bluuebunny/crossref_metadata_2025 huggingface dataset:
Elastoresistance Effect in Iron Single Crystals
Authors: Martin M. C. , Morrow D. R.
Published: April 2005

The potentiometer circuit designed for measuring minute variations in small resistances developed by P. W. Bridgman has been used to measure the effect of tension, applied in a direction parallel to that of the current, on the resistance of iron single crystals (elastoresistance). Correction for strain permitted the calculation of the more informative physical characteristic, the elastoresistivity. In order to obtain at least an indication of the expected anisotropy of elastoresistivity, two single crystals of different orientations were investigated. Deformation temperatures of +30° and −78°C were used to observe the effect of temperature on the (relative) elastoresistivity. The increase in Δρ/ρ with decreasing temperature was larger than anticipated. The elastoresistivity and elastoresistance showed considerable anisotropy.
Internal Friction in Al-Cu Alloy
Authors: Quader M. A.
Published: April 2005

Measurements of the internal friction in pure Al and two aluminium alloys with 2 and 2.95 wt % Cu were made using a torsional pendulum. With solution-treated and quenched alloys a weak internal friction peak (peak I) was obtained at the same temperature range at which grain boundary relaxation occurred in pure Al. The peaks disappeared after a few minutes of aging due to the blocking of grain boundary relaxation on precipitation. The activation energy H corresponding to this peak is 32±1 kcal/mole for both the 2 and 2.95% alloys. A grain boundary peak also appeared in furance-cooled 2% alloy with H = 31±1 kcal/mole, but instead of a peak an inflexion point appeared in 2.95% alloy. For pure Al, H = 32.4 kcal/mole was obtained. Due to re-solution of the precipitates at higher temperatures another strong internal friction peak (peak II) appeared a few degrees below the solubility temperatures for both the alloys. The position of the peak is insensitive to the frequency of measurements but the peak height decreases on increasing the frequency. From the rigidity modulus measurements the solubility temperatures for the 2 and 2.95 wt % Cu in Al are obtained and are found to be in good agreement with previous results. An internal friction peak due to Zener relaxation, however, has not been observed in these alloys.
Calculation of Averages for Primary Recoil Distributions
Authors: Leibfried G.
Published: April 2005

The slowing down of an energetic particle in a random assembly of scattering centers is discussed. Certain averages for physically interesting quantities can be calculated in a very general form, including unequal masses of scattering and slowing down particles. The averages refer to quantities such as the total distance traveled (L) and the vector distance to the final positions (xi) and powers thereof. Two assumptions simplify the evaluation of the general results considerably: (α) The mean free path λ is a simple power of the energy E: λ(E)∼Eμ; (β) the distribution g(E; ε) of energies ε after one collision with initial energy E does not change its shape with E: Eg (E; ε)=κ(ε/E). A special distribution of this kind is the hard core distribution. Under assumptions α and β all calculations are reduced to the evaluation of an integral like ∫κ(η)ημdη. For equal masses and the hard core distribution, one can easily calculate averages of any power of L and obtain the distribution function of L, this being proportional to L1/μ exp(−L/λ). Under the assumption β alone, with arbitrary λ(E), results are given for special distributions and equal masses (including the hard core distribution). The evaluation of the averages now requires simple integrals over λ for linear averages and double integrals for quadratic averages with known integral kernels. For unequal masses, approximations are discussed.
Electrical Conduction and the Photovoltaic Effect in Semiconductors with Position-Dependent Band Gaps
Authors: Emtage P. R.
Published: April 2005

The semiphenomenological transport equations that are commonly used in the theory of semiconductors have been rewritten in variables appropriate to the discussion of an illuminated isothermal semiconductor in which the band gap is a linear function of one of the position coordinates. It has been found necessary to neglect those terms in the transport equations that arise from variations in mobility and effective mass. The first section considers electrical conduction in a uniformly doped specimen under weak illumination; deviations from Ohm's law were found to be small. In the second section, the potential distribution in a highly illuminated sample of such material, both with and without a junction present, is found. The major contribution to the total potential is the same as that found earlier by Tauc. These results are then used to determine the best geometry for a solar-energy converter in which such materials are used, and to calculate the efficiency of this converter as a function of illumination. The greatest efficiency possible was found to be 43%.
Magnetic Field Reversal by Relativistic Electrons Which Slow Down While Circulating in a Uniform Impressed Magnetic Field
Authors: Tonks Lewi
Published: April 2005

The prior restriction to conservative motion of the electrons has been removed, but scattering has still been neglected. The rate of energy loss has been used to derive the stationary distribution over a range of energy (or momentum) and canonical angular momentum for an arbitrary magnetic field distribution. A necessary ingredient is the retardation of the electrons; the radiative component of this has been estimated, but not included; the dynamical friction component, arising from motion through a uniform, fully ionized plasma, has been used as the sole contributor to energy loss. This friction also affects the canonical angular momentum and the latter's change in one cycle relative to the energy change has been formulated. Maxwell's equation connecting magnetic field with current density, applied to the stationary distribution, has permitted the formulation of the relation between field and the other variables. This completes the number of relations required to determine the magnetic field (eigenfunction) arising from a given rate of electron injection (eigenvalue): The trajectory equations have been derived.

It has been necessary to picture physically the complete evolution of a trajectory from injection to stopping, both to understand what the mathematics says and to devise an adequate machine program. When field reversal occurs, then just before the electrons die, the electron swarm divides into two counter-rotating eddies. Two iterative solution techniques have been used to calculate the field distributions for a range of initial energies, field strengths, and injection rates. A striking result is that once reversal of field occurs by increasing the injection rate, it is generally true that the reversed field varies little, but the layer becomes progressively thinner as the injection rate increases further. At some rate the layer thickness passes through zero and thereafter the injection radius lies not at the apocenter of the initial trajectory but at the pericenter, the layer protruding from its prior position.

For full-energy radii of gyration which are less than about one-third the injection radius, anomaolus solutions appear which are unstable. A number of aspects of the problem of incorporating an E layer into a thermonuclear device are briefly discussed, namely, the effect of scattering, the possibility of two-beam instability, the injection of the electrons, effects of end reflection in a finite-length layer, electrodynamic effects, and plasma diamagnetism.
Control of Population Inversion in Pulsed Optical Masers by Feedback Modulation
Authors: Collins R. J. , Kisliuk P.
Published: April 2005

The output power level of an optical maser is dependent on the level of inversion which can be reached. Using a technique in which the optical feedback is modulated by a shutter disk, an enhancement of the output power level of a pulsed ruby optical maser was observed. The higher level of output power occurred for only a short pulse. An explanation is given and the observed effect compared to the expected value.
Atom Ejection in Low Energy Sputtering of Single Crystals of fcc Metals and of Ge and Si
Authors: Anderson G. S.
Published: April 2005

The spatial distribution of atoms ejected from low index planes of Cu, Ni, Au, Al, Ge, and Si have been studied for bombardment by Hg+, Ne+, and Ar+ ions of energies up to 800 ev. In addition, the atom ejection for Hg+-ion bombardment of various Ge planes (12° apart) belonging to the [110] zone has been investigated in detail. For the fcc crystals, ejection was observed in 〈110〉 directions at all energies, in〈100〉 directions at higher energies, and in 〈411〉 directions under certain conditions. The ejection in the 〈110〉 and 〈100〉 directions are interpreted to be the result of focusons intercepting the surface with sufficient energy to cause a surface atom to be ejected. It is shown that a reasonable interpretation of the atom ejection in 〈411〉 directions is that a 〈110〉 focuson may intercept and eject a surface atom which is in a twin position rather than a normal position. For ion bombardment of Ge and Si atom ejection is observed in 〈111〉 and 〈100〉 directions. A possible interpretation is that many of the natural interstitial positions are filled near the surface as a result of the bombardment and that the structure resembles more that of a bcc structure. The systematic deviation in ejection directions from the associated crystallographic direction observed for the Hg+-ion bombardment of various Ge surfaces suggests that the atomic collisions resulting in atom ejection for Ge and Si occur in the outer few surface layers.
Fusion Plasma Injection
Authors: Linlor William I.
Published: April 2005

An experimental study was made dealing with the passage of a beam of 100-kv ions (H+ and H2+) across a magnetic field by means of a crossed electric field. The Lawrence Radiation Laboratory (Livermore) 1-ampere, 100-kv accelerator was used. The pressure in the crossed-field chamber was about 10−5 mm Hg. No difficulties were encountered for currents up to about 10 ma; the current density in the beam and the available aperture determined this upper limit.
Conductivity Injection and Extraction in Polycrystalline Barium Titanate
Authors: Lehovec Kurt , Shirn George A.
Published: April 2005

Direct current electric fields applied to polycrystalline barium titanate cause slow changes with time of current, potential distribution, and coloration. At temperatures between 250° to 300°C and with several thousand volts/cm applied, the current increases initially, then decreases, and then increases again. An analysis of the potential distribution indicates injection of a high conductivity region from the cathode, whereby the field at the cathode is decreased and the field at the anode is increased, followed by injection of a low conductivity region from the anode which travels to the cathode, causing a high field at the cathode and renewed injection of high conductivity from the cathode. Drift mobilities for the low conductivity region have been estimated.
Degree of Perfection of Ice Crystals Determined from Primary and Secondary X-Ray Extinctions
Authors: Zajac Alfred
Published: April 2005

The primary and secondary x-ray extinctions have been investigated in ice crystals. This led to an estimate of the sizes and the degree of misalignment of the mosaic blocks.
Scattering of an Electron Beam by a Neutral Gas
Authors: Parzen P.
Published: April 2005

Expressions are derived for the moments of the distribution function of an electron gas created by the passage of an electron beam through a slab of neutral gas. A spherical harmonic method including the effects of energy loss is used. For completeness, the case of no energy loss is also considered. No special assumptions as to the angular behavior of the scattering cross section are made. It is assumed, however, that the mean free path is independent of speed.
Relaxation Method for Studying Vacancies in Solids
Authors: Korostoff E.
Published: April 2005

A method is described for studying vacanices in solids that is based on determining the dependence of the approach of vacancy concentration to equilibrium in a specimen subjected to a periodic temperature variation. The approach to equilibrium is determined by comparing the instantaneous response of electrical resistivity to the periodic temperature variation. It is shown that quantitative determination may be made of vacancy migration energy, of vacancy formation energy, and of source and sink spacing. Numerical calculations are carried out for gold.
Low Voltage Electron Diffraction Study of the Oxidation and Reduction of Silicon
Authors: Lander J. J. , Morrison J.
Published: April 2005

Low voltage electron diffraction and pumping speed measurements have been used to study the reactions of oxygen with clean Si (111) and (100) surfaces in the temperature range between 600° and 1000°C and the oxygen pressure range between 7×10−9 and 1×10−4 mm Hg. The results support the contention that a wide region in which Si is atomically clean exists in this range. Measurements of steady states yield an activation energy of about 90 kcal/mol for the clean-up process. The results also suggest a practical method for producing pure coatings of SiO2 by a technique similar to, but with several advantages over, the familiar Si+SiO2 reaction process.
Magnetic Field Effects on InSb Tunnel Diodes
Authors: Esaki L. , Haering R. R.
Published: April 2005

For InSb tunnel diodes placed in a magnetic field H, the ratio of longitudinal to transverse tunnel currents yields a relatively direct measurement of the tunneling exponential λ (V). For a typical InSb diode we found λ0, the zero bias value of λ, to be 10.7±0.2, which implies an effective built-in junction field of 5.7±0.1×104 v/cm. This value agrees well with the maximum and average junction fields calculated using the known doping concentrations and assuming a step junction. The pre-exponential tunneling factor is found to be (1.8±0.4)×107 amp/v cm2, which is about 30 times larger than Kane's theoretical result. The voltage dependence of λ is found to be expressible as λ=λ0(1−V/V0)−1/n with V0=0.2 ev and n=2.2.
Enhanced Photoemission and Photovoltaic Effects in Semitransparent Cs3Sb Photocathodes
Authors: Wooten Frederick
Published: April 2005

Measurements were made of photoemission and photovoltaic effects in thin (300–1250 Å) films of Cs3Sb, on a glass substrate, by scanning with a 20 μ-diam light spot. Enhanced photoemission and photovoltaic effects are obtained in regions within 1 to 3 mm from an Al electrode contact. Enhancement is about 25% with white light, and as much as a factor of 2.5 at 6200 Å. A band model is proposed in which the top of the valence band is fixed with respect to the Fermi level at the vacuum surface, but bends up at the glass substrate and, even more, at the electrodes.
Anisotropy of Self-Diffusion in Alpha Uranium
Authors: Rothman S. J. , Hines J. J. , Gray J. , Harkness A. L.
Published: April 2005

Self-diffusion along the three principal crystallographic directions of alpha uranium has been measured on mosaic structured single crystals by the tracer-sectioning method. The diffusion coefficients at 625.5°C are D[100]=D[001]=1.95×10−13 cm2/sec,D[010]⩽10−14 cm2/sec. It appears that the mosaic structure has not affected the diffusion significantly.
Theory of Dislocation Mobility in Pure Slip
Authors: Lothe Jens
Published: April 2005

The mobility during glide of uniformly moving dislocations or dislocation segments supposed not to be obstructed by any Peierls' barrier is estimated. For a straight freely moving dislocation, the strong anharmonicities in the core region, the thermoelastic (edge dislocation) and the phonon viscosity effect give rise to a drag stress at ordinary temperatures T∼θ, θ being the Debye temperature, of the order σ∼110ε×V/c in insulators. In metals the thermoelastic effect is negligible, while the core anharmonicity effect and the phonon viscosity effect will be of the same order of magnitude as in insulators. In the above formula, ε=thermal energy density, V=dislocation velocity, and c=velocity of shear waves. The scattering of phonons by the dislocation also causes a drag stress at ordinary temperatures of the order of magnitude of the above formula.

All of the above mentioned contributions to the drag stress go rapidly to zero with decreasing temperature. However, if the dislocation is constrained by the Peierls' barrier except at freely moving kinks, the kink mobility determines the dislocation mobility. It is shown that the scattering of phonons of a half-wavelength longer than the kink width causes a drag stress which may outweigh all other contributions up to ordinary temperatures, and which persists with decreasing temperature as T down to a temperature ∼θb/D, where b=the lattice spacing constant and D is the kink width.
Properties of Bi2Te3-Sb2Te3 Alloys
Authors: Smith Mac J. , Knight R. J. , Spencer C. W.
Published: April 2005

The phase diagram for the Bi2Te3–Sb2Te3 pseudo-binary system is of the solid-solution type, where the distribution coefficient k is equal to unity at 33.3 and 66.7 mole % Sb2Te3. The c lat tice parameter remains essentially constant across the diagram at 30.49 Å for both slowly crystallized and quenched alloys. For quenched alloys the a lattice parameter decreases almost linearly, from a value of 4.487 Å, for pure Bi2Te3, to a value of 4.275 Å, for pure Sb2Te3; however, a significant contraction from linear variation is found in slowly crystallized materials. EG diminishes in an essentially linear fashion from 0.16 eV, for pure Bi2Te3, to 0.12 eV at 24.2 mole % Sb2Te3 in both slowly crystallized and quenched materials. EG remains approximately constant from 24.2 to 66.7 mole % Sb2Te3 for slowly crystallized materials but continues to drop for quenched materials.
Contribution of Divacancies to the Magnetic Aftereffect in Nickel
Authors: Klein Miles V. , Kronmüller Helmut
Published: April 2005

This paper presents a theoretical discussion of the results to be expected from magnetic aftereffect measurements on Ni containing a sufficient number of divacancies. Calculations are made of the stabilization energy for 109°−〈001〉 and 180°−〈110〉 Bloch walls, the walls expected to be most mobile at low magnetic fields. The results show features characteristic of the 〈110〉 symmetry of the divacancies that are not shared by centers with 〈100〉 symmetry: (1) The existence of two relaxation modes having different relaxation times and different interaction energies with the magnetization vector, and (2) the nonvanishing of the stabilization force on 109° walls at large Bloch wall displacements.
Some Electrical Properties of the Porous Graphite Contact on p-Type Silicon
Authors: Harman George G. , Higier Theodore , Meyer Owen L.
Published: April 2005

Some unusual properties of the porous graphite contact on p-type silicon are described. Current through the sample reaches a saturation level that is inversely proportional to the amount of adhered water vapor. Other gases such as ammonia, H2S, and HCl modify the shape or amplitude of the saturation current. There is a hysteresis loop in the low voltage region which is similar in appearance to that of a ferroelectric. The general method of measurement can be applied to studying the semiconductor surface as well as the contact phenomena. The possible applications include such devices as current regulators, humidity detectors, and surface-barrier radiation detectors.

An electronic band model, which includes a trap-dominated inversion layer, is presented to explain the phenomena. This model also integrates various conflicting theories of metal-semiconductor contacts.
p-n Photovoltaic Effect in Cadmium Sulfide
Authors: Grimmeiss H. G. , Memming R.
Published: April 2005

So-called front-wall cells have been produced from CdS by inwards diffusion and subsequent selective etching away of the metal (Cu, Ag, Ni) producing the barrier layer. In particular, measurements were carried out of the dark current as a function of the voltage applied at different temperatures, of the shortcircuit current and the open-circuit voltage as a function of tempering time, illumination and temperature; and the spectral sensitivity of the short-circuit current was compared with the photoconductivity. It is shown that the photovoltaic effect can be explained not by a photoionization of electrons from the free metal but only by a p-n photoeffect. On the assumption of an impurity conduction in the p region the properties of the p-n photovoltaic effect are discussed.
Effect of Crystal Perfection and Polarity on Absorption Edges Seen in Bragg Diffraction
Authors: Cole H. , Stemple N. R.
Published: April 2005

When a single crystal is used in an x-ray spectrometer to display the continuous spectrum of an x-ray tube by Bragg diffraction, absorption edges characteristic of the atomic species in the crystal may be observed. The change in diffracted power across an edge is fundamentally due to a change in the atomic scattering, especially the imaginary part of the scattering, of the species whose edge it is. This produces a sharp anomaly in both the structure factor and the absorption factor of the reflection being used. The explicit effect of the absorption is a function of the perfection of the crystal face; the change in the structure factor depends uniquely on (hkl) for noncentrosymmetric crystals. Thus, the absorption edges may be used as a tool to study perfection of crystal faces and polarity of polar axes. The K edges of Ga and As seen in reflection from (111) and (1̄1̄1̄) faces of perfect and mosaic crystals of GaAs are discussed both theoretically and experimentally in some detail. The linear absorption coefficient of GaAs and Ge have been measured in the course of the work.
Two-Wave Shock Structures in the Ferroelectric Ceramics Barium Titanate and Lead Zirconate Titanate
Authors: Reynolds C. E. , Seay G. E.
Published: April 2005

Two ferroelectric ceramics, Pb (Zr0.52, Ti0.48)O3 with 1 wt % Nb2O5 and pure BaTiO3, were studied under shock wave loading. Plane shock waves having pressures ranging from 2 to 175 kbar were produced by high-explosive driving systems. Measurements were made with a streak camera and shock-detecting ferroelectric wafers. Both ceramic materials showed evidence of a two-wave structure over a wide range of shock pressures. Results indicate that these two-wave structures are characteristic of the elastic properties of the materials and are not due to phase transitions from ferroelectric to paraelectric. Pressure-volume Hugoniot curves are presented for both materials. Electrical charge released to an external load by Pb (Zr0.52, Ti0.48)O3 with 1 wt % Nb2O5 was measured as a function of the pressure of a shock which was moving parallel to the axis of polarization. The primary mechanism in this reduction of polarization by shocks was found to be, not a phase transition or domain switching, but merely a reduction of the dipole moment by axial compression.
Maximum Field of Magnetized Disks and Cylinders
Authors: Mammel W. L. , Morgan S. P.
Published: April 2005

Tables and plots are given of certain definite integrals which facilitate the calculation of an upper bound on the field attainable with a given configuration of magnetic material, when the volume occupied by magnetic material consists of a combination of solid and hollow circular cylinders. Such estimates are useful in the design of powerful electromagnets.
Influence of Crystal Growth on Domain Behavior in Yttrium Iron Garnet
Authors: Lefever R. A. , Chase A. B. , Wickersheim K. A.
Published: April 2005

The behavior of magnetic domains in certain sections of single crystal yttrium iron garnet is related to growth history. Discontinuities in domain patterns coincide with lines of intersection of vicinal faces on the growth surfaces of the crystals, and regions delineated by the discontinuities show differences in magnetic behavior. The relationship of these effects to oriented strains resulting from growth processes is considered.
Method for Evaluating the Quality of an Epitaxial Overgrowth Layer of Silicon on a Single-Crystal Silicon Seed
Authors: Jackson D. M. , Newkirk J. B. , Urban M. J.
Published: April 2005

Glancing angle x-ray diffraction photographs are used in the evaluation of the quality of epitaxial silicon overgrowths. Comparisons are made between the results obtained from high quality growth and highly polycrystalline and slightly nonepitaxial structures. The method is a reliable technique for detecting the presence of randomly oriented silicon in amounts exceeding the equivalent of 5 μ in thickness.
Elastic Constants of Single-Crystal Mo and W between 77° and 500°K
Authors: Bolef D. I. , De Klerk J.
Published: April 2005

Using a high frequency cw mechanical resonance technique, the adiabatic elastic constants of single crystals of molybdenum and tungsten were measured between 77° and 500°K.
Effect of Compton Scatterings by Air Molecules on the Sharpness of a Beam of Gamma Rays
Authors: Robinson Lawrence Baylor
Published: April 2005

A special problem involving the passage of a beam of gamma rays through air is examined. The effect of Compton scatterings on the sharpness of the gamma-ray beam is discussed. Other mechanisms whereby the beam is softened are not included because the interest is only in the component of the beam which suffers little energy loss.

The problem of interest is similar, in some respects, to multiple scattering of electrons with negligible energy loss. The mathematical expression for the collision process is different, however. A method used by Fermi in regard to multiple scattering of electrons is also used here. The Klein-Nishina cross section for Compton scatterings is introduced into the present problem in order to obtain scattering probabilities.

Some numerical results are obtained which can be applied to cobalt-60 gamma rays. The results are presented in graphical form.
Role of Carburization in the Suppression of Emission from Barium-Activated Tungsten and Molybdenum Surfaces
Authors: Rittner E. S. , Levi R.
Published: April 2005

A study has been made of the inhibition of emission from barium-activated tungsten dispenser cathodes and adjoining molybdenum electrodes which can be produced by carburization. X-ray diffraction and metallographic techniques have been employed coupled with emission measurements as a function of time, temperature, and arrival rate of Ba+BaO. Performance characteristics including the extent of the emission suppression and its time dependence are presented. It is concluded that the emission inhibition results from greatly reduced activator coverage of the surface of the carbide relative to that of the metal owing to much weaker adsorption forces. Return of emission coincides with disappearance of the carbide layer from the surface via diffusion.
Sputtering Yields at Very Low Bombarding Ion Energies
Authors: Stuart R. V. , Wehner G. K.
Published: April 2005

The spectroscopic method has been used to study sputtering yields under normally incident ion bombardment at very low ion energies. Data have been extrapolated to determine threshold energies for sputtering under normal incidence. These estimated thresholds are approximately the same energy (roughly four times the heat of sublimation) as the displacement thresholds for radiation damage. The mass ratio between ion and target atoms plays hardly any role in the thresholds.
Details of Ion Drift in an n-p Junction
Authors: Lehrer F. A. , Reiss H.
Published: April 2005

The motion of lithium in an n-p junction under reverse bias is discussed. Expressions are derived for the distribution of lithium in the ``intrinsic'' layer as it depends on time. Results for the width of this layer agree with the earlier calculations of Pell. Information concerning this width simplifies the calculation of the detailed distribution. Thus it is convenient to combine Pell's method with ours to supply an expeditious method for arriving at the distribution. The results of the calculation indicate that the so-called ``intrinsic'' layer produced by drift under reverse bias should be very highly compensated over most of its extent.
An Electromechanical Effect in Semiconductors
Authors: Westbrook J. H. , Gilman J. J.
Published: April 2005

The resistance of semiconducting crystals to indentation deformation has been found to be lowered significantly (up to 60%) by the simultaneous presence of a small potential (0.05 to 10 V) between the indenter and the crystal surface. This electromechanical effect appears to be confined to the plastic strain region of a surface layer of material 2–3 μ deep.

A large body of experiments of varied nature have established that the effect is real and not spurious. Similar effects are observed in a number of different semiconductors (Ge, Si, InSb and SiC) but not in metals or ionic crystals. The effect disappears at elevated temperatures but becomes enhanced below room temperature. It is not sensitive to the type of current carrier. The roles of surface preparation, crystallographic orientation, kind and concentration of charge carrier, geometry, and time have also been examined. Other and possibly related experiments show significant enhancement of the surface photovoltage (the Dember potential) by a longitudinal electric field. All of these experiments are extensively documented and discussed but no satisfactory model or mechanism has yet been conceived.
Adsorption of Tin on Iron and Cobalt Particles in Mercury
Authors: Luborsky F. E.
Published: April 2005

The magnetic properties of iron particles in mercury with diameters smaller than 500 Å are sensitive to to the adsorption of tin. The intrinsic coercive force and remanence both change on the addition of tin until an amount has been added corresponding to the adsorption of roughly one monolayer. The particle sizes calculated from these adsorption data are consistent with previous size determinations. Diffusion of tin into the iron was not significant at room temperature. The addition of tin to dispersions of cobalt particles in mercury produced changes in magnetic properties related principally to a rapid diffusion of tin into the cobalt.
Behavior of Germanium in Gallium Arsenide
Authors: Vieland L. J. , Seidel T.
Published: April 2005

The amphoteric behavior of germanium in gallium arsenide has been studied quantitatively for small variations in melt composition around the maximum melting point.
Correspondence between Pierce's Coupled Mode Amplitudes and Quantum Operators
Authors: Louisell W. H.
Published: April 2005

In this tutorial note, we show that the normal mode amplitudes of Pierce's coupled mode theory correspond to the creation and annihilation operators of quantum field theory. We show that the classical equations of motion in terms of Pierce's mode amplitudes are identical to the Heisenberg equations of motion for the creation and annihilation operators, and correspond to the quantized treatment of the classical problem.
Effects of Heavy Deformation and Annealing on the Electrical Properties of Bi2Te3
Authors: Schultz J. M. , McHugh J. P. , Tiller W. A.
Published: April 2005

Heavy plastic deformation producing nonbasal slip in Bi2Te3 changes the material from p type to n type and decreases its resistivity. From Hall coefficient measurements, it appears that an excess of about 2×1020 negative carriers can be generated in the lattice. Annealing the deformed samples at different temperatures and in different environments causes large changes in this excess carrier concentration. A simple theoretical model based on point defect generation by the plastic deformation accounts for the results. From this model, it appears that tellurium vacancies are the predominant electrically active point defects. These Te vacancies are annihilated by dislocation climb and array formation during annealing. The effect of dissolved oxygen in Bi2Te3 is to add donor states to the system.
Influence of the Kα1 α2 Doublet on the Determination of the Twin Fault Probability from X-Ray Diffraction Profiles
Authors: Witt F. , Schoening F. R. L.
Published: April 2005

The contribution of the Kα1α2 asymmetry to the total observed asymmetry is calculated for x-ray diffraction profiles from fcc specimens containing twin faults. The profiles are approximated by exp(−k2x2), (1+k2x2)−2, or (1+k2x2)−1. Calculations, using data from filed and annealed Permalloy, show that the α1α2 asymmetry introduces no serious error in determining the twin fault probability as long as the observations are made at values of the abscissa which correspond to at least half the distance from the profile maximum to the profile zero point. For asymmetries measured closer to the profile maximum, the α1α2 asymmetry can become important. A method to correct for the α1α2 asymmetry is given.
Observation of Domain Wall Resonances in Ferrimagnetic Oxides
Authors: Boyd E. L. , Budnick J. I. , Bruner L. J. , Blume R. J.
Published: April 2005

The observation of domain wall resonances by swept frequency spectrometer techniques is reported. These resonances appear as groups of very strong lines approximately 200 kc apart in the frequency range 80 to 20 Mc.
Extended Space-Charge Theory in Low-Pressure Thermionic Converters
Authors: McIntyre Robert G.
Published: April 2005

The problem of space-charge limited currents in a diode with plane-parallel electrodes is considered for the case where space-charge limitations are counteracted by the introduction of ions at the cathode. The ``no-collision'' approximation is used, in which inelastic and short-range elastic collisions are neglected, and each particle interacts with the Coulomb field of all the other particles. The electrostatic potential is determined, in a self-consistent manner, from Poisson's equation. The equations are simplified by transforming to reduced variables in a manner described by Langmuir and others. The first integrations of Poisson's equation are given for the six most important cases. The first of these has been reported by P. L. Auer, but rigorous analysis of the remaining five cases has not been previously reported. Analytical solution of the first-order differential equations derived is impossible. Numerical solutions have been obtained for illustrative purposes on the IBM-704 computer. More complete numerical solutions are being compiled.
Mobility of Edge Dislocations on {112} Slip Planes in 3.25% Silicon Iron
Authors: Erickson John S.
Published: April 2005

The possibility that {112} planes in 3.25% silicon iron are active slip planes is investigated. This is found to be the case for certain axial orientations when the deformation temperature is above approximately 184°K. Below this temperature, the {110} plane is the observed operative slip plane. Utilizing a dislocation site etch-pitting technique and a method of introducing dislocations into the material devised by Stein and Low, measurement is made of the velocity of edge-type dislocations on {112} planes in 3.25% silicon iron single crystals. The velocity of these dislocations is found to be very sensitive to the applied stress in the range of velocities examined which is from 10−7 to 10−2 cm/sec. Three temperatures of testing are investigated: 198°, 233°, and 298°K. A method for the determination of the operative slip plane in 3.25% silicon iron as a function of the deformation temperature and the orientation of the deformed samples is proposed. This results in the observation that the stress to cause any given dislocation velocity increases more rapidly with lowering deformation temperature when slip occurs on {112} planes rather than on {110} planes.
Diffusion, Solubility, and Electrical Behavior of Li in GaAs Single Crystals
Authors: Fuller C. S. , Wolfstirn K. B.
Published: April 2005

The solubility, diffusion, and electrical behavior of Li in GaAs have been investigated by means of chemical analysis, conductivity, and Hall-effect measurements. Both floating-zone and Bridgman crystals have been examined.

The solubility of Li in GaAs from the equilibrium surface alloys has been determined from 500° to 1150°C. A maximum solubility of 4×1019 Li cm−3 occurs at about 1050°C. Solubilities from surface Li2O and gaseous LiBr have also been determined over limited temperature ranges.

Li diffusion has been followed by electrical and chemical methods. The diffusion is nonideal and follows the relation, D*=0.53 exp(−1.0/kT), where D* is the apparent diffusion coefficient. Li produces ``automatic'' compensation of GaAs. Out-diffusion of Li results in acceptor formation. This behavior has been examined in detail and interpreted by postulating initial formation of stable (Li+Li=) doublets which, through the hole-electron equilibrium, cause Li to dissolve as Li+ donors to near compensation.

A marked effect of donor doping on the solubility of Li has been found.

Certain unexplained differences between crystals exist which are being further investigated.
Single-Domain Magnetization Curves for the General Ellipsoid
Authors: Johnson Clark E.
Published: April 2005

Single-domain magnetization curves have been extended to the general ellipsoid. The calculation was carried out on an IBM 705 computer and was an iterative minimization of the energy as a function of the direction of magnetization for an arbitrary applied field. The results are similar to those of Stoner and Wohlfarth for ellipsoids of revolution. Tables containing reduced magnetization as a function of the magnitude and direction of the applied field and shape are available.
Magnetic Susceptibility of Gadolinium and Dysprosium Sesquioxides at Elevated Temperatures
Authors: Arajs Sigurds , Colvin R. V.
Published: April 2005

Magnetic susceptibilities of Gd2O3 and Dy2O3 have been studied from about 300° to 1500°K and 300° to 1250°K, respectively. The paramagnetic susceptibility data of both oxides obey the Curie-Weiss law. This information supports the suggestion that the small deviations from the Curie-Weiss law found in gadolinium and dysprosium metals are due to conduction electron magnetization. The ions Gd3+ and Dy3+ in the oxides possess the Bohr magneton numbers 7.80 and 10.52, respectively.
Optical Maser Emission from Trivalent Praseodymium in Calcium Tungstate
Authors: Yariv A. , Porto S. P. S. , Nassau K.
Published: April 2005

Coherent emission at 1.047 μ from trivalent praseodymium in calcium tungstate was observed. This emission coincides with strong infrared fluorescence at the same wavelength and was found to be stimulated mostly by absorption of blue light by the 3P0, 3P1, and 3P2 bands. The emission corresponds to a 1G4→3H4 transition with the terminal level 377 cm−1 from the ground state. The oscillation threshold was the same at 4.2°, 20°, and 78°K. No stimulated emission was observed at room temperature. The lifetime of the metastable state 1G4 is 50×10−3 sec. A new technique used to measure the lifetime is described.
Electrical Resistivity and X-Ray Diffraction Study of the Beta AgCd-AuCd System
Authors: Rothwarf F. , Muldawer L.
Published: April 2005

Resistivity data as a function of temperature and composition have been obtained for solid solution alloys of β-AgCd and β-AuCd. Silver substitution for gold in β-AuCd produces a lowering of the temperature of the diffusionless transformation and changes the nature of the transformation for the higher cadmium concentration alloys. Small substitutions of gold for silver in β-AgCd also lower the transformation temperature while larger substitutions raise it. Ordering of gold and silver near the composition AgAuCd2 has been observed by x-ray diffraction and confirmed by residual resistivity measurements. This ordered structure is identical to that of the Heusler alloy; at lower temperatures ordered AgAuCd2 transforms to a more complex phase. Separate disorderings involving the gold-silver sublattice and the cadmium sublattice have been observed. Away from the composition AgAuCd2, residual resistivity measurements show the expected parabolic behavior. Some of these phenomena can be qualitatively explained in terms of ion-core and electro-negativity differences.
Search for an Effect of Surface Charging on the Superconducting Transition Temperature of Tin Films
Authors: Bonfiglioli G. , Malvano R. , Goodman B. B.
Published: April 2005

An attempt has been made to measure the rate of change of superconducting transition temperature Tc, as a function of surface charge density σ, in tin films. For films having thicknesses of 190, 670, and 1460 Å, |dTc/dσ| was found in all cases to be less than 30 deg cm2 C−1, the limit of sensitivity of the present apparatus. This negative result is compared with Glover and Sherrill's finding that in a tin film 70 Å thick, dTc/dσ = −460 deg cm2 C−1.
Sign of Charged Dislocations in NaCl
Authors: Caffyn J. E. , Goodfellow T. L.
Published: April 2005

An interpretation of previous experiments on the movement of charged dislocations in ionic crystals is given. It is shown that those experiments involving bending do not allow an unambiguous determination of the sign of the charge to be made and the contradictory results obtained from indentation experiments can be resolved on the assumption that the dislocations carry a positive charge.
Electron Optical Investigation of Thin Films of Lithium on Tantalum, Platinum, and Carbon Substrates
Authors: Esquivel A. L. , Fung Ai-Chun , Rhoads H. U. , Weber A. H.
Published: April 2005

Thin films of lithium when evaporated onto well-polished, chemically cleaned, and outgassed Ta and Pt substrates formed uniformly thick layers (in the range 240–1600 Å) suitable for the p-n reaction in the Van de Graaff generator. A thin carbon coating, (about 300 Å thick) evaporated upon the Li film from a heated carbon filament immediately following the deposition of lithium on Ta and Pt substrates, insulated chemically the lithium from the air with its water vapor content and also provided carbon replicas of the Li films surface for electron microscopy.

Proton bombardment of the carbon-coated Li films had no visible effect on the carbon coating nor on the Ta or Pt substrate. However, after a proton beam bombardment of 10 μA-min at 1.88 MeV, the Li films gave evidence of some initial damage effect (growth of grain size plus surface unevenness) which appeared to anneal away with subsequent bombardment.

Orientation effects were observed in Li films deposited upon carbon substrates (in turn deposited on nickel lectromesh grids) in a special evaporator, attached to and forming a part of the vacuum system of the electron microscope (RCA type EMU-2B) in order to avoid contamination of the Li with the laboratory atmosphere. Electron diffraction patterns revealed the following: (1) random orientation for the thinner (240 Å, approximately) Li films and (2) preferred orientation of the (110) and (200) planes nearly perpendicular to the surface for the thicker (1600 Å, approximately) films.
Resonances in the Positive Column of a Low-Pressure Arc Discharge
Authors: Battocletti J. H. , Hershberger W. D.
Published: April 2005

When an em (electromagnetic) wave of fixed frequency is incident on the cylindrical positive column of a low-pressure mercury vapor arc discharge with its electric field and direction of propagation both perpendicular to the column axis, a spectrum of resonances of reflection and transmission occurs as the discharge current of the positive column is varied. In addition to the expected cylindrical plasma resonance, a set of lesser resonances may be distinguished. The locations of these resonances have been extensively studied experimentally as functions of temperature and signal frequency for four tubes of different cross sections. It is shown that temperature, which is governed by losses in the plasma column and by the ambient temperature, has a substantial effect on the location of the resonances. By using this effect, spectra of resonances are easily obtained over a frequency range of 4400 to 22 000 Mc for the smallest tube. In addition, the sharpness of the cylindrical plasma resonance is calculated from experimental data and compared with theoretical curves of Q which have been determined from equations which take into account radiation and collision damping.
Electron Microscope Observation of a Radiation-Nucleated Phase Transformation in Mica
Authors: Price P. B. , Walker R. M.
Published: April 2005

Synthetic fluor-phlogopite mica samples were irradiated with fission fragments, stripped into thin sheets (≲3000 Å), and annealed in air at various temperatures to study the behavior of the tracks which were formed along the paths of the fission fragments. Transmission electron microscope observations showed that the appearance of the tracks was unaltered below 775°C. At ∼800°C tracks began to thicken at their intersections with the mica surfaces and to thin in the region between the surfaces. The thickened ends grew into plate-like particles whose selected area diffraction patterns were consistent with that of forsterite. This compound is known to be formed during the high-temperature decomposition of unirradiated mica. The experiments thus demonstrate that individual fission fragment tracks can serve as nucleation sites for a phase transformation in mica.
Shape-Sensitive Uniaxially Magnetized Domains in Ni-Fe Films
Authors: Muckenhirn O. W. , Monnier M. H. , Besser P. J.
Published: April 2005

Thin Ni-Fe films which exhibit uniaxially magnetized domain patterns whose boundaries tend to follow the physical boundary of the film can be produced by a special evaporating technique if oxygen and minute quantities of diffusion pump oil are added to the system prior to evaporation. This paper describes the properties of these ``shape sensitive'' films and the factors influencing their production. A hypothesis which correlates these factors with the film properties is proposed.
Transition Radiation with a Finite Plate
Authors: Parzen P. , Nomicos G.
Published: April 2005

The transition radiation due to a modulated infinite electron beam passing through a finite infinitely conducting circular plate is computed. Numerical results are worked out for various ratios of plate radius to wavelength with a 300-MeV electron beam. These results compare favorably with an approximate expression derived from a Russian paper.
Use of Modified Free Energy Theorems to Predict Equilibrium Growing and Etching Shapes
Authors: Jaccodine R. J.
Published: April 2005

This paper offers a construction that gives the limiting or ``equilibrium'' shape of an etching crystal. The conditions for hillock and pit stability and face rounding are also obtained.

Experimentally, germanium cylinders with different zone axes were etched to develop ``equilibrium cross sections.'' These were in good agreement with the construction. Other uses of the construction are discussed.