bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Carrier Traps in Polyethylene under Gamma-Ray Irradiation
Authors: Yahagi Kichinosuke , Shinohara Kenichi 
Published: April 2005

Stimulated currents are detected with increasing temperature in polyethylene films following the irradiation with high-energy electron beams at 77°K. A peak current occurs at about 200°K in low-density specimens and 250°K in high-density ones.
Induced currents I under gamma-ray irradiation of polyethylene at room temperature depend on dose rate R via I ∝ RΔ. In high-density polyethylene preirradiation by electron beams of about 5×107 rads at room temperature Δ increases from 0.5 to 0.84 and is accompanied by a decrease of induced current. In the low-density specimens Δ decreases from 0.8 to 0.6 and the induced current increases with the same preirradiation. After boiling the preirradiated specimen for 5 min, Δ becomes 0.5 in both cases, and in the high-density specimens the induced current I returns to that of the nonirradiated sample. This behavior suggests that the increase and decrease of carrier traps by these treatments influence the induced current characteristics. Another factor influencing the induced conductivity is the crystallinity; with decreasing crystallinity the induced conductivity of all specimens decreases, while in most cases Δ values increase. This behavior suggests the domination of electrons as charge carriers and that they are able to flow more easily in the crystalline parts than in the amorphous parts.
Optical Frequency Plasma Resonance in Gases
Authors: Minck R. W. , Rado W. G. 
Published: April 2005

An intense optical beam is reflected backwards from a laser-induced spark in argon and nitrogen gas at high pressures. The reflected beam is about 10% as intense, diverges with a comparable angle, and has the same frequency (to within about 0.01 cm−1) as the incident beam. By simultaneously focusing a weak second harmonic beam onto the discharge, the reflectivity at the higher frequency was measured. One percent of the incident harmonic beam was reflected in a nearly collimated beam, and with no apparent frequency shift (less than 0.05 cm−1).
The proposed model is that stationary region having very high electron density (ne≈2×1021 electrons/cc) is created in the focal volume and exhibits plasma resonance at the laser frequency. The resonance would appear quite damped due to the high collision rate.
Experiments have been performed which support the hypothesis and discriminate against several other possible explanations such as reflection from the mismatch of index of refraction at the shock front, stimulated Brillouin scattering, and stimulated plasma-wave scattering.
Thermal Conductivities of MgO, Al2O3, and ZrO2 Powders to 850°C. I. Experimental
Authors: Godbee Herschel W. , Ziegler Waldemar T. 
Published: April 2005

Thermal conductivities were measured for extensively characterized magnesia, alumina, and zirconia powders. Thermal conductivities of the powders in dry air at atmospheric pressure were determined at volume fractions solid varying from 0.49 to 0.70 as a function of temperature from about 100° to about 850°C. Particle-size distribution, chemical composition, x-ray diffraction pattern, weight loss on heating, pore-free density, and surface area of each powder were measured. Thermal conductivities were determined by a steady-state method employing radial heat flow in a hollow cylinder and by an unsteady-state method based on the model of heating a cylinder of a perfect conductor surrounded by an infinite amount of the material whose thermal conductivity is being measured.
The thermal conductivities of the powders increased with increasing volume fraction solid. The influence of gas conductivity was greater than that of the solid on the thermal conductivity of the powers. The thermal conductivity for each powder measured increased at a decreasing rate with increasing temperature, following an approximately quadratic temperature dependence. Thermal conductivity was increased by the presence of a sorbed water film as well as by mechanical pressure on the particles.
Effects of Gases on the Properties of Vapor-Deposited Ni-Fe Films
Authors: Paul M. C. , Hanson M. M. 
Published: April 2005

Effects of O2, N2, H2, and H2O on characteristics of vapor-deposited Ni-Fe films are determined with the aid of quadrupole and monopole gas analyzers. Data obtained for films deposited in getter-ion or oil-diffusion-type vacuum systems show that the presence of high oxygen partial pressures during deposition has a pronounced effect on the anisotropy field, coercive force, magnetoelastic strain coefficient, and product of easy axis dispersion and anisotropy field, while the other gases tested have little if any effect on film properties. High oxygen pressures or slow deposition rates during formation of the initial few-hundred-angstrom layer, followed by ``normal'' deposition, showed that propagation of a physical structure established in the initial layer is probably not responsible for the effects brought about by oxygen.
Post-deposition annealing in an oxygen-rich atmosphere resulted in changes of magnetoelastic strain coefficient, indicating a surface oxide effect and/or diffusion into the films. ``Soaking'' glass substrates in high oxygen partial pressures for a short time prior to deposition did not have a noticeable effect on film properties, but treatment of substrates with oxygen-bearing chemicals prior to deposition did cause significant changes in film properties.
Attempts to find oxides in the Ni-Fe films by electron-diffraction techniques were unsuccessful, but microscopy studies revealed smallest grain size in films which were deposited in the presence of highest oxygen pressures. Electron-diffraction analysis of pure nickel and pure iron films deposited in oxygen-rich atmospheres showed the presence of NiO, FeO, Fe2O3, and Fe3O4.
Lamellar Crystallization and Melting of Polyoxymethylene
Authors: Carter D. R. , Baer Eric 
Published: April 2005

Polyoxymethylene has been crystallized isothermally from the melt and from solution, and has been analyzed for the lamellar fold period as related to the melting behavior. The melt-crystallized samples gave intense low-angle x-ray and DTA peaks, and in addition produced weak x-ray reflections and shoulders on the DTA melting peaks. The strong peaks yielded Tm0(s)=210±10°C, and two independent methods of calculating δe(s) place its value at 150 erg/cm2 with a maximum variation of ±40 erg/cm2. A method of plotting the data is proposed which allows a determination of δ from the experimental data of about 14 erg/cm2. The weak peaks, although not as accurate as the strong ones, yielded Tm0(w)=182°±2°C and δe(w)=37±10 erg/cm2.
Dried single-crystal mats gave a single low-angle x-ray reflection which when plotted with the appropriate melting point caused the data to lie with the weak bulk data. A second, higher temperature endotherm appears upon slow melting of the single crystals. It has not yet been fully explained, but it appears to be related to an abrupt increase in fold period.
X-Ray Source-Image Distortion Technique for the Study of Crystal Distortion and Vibration
Authors: Young R. A. , Wagner C. E. 
Published: April 2005

A technique is described which permits graphic display and quantitative determination of ultrasonic oscillation amplitudes, and of warping and other macroscopic strains, in crystals. An x-ray ``source image'' appears superimposed on the crystal image formed by one diffracted beam from a stationary crystal. ``Source-image'' distortion (SID) occurs on reflection from distorted regions of the crystal. X-ray sources ranging from 100-μ spots to 15-mm line sources interrupted by Soller slits have been used. The latter experimental arrangements bear some similarities to those described by Cullity and Julien, by Barth, and by Carlson and Wegener. Lattice tilts of ∼1′ and lattice strain variations (Δd/d) of ∼10−4 can be routinely detected and separately identified. The underlying crystal image often contains useful topographic information of limited quality.
SID photographs showing distortion produced in quartz plates by mounting clips, cements, cracks, and piezoelectric oscillations are presented. An example of direct measurement and mapping of vibrational amplitudes, e.g., 650±25 Å in one case, in piezoelectrically oscillating crystals is given. Oscillation mode characterization has been aided by the SID demonstration of a 180° phase relation in some cases and by both SID and topographic display of the pattern of vibrational activity.
Filamentary Injection in Semi-Insulating Silicon
Authors: Barnett A. M. , Milnes A. G. 
Published: April 2005

Double injection in semi-insulators causes a negative resistance regime. The voltage across the bulk material drops from the value necessary for the onset of negative resistance to a value that may remain fairly constant while the current increases by an order of magnitude or more. This region exists because the double-injection occurs initially along a filament in the bulk material. Its current growth is marked by a constant voltage region followed by an I vs V1.5–1.9 relation, somewhat similar to the V2 region predicted by Lampert and others.
The existence of filamentary breakdown has been inferred by very indirect evidence up to now, although Ridley has shown that it might be expected from considerations of energy. The present study shows the development and growth of double-injection filaments in semi-insulating silicon, by photographing them with their own recombination radiation. The silicon used was approximately 104Ω·cm at 77°K and contained 6×1016 cm−3 indium atoms as the deep acceptor responsible for the semi-insulating character.
A theoretical model is presented for the current density within the filament. The current densities observed by densitometer studies of the recombination radiation photographs are in reasonable agreement with this model. Experimental V−I characteristics are also predicted by the theoretical study.
Response of Si and GaP p-n Junctions to a 5- to 40-keV Electron Beam
Authors: Czaja W. 
Published: April 2005

This paper reports the use of the scanning electron beam technique for a determination of diffusion lengths in Si and GaP p-n junctions and of the recombination cross section of dislocations in n-type Si. This determination is based on the measurement of the current generated in reverse-biased Si and GaP p-n junctions by an electron beam of 5–40 keV energy. After applying corrections for backscattered and secondary emitted electrons the junction current determined experimentally is compared with calculated values using known principles of charge collection in p-n junctions. Diffusion lengths on both sides of the depletion region enter the calculations as free parameters which are adjusted to fit the experimental data. The experiments described are directly related to the display of lattice defects previously investigated by the same technique.
Si p-n junctions: The experiments lead to a diffusion length profile in the phosphorus diffused n region which qualitatively can be understood from the concentration profile in the same region. An upper limit of the cross section for recombination at dislocations in n-type silicon has been determined as 1.9×19−12 cm2. The results support the mechanism of contrast creation in the scanning electron beam display of dislocations as proposed earlier.
GaP p-n junctions: Diffusion lengths on both sides of the space-charge region have been found to be at least in order of magnitude agreement with values determined by other experimental techniques.
Some Surface Current Phenomena in Type II Superconductors
Authors: Ullmaier H. A. , Gauster W. F. 
Published: April 2005

For a cylindrical sample of an imperfect type II superconductor in an external field Hext parallel to its axis, it is found that in the mixed state no flux enters or leaves the specimen within an interval Hext±ΔH; the positive or negative sign applies when Hext is reached in a decreasing or increasing field, respectively. Similarly, when the sample is cooled in a field Hext, an increase of the external field less than ΔH does not change the trapped flux.
ΔH depends only on Hext and not on B, the bulk flux density, which itself depends on the magnetic history of the specimen and its defect structure (flux pinning, bulk critical current). ΔH is affected by various surface treatments, such as machining and chemical polishing, but not significantly by metal plating.
The results can be explained in terms of an intrinsic surface critical current, and comparison with existing theoretical calculations yields reasonable agreement.
Damping Peaks in Deformed Nickel
Authors: Sommer Alfred W. , Beshers Daniel N. 
Published: April 2005

The internal-friction spectrum of zone-refined nickel [R(273°K)/R(4.2°K)=600] has been examined at 30 kc/sec, in the temperature range 77°-350°K. Plastic deformation produces two prominent relaxation peaks, each the sum of several simple peaks. At 30 kc/sec, one peak, which occurs at 138°±7°K, has been identified as the Niblett and Wilks peak, and the other, which has its maximum at 248°±40°K, has been shown to be the Bordoni peak. Both peaks have been studied as a function of cold work, grain size, state of annealing, and strain amplitude.
One major result of these studies is a demonstration that the Bordoni peak is only large at low-to-moderate flow stresses and vanishes at high flow stress (greater than 50 000 psi) with the Niblett and Wilks peak being the predominant feature of the damping spectrum at the higher-flow stresses (greater than 30 000 psi). Moreover, the present results in Ni show such similarity to results obtained on deformation-induced peaks in bcc metals that, if the definition of the Bordoni peak given by Niblett and Wilks is broadened to include Ni, then the peaks in bcc metals can also be included under the definition. Arguments are presented to show that the Bordoni relaxation is best described by the Seeger—Paré hypothesis.
Impurity Effects on the Basal Plane Solidification Kinetics of Supercooled Water
Authors: Michaels Alan S. , Brian P. L. T. , Sperry Peter R. 
Published: April 2005

Growth rates of ice on the basal plane from pure water and from dilute solutions of selected ionic salts, surfactants, and water-soluble polymers were measured by an improved technique of capillary crystallization for supercoolings ranging from 0.03° to 0.2°C. The corresponding velocities ranged from 10-6 cm/sec to 5×10-4 cm/sec. Corrections for bulk mass transfer and heat transfer effects were applied to the kinetic data.
The kinetic data for pure water, although in agreement with those of Hillig near supercoolings of 0.07°C, diverge from the earlier results toward lower velocities at both lower and higher supercoolings. The data nonetheless support the general conclusion of Hillig that growth of undamaged ice crystals on the basal plane proceeds by two-dimensional nucleation.
Both growth-rate enhancements (up to a factor of about five) and retardations (up to a factor of about three) were observed during crystallization in the presence of additives. The type of effect and its magnitude were dependent on the nature of the additive, its concentration, and upon the degree of supercooling. Certain effects of ionic salts appear related to freezing potential phenomena reported by several earlier workers. Growth acceleration, found to occur to varying degrees with all classes of additive, may have been a consequence of dislocations introduced in the crystal by the additive during growth.
Acoustoelectric Waves in Piezoelectric Materials
Authors: Prohofsky E. W. 
Published: April 2005

The electron-piezoelectric sound wave interaction gives rise to three distinguishable phenomena: gain, acoustoelectric effects, and nonlinear mixing. The acoustoelectric effects, through coupling to the gain, cause interaction between sound waves which give rise to flux wave propagations. These waves travel at the velocity of sound and can have gain much larger than that of the ordinary peizoelectric waves.
When the nonlinear mixing is taken into account, the mixing may be rapid enough to alter the collective wave to that of a second sound wave with velocity 1/√3 vs. The nonlinear mixing is examined, and it is proposed that the second sound conditions can only exist when a delicate balance is achieved between coherent gain and loss.
Dielectric Dissipation in NaCl and KCl below 4.2°K
Authors: Grissom David , Hartwig William H. 
Published: April 2005

Dielectric loss tangents for NaCl and KCl single crystals are presented for the frequency range 40–1000 Mc/sec from 4.2° to 1.8°K. The tan δ-frequency-reciprocal temperature surface shows considerable structure with loss tangents in the range of 2–9×10−5. Debye relaxation associated with crystal defects appears to be the dominant mechanism, with individual peaks becoming resolved above the background caused by peaks at other frequencies.
A NaCl sample shows a loss peak near 300 Mc/sec at 4.2°K, with its high-frequency shoulder distorted by an adjacent peak. At lower temperatures the peaks move closer and to lower frequencies. The activation energy is estimated to be 0.0011 eV and occurs at approximately one lattice site in 5×1010. The loss mechanism suggested is electron relaxation between neighboring multivalent impurities. The loss would be indistinguishable at room temperature, but is calculated to occur at 4.6 Gc/sec with a peak loss tangent of 3.2×10−7.
Multiple Diffraction Effects in Annealed Permalloy Films
Authors: Alessandrini E. I. 
Published: April 2005

Transmission electron diffraction and electron microscope techniques have been used in studying the effects of annealing temperatures on the structure of thin Permalloy films. Single-crystal and polycrystalline films were epitaxially grown by vapor deposition of an (81% Ni, 19% Fe) alloy on heated freshly cleaved (100) faces of rocksalt. Annealing experiments, at temperatures between 300° and 700°C, were carried out in an electron diffraction instrument after the films had been floated off the rocksalt and mounted on 200-mesh Ni grids.
The diffraction patterns of the single-crystal and polycrystalline as-grown and annealed films showed the effect of annealing twins on the number of extra reflections which appeared. The observed irrational spots and rings could be directly explained by the presence of twinning and double diffraction in a face-centered cubic structure. Weak reflections which appeared at forbidden (110) positions can be shown to result from double diffraction of (200), (020), and (002) positions, and are generated when {111} planes are textured and oriented in a [110] direction to the primary [100] orientation of the pattern. A dark-field electron microscopy study from these reflections further substantiates a double diffraction hypothesis. The reflections occur at temperature ranges below and above the critical ordering temperature for Permalloy and cannot be attributed to a superlattic structure. In addition, since annealing was carried out in vacuums in the high 10−7 Torr range, as well as in a reducing environment, the possibility that selective oxidation occurred was very unlikely.
Influence of Jog Concentration on the Conservative Motion of Dislocations in Copper
Authors: Petroff Pierre , Washburn Jack 
Published: April 2005

In an annealed crystal of low dislocation density, the critical resolved shear stress necessary to move circular prismatic edge-dislocation loops along their glide cylinders was compared to the range of stresses within which various segments of the three-dimensional network began to move. Etch-pit observations showed that the first segments of the network moved at 2 g/mm2 but that only 60% had moved when the maximum resolved shear stress had reached 38 g/mm2.
Circular prismatic loops, which because of their shape have a high jog concentration, were found to move at a critical resolved shear stress greater than 50 g/mm2. It was suggested that jog concentration should be expected to vary from one segment to another of the three-dimensional network in an annealed crystal, and that this is probably one important reason for the widely different stresses at which individual segments begin to move.
Electronic Beam Scanning of Injection Lasers
Authors: Fenner G. E. 
Published: April 2005

Experiments are described that resulted in the spatial scanning of the coherent emission of a GaAs junction laser at 77°K. By electrically separating the p side of the junction into several sections the current distribution is deliberately made nonuniform. Necessary conditions for the continuous shifting of the beam across the width of the diode are given. Several geometries, satisfying these conditions, are considered and evaluated with respect to simplicity of experimental verification. It was found possible to actually scan the beam continuously across the entire width of the diode (about ½ mm) by employing two fixed, pulsed, current sources and only one variable resistor.
Nonhomogeneities in emission intensity are related to the presence of ``spots'' reported since the early measurements in GaAs lasers. It is shown that these ``spots'' are determined by material parameters in the vicinity of the junction itself rather than by local conditions which might be caused by the current distribution.
Mechanism of Ultrasonic Loss in Silicon and Aluminum
Authors: Sylwestrowicz W. D. 
Published: April 2005

Attenuation in single crystals of silicon was measured as a function of frequency with a previously described technique. It was confirmed that, as in the case of aluminum, this dependence, in the range of frequencies from 20 to 110 Mc/sec, is of the form α=α0 exp (Cf), where α is attenuation, f is frequency, and α0 and C are constants. Heat-treating experiments indicate that the form in which oxygen is present in the material has a pronounced effect on the energy loss. Multiple scattering is proposed as a mechanism of loss in silicon and aluminum single crystals. An empirical model of multiple scattering is discussed.
It is confirmed that dislocations in silicon, at room temperature, do not contribute to the observed energy loss. Also it is proposed that the accepted relation for the evaluation of thermoelastic losses should be modified.
Polycrystalline Spin Wave Theory of Ferromagnetic Resonance Compared with the Tilting Experiment
Authors: Risley A. S. , Johnson E. G. , Bussey H. E. 
Published: April 2005

Schlömann's spin wave theory of polycrystalline ferromagnetic resonance has been tested in detail using the tilting method reported earlier. Among the quantities measured were the linewidth ΔH, and the maximum value of the imaginary part of the effective susceptibility (χm″)eff. The measurement method is equivalent to measuring asymmetric (Nx≠Ny) ellipsoids and thus, introduces another shape dependence in addition to that due to spin waves. Direct comparison with the symmetric (Nx=Ny) form of the theory is inaccurate. A proper comparison can be made in two ways: (1) generalizing the theory to include the Nx≠Ny case and then using the data directly, (2) transforming the data and then comparing with the Nx=Ny theory. Both comparisons are reported and their equivalence is demonstrated.
It is concluded that Schlömann's theory does not fit the data within the spin wave (SW) manifold. It is suggested that the theory of Sparks may provide a better fit. The difference between coupling models seems to be the basic difference between the two theories.
Experimentally and theoretically, ΔH and (χm″)eff are different quantities. The dispersive effects of spin wave coupling are shown to be the cause of the difference between the theoretical ΔH and (χm″)eff.