bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion of Chromium in Nickel
Authors: Murarka S. P. , Anand M. S. , Agarwala R. P. 
Published: April 2005

Diffusion of chromium in pure nickel has been studied by radioactive tracer and residual activity technique. The diffusion coefficient (in units of cm2/sec) in the range 600°−900°C is given by DCr/Ni=0.03 exp(−40 800/RT) and in the range 350°−600°C is given by DCr/Ni=5.45×10−9 exp(−13 700/RT).
The bimodal diffusion behavior has been explained on the basis of solid solubility of chromium in nickel, which falls very rapidly from 1000°C downwards. The entropy of activation for high-temperature diffusion falls very well on the entropy vs activation energy curve for lattice diffusion in nickel.
A Backward-Wave Surface Mode in a Plasma Waveguide
Authors: Carlile R. N. 
Published: April 2005

The phase characteristics of a backward-wave pass-band mode have been measured in a plasma waveguide, consisting of a circular waveguide that is coaxial with the positive column of a mercury-vapor discharge. The mode has been identified as an n = 1 surface mode similar to that described by Trivelpiece.
It is shown that zero-temperature plasma-waveguide theory predicts this mode accurately. This theory predicts that a simple relation exists between the lower cutoff frequency of the n = 1 mode and the electron plasma frequency. It is demonstrated that the calculated electron plasma frequency obtained from this relation, where the cutoff frequency is determined from a measurement of the phase characteristics, agrees well with an independent measurement of electron plasma frequency by the well-known cavity-perturbation method.
Both the n = 1 and symmetric n = 0 modes were excited by a novel coupler called the double-ring coupler.
Noise measurements on the n = 1 and symmetric n = 0 modes indicate that the output signal-to-noise ratio is independent of input signal power and is about 7 dB for the n = 1 mode and varies from about 7 to greater than 30 dB for the n = 0 mode. A simple model of the plasma is proposed which explains all the noise observations reported here. Crawford and Lawson independently proposed a similar model.
Photocontrolled Surface Conductance in Anodized InSb
Authors: Mueller R. K. , Jacobson R. L. 
Published: April 2005

Anodized p-type InSb, cooled to the extrinsic conduction range in the dark, was found to have an n-type inversion layer at the surface. Illumination changes the n-type inversion layer to a p+ accumulation layer; any intermediate surface condition can be obtained by controlled exposure. A method for determining the surface conductance of the inversion layer is described. This method utilizes a high-impedance grain boundary barrier to avoid shunting of surface conduction by bulk conduction. The highest surface conductance on unilluminated anodized samples was found to be 100 μmhos/square.
Spectral response measurements show that photons in the energy range 0.8 to 3.5 eV are effective. The effect is believed due to photoemission of electrons from the InSb into the oxide. Transient response measurements for light on and off conditions on n- and p-surfaces support this model.
Dislocation Damping due to Kink Motion
Authors: Suzuki Tetsuro , Elbaum Charles 
Published: April 2005

The ultrasonic attenuation and velocity change that result from the damping due to motion of dislocation kinks have been calculated on the following assumptions: (1) the frequency of thermal creation of kinks is smaller than the frequency of the applied stress; (2) the frequency of thermal motion of the kinks is larger than the frequency of the applied stress.
The characteristics of the attenuation calculated from the above assumptions differ from those of the string model for dislocation damping as follows. First, the resonance frequency depends on kink spacings and on the distance between pinning points on the dislocation. Second, for strain amplitude in excess of a critical value given in terms of kink spacings and the distance between pinning points, the attenuation decreases with increasing strain amplitude.
Disordering of Defects in Single Crystals of Zinc Sulfide
Authors: Chadderton L. T. , Fitzgerald A. G. , Yoffe A. D. 
Published: April 2005

Stacking faults are observed in zinc sulfide (wurtzite) single crystals on basal planes (0001) and on prismatic planes (112̄0) and (12̄10) to the growth surface.
The degradation of these stacking faults in different environments is described. The loop contrast observed to form at stacking faults on prismatic planes when exposed to high electron beam intensities in the electron microscope is explained by a thermally activated mass-transport mechanism. Migration of vacancies or atoms occurs depending on whether the stacking fault is extrinsic or intrinsic, respectively. Subjecting crystals to high pressures (about 60 kbar) results in an increase in the number of basal plane stacking faults. This is equivalent to a gradual phase change occurring over several atomic planes. Thermal etch figures observed by transmission electron microscopy in crystals annealed at 700° and 900°C are identified as a crystallographic polarity effect.
Effect of Chemisorbed Oxygen on Photovoltaic and Photoconductive Processes in Rutile
Authors: Keezer R. 
Published: April 2005

Adsorbed oxygen increases both the response and the response time for the photovoltaic effect in rutile.
The model for the effect of chemisorbed oxygen on the photoconductivity has been modified to take into consideration the effect of oxygen pressure. The conductance of rutile, measured as a function of oxygen pressure, agrees with the modified model.
The increase in photovoltaic response and response time with exposure to oxygen has been explained in terms of the barrier layer formed by chemisorbed oxygen.
Effect of Irradiation on Magnetic Properties of Fe-Ni Alloys
Authors: Schindler A. I. , Kernohan R. H. , Weertman J. 
Published: April 2005

Hysteresis loop measurements were conducted on several commercial iron-nickel alloys during neutron irradiations at 90°K and at temperatures up to 175°C, in both zero and saturating magnetic fields. Isochronal annealing tests were also performed on the alloys after irradiation. The low-temperature irradiation results indicated that magnetic properties are affected not by the point defects themselves but by their motion and eventual disposition. The radiation-induced changes appeared similar in many ways to those observed in these alloys upon magnetic annealing.
Experiments on the alloys at temperatures from 70° to 175°C in a saturating magnetic field showed that the activation energy of the radiation-induced process was 0.3 eV. In all cases the radiation-induced changes were annealed out at temperatures below the usual ordering temperature for Ni3Fe. This recovery process appeared to be dependent upon the state of the magnetization of the sample.
Method for Hall Mobility and Resistivity Measurements on Thin Layers
Authors: Lange Julius 
Published: April 2005

A method for measuring Hall mobility and resistivity in thin layers of semiconducting materials uses four contacts near the center of a sample that is large in comparison to the contact spacing. The measured value of the Hall coefficient is independent of the relative positions of the contacts. For resistivity measurements the contacts have to lie on a circle; the error due to a 10% deviation from this condition is 3%. If the contact spacing is110 of the smallest sample dimension the Hall coefficient is accurate to 2.5% and the resistivity measurement to 5.5%.
Where it is not possible to make the sample large in comparison to the contact spacing, a circular sample and a square array of contacts is proposed. Arrangements which do not fit either case but closely approach both can be treated by first using the infinite sheet method and then correcting for the finite size of the sample by the circular sheet method.
These methods may be useful where it is not convenient to form either Hall bridges or contacts to the edge of the sample, as in the van der Pauw method. Measurements on epitaxially grown layers might be carried out by this method.
Analysis of Enhanced Diffusivity in Nickel
Authors: Wazzan Ahmed R. , Dorn John E. 
Published: April 2005

The coefficient of self-diffusion in annealed and prestrained nickel single crystals, Du, determined in the temperature range 948° to 1023°K by radioactive counting of the surface is Du=1.9 exp(−66 800/RT) cm2sec−1.
The coefficient of self-diffusion in annealed and prestrained fine-grained nickel crystals, Du′, in the same temperature range is independent of the degree of prestrain: Du′=1.1×10−7 exp(−32 300/RT) cm2sec−1.
The coefficient of self-diffusion in nickel single crystals undergoing plastic deformation, Dd, was determined for strain rates ranging from 0.01 to 0.1035 h−1 in the same temperature range. Dd appears to vary with strain but eventually reaches an asymtotic value D̄d. At a constant temperature, D̄d/Du is almost linearly dependent on the strain rate ε: D̄d/Du=1+Kε̇, where K is 162, 225, and 470, (h−1) for temperatures 1023°, 973°, and 948°K, respectively.
Growth and Dislocation Structure of Single-Crystal Ga (As1−xPx)
Authors: Wolfe C. M. , Nuese C. J. , Holonyak N. 
Published: April 2005

The preparation of single-crystal GaAsP by halide vapor transport is described. That dislocation free GaAsP can be achieved was verified experimentally for whiskers grown by the vapor-liquid-solid method. In the growth of monocrystalline ingots for device purposes, growth mechanics and the resulting crystal habit are strongly influenced by degenerate Zn, Te, and Se doping. Since n-type crystals require higher supersaturations, single-crystal growth is easier to obtain with Zn doping.
The as-grown dislocation structure of ingots with low-index natural facets is examined by decoration and etching. Typical densities are 5×103 to 106/cm2. From their simple crystallographic orientations different dislocations are identified. 〈211〉, {111} and 〈100〉, {110} edge dislocations are observed in {110} polygonization walls. Values of mobility and carrier density are evaluated from a device point of view. Laser diodes with threshold currents as low as 3000 A/cm2 at 33.3% GaP have been obtained from this material.
Effects of Single Neutron-Induced Displacement Clusters in Special Silicon Diodes
Authors: Gereth R. , Haitz R. H. , Smits F. M. 
Published: April 2005

Radiation damage in uniform silicon avalanche diodes having an active volume of 10−11 cm3 has been investigated. Radiation-induced centers contribute to the carrier generation within the diode breakdown region, causing a corresponding increase in the avalanche pulse rate of the diode.
The high sensitivity and the small volume of the diodes allow the study of permanent radiation damage resulting from single primary neutron collisions. By measuring the distribution function of the pulse rate on a statistical lot of diodes, a relationship between the pulse rate and the energy dissipated in atomic processes is derived. A superlinear increase of pulse rate with energy is observed. In general the higher pulse rates have a temperature dependence characterized by a lower activation energy than is the case for the lower pulse rates.
For comparison, the effect of 2-MeV electron irradiation has been studied. The pulse rate is found to increase linearly with integrated flux. At low fluxes the pulse rate is dominated by generation centers only, while in heavily irradiated diodes trapping effects become observable. Also at low fluxes the observed activation energy for carrier generation is 0.66 eV, while at higher fluxes this activation energy is lower by as much as 0.3 eV.
The dependence of the observed activation energy on the flux in the electron case and the generally lower activation energies for the higher pulse rates in the neutron case is attributed to a tunneling interaction between individual defects. The defects in the larger neutron displacement damage clusters will have a wider spread in energy levels than those in the smaller clusters. This, in connection with the interaction between the individual defects, results in a reduced activation energy and an increased pulse rate.
Removal of Thin (20 Å) Layers of Metals, Metal Oxides, and Ceramics by Mechanical Polishing
Authors: Whitton J. L. 
Published: April 2005

The method of vibratory polishing has been applied to the reproducible removal of thin layers from metals, oxides, and ceramics. The rate of removal depends on the hardness of the material being polished, and for the materials tested, i.e., W, Ta, Si, Zr, Au, UO2, Ta2O5, and ZrO2, is in the range of a few atom layers (20 to 50 Å) per minute of polishing time. Experimental details are described and the results obtained are shown.
Studies have been made of the surfaces of these materials by x-ray diffraction, reflection e lectron diffraction, and electron microscopy to determine the effect of the polishing on crystal structure and surface topography. The results show that all the materials except gold have surfaces smooth to within 50 Å, that W and Ta single crystals have disturbed or deformed layers of less than 250 Å and that single-crystal Si is not deformed at all.
Penetration of an Ion Through a Monolayer of Similar Ions Adsorbed on a Metal
Authors: Gadzuk J. W. , Carabateas E. N. 
Published: April 2005

A fractional monolayer film of ions is formed by the adsorption of a gas onto a metal substrate. These ions form a discrete dipole layer, the potential across it being the change in electron work function of the surface. As additional ions are brought to the surface, they penetrate only a fraction f of the potential across the dipole layer.
In this work the penetration coefficient f valid for the entire range of coverages is derived for two limiting types of films, immobile and mobile. By considering thermal effects, a penetration coefficient for partially mobile films is also derived. The values obtained for the penetration coefficient are applicable to any substrate-adsorbate system.
The theoretical expressions for the penetration coefficient are evaluated for cesium on tungsten and compared with the data of Taylor and Langmuir.
Two-Stream Cyclotron and Plasma Wave Interactions
Authors: Maxum B. J. , Trivelpiece A. W. 
Published: April 2005

Cyclotron and plasma wave interactions between drifting electron streams in a steady axial magnetic field are studied for configurations of finite transverse cross section. It is shown for the case of equal and opposite drift velocities, that there exists an instability at approximately one-half the cyclotron frequency. This instability is a consequence of the coupling between the slow space-charge wave on one stream and backward cyclotron wave on the other stream. This coupling can occur whenever the streams are of finite transverse cross section.
In order to verify some of the features of this instability, experiments in which two coaxial oppositely directed electron beams were passed between two planes, were carried out for a limited range of electron drift velocity and magnetic field values. These experiments demonstrated the existence of an instability at one-half the cyclotron frequency, in agreement with the theory. It was found experimentally that at a particular stream velocity the instability could exist over a small range of magnetic field values. The upper limit of magnetic field can be explained by the assumption that nonlinearities result in a thermalization which causes the velocity spread on the electron beam to become comparable to its mean velocity. The lower limit is a consequence of the finite length of the interaction region.
Although the measured signal level was much less than that expected on the basis of converting a reasonable fraction of the beam energy to rf energy, it was found that the signals observed had a narrow frequency spread (−3 dB width was 10 kc/sec at 50 Mc/sec).
Nature of Long-Range Order in Cu3Au and Cu72Au28
Authors: Schwartz L. H. , Cohen J. B. 
Published: April 2005

Diffuse x-ray scattering and the intensity of Bragg peaks from single crystals of Cu3Au and Cu72Au28 have been studied for various degrees of long-range order. Equations are developed for the effects of differences in atomic size of the species and zero-order temperature effects on diffraction from an alloy when long-range order is present. A peak due to differences in atomic size is predicted under the superstructure reflections as well as under the fundamentals when order is not perfect; this prediction is experimentally confirmed. If the local order is not large for coordination shells greater than the eighth or ninth, then the Warren short-range order parameters can be accurately determined from data along only two lines in reciprocal space.
The results indicate that excess Au atoms, replacing Cu in Cu3Au, distribute themselves at random when Cu72Au28 is heat-treated for maximum long-range order. Thus there is no marked tendency for the Au atoms to avoid each other. Local order develops among misplaced atoms as the long-range order decreases with increasing temperature and just below the critical temperature this local order is similar in both Cu3Au and Cu72Au28. There are about the same number of wrong first bonds just below the critical temperature Tc for both alloys, even though the degree of long-range order indicates that there are more wrongly occupied sites for the nonstoichiometric alloy than for Cu3Au. (The data for Cu3Au are in agreement with Cowley's latest thermodynamic treatment and Peierl's theory.)
The results for both ordered alloys can be explained in terms of a large number of small antiphased regions in a well-ordered matrix. These regions are essentially two dimensional except near the critical temperature for the nonstoichiometric alloy where they are three dimensional. They vary in composition from point to point in the structure. The extra Au atoms in Cu72Au28 may play a key role in forming these as the temperature is raised, as they appear in the boundaries of the domains.
The atomic volumes of Cu and Au in ordered Cu3Au and Cu72Au28 are the same as in the pure metals; their rms vibrations are similar.
Magnetic Properties of Several Substances in Strong Pulsed Fields
Authors: Guillot Maurice , Pauthenet René 
Published: April 2005

An experimental determination of the magnetization laws for the Gd+3, Dy+3, Tb+3, Ho+3, Er+3, Yb+3 ions in the garnet structure gallates is presented as well as proof for the quenching of the moment, and a calculation for the saturation magnetization and the thermal variation of spontaneous magnetization of the corresponding ferrite.
The ferro—antiferromagnetic transition of UO3CoO at 4.2°K is determined and the magnetic properties of the MnAu2 alloys are discussed.
Substitution of Divalent Cobalt in Yttrium Iron Garnet
Authors: Geller S. , Williams H. J. , Espinosa G. P. , Sherwood R. C. 
Published: April 2005

Magnetic and crystallographic data are reported on the systems {Y3}CoxFe5−2xMxO12, M≡Si and Ge. When M≡Si, the maximum value of x appears to be between 1.00 and 1.25, while when M≡Ge, the maximum value of x=2.50. A distribution of the ions in these garnets is proposed that is compatible with the results and conclusions obtained on all other substituted yttrium iron garnet systems. In particular, it appears that a constant 20% of the Co2+ ions enter tetrahedral sites. When x≥1.00, some Ge4+ ions enter octahedral sites.
The garnet {Y2.7Ca0.3}CoFe2.7Ge1.3O12 has a compensation point at 236°K; it is the first garnet reported which has a compensation point resulting from a difference in the temperature behavior of only the a and d sublattice magnetizations. The other garnets having compensation points all contain magnetic rare-earth ions in the c sites.
The garnet {Y2.5Ca0.5}CoFe3V0.5Ge0.5O12 has a higher Curie temperature, 410°K, than that, 350°K, of {Y3}CoFe3GeO12. This is in accord with the expected effect of pentavalent vanadium substitution.
The full-length paper with the above title appeared elsewhere.1
Parallel Pumping in Narrow Linewidth Planar Mn–ZnY
Authors: Dixon Samuel , Tauber Arthur , Savage Robert O. 
Published: April 2005

Parallel pump measurements were made on Mn-substituted single-crystal ZnY at room temperature and 17.2 kMc/sec. The experimentally determined values of 1500 Oe for Hc and 1700 Oe for Hd were found to be in good agreement with theoretical predictions. The threshold rf field at Hc is 0.65 Oe. This threshold field for spin-wave instability gives a spin-wave linewidth (ΔHK) of 1.24 Oe. The susceptibility curve rises sharply at Hd, peaks in the vicinity of Hc, and then falls off slowly at lower values of dc field.
The ferrimagnetic resonance linewidth and dc magnetization were studied as a function of increasing Mn substituent at room temperature. The resonance linewidth decreases with increasing Mn substitution. A minimum of 3.8 Oe at 9.0 kMc/sec is observed in crystals with approximately 4 to 5 wt % Mn. The magnetization decreases linearly with increasing Mn substituent.
Nuclear Magnetic Relaxation in Magnetite
Authors: Mizoguchi T. , Tomono Y. 
Published: April 2005

The nuclear magnetic relaxation of 57Fe on tetrahedral sites in polycrystalline magnetite has been studied by spin-echo method with special interest in the relation to the low temperature transition and the electron diffusion among octahedral sites. Spin-lattice relaxation time T1 increases from about 0.7 msec at room temperature to 9 msec at 130°K. At the transition point (118°K) T1 decreases abruptly by the factor of about seven. It makes a minimum of 0.6 msec at about 88°K, then increases with decreasing temperature up to about 500 msec at 4.2°K.
The minimum of T1 may be interpreted by the electron diffusion among B sites. This effect is considered to be dominant from the transition temperature to liquid-nitrogen temperature. The discontinuity of the relaxation time at the transition temperature suggests that the hopping frequency increases very rapidly as the order collapses and this mechanism becomes no more effective to the nuclear magnetic relaxation.
Spin-spin relaxation time T2 is equal to T1 above about 60°K and becomes smaller than T1 below that temperature. T2 (=10 msec) at 4.2°K may be attributed to Suhl's interaction.
Kerr Effect and Bitter Pattern Measurements of Easy-Axis Distributions in Uniaxial Permalloy Films
Authors: Dove D. B. , Long T. R. 
Published: April 2005

Measurements on small regions (1 mil2) of magnetic films have been made with a Kerr magneto-optic apparatus that utilizes a laser light source and employs narrow-band detection techniques. Sensitivity is adequate to allow observations on permeabilities, remanent flux, and other properties. At the same time, Bitter patterns may be obtained facilitating detailed correlation between dynamic magnetic behavior and remanent state domain patterns.
Bitter patterns have been recorded during the course of an angular distribution fall-back experiment. The pictures have been assembled sequentially as a motion picture showing the remanent domain state developed throughout the experiment. Dynamic Kerr effect observations show that significant domain wall rearrangements occur near zero transverse field. The direction of M in small regions of single domain films has been determined to 0.1° using an MH alignment technique, and hence an alternative estimate of the angular distribution of easy axes is obtained. Strong transverse magnetostatic coupling between regions is of importance in both the fall-back and MH alignment measurements. The validity of various easy axis distribution measurements is discussed in the light of present observations.