bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cleavage Cracks and Dislocations in LiF Crystals
Authors: Gilman J. J. , Knudsen C. , Walsh W. P. 
Published: April 2005

It is shown that dislocations are nucleated ahead of the tips of cracks that move slower than ∼6×103 cm/sec in LiF crystals. The motion of cracks that move slower than ∼3×103 cm/sec is unstable; that is, the velocity oscillates.
About 2×105 cm/sec is the terminal velocity for (100) cleavage cracks in LiF.
For constant driving force, cracks move more slowly in crystals with high dislocation densities than in relatively perfect crystals.
Apparent Temperatures of Some Terrestrial Materials and the Sun at 4.3-Millimeter Wavelengths
Authors: Straiton A. W. , Tolbert C. W. , Britt C. O. 
Published: April 2005

This paper describes a 4.3-mm radiometer and measurements made with it of the apparent temperature of various terrestrial materials, the attenuation through the atmosphere and the temperature of the sun. Materials whose apparent temperatures were measured included water, wood, metal, grass, asphalt, gravel and asbestos. Since their apparent temperatures are dependent upon their reflectivity, these data are interpreted in terms of the background reflected by the materials.
The attenuation vertically through a clear sky ranged between 1.6 and 2.3 db. The sun, of optical disk size, was found to be between 104 and 1.2×104°K on May 3 and June 17, 1957.
Diffusion of Tungsten in Nickel and Reaction at Interface with SrO
Authors: Allison Herbert W. , Moore George E. 
Published: April 2005

Diffusion rates of tungsten in single crystal and polycrystalline nickel were measured at temperatures between 1100°C and 1275°C by using radioactive tungsten185 and a sectioning technique. Grain boundary diffusion was observed by use of radioautographs. A simple vacancy mechanism accounts for nearly all of the diffusion; some refinement is required for the transport observed at greater depths.
The rate of reaction of polycrystalline 4.9% tungsten-nickel alloy with SrO was measured by the hydrogen evolution technique at temperatures between 830°C and 1280°C. The rate indicates that the production of Sr in amounts up to 200 μg cm−2 is not limited by diffusion of tungsten in the nickel core.
High Q Quartz Crystals at Low Temperatures
Authors: White Donald L. 
Published: April 2005

The Q (quality factor) of natural quartz was measured from 4.2°K to over 100°K. The quartz was in a high precision AT crystal unit vibrating on overtones of the thickness shear at about 6.3 mc and 8.8 mc.
At higher temperatures the Q varied rapidly with temperature, but did not depend on the particular mode of vibration.
At low temperatures (say less than 10°K) the Q also depended on the mode of vibration. At these low temperatures the Q became very large—a record of 55 million was observed on one mode at 4.2°K. Apparently another loss mechanism dominates at low temperatures, and very likely this mechanism may not be intrinsic to quartz. The mounting structure or gold electrodes may be the primary source of energy loss in the liquid helium temperature range.
Diffusion and Elastic Collision Losses of the ``Fast Electrons'' in Plasmas
Authors: Medicus G. 
Published: April 2005

(I) When the energy spectrum of plasma electrons consists of two clearly separable groups—a high-energy, primary, non-Maxwellian, and a low-energy, secondary, Maxwellian one—the characteristic linear part of the corresponding probe curves, extrapolated to plasma potential, directly determines the random current density of the fast group. With a hemispherical anode and a hollow hot cathode near its center, in Ne of about 1 mm Hg pressure, the flow of the fast group at low diode currents follows closely the spherical case of diffusion. The experimental data, by means of the diffusion law, can be evaluated for the mean free path l of the fast electrons. It is found that l is independent of the plasma density and is about equal to the value calculated from the cross-section function for 10–16 volt electrons in Ne.
(II) The Diffusion law being applicable, the elastic collision losses of the fast group can be calculated. They are found to be relatively small compared to the total energy losses of the fast electrons. The results will be used in an attempt to determine the energy transfer from the fast group to the Maxwellian group, to be described in a subsequent paper.
The most remarkable result is the low interaction of the fast group with the Maxwellian group at low total plasma densities where the partial density of the slow group is always comparable to or even much higher than that of the fast group.
Studies of High-Velocity Impact in Wax
Authors: Partridge William S. , Clay Wallace G. 
Published: April 2005

Penetration of wax pellets into wax targets was found to vary linearly with the cube root of the pellet mass and the pellet velocity up to velocities in excess of twice the sonic velocity in the wax target. The crater area varies directly as the impact velocity, but there is a marked increase in the constant of proportionality above the target sonic velocity. The volume of the crater per unit energy of the pellet was found to be 2.23×10−8 m3/joule for the lower velocity range and above the target sonic velocity the value was found to be 2.75×10−8 m3/joule.
It was observed that a large part of the crater volume is created by deformation of the target material and that only a small part is due to ejection of the target material.
Application of the Ion Bombardment Cleaning Method to Titanium, Germanium, Silicon, and Nickel as Determined by Low-Energy Electron Diffraction
Authors: Farnsworth H. E. , Schlier R. E. , George T. H. , Burger R. M. 
Published: April 2005

The ion-bombardment cleaning method has been successfully applied to the (100) faces of germanium, silicon, and nickel, and to the (0001) face of titanium. Conditions and precautions necessary for the production of clean surfaces are described. Tests have been made for contamination from the ambient during the cleaning procedure for germanium. It has been shown that contamination approximating one-half monolayer does not occur under the conditions which were obtained, and that the method is capable of producing surfaces which are atomically clean.
Results for clean (100), (111), and (110) germanium faces and the (100) silicon face indicate that the atomic positions in the surface planes are not the same as the corresponding positions in the bulk structure. For (100) nickel and (0001) titanium, the positions of the atoms in the surface planes are in agreement with x-ray data. In the case of titanium, an unidentified surface structure was present until after several cycles of alternate heating and ion bombardment. In the case of nickel, a double-spaced surface monolayer and in some cases a single-spaced, simple-square structure, attributed to carbon, was present until after several cycles of alternate heating and ion bombardment.
Attainment of Ultrahigh Vacua, Reduction in Surface Desorption, and the Adsorption of Hydrogen by Evaporated Molybdenum
Authors: Hunt Angus L. , Damm Charles C. , Popp Earl C. 
Published: April 2005

Deposition of molybdenum by vaporization from simple hairpin filaments has been found to reduce pressures in both unbaked and moderately baked stainless steel vacuum systems to 4×10−10 mm Hg. A deposit of 300 mg from a single filament, 0.050 in. in diameter and 6 in. long, has maintained an unbaked 85-liter volume at pressures below 10−9 mm Hg for over 40 hr with the aid of a small well-trapped diffusion pump. For a substrate area of 8×103 cm2, the initial pumping speed of a molybdenum deposit was found to be as high as 105 liters/sec for hydrogen and 8×104 liters/sec for deuterium. The sticking probability for either hydrogen or deuterium on this deposit is estimated at 0.3.
A similar system, baked at 200°C for several days while pumped by an oil-free ion pump, attained 2×10−10 mm Hg with molybdenum evaporation. When the ion pump was valved off, the pressure in this 75-liter system remained at 2×10−10 mm Hg for two weeks with no external pumping.
Emission Fluctuations of Tungsten-Based Barium Dispenser Cathodes
Authors: Brodie I. 
Published: April 2005

Emission fluctuations in five different types of tungsten-based barium dispenser cathodes have been measured as functions of both frequency and current density. Two of the cathodes were of the L variety and the remainder of the ``impregnated'' variety. The L cathode spectra show that the emission fluctuations are caused by fluctuations in the number of adsorbed atoms on the tungsten emitting surface. The amplitude of the fluctuations is governed by the average surface coverage and theoretical studies indicate that the shape of the spectra is governed by the diffusion processes by which the surface is replenished.
The results from the impregnated cathodes indicate that the contribution of the impregnant in the pore ends to the total noise is only significant when the pore ends supply an appreciable fraction of the total emission from the cathode, the majority of the surface, which is barium activated tungsten, behaving as an L cathode surface.
Work Function Variation of Metals Coated by Metallic Films
Authors: Gyftopoulos Elias P. , Levine Jules D. 
Published: April 2005

A theoretical correlation is derived to account for the variation of the work function of refractory metals coated by metallic films for all degrees of coverage. This correlation is based on an extension of the concept of electronegativity to composite surfaces and use of Pauling's rule about electronegativity and dipole moment of complex molecules. A series of theoretical curves is given for different crystallographically ideal surfaces of refractory metals such as W, Mo, and Ta coated by Cs, Sr, Ba, and Th.
The derived correlation is compared with available experimental data for which the experimenters specify the exact conditions under which the experiment is performed and excellent agreement between theory and experiment is established.
It is shown for the first time that the maximum work function variation does not necessarily always occur either when a full monolayer is reached or at a definite fractional coverage. The exact position of the maximum variation is a function of the adsorbate and substrate materials and the type of the substrate surfaces. It is also shown that it is erroneous to characterize a monolayer as the point at which maximum emission (or maximum work function variation) is achieved because such a maximum may be flat and extend from half a monolayer to one monolayer.
Diffraction from Layer Faults in bcc and fcc Structures
Authors: Wagner C. N. J. , Tetelman A. S. , Otte H. M. 
Published: April 2005

Calculations, using the Warren-Mering method, of the broadening and shift of the x-ray diffraction peaks in powder patterns have been performed for the situation in which an interplanar spacing change occurs at the fault plane. Deformation-spacing faults on the {211} layers of the bcc lattice and the {111} layers of the fcc lattice, and spacing faults are discussed in detail. The principal effect of the spacing change is to introduce additional broadening and peak shifts, the magnitude (and direction, in the case of the peak shifts) of which depends on the reflection. In bcc structures the effect is particularly striking because no peak shifts are expected in the presence of stacking faults whose interplanar spacing is unchanged.
Measurements were made on three cold-worked bcc materials: Ta, Nb, and a stainless steel martensite. No measurable peak shifts were found in Ta. In Nb and in the martensite, however, small shifts were observed and were in directions predicted from the theory; the shifts could therefore be interpreted and indicated an expansion of the layer spacing at the fault.
The State of the Art of Magnetic Memories
Authors: Simkins Q. W. 
Published: April 2005

A broad range of magnetic memories finds extensive use in today's data processing equipment. The most significant factors in evaluating a memory for a given application are reliability, cost, size, speed, and function. Ferrite core memories with capacities of 103 to 106 bits and with cycle times as short as 0.5 μsec are in use. Recent developments in this area, including partial switching, 2 cores/bit, and new core fabrication techniques, will be discussed.
There have been extensive development efforts recently in many forms of magnetic metal film devices. Many geometries, modes of operation, fabrication techniques, substrate materials, and film compositions are being used. A comparison of some of the resulting devices will be made, and the effects of the factors listed above will be discussed. The application of metal film memory devices will be considered and a comparison drawn with ferrite devices.
Techniques for achieving special purpose functions such as nondestructive readout, read-only and associative memory using magnetic elements, will also be described and compared.
A Permanent Magnet Twistor Memory Element of Improved Characteristics
Authors: Alexander E. J. , McAlexander J. C. , Young L. H. , Salhany R. J. 
Published: April 2005

A card changeable permanent magnet twistor memory element of improved characteristics has been designed. The desired characteristics were obtained by:
(1) Halving the solenoid width to enhance the drive field.
(2) Replacing the copper return wire in the twistor pair with a reverse wrapped twistor wire.
(3) Installing a Permalloy sheet between the word solenoid and the solenoid board to reduce interaction fields within the memory.
(4) Annealing the twistor wire to lower the coercive force and to increase the squareness ratio of the moly-Permalloy tape.
The chief result of these changes is that the net switching field at the bit is substantially increased and therefore the outputs of the memory are less dependent on the properties of the magnetic materials.
A 210 000 bit card changeable permanent magnet twistor memory utilizing the new element design has been constructed and evaluated.
In comparison to previously reported permanent magnet twistor memories, the new design is characterized by twice the speed, 2.5 times the bit density, 3 times the output voltage level, 2.5 times the signal available for ``1–0'' discrimination, and 4 times the strobe time tolerance.
Observation of Antisymmetric Exchange Interaction in Yttrium Orthoferrite
Authors: Treves D. , Alexander S. 
Published: April 2005

Sensitive static torque measurements were carried out on single crystals of YFeO3 in order to determine if weak ferromagnetism in this material is caused by single ion magnetocrystalline anisotropy or by anisotropic exchange interaction.
The following symmetry considerations show a priori which cubic and higher terms in the torque can be nonzero. The magnetic energy F is expanded in a series in the applied field H F=Σ σi(0)Hi+12 Σ χijHiHj+Σ CijkHiHjHk+…. Using the fact that F must be invariant under all the symmetry operations of the magnetic point group appropriate to these crystals, one finds that the only cubic coefficients that may be nonzero are Cxxz, Cyyz, Czzz. The expression for the torque T is found using the relation σi = ∂F/∂Hi, where σi are the components of the total magnetization, and T=H×σ.
The ferromagnetic component σ(0), the susceptibility χ, and cubic coefficients Cijk were calculated assuming a two sublattice system for the anisotropic exchange model and also for the single ion magnetocrystalline anisotropy model. The comparison of the measured coefficients to those calculated for the two models indicates that the anisotropic exchange mechanism is predominant in causing weak ferromagnetism in YFeO3.
Stress Effects on the Magnetic Properties of Evaporated Single-Crystal Nickel Films
Authors: Freedman J. F. 
Published: April 2005

Nickel single-crystal films grown epitaxially on NaCl at elevated temperatures shown anomalously large values for the crystalline anisotropy constant, K1, as well as for K1, the perpendicular anisotropy (i.e., the anisotropy resulting from rotation out of the plane of the film). These values decrease to normal bulk values when the films are floated off the rocksalt.
It has been shown by x-ray diffraction that the as evaporated films exist in a highly strained condition, resulting in a tetragonal distortion of the cubic symmetry. The parameters of the unit cell change from a0=3.524 A for unstrained nickel to a=b=3.500 A in the plane of the film and c=3.546 A normal to the film. It is also shown that the stress causing this strain is elastic in character and is relieved by floating the film off the rocksalt.
A calculation using bulk elasticity data yields a planar compressive stress σ=−1.2×1010 d/cm2. The magnitude and direction of the stress indicates it results from the difference in thermal expansion between the nickel film and the NaCl substrate.
This externally applied stress system influences the magnetic state of the film by contributing to the total energy of the system through a magnetoelastic interaction. Employing the five-constant magnetostrictive equation, it is shown that a planar compressive stress of this magnitude does result in an anomalously high crystalline anisotropy value, as well as an anomalously high value of the anisotropy perpendicular to the plane of the film.
Magnetoelastic Behavior of Thin Ferromagnetic Films as a Function of Composition
Authors: Mitchell E. N. , Lykken G. I. 
Published: April 2005

A series of films of composition varying from 72% Ni, 28% Fe to 90% Ni, 10% Fe were evaporated at a pressure of the order of 10−5 mm Hg onto a heated glass substrate (250°C) in the presence of a magnetic orienting field in the plane of the film. The composition was controlled by placing a charge of the selected composition on the filament in an amount just sufficient to make the desired 3000 A film when all of the material was evaporated.
The magnetoelastic behavior of the films was studied by measuring η=ΔHk/(Δl/l), here ΔHk is the change in the anisotropy field upon the application of a stress sufficient to strain the film an amount Δl/l (typically 4×10−5). η was found to decrease linearly with composition to a first approximation with a slope of −26.5×103 oe per percent nickel, with η being zero for a film composed of 81.5% Ni, 18.5% Fe.
The value of η was compared with that of Λm for bulk material where Λm is the change in the magnetization divided by the applied stress in the case where the stress approaches zero and where the bulk material is biased by an applied field sufficient to yield the maximum change in Λ. Using bulk data for the saturation magnetization and Youngs modulus the value of η measured here yields a value for Λm which is too large by an order of magnitude.
Fine-Grained Ferrites. II. Ni1−xZnxFe2O4
Authors: Malinofsky W. W. , Babbitt R. W. , Sands G. C. 
Published: April 2005

A series of fine-grained single-phase ferrites was prepared according to the formula Ni1−xZnxFe2O4, where x took the values 0, 0.10, 0.33, 0.50, and 0.67. A previously-described process combining the so-called flame-spraying and hot-pressing techniques was used to obtain grain sizes of approximately 0.1 micron in the densified bodies. μ′ and μ″ were measured to 1000 Mc, with grain size and composition as parameters. Measurements were also made to 3800 Mc on a ferrite annealed through the critical size for multi-domains, confirming previously-reported theory that magnetic poles on the domain walls are the source of the microwave peak at about 2000 Mc. Wall displacement appears to contribute to the static μ0 in large-grained ferrites when x&gt;0.
In addition, the temperature dependence of initial permeability μ0 was studied. The temperature coefficient of μ0 was found to increase with grain size. While the μ0 vs temperature curves were of various shapes generally, still a set of ferrites made up of differing compositions and grain sizes were obtained having linear temperature dependences. Of practical interest are those with slopes of −220 ppm/°C, 0 ppm/°C (NPO), and 220 ppm/°C.
Microwave properties were studied also. Because zero-field (Hdc=0) measurements showed that fine-grains (i.e., below the critical size for multidomains) eliminated the so-called microwave loss peak in the rf dispersion, a decrease in the low-field loss follows. Also, microwave measurements of the main resonance loss susceptibility vs rf power were made at X band using a cavity technique. Although normal critical fields hc were generally found, one sample with x=0.67 and ΔH=655 oe showed an anomalous rise in χ″/χ0″ at high powers, significantly expanding its power-handling capability.
Textured 6.5% Silicon-Iron Alloy
Authors: Facaros G. , Aspden R. G. 
Published: April 2005

Sheet of an iron base alloy containing 6.5% silicon and second phase inclusions was prepared by hot rolling and pack rolling. Two structures were obtained by varying the rate of heating to the final annealing temperature. A slow rate of heating yielded {110} grains in a secondary recrystallization structure, and a fast rate, the primary recrystallization and normal grain growth structure. Only during the slow rate of heating were inclusions effective in suppressing normal grain growth and in promoting growth of {110} secondaries.
The secondary recrystallization texture was of the {110} 〈001〉 type. The normal grain growth texture had a similar degree of alignment of 〈100〉 directions with the rolling direction and a nearly random distribution of planes of the 〈100〉 zones parallel to the rolling plane. Similar dc and ac magnetic characteristics were observed for these two structures since they had the same degree of alignment of 〈100〉 directions (easy directions of magnetization) with the rolling direction.
A Method of Magnetic Annealing of Vanadium Permendur-Type Alloys
Authors: Burket R. E. , Stewart D. M. 
Published: April 2005

A method of magnetic annealing of 2 V Permendur (2% V, 49% Co, 49% Fe) stamped rings and laminations in zero externally applied magnetic field is discussed. It is shown that an internal magnetic field biasing technique yields highly improved magnetic properties.
This method involves magnetizing the samples when they are still in a hard condition, i.e., as stamped or low temperature (500° to 600°C) annealed, and then subsequently annealing them at the normal time and temperature employed for the development of optimum magnetic properties (800–900°C). No external magnetic field is applied during any of the anneals.
This technique utilizes the internal magnetic field which remains after magnetizing the samples at room temperature. It is shown that a marked improvement may be obtained in 1-DU type laminations although the samples are unstacked after the initial magnetization (before annealing). Apparently, although the samples are partially self-demagnetized, there is still a sufficiently high internal field remaining to produce a self-magnetic annealing effect during the anneal. It is also shown that the cooling rate employed in this anneal is important—just as it is in conventional magnetic annealing.
Normal dc and 60 cycle magnetic properties are presented for 0.014-in. ring and 1-DU samples from a number of heats. The data indicate that the effect is manifested by a two to threefold increase in the dc μmax and a 35 to 50% increase in the rectangularity of the dc hysteresis loop (Br/Bm). It does not necessarily cause a decrease in the dc coercive force or the 60-cycle watt loss.