bluuebunny/crossref_metadata_2025_split huggingface dataset:
Noise in Oxide Cathode Coatings
Authors: Hannam H. J. , Van Der Ziel A. 
Published: April 2005

Noise measurements have been performed on oxide-coated cathodes at frequencies of 8 Mc and of 30 cycles. At 8 Mc, where thermal noise and shot noise predominate, the measurements show thermal noise at high cathode temperatures (pore conduction region) and at low cathode temperatures (grain conduction region) with a pronounced noise peak caused by shot noise in the temperature range where pore conduction switches over to grain conduction.
Noise measurements at 30 cycles where flicker noise (with a 1/f noise spectrum) predominates, indicate that the pore noise corresponds to the flicker noise expected for a semiconductor with a voltage-independent conductivity, whereas the grain noise corresponds to the flicker noise expected for a semiconductor with voltage-dependent conductivity. The measurements also show that the pores are inherently noisier than the grains at low frequencies. The results agree with a qualitative theoretical analysis.
Photoconductive Response of Single Crystal Germanium Layers Prepared by the Pyrolytic Decomposition of GeI2
Authors: Cronemeyer Donald C. 
Published: April 2005

Layers of single crystal germanium have been prepared by pyrolytic decomposition of GeI2 at about 350°C upon single crystal seeds of germanium by J. C. Marinace. The substrate germanium could be removed and the resultant thin layers (∼5×10−3 cm) studied. The Hall coefficient and resistivity measured on these layers by Dunlap et al. showed that the layers as grown were usually n type and contained about 1016 donors/cm3. These donors are situated at 0.22±0.04 ev below the conduction band.
In the work reported here, the photoresponse of such layers at 77°K was found to extend to about 6 μ in substantial agreement with this thermal activation energy. The 0.2-ev donors apparently can be annealed out by prolonged heating at 550°C. The layers could also be intentionally doped with standard acceptors such as Al during formation. It was hoped that it would be possible to obtain the incorporation of Au into the layers. For this purpose, layers for which Au doping was attempted were annealed to remove the 0.2-ev donors. Although some of the layers became p type, a comparison of the photoresponse at 77°K with the photoresponse obtained for a 5×10−3 cm thick p-type plate of regularly Au-doped germanium showed no evidence for the 0.15 ev Au level. Likewise, annealed layers for which Ag doping was attempted were examined but yielded no positive identification of the 0.14-ev level of Ag.
Nucleation of Dislocations Accompanying Electric Breakdown in LiF Crystals
Authors: Gilman J. J. , Stauff D. W. 
Published: April 2005

``Dislocation Lichtenberg figures'' have been discovered on the surfaces of LiF crystals subjected to high inhomogeneous electric fields. The figures consist of thousands of dislocation loops arranged along [100] dendritic branches which are terminated by [110] branches. Etching is necessary to reveal the figures.
It is shown that electric fields can nucleate dislocations in LiF crystals.
Rapid X-Ray Determination of a Complete Pole Figure
Authors: Newkirk J. B. , Bruce L. 
Published: April 2005

The Decker, Asp, and Harker technique and the Schultz technique for obtaining pole figure x-ray data in the transmission and back-reflection regions, respectively, are shown to give sufficient data for a complete pole figure, with consistent intensity contours in a 15° annulus of overlap. An improved integrating specimen holder, based on the design of Geisler, was found to perform satisfactorily for transmission and back-reflection operation.
A powder method for making all-metal sheet specimens with randomly oriented crystals is described. The use of this type of random sample for establishing background and 1X intensity levels for a corresponding textured specimen is shown to give results which are only semiquantitative when normal filtered radiation is used.
An Improved X-Ray Method for Determining Cation Distribution in Ferrites
Authors: Skolnick L. P. , Kondo S. , Lavine L. R. 
Published: April 2005

Cation distribution in many ferrites has been difficult to determine by x-ray diffraction since the scattering factors of such cations as Ni, Co, Mn, and Cu are close to that of Fe. By using radiation of a wavelength close to the absorption edge of one of the cations, as suggested by Bertaut, sufficient difference in x-ray scattering factors can be developed because of anomalous dispersion, thus allowing the cation distribution to be ascertained. This method was employed in the case of nickel ferrite.
As a modification of Bertaut's technique, ratios of intensities of the diffracted peaks for FeKα and FeKβ radiation from nickel ferrite were used to eliminate certain factors in the intensity equation which are difficult to calculate, for example, the absorption and temperature factors.
A least-squares technique was used to determine the best values of the cation distribution and the oxygen position for the intensity ratios obtained for seven reflections. It was found that the cation distribution coefficient was 0.48±0.02, in agreement with the results obtained by magnetic-moment measurements and neutron diffraction. The oxygen positional parameter was found to be 0.240±0.002 of the lattice parameter with an octahedral position at the origin, which is in good agreement with the value obtained using neutron diffraction.
The method appears to be of general value in distinguishing between two elements distributed over nonequivalent positions in a crystal lattice when their x-ray scattering factors are almost equal.
Static and Dynamic Behavior of Thin Permalloy Films
Authors: Smith D. O. 
Published: April 2005

Thin magnetic films (∼1000 A) evaporated onto a heated glass substrate in the presence of a dc magnetic field develop a uniaxial magnetic anisotropy energy of the form Ek=Ksin2φ, with φ measured from the deposition field. Such films promise to outperform ferrite cores in digital-computer memory-systems by several orders of magnitude. A detailed static and dynamic theory based on the above anisotropy energy and the Landau-Lifshitz dynamical equation is presented. The static theory contains the unique feature of the coercive force parallel to the easy axis being dependent on a field in the plane of the film and perpendicular to the easy axis. Experimental verification of the theory is given.
The dynamic theory considers both steady-state and pulse response. The steady-state solution is well known; the pulse solution must take very careful account of all the important torques acting in a switching experiment, and numerical results are obtained by the use of a digital computer. Experimentally, steady-state resonance is measured from 100 to 10 000 Mc and pulse switching down to 3 mμsec. Both types of experiment are in good agreement with each other and with the theory.
Effects of Magnetic Fields upon Anisotropic Iron Crystals
Authors: Watson John H. L. , Arrott Anthony , Freeman Michael W. 
Published: April 2005

Problems inherent to magnetic alignment of alpha iron crystals are discussed and explained by electron microscopic observation of the behavior of the single domain crystals under the effect of magnetic fields. With these specimens, which possess a fraction of magnetically unfavorable dendrites, intrinsic coercive forces of over 1700 oersteds have been measured without alignment.
``By no endeavour can a magnet ever attract a silver churn''
(W. S. Gilbert: Patience, Act II).
Effect of Sample Thickness on the Field Annealing of 6.5% Si–Fe
Authors: Albert P. A. 
Published: April 2005

Iron alloys containing about 6.5 weight percent silicon are known to respond to heat treatment in a magnetic field. Since the degree of response has been observed to vary with sheet thickness, a study was made to better define this variation.
Two different alloy compositions were cast in cylindrical molds. The ingots were drilled to form hollow cylinders which were sliced and polished to rings of final thicknesses of from 0.150-in. to 0.0025-in.
dc hysteresis loops were measured on samples as annealed 2 hours at 1000°C in dry hydrogen, and as subsequently cooled at 40°C/hr from 900°C in a circumferential magnetic field of 10 oe.
The differences in coercive force and maximum permeability between samples field annealed and not field annealed are thickness dependent, and are greater for thicker samples.
The effects of thickness on coercive force are lessened by electropolishing, which greatly reduces the slope of the Hcvs (1/d)-curve for both the field-annealed and not field-annealed states. The maximum permeability is not found to be affected by electropolishing.
Performance of Permanent Magnets at Elevated Temperatures
Authors: Roberts W. H. 
Published: April 2005

The objective of this investigation was to determine the effect of temperature up to 600°C and vibration on the performance of Alnico V and Alnico VI magnets. Data is presented on the effect of cycling stability, coefficient of remanence, extended exposure to elevated temperature and vibration.
The results of this investigation show that the use of Alnico V and Alnico VI in most instrument and control applications is feasible up to 500°C. However, a considerable loss in properties should be expected if the temperature exceeds 500°C.
Understanding and Predicting Permanent Magnet Performance by Electrical Analog Methods
Authors: Parker R. J. 
Published: April 2005

Permanent magnet performance problems are by their nature cut and try and an optimum solution in even a simple application requires considerable time and effort and is to some extent an art. As advances in the technology of making the permanent magnet allow a wider range of magnetic properties and physical arrangements the need increases for a firm engineering approach in this problem area. In this paper the author describes a complete data system and apparatus using electrical analogs in which the unit properties of a permanent magnet and its external loading may be conveniently set up and varied.
Constant voltage sources and linear resistance elements with predetermined switching points allow the nonlinear B-H relationship to be set up for any permanent magnet material.
The magnet volume and the space surrounding the magnet structure is zoned in a unique manner which allows leakage permeance from each zone to be lumped and estimated from charts as a function of magnet surface area and circuit configuration in terms of resistance.
Zoning allows an accurate integration of magnetomotive force and the effective magnetomotive force is associated with each leakage zone so that each zone adjust itself to a point on the B-H curve as dictated by the loading it sees, exactly simulating the actual magnet conditions. Rules of thumb and experience factors are minimized and accuracy is only limited by the correctness of the lumped permeance values.
Permeance data for the program has been developed and plotted as families of curves relating geometry and effective permeance. Formulas, measurements on existing magnet structures, and electrostatic capacitance measurements have been used extensively to prepare valid permeance relationships.
Easily changed electrical quantities allow rapid exploration of combinations of unit properties and circuit geometry by reading meters calibrated in terms of B and H for each zone. Useful gap flux and the external energy in each space zone are also easily read on meters.
Having established the electrical circuit representing the permanent magnet and its external field it is also possible to simulate minor loop operation and to meter the change in potential energy as it is alternately stored in the magnet and returned to the external field as the external load is changed over the operating cycle. This simulation of the dynamic function of the magnet is of value in accurately estimating force-distance relationships in mechanical work applications and in the analysis of the permanent magnet generator problem involving stability and performance under various load conditions.
Ferromagnetic Resonance in Yttrium Iron Garnet at Low Frequencies
Authors: Spencer E. G. , LeCraw R. C. , Porter C. S. 
Published: April 2005

Single crystals of yttrium iron garnet (YIG) exhibit the narrowest resonant line of all known ferromagnetic materials, being as low as 2.3 oe for the full width at half height for polished spheres at 9300 mc. Ferromagnetic resonance on polished YIG disks was observed at frequencies as low as 44 mc, for an applied dc field of 1000 oe. Conversely, resonance was observed for fields as low as 300 oe, for a frequency of 2000 mc.
Nonlinear effects in ferromagnetic materials can be evidenced by the excitation of unstable spin wave modes, such as were discovered at x band by Bloembergen and his colleagues. In their case the dc fields required for this subsidiary resonance were approximately one half that required for resonance of uniform precession. When measurements are made on a sphere at a frequency low enough so that Hres&lt;8πMs/3, Suhl's theory shows that the dc field required for the minimum threshold of the subsidiary resonance is identical with that required for resonance of the uniform precession. In this case the critical rf fields required are particularly low being given in terms of the line width to an order of magnitude as hcrit=ΔH2/4πMs.
Measurements have been made of hcrit, for the subsidiary resonance as a function of frequency for polished single crystal spheres of YIG. Based on a 4πMs of 1725, the frequency below which coincidence of the uniform precession and subsidiary resonances occur, is 3220 mc. Below 1610 mc the dc fields for resonance are insufficient to saturate the sphere and domains are formed. Values are given for hcrit, spin-wave angle θ, and spin-wave number k for frequencies of 1610 to 3220 mc. At 2200 mc a min in hcrit occurs. At this frequency hcrit=2.0 millioersteds, the power incident on the cavity is 20 microwatts and the power absorbed by the sample is of the order of a microwatt. The experimental results are discussed in terms of Suhl's theory.
Exchange Anisotropy in the Iron-Iron Oxide System
Authors: Meiklejohn W. H. 
Published: April 2005

Exchange anisotropy is the result of a magnetic interaction between a ferromagnetic and an antiferromagnetic system. This interaction was discovered in the Co–CoO system, wherein cobalt is the ferromagnetic and cobaltous oxide is the antiferromagnetic system. The material consisted of fine particles (∼200 A) of cobalt which had a coherent cobaltous oxide film. Above the Néel temperature where the CoO is the paramagnetic state the material had the expected behavior of a ferromagnetic. Below the Néel temperature the interaction between the ferromagnetic cobalt and the antiferromagnetic cobaltous oxide resulted in a displaced hysteresis loop and a nonvanishing value of the rotational hysteresis for applied magnetic fields greater than 2K/Is. Further investigation of the temperature dependence of this system has shown that the high field (H&gt;2K/Is) rotational hysteresis vanishes precisely at the Néel temperature of cobaltous oxide.
Work on the Fe–FeO system has shown a nonvanishing value of rotational hysteresis for temperatures below the Néel temperature of FeO and for magnetic fields greater than 2K/Is for iron. The temperature dependence of this high field rotational hysteresis shows that it vanishes at precisely the Néel temperature of FeO.
Magnetostriction and Elastic Properties of Ferromagnetic Substances at High Magnetic Fields
Authors: Sato Hiroshi 
Published: April 2005

The manner in which the anisotropic forced magnetostriction contributes to the magnetostriction of ferromagnetic substances at high magnetic fields is discussed from a localized model of ferromagnetism. With this assumption, the free energy of a ferromagnetic substance can be conveniently divided into several terms and it can be concluded quite naturally that a free-energy term corresponding to that of ferromagnetic anisotropy gives rise to an anisotropic forced magnetostriction. In the past, the isotropic forced volume magnetostriction has been considered to be the only cause of the forced magnetostriction. This is probably one reason for the discrepancies between the experimental value of the volume magnetostriction and the theoretical value expected from the pressure dependence of the Curie point, etc.
From a similar point of view, anomalous behavior of elastic properties of a ferromagnetic substance, such as the change of the temperature coefficient of the elastic constants at the Curie point, the dependence of the elastic constants upon the direction of the magnetic field, etc., are explained as an intrinsic change in the elastic constants with spontaneous magnetization. In the past, these effects have been explained only as a result of the deformation of the crystal lattice due to the spontaneous magnetostriction (volume effect, morphic effect).
Improved Torque Magnetometer
Authors: Byrnes W. S. , Crawford R. G. 
Published: April 2005

A new automatic recording torque magenetometer has been designed and constructed. This instrument will automatically plot the torque exerted on a thin ferromagnetic disk slowly rotating in a uniform magnetic field as a function of the angle between a reference direction in the disk and the direction of the applied field. The torque exerted on the disk is converted into a dc electrical signal. Conversion is accomplished by coupling the mechanical torque system to a strain gauge transducer whose electrical output is used to drive a dc strip chart recorder.
This type of torque magnetometer was first designed by D. S. Miller. Emphasis is placed on various design features of the new magnetometer that are considered improvements over the original. In particular improvements have been made on the bearings, shaft, and strip which constitute the important features of the instrument. Depending on the transducer that is used, the measurable torque range is 0 to 70×103 ergs. The sensitivity of the highest range is approximately 2×103 ergs/mv.
Measurement of Ternary Distribution Coefficients in Silicon
Authors: Navon David 
Published: April 2005

A method is described for determining the distribution coefficient of an impurity introduced into a semi-conductor by a fused metal contact. Coefficients for the segregation of antimony, arsenic, gallium, and aluminum from a silver contact to silicon at 1250°C are less than at the silicon melting point (1408°C). Gold-doped contacts to silicon yield similar values for the distribution coefficient of these impurities. This value is independent of the concentration of the impurity in the gold or silver alloy for small (less than 1%) percentages of the impurity. At 1250°C, the segregation of aluminum from a dilute solution of aluminum in silver is about the same as from 100% aluminum.
The diffusivity of silicon atoms through a liquid zone containing aluminum and saturated with silicon is greater, at any particular temperature, than the diffusivity through a silver-silicon zone at the same temperature. However, these values approach each other at the silicon melting point.
Stability of an Electron Beam on a Slalom Orbit
Authors: Cook J. S. , Louisell W. H. , Yocom W. H. 
Published: April 2005

A study is made of an electrostatic method of focusing an electron beam in a traveling wave tube in which the beam traverses a slalom-like orbit between the wires of the slow wave structure. The requisite field is produced by a row of equally spaced wires at the same potential placed midway between two parallel plates at another potential.
The equations of motion are solved to find initial conditions for stable orbits. Space charge effects are considered.
A large slalom tester was built to compare experimental and theoretical results. The agreement between the computed and measured current transmitted is surprisingly close. There is also good agreement between the measured and computed beam perveance.
Analysis of a Multipole State Separator and Focuser for Polarizable Molecules
Authors: Vonbun Friedrich O. 
Published: April 2005

The electrostatic field of a multipole focuser, consisting of parallel rods arranged in a circle, is treated. The field equation is derived from the known field of a two-wire line, and results are given in the form of equations that express the field in terms of practical parameters. The field and the radial gradient of a (p+q)-pole focuser is compared to that of a p-pole focuser in order to indicate the value of increasing the number of poles.
Both a complete and a simplified set of differential equations (in cylindrical coordinates) of the path of polarizable molecules in this inhomogeneous field are also given. Based on the simplified differential equations, the path of a NH3 molecule in the J=K=3 (MJ=3) inversion state is graphically presented.
Orientation Study of Ultra-Thin Molybdenum Permalloy Tape
Authors: Koh P. K. 
Published: April 2005

Quantitative pole density stereograms of {111}, {220}, {200}, and {113} poles of ⅛ mil molybdenum Permalloy tape were developed in order to establish its cold-rolled deformation texture and annealed textures.
Cold rolling the tape induced multiple slip common to all face-centered-cubic metals and developed (110) [3̄35] and (110) [33̄5] end orientations which deviate 5° about [110] from the recognized {100} &lt;112&gt; brass deformation texture.
On annealing at 771°C the cold-rolled tape was found to develop (120) [001] + (210) [001] and (113) [7̄8̄5] + (113) [785̄] orientations as components of the annealed texture which bear in general at 35°–45° rotation orientation relationship about &lt;111&gt; with the cold rolled end orientations.
Annealing at 1160°C developed the same texture as that obtained after 771°C annealing.
From the pole figures made on 927°C annealed tape, the same annealed texture prevailed whether the pole figure was made on its full ⅛ mil thickness or on its central 0.00005-in. section.
Hysteresis loop tracings made on the cold rolled tape revealed an apparent direction of easy magnetization along the rolling direction. No easy magnetization direction was revealed in the rolling plane on the annealed tapes. These findings support the deductions from the corresponding pole figures.
Volumes and Surface Areas of Pendular Rings
Authors: Rose Walter 
Published: April 2005

A packing of spheres is taken as a suitable model of porous media. The packing may be regular and the sphere size may be uniform, but in general, both should be random. Approximations are developed to give the volumes and surface areas of pendular rings that exist at points of sphere contact. From these, the total free volume and interfacial specific surface area are derived as expressive of the textural character of the packing.
It was found that the log-log plot of volumes and surface areas of pendular rings vary linearly with the angle made by the line joining the sphere centers and the line from the center of the largest sphere to the closest edge of the pendular ring. The relationship, moreover, was found not to be very sensitive to variation in the size ratio of the spheres in contact.
It also was found that the addition of pendular ring material to various sphere packings results in an unexpected decrease in the surface area of the boundaries that confine the resulting pore space.