iron products do not have a strong texture. The development of a process for grain orientation in commercially pure iron could be expected to substantially improve the magnetic properties, making possible new applications.
In order to obtain a strong secondary recrystallization texture of the cube-on-edge type it is necessary to restrain grain growth of the primary structure, so that this fine-grained structure is maintained until secondary growth occurs at higher temperatures. Inhibitors added to the melt have not been effective in inhibiting the strong normal grain growth in commercially pure iron.
Effective inhibition of normal grain growth has been accomplished by diffusing extra sulfide inhibitors into the primary grain boundary in a very early stage of the final anneal. This has the effect of inducing a strong secondary growth into a material that will not normally support this type of secondary recrystallization.
Magnetic properties of highly oriented flat-rolled iron are given for sheet thicknesses from 6 to 25 mils. Comparisons of properties are made with 3% silicon iron and 50% cobalt—iron sheet.
Simultaneous Nanosecond Kerr Magneto-Optic and Inductive Measurements of Coupled Films
Authors: Chang H. , Genovese E. R. 
Published: January 2005

A technique for magneto-optic sensing of film switching in 5 nsec over an area 20-μ in diameter has been reported by Thompson and Change (Ref. 1). The technique, when used in conjunction with inductive sensing, enables the analysis of the switching behavior of each layer in a coupled film structure. An experimental structure consists of an insulated ground plane on top of which two Permalloy layers (125-μ wide, 900 Å/layer) sandwiching a word conductor (125-μ wide, 2-μ thick, 6 μ above ground) are deposited with each axis along the strips. Two strands of lines (100-μ wide on 200-μ centers) on glass are connected in parallel to form a bit/sense line. The sense line is 40 μ above the coupled film lines. The openings between strands provide optic access for Kerr magneto-optic sensing of the top film.
The word current and its ground image create fields of the same polarity at the bottom film, but of different polarities at the top film. It has been surmised that only the bottom film is switched by the drive current and its image, while the top film is switched by the stray field from the switched bottom film. Experimental results, indeed, confirm the above. Furthermore, the switching speed of the bottom film is found to be limited by flux trapping in the ground plane. During read, the switching speed of the top film is limited by its own demagnetizing field cancelling the stray field. During write, the switching speeds of both films are limited by the subtraction of shape-anisotropy field from induced-anisotropy field due to hard direction-flux closure. The device signal is found to be only slightly altered by a hard-direction bias field in the range of ±10 Oe.
Magnetic Recording Materials
Authors: Speliotis D. E. 
Published: January 2005

The increasing demand for higher storage capacity in magnetic recording media has led to an intensive examination of magnetically hard particles and films in a search for better magnetic properties and improved storage capabilities than those offered by the traditional particulate dispersions of γ-Fe2O3 micropowders.
In this paper, we discuss the effect of the magnetic properties and of the thickness of recording surfaces in high-resolution recording applications, and specify design criteria for their optimization.
The properties and the origin of magnetic hardness in oxide and metallic particles and in metallic films are discussed, and their high-resolution recording behavior is compared. It is concluded that the greatest potential in particulate coatings is offered by single-domain ferromagnetic metallic particles, while ultimate recording optimization can be achieved in thin metallic surfaces.