bluuebunny/crossref_metadata_2025 huggingface dataset:
Scanning Electron Microscope as a Means of Studying Microplasmas at High Resolution
Authors: Neve N. F. B. , Hughes K. A. , Thornton P. R.
Published: April 2005

Preliminary investigations of microplasmas in silicon diodes have been made using a scanning electron microscope. The qualitative results given here establish the value of the method. It is shown that it is possible (a) to examine the surface topography of the microplasma region with high resolution, (b) locate any internal defects in or near the depletion region associated with the microplasma, and (c) ``map out'' the localized area of avalanche breakdown. Three examples of such studies are given. The current limitations of the method are discussed. It is concluded that the quantitative development of the method is straightforward. Other applications of the method are proposed.
Stacking-Fault Energy of a Ag-In Alloy from Node Measurements
Authors: Gallagher P. C. J.
Published: April 2005

Experimental measurements of the inscribed radius, the outer radius, and the character of extended nodes have been compared with the theoretical predictions of the recent work by Brown, Siems, and Jo/ssang et al. The most comprehensive comparison has been made for the two former theories, which have been found to predict accurately the observed node parameters. Within the range γ/Gb <10−2 the node method appears to be an excellent means of determining the stacking-fault energy.
Dynamic Friction Measurements on Belts of Viscoelastic Materials
Authors: Cunningham R. G.
Published: April 2005

The frictional behavior of belts of viscoelastic materials slipping on metal rollers has been investigated as a function of the amount of slip. The results show that the exponent in the relation Ff/A = a(Fn/A)x, relating frictional force per unit area to normal pressure, was greater than unity at low values of slip. This may be due to a height distribution of microscopic asperities on the surfaces.

The value of the exponent generally decreased as the slip increased. This can be explained by assuming that the deformational response of the viscoelastic material becomes more elastic as the slip is increased. A corresponding increase in the proportionality constant can be accounted for if the shear strength of these materials increased at a faster rate than the stress-strain proportionality constant as the slip was increased.
Test of the Manning Vacancy-Flux Correction in α Cu-Zn
Authors: Schmatz D. J. , Domian H. A. , Aaronson H. I.
Published: April 2005

Manning has devised a treatment to correct self-diffusivities calculated from Kirkendall effect experiments by means of the Darken analysis for the flux of vacancies accompanying diffusion in a concentration gradient. An iterative technique has been developed which permits the Manning correction to be made directly on self-diffusivities determined from Kirkendall effect data. This technique has been applied to interdiffusion data in α Cu-Zn taken from the literature. The variation with zinc content of the DZn*/DCu* (self-diffusivity) ratios was found to be satisfactorily consistent with the ratios determined from literature data on radiotracer self-diffusivities only after the Manning correction was applied, in strong support of the validity of Manning's treatment. Individual values and the Arrhenius equation constants of the Manning-corrected self-diffusivities, on the other hand, remain inconsistent with comparable radiotracer data, perhaps because of the insufficient accuracy of the data so far obtained from Kirkendall effect experiments.
Effect of Crystallite Size on the Infrared Dispersion of LiF Films
Authors: Martin T. P. , Turner A. F.
Published: April 2005

The infrared reststrahlen reflectance and the crystallite size of evaporated thin films of LiF were found to increase with increasing substrate temperature during evaporation. The change in reflectance did not appear to be due to interference, porosity, or scattering. It was therefore assumed to be indicative of a change in the optical constants of LiF. The index of refraction of the LiF films was calculated from reflectance measurements using the classical dispersion relation with two terms in the summation. The main term had a resonance at 32.5 μ and the perturbing term at 20 μ. As the crystallites became smaller (10 000−1000 Å), damping in both terms increased, the strength of the main resonance became slightly smaller, and the strength of the secondary resonance greatly increased. The damping and the secondary resonance are both thought to have anharmonic origins. It is suggested that such effects are enhanced at the surface of a crystallite where momentum conservation is relaxed.
Strain Energy of Screw Dislocation Arrays
Authors: Johnson H. H.
Published: April 2005

The hydrodynamic analogy is used to analyze the strain energy associated with screw dislocation arrays. The dislocation strain energy is shown to be mathematically identical to the kinetic energy of flow in hydrodynamics. Formulas are developed for calculating strain energy density and strain energy from the complex stress and potential functions, respectively. The theory is applied to single dislocation pileups in both infinite and finite media, and to dislocations upon two parallel glide planes in an infinite medium.
Electrical Properties of Thin-Film Capacitors of the Dy2O3-B2O3-SiO2 System
Authors: Hacskaylo Michael , Smith Richard C.
Published: April 2005

Thin dielectric films formed by evaporating a Dy2O3-SiO2-B2O3 mixture of a weight ratio of 80:10:10 exhibit excellent electrical, atmospheric, and mechanical stability in the temperature range from room ambient to 500°C. The mixture can be readily deposited from tantalum boats. The dielectric constant is about 4.5 and the dissipation factor varies from 0.003 to 0.006 at room temperature with a breakdown field strength of 4.0×106V/cm. The change in capacitance is about 5% at 470°C and about 20% at 500°C. The dissipation factor changes from 0.003 to 0.20 in the same temperature range. The film does not fracture or exhibit mechanical deformation at 500°C.
Measurement of the Transmission Spectra of 1-MeV Electrons with Normal Incidence on Aluminum Slabs
Authors: Rester David H. , Rainwater Walter J.
Published: April 2005

Measurements of transmission energy spectra of 1-MeV electrons with normal incidence on aluminum slabs have been made as a function of transmission angle. Slabs of thicknesses 0.11, 0.22, and 0.33 g/cm2, equivalent to 0.2, 0.4, and 0.6, the range of 1-MeV electrons in aluminum, were used. The electron spectra were obtained with lithium-ion-drift silicon detectors. The experimental results have been compared to calculated results obtained by use of Monte Carlo techniques. These data were found to agree except at the transmission angles less than 30 deg for the 0.11-g/cm2 slab.
Formation and Bleaching Properties of the T Bands in KCl
Authors: Ring James G. , Grossweiner L. I.
Published: April 2005

Optical bleaching of additively colored or 60Co irradiated KCl with ``F light'' and/or red light at 100°C produces three new absorption bands at 839 mμ (T1), 894 mμ (T2), and 992 mμ (T3) which have been designated as ``T bands.'' The most prominent T band is T2, with a thermal stability exceeding the R and N bands and less than the M and F bands. Illumination of a crystal containing T bands at −195°C causes a temporary interconversion between the T2 and T3 bands, the direction depending on the spectral intensity of the ambient light. The transformation kinetics were investigated with 20-μsec pulse and steady bleaching techniques and were found to be of first order. The rate constants are linear functions of the light absorption rates in the T2 and T3 bands with significant dark contributions. The analysis indicates that the temporarily bleached T2 and T3 centers maintain a constant concentration ratio. The available information indicates that the T bands are due to distinct F-aggregate color centers, possibly isomers of F5, and that the T2 and T3 centers are closely related in structure.
Recombination Centers in Gamma-Irradiated Silicon
Authors: Hirata M. , Hirata M. , Saito H.
Published: April 2005

The minority carrier lifetime in gamma-irradiated silicon crystals was studied. The doping impurity was phosphorus, arsenic, or boron, and the crystals were either float-zoned or pulled from the melt. The silicon E center was found to be the dominant recombination center in float-zoned, n-type crystals after irradiation. The capture cross section of the center for holes was measured to be 1.1×10−13 cm2 in phosphorus-doped silicon. The activation energy for annealing of an E center has been reported to be 0.94 eV, and the corresponding activation energy for the annealing in arsenic-doped crystals was found to be 1.5 eV. After annealing at 160°C, where the E center is known to anneal, the existence of some other energy level at about 0.4 eV below the conduction band was detected. In crystals other than float-zoned n-type, the A center governed the recombination. The cross section of this center was found to be 1.5×10−14 cm2 for holes and 2×10−16 cm2 for electrons. The introduction rate of the A center was found to be the same for a variety of samples. The value was 1.3×10−3 defects/cm3 per photons/cm2.
Properties of Clean Silicon Surfaces by Paramagnetic Resonance
Authors: Chung M. F. , Haneman D.
Published: April 2005

Silicon crystals crushed in ultrahigh vacuum (∼10−9 Torr) display an electron spin resonance signal close to g=2.0055 with a width of 7.0 Oe. The signal is strongly affected by exposure to 10−2 Torr of molecular hydrogen (increase ≈60%) and oxygen (increase ≈80%), indicating that it is associated with surfaces. From surface area measurements, the ratio of dangling bonds to surface atoms was found to be approximately 1 to 5. High-vacuum heat treatment causes an irreversible decrease in the surface resonance at 380°C (1-h heating), but the signal is still increased by gas exposure. Above approximately 610°C the relatively weak remaining signal is now decreased by oxygen exposure, indicating a second surface transformation which correlates with that observed in this temperature region by low-energy electron diffraction. It is concluded that the surface structures for both cleaved and annealed clean silicon surfaces involve dangling bonds, the concentrations being of order 20% and 2%, respectively. Consequences with respect to surface atom arrangements are discussed.
Diffusion of Lithium into Ge and Si
Authors: Pratt B. , Friedman F.
Published: April 2005

Lithium was diffused into Ge and Si at temperatures 300°−400°C and 400°−500°C, respectively. The diffusion was carried out in an inert gas atmosphere by decomposing LiAlH4. The concentration of Li impurities as a function of depth from the surface of the sample was determined by lapping down thin layers of the diffused part of the sample and measuring the conductance of each of these thin layers. An erfc was chosen to fit the experimentally measured concentration curve from which the diffusion constant D for each temperature of diffusion was determined. The following dependence of temperature was found: D=9.10×10−3exp(−13100/RT) for Ge,and D=2.65×10−3exp(−14500/RT) for Si,where D is measured in cm2/sec, T in °K, and R=1.98 cal/°K.

The deviation in the experimental values of D was not more than ±10% for Ge and ±20% for Si.
Premelt Variation of Current, Temperature, and Resistance in Exploding Wires
Authors: Hobson Arthur , Manka C. K.
Published: April 2005

Theoretical expressions, valid through the first 1/5 cycle, are obtained for the time variation of current, temperature, and resistance in the premelt stage of a wire explosion. These expressions are given in terms of the initial wire and circuit data. The results are compared with experimental determinations of the current and resistance in nickel wire exploded in air.
Decay of Space-Charge Waves on Electron Beams
Authors: Gunshor R. L.
Published: April 2005

The decay of space-charge waves with distance is observed in an electron beam with a velocity spread. This effect has previously been attributed to spatial Landau damping. We extend Landau's theory to include finite diameter electron beams and calculate the steady-state damping of the fast and slow space-charge waves using measured axial velocity distributions. For a density modulated beam injected from a shielded cathode, it is found that the fast wave does not exhibit Landau damping, while the slow wave is damped of the order of 0.1 dB per plasma wavelength. It is concluded that the large initial damping observed by Mihran is due to a ballistic or free-streaming process, and is not primarily due to Landau damping as calculated for the steady-state regime.
Dynamic Polymorphism of Some Binary Iron Alloys
Authors: Loree T. R. , Fowler C. M. , Zukas E. G. , Minshall F. S.
Published: April 2005

Investigations of the pressure-induced polymorphism of the Fe-V, Fe-Mo, Fe-Co, and Fe-C alloy systems have been carried out by dynamic techniques. The addition of vanadium to iron is found to raise the transition pressure very strongly, to some 575 kbar for 25 wt% vanadium content. The Fe-Co study indicates that long-range order does not have an appreciable effect on the transformation. The initial mixed phase state of the Fe-Mo system is clearly manifested in the transition behavior, generally fulfilling expectations. Variations of the transition parameters by various sample heat treatments are demonstrated in the Fe-C system investigation. The dynamic transformation parameters for pure iron have been reappraised, and are found to be Pb=129±1 kbar, v/v0=0.9360±0.0005. A summary of transition pressures for binary iron alloys is provided.
Forward Velocity of 180° Ferroelectric Domain Walls in BaTiO3
Authors: Stadler H. L.
Published: April 2005

``Forward'' velocities (parallel to the polarization direction) of 180° domain walls in BaTiO3 have been measured by direct, stroboscopic observation from less than 0.01 to more than 1000 cm/sec. The velocities vf can be expressed as vf = (5500 cm/sec) exp[(−1.8 kV/cm)/E], where E is the applied field.
Rheological Aspects of Drop Formation
Authors: Manfré G.
Published: April 2005

A generalized form of the Hagen-Poiseuille law was used to account for the presence of surface tension and this law was applied to liquid extruded in the form of drops from a capillary tube. The extruded volume and the various pressures were found experimentally as functions of time, while there was a theoretical development of two formulas. One formula described the increase of the extruded volume during the formation of a drop, and the other formula related the time of the drop formation with the height of the gravity head of the liquid in the container. The experimental and theoretical values showed good agreement.
Hall Effect and Resistivity of Zn-Doped GaAs
Authors: Ermanis F. , Wolfstirn K.
Published: April 2005

The Hall effect and resistivity of GaAs doped with zinc to a concentration range 1×1017 to 1×1019 zinc atoms/cm3, were measured as a function of temperature from 4° to 750°K. The electrical data are correlated with zinc concentration determined by radiotracer techniques to show that zinc in GaAs in this concentration range is a singly ionized acceptor. The ionization energy of zinc is shown to be concentration dependent, varying from 0 eV at 1×1019 to 0.024 eV at 1×1017 zinc atoms/cm3.
Multiple Reflection Effects in the Faraday Rotation in Thin-Film Semiconductors
Authors: Palik E. D. , Stevenson J. R. , Webster J.
Published: April 2005

The free-carrier Faraday rotation has been measured at room temperature for an n-type epitaxial PbS film at infrared wavelengths in the range 3–30 μ. The rotation as a function of wavelength shows oscillatory behavior due to multiple reflection effects. The oscillations are closely in step with those observed in the zero-field transmittance of the sample. The effects are satisfactorily accounted for by exact calculations based on equations given by Donovan and Medcalf.
Diffusion into a Rectangular Parallelepiped from a Well-Stirred Fluid
Authors: O'Keeffe M.
Published: April 2005

It is shown that the solution to the problem of the fractional uptake mIII(a1, a2, a3), at time t, by a rectangular parallelepiped of dimensions 2a1×2a2×2a3 from a well-stirred fluid is given by 1−mIII(a1, a2, a3)=[1−mI(a1)][1−mI(a2)][1−mI(a3)],where mI(ai) is the well-known solution for the fractional uptake by an infinite plane sheet of thickness 2ai, viz. 1−mI(ai)= ∑ n[2α(1+α)/(1+α+α2qn2)] exp(−Dqn2t/ai2).Here α is the ratio of number of moles in the fluid phase to the number of moles in the solid phase, D is the diffusion coefficient, λ and the qn are the nonzero roots of tan qn=−αqn.
Nonlinear Behavior of Ferromagnetic Thin Films
Authors: Berteaud André-Jean , Pascard Hubert
Published: April 2005

The authors report a study of the behavior of Permalloy thin films at high microwave signals. The cases where films are polarized either parallel or perpendicular to the film plane are successively investigated at X and V bands. With a parallel polarization, the absorption via a first-order process can be present at X band either as a subsidiary absorption or as a premature decline of the main resonance, depending on the film thickness. At V band, only a subsidiary absorption was expected; it was effectively observed in some films with a large critical field (≃45 Oe). With perpendicular polarization, new experimental observations (such as an important main resonance shifting, a large variation of the linewidth at low level, a saturation of the uniform mode via a second order process, and a foldover effect leading to relaxation oscillations) at X and V bands were made and explained. Finally, with a strong interaction between films and electromagnetic waves having thus been shown, possible applications such as power limiters are indicated.
Structure, Growth, and Properties of Twist and Tilt Grain Boundaries in Bicrystals of NaCl
Authors: Fuschillo N. , Gimpl M. L. , McMaster A. D.
Published: April 2005

Grain boundaries having from 2° to 45° mismatch across the interface were grown for pure tilt and pure twist misorientation in NaCl by the Czochralski technique. The method of crystal growth and the techniques required for good control of the misorientation and the planarity of the grain boundary are described. The substructure of twist and tilt NaCl bicrystals was examined using both optical and electron-microscopic techniques. The tilt grain boundaries were found to be strong mechanically and not easily cleaved apart. The twist grain boundaries were very weak mechanically, especially at mismatch angles greater than 20°, and exhibited anomalously rapid diffusion or capillary flow effects along the grain boundary.

Grain boundaries in the bicrystals were examined by: (1) pulling the crystals apart at the grain boundary and (2) by polishing away one side of the bicrystal to within 0.5 mm of the grain boundary. (The grain boundary surface could then be examined by focusing through the layer of NaCl.) Both of these techniques showed that the twist bicrystals were held together by small regions or spots of continuity at the grain boundary. The spot density ranged from 500/cm2 to 20 000/cm2 for 45° and 10° twist bicrystals, respectively. No substructure was observed for tilt grain boundaries. This may explain not only the extreme mechanical weakness of twist grain boundaries, but may also help to explain brittle fracture in polycrystalline ionically bonded solids generally, including ceramics and other alkali halides, and phenomena, such as the solution embrittlement of AgCl.
Instabilities in a Neutralized Electron Stream in a Finite-Length Drift Tube
Authors: Frey Jeffrey , Birdsall C. K.
Published: April 2005

Instabilities in one and two drifting-electron streams neutralized by nondrifting ions and bounded transversely and axially are presented in mathematical and physical detail. Solutions for growth rates are obtained from the dispersion relation for a cylindrical stream of cold electrons and cold ions plus the boundary conditions at the gridded ends of the drift region. The new results in addition to the critical current (or critical perveance=190×10−6) given by Pierce in 1944 are: (i) less approximate inclusion of finite drift length, (ii) ac motion of ions, (iii) detailed physical description, (iv) growth rates over a range of parameters. The results show instability for immobile ions with the critical perveance value agreeing with that given by Pierce, but show marginal stability for mobile ions, contrary to Pierce and to the experiments of Atkinson. The difference between mobile and immobile ion solutions is ascribed to the ability of ions to neutralize (or not) excess electron charge in the vicinity of the output grid. The relation to stream-ion wave amplification is discussed. The relation of the solutions presented here to those for a cylindrical stream which is not neutralized but is thin enough to have only small velocity variation radially is also discussed.
Growth of Laser-Quality Rare-Earth Fluoride Single Crystals in a Dynamic Hydrogen Fluoride Atmosphere
Authors: Robinson M. , Cripe D. M.
Published: April 2005

Very high optical quality single crystals of LaF3, CeF3, PrF3, and NdF3 have been grown. With a multiport graphite crucible, as many as six crystals have been prepared in a single experiment. The crystals were grown in a dynamic helium-hydrogen fluoride atmosphere in a modified Stockbarger-type furnace. Ion exchange purification methods have resulted in LaF3 crystals transparent to 0.14 μ.
Ohm's Law for Nonisothermal Plasma with Thermal Diffusion
Authors: Wilhelm H. E.
Published: April 2005

Generalized Ohm's law is derived for a nonisothermal partially ionized gas under consideration of the conductive thermal diffusion effect and the thermal barodiffusion effect. Explicit expressions are given for the electrical conductivity parallel and transverse to the magnetic field and the Hall coefficient.
Some Effects of Nonuniform Pumping on the Mode Structure of Solid State Lasers
Authors: Warter Peter J. , Martinelli Ramon U.
Published: April 2005

The effects of nonuniform pumping upon the structure of near-axial low-order transverse modes of a laser cavity are considered. For transverse variations of the pumping level, the mode profiles may be severely distorted. The primary cause of the distortion arises from the spatial variation of the anomalous dispersion term in the dielectric constant associated with the laser line. Modes on the high-frequency side of the line center are distorted in such a way as to increase their gain relative to modes lying on or below line center. The results show that mode profile distortions are significant for pumping level variations of a few percent.
Nucleation Rate of Vacancy Clusters in Crystals
Authors: Davis T. L. , Hirth J. P.
Published: April 2005

Homogeneous nucleation theory is applied to the process of vacancy condensation in crystals. The results show that homogeneous nucleation cannot account for the observed densities of vacancy clusters in quenched fcc crystals. Nucleation must be heterogeneous in such cases. The implications of these results with respect to the formation energies of the various clusters are discussed.
Flow of Gases through Helical Capillaries
Authors: Creutz E.
Published: April 2005

The isothermal flow rates of H2, He, and N2 through several helically coiled capillaries in the laminar, transition, and turbulent ranges are found to follow the expression y=x(2−axn1)2+x12(1−2−axn2)2, where x is the ratio of the product of the average pressure times the pressure drop in the capillary to the value of pressure times pressure drop which produces the transition from laminar to turbulent flow in a straight capillary of the same length and diameter, and y is the ratio of any observed flow rate to that flow rate which corresponds to the transition in the straight capillary. The experimental value of y corresponding to x=1, called y0, is given by 1−y0=12e−0.044(D/d)1/2, where D is the coil diameter and d is the capillary diameter. n1 and n2 are given by n1≐12+110(Dd)3/8;  n2≐12+215(Dd)3/8. The quantity a (<1) is obtained by solving y0=(2−a)2+(1−2−a)2, using the value of y0 obtained from Eq. (ii). The above equations hold for porous media also, when the following values are used: D=0,  n1=n2=12,  a=1, in which case y0=12 as determined previously.

The flow apparently may be stabilized against turbulence by centrifugal forces in tightly wound helices up to Reynolds numbers equal to at least 8000, consistent with previous observations by others with liquids.
Further Applications of Kikuchi Diffraction Patterns; Kikuchi Maps
Authors: Levine E. , Bell W. L. , Thomas G.
Published: April 2005

Composite Kikuchi electron diffraction patterns have been obtained which map out reciprocal space for silicon over the 〈001–011–111〉 stereographic triangle. These maps enable unknown diffraction patterns to be quickly solved even when they do not contain any Kikuchi poles. Unlike spot patterns, the Kikuchi patterns and maps uniquely represent the crystal symmetry. Some applications of these maps in crystallographic and electron microscopy investigations are discussed.
A Comparative Study of Exploding Wires in Air and Water
Authors: Edelson H. D. , Korneff T.
Published: April 2005

The results of a comparative study of exploding wires in air and water are presented. It is shown that under water the wire explosion presents a more orderly structure then the equivalent explosion in air. The possibility of axial temperature variations in the wire before rupture is postulated. The elimination of the plasma sheath commonly associated with the explosion in air is noted.
Diffusion of Radiotracer Sodium by the Residual Surface Counting Technique in Soda-Alumina-Silica Glasses
Authors: Garfinkel Harmon M. , Rauscher Herbert E.
Published: April 2005

Proportional counting (beta rays) with considerable self-absorption and scintillation counting (gamma rays) with negligible self-absorption effects were found to yield essentially the same results in the two electrode glasses studied. It was found experimentally that the self-absorption of the beta radiation could be represented by a Beer-Lambert type law. For a glass of composition 27Na2O·3Al2O3·70SiO2 the results are best represented by DNa=2.96×10−4 exp(−13.7±0.4 kcal/g·ionRT) cm2 sec−1over the temperature range 228°–436°C, and for 11Na2O·18Al2O3·71SiO2 by DNa=5.02×10−4 exp(−14.5±0.3 kcal/g·ionRT) cm2 sec−1over the temperature range 352°–716°C. Comparison of these results with those reported by Eisenman for the hydrated glass shows that the effect of water is to speed up the diffusion process.
Thermoelectric and Electrical Measurements in the Erbium-Tellurium System
Authors: Haase D. J. , Steinfink H.
Published: April 2005

Electrical conductivity and thermoelectric measurements of the intermediate phases in the Er-Te system over the temperature range 170°K to 850°K show that in the intrinsic region the concentration of erbium atoms in the solid solution series Er2Te3-ErTe is directly related to the number of carriers present. The erbium atoms act as impurity donors in the extrinsic region as their concentration increases from the terminal composition Er2Te3, which is p type, to ErTe which is n type.
Vacuum Thermionic Work Functions of Polycrystalline Be, Ti, Cr, Fe, Ni, Cu, Pt, and Type 304 Stainless Steel
Authors: Wilson R. G.
Published: April 2005

Experimentally measured effective vacuum thermionic electron work functions are reported for well outgassed polycrystalline surfaces of beryllium (3.67 eV), titanium (3.6 to 4.3 eV), chromium (3.90 eV), iron (4.47 eV), nickel (4.41 eV), copper (4.42 eV), platinum (5.6 to 5.8 eV), strongly (210) oriented, and 304 stainless steel (4.3 eV) in a clean, 10−9-Torr vacuum environment. Special techniques were employed to insure accurate current, area, and temperature values. Purities, heat treatment histories, outgassing conditions, and x-ray crystallography measurements of the surfaces are included.
Determination of the Particle Velocity in Detonating Gases by a Magnetohydrodynamic Principle
Authors: Bowser M. L. , Murphy J. N. , Hay J. E. , Gibson F. C.
Published: April 2005

A technique for experimentally determining the hydrodynamic particle velocity in gaseous detonations is described. The technique is based on the magnetohydrodynamic interaction of the ionized reactants and products with an externally applied magnetic field. Particle velocities in 2H2+O2 and 2H2+2O2 detonations were found to be 1.3 mm/μsec and 0.96 mm/μsec, which are in good agreement with those calculated from detonation rate and pressure.
Coupled Electron-Hole Cascade in a Free Electron Gas
Authors: Ritchie R. H.
Published: April 2005

The coupled electron-hole cascade in an electron gas is described by a space- and angle-independent transport equation. Analytic cross sections employed for the various processes are appropriate to a high density electron gas and for low to moderate excitation energies. The solution of the integral transport equation may be expressed in analytic form. It is found that the cascade process results in the accumulation of extremely large numbers of electrons and holes close to the Fermi surface.
Radiation Blistering: Interferometric and Microscopic Observations of Oxides, Silicon, and Metals
Authors: Primak William , Luthra Jagdish
Published: April 2005

Photographs and descriptions of the phenomena are given. Most of the observations were of magnesium oxide, a few were of spinel and corundum. The fringe systems arising from a blister (two films on a substrate) are described. Results are given for miscellaneous H+, D+, He+, and He++ bombardments, 0.025–4 MeV. Measurements are given of blister heights, diameters, shell thicknesses, and depths of cavities left after blister shells break away (exfoliate). Effects arising from superficial deposited films are described. Blistering was found on polycrystalline copper bombarded with H+ or He+ and on polycrystalline nickel with He+ only. Blistering was not found on several other metals bombarded similarly. For the oxides, blistering was first noted at ∼3×1017, while for the metals at ∼8×1017. The effects of gas permeability, radiation expansion, and elastic moduli on blister growth are discussed. The dispersion of refractive index of magnesium oxide is given.
Surface Layer of BaTiO3
Authors: Callaby D. R.
Published: April 2005

The activation field α of barium titanate single crystals has been measured over a range of thicknesses from 350 μ to 4 μ using liquid electrodes. From these measurements it has been deduced that barium titanate has a surface layer of layers with a total thickness of 25±5 μ. The activation field of the bulk material is 5 kV/cm and that of the surface layer is 15±5 kV/cm.
Interaction of Laser Radiation with an Absorbing Semi-Infinite Solid Bar
Authors: Penner S. S. , Sharma O. P.
Published: April 2005

Thermal stress development in partially transparent rods may be studied by using a laser source for controlled energy deposition. We have solved the relevant heat transfer problem for a one-dimensional geometry and indicated briefly some experiments for studying stress wave evolution prior to ablation and thermal equilibration.
Chemical Potentials and Initial Sintering in Pure Metals and Ionic Compounds
Authors: Readey Dennis W.
Published: April 2005

The chemical potentials of the constituents of a pure metal and of a pure ionic compound are derived from the grand partition function for the crystal including vacancy and pressure effects. The results are applied to sintering by considering it as a chemical diffusion problem. The results obtained corroborate those obtained by others who have used different approaches to the problem.
Application of the Vlasov Equation to the High-Frequency Stability of Finite Relativistic Beam-Plasma Systems
Authors: Dorman G.
Published: April 2005

The response of a finite relativistic beam-plasma system to small disturbances is analysed using the coupled Vlasov-Maxwell equations. It is shown that when |ω−kV0|2≫ωβ2, where ωβ is the betatron frequency and V0 the drift velocity of the beam, straight-line orbits are sufficiently accurate to describe the beam-particle trajectories. Dispersion relations are derived for a finite beam and for both infinite and finite plasma configurations. The effect of a finite but large beam radius is shown to increase the growth of the electrostatic instability.
Interstitial Diffusion of Copper and Silver in Lead
Authors: Dyson B. F. , Anthony T. , Turnbull D.
Published: April 2005

The diffusivities D of copper and silver in high-purity lead have been measured by a radioactive tracer technique. They are described by DCu/Pb = 7.9×10−3e−(8020/RT) cm2 sec−1, DAg/Pb = 4.6×10−2e−(14 440/RT) cm2 sec−1. These results, in combination with those of Seith and Keil and Ascoli et al., show that the rates of diffusion of the noble metals in lead are several orders of magnitude greater than the self-diffusion rate of lead DPb. We have found that DPb is not measurably affected by the dissolution of either gold, in agreement with Seith and Keil, or of copper. The results indicate that neither the vacancy, interstitialcy, nor exchange mechanisms are predominant in the diffusion of these solutes. It is concluded that the noble metals are dissolved in lead at least partially in the interstitial state and that they diffuse almost wholly by an interstitial mechanism.
Diffusion of Gold and Silver in Tin Single Crystals
Authors: Dyson Brian F.
Published: April 2005

The diffusivities D of gold and silver in high-purity tin have been measured along the ``c'' and ``a'' directions in the temperature range 135°–225°C. They are described by DAu/Snc = 5.8×10−3 exp−(11 000/RT) cm2sec−1, DAu/Sna = 1.6×10−1 exp−(17 700/RT) cm2 sec−1, DAg/Snc = 7.1×10−3 exp−(12 300/RT) cm2 sec−1, and DAg/Sna = 1.8×10−1 exp−(18 400/RT) cm2 sec−1. These results are characterized by a very large anisotropy of diffusion compared with that found for the self-diffusion of tin. Furthermore, these solutes diffuse orders of magnitude faster than the self-diffusion of tin and also they diffuse fastest along the ``c'' direction, whereas tin diffuses fastest along the ``a'' direction. This unusual behavior is interpreted as evidence that silver and gold dissolve interstitially in tin and diffuse by an interstitial mechanism.
Some Observations on Low-Temperature Field-Ion Microscopy
Authors: Feldman Uri , Gomer Robert
Published: April 2005

The operation of a He-ion microscope immersed in a liquid H2 cryostat is shown to be feasible and to lead to ultrahigh vacuum before, during, and after microscopy, thereby facilitating experiments in which surface contamination must be avoided. Measurements of ion current at various temperatures are reported and discussed. The variation of end form with field evaporation temperature for tungsten from 200°–600°K is shown to lead to local field enhancement in the (100) region at high temperature, partly because of increased local disorder.
Ionic Displacement in the Alkali Halides
Authors: Torrens Ian McC. , Chadderton Lewis T. , Morgan D. Vernon
Published: April 2005

Computer simulations of dynamic radiation damage events in the alkali halides reveal the importance of the focusing of energy in these lattices. Ionic displacement for KCl is most probable in the 〈110〉 direction, when the energy is in the region of 30 eV or greater and is least probable in the 〈100〉 direction.
Oxygen-Defect Complexes in Neutron-Irradiated Germanium
Authors: Whan R. E.
Published: April 2005

The recovery processes in neutron-irradiated oxygen-doped germanium have been studied by measuring the growth and decay of infrared absorption bands associated with oxygen-defect complexes. After a neutron irradiation at −50°C, the absorption band assigned to the stable oxygen-vacancy complex is barely detectable but increases upon annealing to 50°C. These results indicate that additional vacancies are produced by the dissociation of the large defect clusters formed by neutron irradiation. Annealing to higher temperatures produces the same bands in the same sequence as those which developed in the spectra of electron irradiated samples upon annealing. Comparisons of the annealing curves of the absorption bands produced by the two types of irradiations, however, reveal a general shift to higher annealing temperatures for the neutron-irradiated samples. These temperature shifts are interpreted as resulting from changes in equilibria of the oxygen-defect complexes caused by the dissociation of clusters into simpler defects. No similar evidence for the presence of clusters above annealing temperatures of 350°C was observed.
A Method of Utilizing Nuclear Reactions in the Study of Oxide Layers
Authors: Ollerhead R. W. , Almqvist E. , Kuehner J. A.
Published: April 2005

The reaction 17O(3He, 4He)16O has been used to investigate the diffusion of oxygen into surface layers of zirconium oxide on zirconium metal under different conditions of time and temperature. The methods used are described in detail, and examples of typical results are given. This technique is generally applicable as a means of investigating the penetration of oxygen into materials up to a depth of about five microns.
Electrical Conduction through SiO Films
Authors: Hartman T. E. , Blair J. C. , Bauer R.
Published: April 2005

The voltage—current characteristics for evaporated SiO films sandwiched between Al electrodes is suggestive of the Schottky emission mechanism for film thickness between 1000 and 10 000 Å. The temperature dependence of the voltage—current characteristics and the photoresponse as a function of photon energy were measured to investigate the mechanism of current flow. The results show that the current density through the SiO film can be described by the following empirical equation: J=αa exp(βV12−γ/kT)[1−exp(−β2V)],where α and γ are constants and a is the SiO film thickness. The most important conclusion is that even though the functional form is similar to that which is obtained for the Schottky emission mechanism, the pre-exponential factor is not the Richardson constant times T2 and γ is not a barrier height corresponding to the threshold for photoresponse. The transient behavior of these films is suggestive of trapping and the resultant voltage—current characteristic may be due to space-charge buildup in the film as described by O'Dwyer.
Solution of the Zone Refining Equation
Authors: Helfand E. , Kornegay R. L.
Published: April 2005

The differential-difference equation governing the concentration distribution Cn(x) in a finite ingot, zone-refined n times, is solved. The solution may be practically applied for the case of a small number of passes. Also the ultimate distribution (n → ∞) is determined (in agreement with Velický). Corrections which vanish as exp(−n/n1) may be estimated from results given in the figures, or calculated exactly from the equations explicitly presented, thus enabling one to ascertain the number of passes required to achieve a desired degree of purification.
Flow and Self-Diffusion of Gases in Capillaries. Part I
Authors: Lund L. M. , Berman A. S.
Published: April 2005

A model is presented for describing transport under a partial pressure gradient (self-diffusion) as well as transport under a total pressure gradient in capillaries of arbitrary length-to-radius ratio over a pressure range extending from the free molecule to the continuum regimes.

The model provides a unified description of the transport and yields the same results as existing theories in the limited ranges appropriate for their application.
Thermal Properties of Thin-Film Polymers by Transient Heating
Authors: Steere Robin C.
Published: April 2005

The high-temperature thermal properties of building material in thick slab form can be measured by a transient method reported earlier by Harmathy. The results here show the technique suitable for thin-film polymers. Recently available ultrathin (0.00025 cm) constantan foil is shown capable of providing constant thermal flux. This foil reduces the original measurement time by two orders of magnitude, from 400 to 4 sec. Sample volume can be reduced at least 90%. Thermal diffusivity, thermal conductivity, and specific heat are measured on an absolute basis, with errors of 2%, 2.5%, and 3%, respectively. Results are given for polyethylene terephthalate, low-density polyethylene, and cork composition, all in the range −50° to 30°C. These results support the accuracy and validity of the technique. The experimental sample can be built up from polymer films as thin as 0.0025 cm. Previously the sample consisted of slabs of approximate thicknesses 1 and 3 cm.
Spin-Wave Resonance of Permalloy Thin Films as Measured in Ultrahigh Vacuum and in Air
Authors: Lykken G. I. , Harman W. L. , Mitchell E. N.
Published: April 2005

Permalloy thin films in the thickness range from 100 to 2530 Å and of melt composition 82% Ni-18% Fe were deposited in an ultrahigh-vacuum system and the standing spin-wave modes (SSWM) of these films were measured in vacuum and in air. The SSWM shifted to higher magnetic fields as the films aged in vacuum, but shifted to lower magnetic fields as they aged in air. Since the SSWM of the films displayed a quadratic dependence on mode number at all times, the observed spectra shifts could be accounted for by changes in g, 4πM, and A/M with no observed changes in pinning. Annealing greatly altered the absorption spectra, indicating that a significant change in the pinning occurred.

It is concluded that spin pinning exists in a modest vacuum (p≃1×10−7 Torr) even before the films have been exposed to the atmosphere and that spin pinning is dependent on the substrate used in that spin pinning is greatly affected by annealing.
Antiphase Domains in Ordered Au3Cu Alloys. II. Comments on ``Electron Diffraction Study of Order in the CuAu3 Alloys'' by Watanabe and Fisher
Authors: Sato H. , Toth R. S.
Published: April 2005

The distinction between the long-period superlattice and the ordinary antiphase domain structure in ordered alloys, which has often been misunderstood, is critically discussed with respect to the alloy Au3Cu. In particular, remarks are directed to the recently published paper by Watanabe and Fisher. Au3Cu is ordered, but the size of antiphase domains remains small even after prolonged annealing. Irrespective of apparent similarities, it is shown that Au3 Cu is not a long-period superlattice. Some discussions concerning peculiar properties of Au3Cu are given.
Oxygen-Defect Complexes in Neutron-Irradiated Silicon
Authors: Whan R. E.
Published: April 2005

The growth and decay of infrared absorption bands in the spectra of oxygen-doped silicon irradiated with fast neutrons or 2-MeV electrons at −50°C have been studied. These bands at 836, 922, 932, and 936 cm−1, are associated with defect impurity complexes, and previously have been observed after electron irradiation at temperatures as low as 80°K. The gradual growth of the 836-cm−1 band, associated with an oxygen-vacancy complex, from the low-intensity measured immediately after neutron irradiation to approximately four times that intensity upon annealing to 275°C is in contrast with the gradual decay of the band observed after electron irradiation over the same temperature range. The growth of the band is attributed to an increase in the concentration of the O-V complex as additional vacancies are evolved from defect clusters produced by neutron irradiation. Shifts in the annealing curves of a band at 865 cm−1, which appears upon annealing above 0°C, and the band at 936 cm−1 suggest that the corresponding complexes also involve vacancies. The constant intensity ratio and identical annealing behavior for the 922 and 932 cm−1 bands indicate that they belong to different vibrational modes of the same complex. No shift in the annealing curves for these bands was observed for the neutron irradiated sample, suggesting that the corresponding complex does not involve vacancies but rather may involve interstitial Si atoms.
Comparison of Neutron and Gamma-Ray Damage in n-Type Silicon
Authors: Stein H. J.
Published: April 2005

Fission-spectrum neutron damage of n-type, float-zone silicon is compared with 60Co gamma-ray damage. The damage was measured at 293°K by the degradation of the minority-carrier lifetime. The room-temperature damage coefficients, defined as K = (1/Φ) [(1/τai)−(1/τ0)], are 5.8×10−6 (neutrons/cm2)−1 sec−1 for neutron irradiation and 2.8×10−10 (photons/cm2)−1 sec−1 for gamma-ray irradiation where τ0 and τai are the initial and after-irradiation carrier lifetimes, and Φ is the integrated flux. The neutron damage coefficient is found to be independent of the irradiation temperature (76°–300°K) in contrast to a marked decrease with decreased irradiation temperature which has been observed in the gamma-ray damage coefficient. Neutron damage recovery is observed over a broad temperature range from 60°–220°C, while gamma-ray damage recovers sharply between 150° and 210°C. These results indicate that the energy transferred to the silicon recoils by the irradiating particle influences the number and kind of primary defects produced at 76°K and also affects defect reordering at higher temperatures.
Charge Distribution in Thermally Grown Silicon Dioxide
Authors: Lindmayer J. , Reynolds J. H.
Published: April 2005

The charge distribution in thermally grown silicon dioxide is determined by measuring the change in the charge density in the silicon inversion layer as the oxide is gradually etched off. It is found that after prolonged annealing at relatively low temperatures the Si-SiO2 system reaches a stable state. In this stable state the average charge depth in the oxide is a constant fraction of the initial oxide thickness. This behavior is independent of growth conditions. It is also shown that exposure to high temperatures in a neutral ambient greatly reduces the inversion layer. It is suggested that the inversion layer is controlled by two types of states in the oxide. One is a permanent electron ``donor'' state, determined by the basic oxide structure. The other is a trapping state which can be created by a short high-temperature exposure.
Comparison of Measured and Predicted Bulk Moduli of Tantalum and Tungsten at High Temperatures
Authors: Soga Naohiro
Published: April 2005

The elastic constants of tantalum have been determined from room temperature to 500°C by means of a dynamic resonance method to obtain the adiabatic bulk modulus at elevated temperature. The adiabatic bulk modulus (Bs) of tantalum is found to be 1897 kbar at room temperature and it decreases almost linearly with a slope (dBs/dT) of −0.11 kbar/°C as temperature rises. The calculation of the Grüneisen constant γ and a parameter δ, defined as − (dBs/dT)/αBs, from the present data shows that both parameters are almost independent of the temperature (1.57 for γ and 3.1 for δ). The constancy of γ and δ at high temperatures has also been tested for tungsten by using the recent data of Lowrie and Gonas [J. Appl. Phys. 36, 2189 (1965)]. The results indicate that both γ and δ are virtually constant at high temperature. The applicability of the following equation to estimate the bulk-modulus-temperature relationship for the refractory metals Ta and W has also been tested: BsT=Bs25−(δγ/V)(HT−H25),

where H is the enthalpy and the superscripts indicate values at 25° and T°C.
Elastic Constants of Selenium in the Hexagonal and Glassy Phases
Authors: Vedam K. , Miller D. L. , Roy R.
Published: April 2005

The elastic constants c33 and c44 of hexagonal selenium have been determined and are compared with the elastic constants of glassy selenium. It is shown that the bonding forces in glassy selenium are mainly of van der Waals type. The temperature variation of these elastic constants in the region of glass transition temperature has also been studied.