bluuebunny/crossref_metadata_2025 huggingface dataset:
Dislocation Etch Pits and Polygonization in High-Purity Copper
Authors: Lovell L. C. , Wernick J. H.
Published: April 2005

A chemical etch has been developed to reveal dislocations on the (111) plane of high-purity copper without prior decorating. By the use of this etch, we have observed that dislocation climb and polygonization did not occur after annealing bent single crystals near the melting point, in agreement with the x-ray results of other investigators.
Thermoluminescence and the Influence of γ-Ray Induced Defects In Single-Crystal α-Al2O3
Authors: Gabrysh A. F. , Eyring H. , LeFebre V. , Evans M. D.
Published: April 2005

In previous work the thermoluminescence of golden sapphire (Al2O3 containing Ni and Mg), which was γ irradiated under liquid nitrogen, was compared with glow curves of fused borax seeded with Ni and Mg. The emission intensity obeyed, reasonably well, the expression I=αN0k′ exp[−1/(dT/dt) ∫ t0tk′dT]. In the present paper it is shown that light-induced glow curves in γ-irradiated sapphire have the form of a second-order decay process, namely I = I0[b / (b+t)]m. Gamma-ray induced thermoluminescence in ruby shows dominant emission bands with maxima at about 150°K and 240°K. Light-induced thermoluminescence in γ-ray damaged ruby shows an afterglow long after the crystal has reached room temperature.
Dislocations and Chemical Etch Pits in Copper
Authors: Ruff A. W.
Published: April 2005

The relation between chemical etch pits and dislocations has been studied in thin single-crystal foils of copper. Both deformed and as-grown crystals in {111} orientations were employed. A procedure was developed for etching thin foils so that both the etch pits and dislocations were simultaneously revealed by transmission electron microscopy methods. Results are also presented from companion studies of unetched foils and replica studies of etched surfaces. Although a relation was found between etch pits and dislocation emergent points, a one-to-one correspondence did not exist. A discussion is presented of other defects which may nucleate etch pits, including some experimental results on deformation-produced prismatic dislocation loops. The relation of the present results to dislocation studies by etching methods alone is discussed.
Chemical Etching of Charged-Particle Tracks in Solids
Authors: Price P. B. , Walker R. M.
Published: April 2005

When a heavy charged particle such as a fission fragment traverses certain materials it leaves a trail of radiation damage which shows up as a track when a sample is viewed by transmission electron microscopy. If a sample of a silicate mineral containing such tracks is immersed in a suitable reagent such as hydrofluoric acid it has been found that the tracks are very selectively attacked. Fine hollow channels are formed along the particle paths while the rest of the material is untouched. A study of this effect in various silicate minerals is reported as a function of etching reagent, etching temperature, and etching time. The minimum width of the etched channels is considerably less than the apparent widths of the tracks prior to etching. It is concluded that the track images result in large part from elastic strains surrounding a damaged core. The etching effect also serves to ``develop'' and ``fix'' particle tracks and hence increases the usefulness of silicate minerals as particle detectors.
X-Ray Diffraction Study of the Effects of Solutes on the Occurrence of Stacking Faults in Silver-Base Alloys
Authors: Adler R. P. I. , Wagner C. N. J.
Published: April 2005

The addition of the solutes cadmium, indium, and tin to silver increases the probability of deformation faults α in filings from 3×10−3 in pure silver to a maximum value of 45×10−3 at the highest concentrations of solute. In addition, the twin fault probability β measured from center of gravity displacements varies from 10×10−3 for pure silver to 30×10−3 for the alloys highest in tin or indium concentration. Lattice parameters ahkl were determined from all available reflections of the cold-worked and annealed specimens and plotted as a function of cos2θ/sinθ. By relating the large scatter of the individual ahkl to the occurrence of deformation faults in the deformed material, the true lattice parameter, a0(CW), and the deformation fault probabilities α of cold-worked materials could be determined. There was an apparent decrease in lattice parameter of the deformed Ag-Sn alloys which was largest (∼0.1%) for the greatest tin concentration (Ag-9%Sn). Using Fourier analysis of line profiles, the effective particle sizes (De)hkl and root mean square strains [〈εL2〉av]hkl½ were determined. The measured effective particle sizes were anisotropic [(De)111/(De)200=1.7] and are primarily a consequence of deformation and twin faulting. The values for the compound fault probability (1.5α+β) from peak shift and asymmetry and from anisotropic particle sizes, i.e., from peak broadening, agreed rather well.
Thickness Dependence of BaTiO3 Switching Time
Authors: Stadler H. L.
Published: April 2005

The ferroelectric switching time of barium titanate single crystals has been measured at room temperature as a function of electric field and crystal thickness. The switching time was found to be independent of crystal thickness at high fields in disagreement with earlier work by Merz, who found the switching time proportional to thickness at the same high fields. At low fields the results are in substantial agreement with Merz and other previous work. At fields E greater than a threshold field of 1.4 (1+0.007 cm/d) kV/cm, where d is the crystal thickness, the switching time ts is given by 9E−1.4±0.1 (kV/cm)1.4 sec. Below this threshold the switching time is adequately represented by ts=0.8 exp[3.5(1+0.007 cm/d) kV/cm/E] μsec for d≳0.007 cm, but for d«.007 cm, the data are fitted better by ts=1.5×103 (Ed)−10.3±0.5 sec (V)10.3. Thus the data do not agree with the predictions of any known surface layer model of BaTiO3 switching.
Rapid Solution Hardening, Dislocation Mobility, and the Flow Stress of Crystals
Authors: Fleischer Robert L.
Published: April 2005

A theory is derived for impurity-controlled dislocation mobility and the resultant temperature variation of the flow stress of lithium fluoride. The theory is suitable to crystals in which the hardening is primarily due to tetragonal lattice distortions such as result from the introduction of magnesium into lithium fluoride, these being defects whose interactions with dislocations have been calculated previously. Dislocation motion is envisioned as a series of thermally activated dislocation jumps through the stress fields produced by individual solute atoms. The theory predicts the observed temperature variation of the flow stress within 25%, approximate values of the slopes of the velocity-stress relations, and the activation energy for dislocation motion.
Reactor Damage in Pure Metals
Authors: Coltman R. R. , Klabunde C. E. , McDonald D. L. , Redman J. K.
Published: April 2005

By relocating the fuel in the vicinity of a liquid helium cryostat located in the Oak Ridge Graphite Reactor it has been possible to separate the thermal and fast components of the reactor neutron flux. Studies of the radiation damage effects arising from each type of flux have been made. It has been found that an appreciable fraction of the reactor damage in several metals arises from thermal neutrons. The effect results from the recoil of an atom from the (n,γ) reaction at the time of thermal neutron capture. The low temperature recovery of thermal neutron damage is greater and shows more annealing peak structure than the recovery of fast neutron damage. Thermal neutron damage concentration studies have been made on cadmium, and pronounced suppression of the annealing is found as the concentration is increased. The mean primary recoil energy from a thermal neutron capture event has been calculated for several elements. Values range from about 50 eV for the heavier elements to several hundred eV for the lighter elements. The relative effects of atomic recoils from decay events and decay beta-atom collisions are estimated and found to be small compared to (n,γ) recoil effects. Damage from fission neutrons has been studied in copper, and it was found that the recovery of this damage is suppressed compared to that obtained from reactor fast neutrons.
Relaxation Oscillation near the Threshold of Instability in Yttrium Iron Garnet
Authors: Wang S. , Bodway G. E.
Published: April 2005

Coherent low-frequency relaxation oscillation in the amplitude of the z component of magnetization and the imaginary part of susceptibility has been observed in YIG at a microwave power level slightly above the threshold of instability. The relaxation time associated with the uniform mode has also been measured. The condition for coherent relaxation oscillation depends critically on the magnitude of the dc magnetic field. The low-frequency oscillation is interpreted to be the beat of two high-frequency components due to a split in the frequency of the k spin wave ωk±Δωk. It is also believed that the period of oscillation is controlled by the relaxation time associated with the uniform mode.
X-Ray Fluorescent Yields from Several Light Elements
Authors: Davidson F. D. , Wyckoff Ralph W. G.
Published: April 2005

Relative emissions and relative fluorescent efficiencies of excitation of K x rays have been measured for various elements in the range between iron and oxygen. Agreement with theory is generally satisfactory.
Grain-Boundary Diffusion of Gold in Copper
Authors: Austin A. E. , Richard N. A.
Published: April 2005

The diffusion of gold into the grain boundaries of copper bicrystals was studied for couples of both a continuous and an instantaneous source. The concentration contours along the grain boundaries were measured by means of electron-probe microanalysis. For the continuous source conditions at 750°C, the ratio of the coefficients of grain-boundary diffusion and lattice diffusion decreased from 6×105 to about 103 with increasing gold concentration from 0.5 to 15 at. % gold. The rate of grain-boundary diffusion decreases even though there is some increase in the rate of lattice diffusion. There was found some contribution of surface diffusion to the couples with an instantaneous or thin source, i.e., 0.5 μ thick. The concentration contours observed in these couples agreed generally with the theoretical solutions.
Theoretical Solutions of Grain-Boundary Diffusion Problem. Approximations and Interpretation of Experiments
Authors: Wood Van E. , Austin Alfred E. , Milford Frederick J.
Published: April 2005

Whipple's exact solution to the idealized grain-boundary diffusion problem has been evaluated numerically for ranges of parameters appropriate to existing and contemplated experiments. From these evaluations the concentration at the grain boundary, the integrated concentration at fixed depth of penetration, and the angle at which isoconcentration contours intersect the grain boundary are obtained, these results being presented in either tabular or graphical form. The ranges of validity of approximate solutions obtained by various authors are discussed on the basis of the numerical results, as is the use of the graphs and tables for the interpretation of experimental data.
Electron Emission from Thin Al-Al2O3-Au Structures
Authors: Kanter H. , Feibelman W. A.
Published: April 2005

Emitter cells with Al2O3 film thicknesses between 67 and 150 Å and Au film thicknesses between 200 and 300 Å were operated at voltages up to 10 V. Typical I-V characteristics for the total cell currents are presented. The curves suggest tunnel emission through the barrier at the Al-Al2O3 interface when the cell is operated for the first time and only small currents have been drawn. After passage of large currents, the I-V characteristics become temperature dependent. The normal energy distribution of the emitted electrons is measured and a linear dependence of the average energy on cell voltages is established. The fractions of current emitted through the Au into the vacuum is determined as a function of the Al2O3 thickness. Using the attenuation lengths of gold reported recently by Mead, an attenuation length of about 24 Å is deduced for electrons, which within the insulator have gained an energy of nearly 3 eV. The emitted current could be increased considerably by depositing a low work function material (Ba) at the gold surface. The maximum fraction of current emitted into the vacuum was 10−2, at an emitted current density of nearly 5 mA/cm2.
Longitudinal Susceptibility of Ferromagnets in Strong rf Fields
Authors: Schlömann Ernst
Published: April 2005

The mechanism of spin-wave instability in an rf magnetic field applied parallel to the dc field is explained by simple, physical arguments. These spin waves give rise to rf and dc magnetic moments parallel to the dc field. The major part of the rf magnetic moment lags a quarter-period behind the rf magnetic field so that the susceptibility is almost purely imaginary. The real part of the susceptibility vanishes unless the frequency of the unstable spin waves differs from half the pump frequency. The dc magnetic moment induced by the rf field is always larger than the amplitude of the rf magnetic moment. The theoretically expected variation of the susceptibility with the rf magnetic field is discussed and compared with experimental data.
Susceptibility of Ferromagnets in a Strong rf Magnetic Field Applied Parallel to the dc Field
Authors: Green J. J. , Schlömann E.
Published: April 2005

The high-power susceptibility has been measured as a function of the dc field at three frequencies on yttrium iron garnet with and without substitutions of holmium and gallium. The structure of the observed curves is attributed to relaxation processes in which two parametrically excited magnons coalesce into a third magnon under conservation of energy and momentum.
Temperature Dependence of Shock-Induced Phase Transformations in Iron
Authors: Johnson P. C. , Stein B. A. , Davis R. S.
Published: April 2005

Shock-induced phase transformations in iron have been investigated in the temperature range 78° to 1158°K. The pressure for transformation over this temperature range has been determined by a technique that depends on microstructural changes associated with a phase transformation. A discontinuity in the temperature-pressure relationship was observed at 115 kbars and 775°K. Two distinct transformation microstructures were observed. It is postulated that the results obtained above 775°K are due to the expected transformation from alpha iron to gamma iron whereas the results below 775°K are related to a transformation from alpha iron to a presently undetermined new phase.
Field Dependence of Photoelectric Emission from Molybdenum
Authors: Jaklevic R. C. , Juenker D. W.
Published: April 2005

Photoelectric emission from a 5-mil single-crystal molybdenum wire was measured at 1000°K with accelerating fields from 0.8 to 142 kv/cm and monochromatic light in the range 238 to 297 mμ. Above 3.6 kv/cm, the data are in good agreement with Fowler-Schottky theory. Apparent threshold energies increase from 4.44 to 4.52 ev with increasing illumination energy, as is expected from emitters of nonuniform work function. Two illumination directions, separated azimuthally by 90°, give identical results. Fowler plots yield identical thresholds of 4.41 ev at room temperature and 1000°K and a Richardson-plot determination of the thermionic emission constants yields eφ**=4.33 ev and A**=38 amp/cm2-deg2. The multiplicity of apparent work functions measured on a single specimen, as well as the marked dissimilarity in the emission constants of molybdenum in sheet and wire form, are explained in terms of patch effect. The theory for the periodic deviation from the photoelectric Schottky effect is extended to describe emitters at elevated temperatures. No evidence for the predicted deviation appears in the experimental photoelectric Schottky data.
Thermodynamics for Nonequilibrium Systems. The Principle of Macroscopic Separability and the Thermokinetic Potential
Authors: Li James C. M.
Published: April 2005

The consequence of the principle of microscopic reversibility used for deriving the reciprocal relations in the linear phenomenological coefficients is derived from the classical hypothesis of the separability of individual processes. The application of the separability principle to nonlinear systems is illustrated with an example, and its ability to suggest microscopic mechanisms is demonstrated. The nature of independence among the processes is discussed in more detail than has been done before, and the number of unknowns, conditions, and the minimum number of experimental coefficients are calculated in the process of finding the independent fluxes and forces. The inapplicability of the principle of minimum entropy production to nonlinear systems is confirmed, and a new dissipation function is found which is a minimum with respect to variations in all the unprescribed forces in a steady state. Such a function is found to be the integral of part of the change of the rate of entropy production with respect to the forces as discussed by Prigogine. The integrability of such a change is due to the classical principle of separability. Since this function can only decrease with time in all natural processes, it is given the name of thermokinetic potential. A possible separation between phonon drag and the energy of transport, and also that between the charge of transfer and the electron wind effect, by measuring higher-order phenomenological coefficients is also discussed.
Diffusion of Au and Cu in a Temperature Gradient
Authors: Meechan C. J. , Lehman Guy W.
Published: April 2005

Measurements have been made of relative marker movements in Au and Cu in the presence of temperature gradients of the order of 1200°K/cm. These experiments yielded results which indicate that a net vacancy current is established in these metals under appropriate experimental conditions. The magnitude and direction of the observed effects are consistent with kinetic theory predictions in conjunction with previously determined vacancy energies. A three-dimensional extension of existing kinetic theory is developed and important factors which do not appear in one-dimensional treatments are discussed. Porosity development in Cu was found under certain conditions and this may be a visual demonstration of the existence of a thermal diffusion effect in Cu.
Ultimate Yield Strength of Copper
Authors: McQueen R. G. , Marsh S. P.
Published: April 2005

Copper specimens were subjected to large dynamic tensions by colliding relatively thin plates with thick plates holding the samples. The collision first produces strong shock waves, from 300 to 600 kbar, that propagate in both directions from the impact interface. Subsequent interaction of the two rarefaction waves resulting from these shock waves produces tensions that cause the material to disintegrate rather than to break in the ordinary manner. Comparison of these recovery experiments with corresponding hydrodynamic calculations show that the yield strength of copper is in excess of 150 kbar. The equation of state of copper used in the calculations is discussed.
Crystallographic Polarity in the II-VI Compounds
Authors: Warekois E. P. , Lavine M. C. , Mariano A. N. , Gatos H. C.
Published: April 2005

Crystallographic polarity associated with the zinc-blende and the wurtzite structures has been studied in the following II-VI sulfides, selenides and tellurides; ZnS, ZnTe, CdS, CdSe, CdTe, HgSe, and HgTe. The CdS and CdSe have the wurtzite structure and the others the zinc-blende structure. Consistent with theoretical calculations, the geometric structure factor for x-ray scattering was found different in opposite directions along the polar axis. Consequently, the two types of surfaces perpendicular to the polar axis were identified. The etching behavior of these surfaces was correlated with the x-ray results so that simple etching tests were developed for the identification of the {111} (zinc blende) or the {00.1} (wurtzite) surfaces.
X-Ray Diffraction Analysis of Crystallite Size and Lattice Strain in Tungsten Wire
Authors: Opinsky A. J. , Orehotsky J. L. , Hoffman C. W. W.
Published: April 2005

The crystal perfection of a series of silica-alumina doped wires ranging from 38 mils to 2 mils in diameter has been studied by x-ray techniques. Undoped wire 10 mils in diameter has also been studied. A minimum crystallite size of approximately 300 A results from cold work. Strain values obtained by the Warren-Averbach analysis have been converted to dislocation densities. Suggestions are made for improvement of the technique.
Theory of Extended Dislocations in Symmetry Directions in Anisotropic Infinite Crystals and Thin Plates
Authors: Spence G. B.
Published: April 2005

Formulas are given for the stress components of dislocations along the c axis and in the basal plane of hexagonal crystals, along cube edges and face diagonals of cubic crystals, and for a few other cases. From these, formulas are derived for hexagonal crystals which relate stacking fault energy to the width and orientation with respect to the Burgers vector of extended dislocations and triple partial ribbons. For materials of very low stacking fault energy the distance between partial dislocations is comparable to the thickness of the films used in thin film transmission electron microscopy. The effect of stress-free surfaces on the dislocation widths is calculated for arbitrarily oriented extended dislocations lying parallel to the single plane surface of a semi-infinite isotropic solid and for 30° extended dislocations and symmetrical, screw triple partial ribbons lying parallel to the plane surfaces of an anisotropic plate. Procedures are given for correcting the widths obtained from electron microscopy. For graphite these corrections are important for extended dislocations in very thin films and for all triple partial ribbons.
Charge Transfer Scattering in High-Velocity Neutral Particle Production
Authors: Johnson Byron L.
Published: April 2005

The scattering of a beam of particles undergoing charge transfer collisions in a gas target has been examined with emphasis on the factors relevant to the design of a source of focused high-velocity (20–40 kev) neutral particles. Incident particles of helium, neon, and argon were used with targets of hydrogen, helium, neon, and argon gas over an energy range of 20 to 40 kev. An equation giving the number of neutral particles as a function of angular spread has been developed and constants determined for its energy and gas target thickness dependence. Maximum percentages of neutrals available from a 20–40 kev helium ion beam incident on a helium gas target varies from 25% in a cone angle of 10−4 radians to 70% in a cone angle of 10−3 radians.
Interdiffusion of Gases in a Low Permeability Graphite at Uniform Pressure
Authors: Evans R. B. , Watson G. M. , Truitt J.
Published: April 2005

An experimental investigation of the interdiffusion behavior of gases in a low permeability graphite was performed by sweeping the opposite faces of a graphite septum with helium and argon at uniform pressure and measuring the diffusive flux of both gases. The objectives were to ascertain the diffusion mechanism, to verify the applicable equations and associated theories, and to determine the parameters required to use these equations. At all experimental pressures, contributions of both normal and Knudsen diffusion effects were detectable via the pressure dependence of the diffusion fluxes. It was found that a previously proposed dusty-gas model formed an excellent basis for correlating the results. The dusty-gas model yields flux equations which predict the diffusion behavior over a wide range of pressures for particular gas concentrations at the boundaries. Only two experimentally determined parameters (characteristic of the gases and graphite) are required. These are: an effective normal-diffusion coefficient obtained through interdiffusion experiments and a Knudsen coefficient obtained through single-gas (permeability) experiments. The procedures used to evaluate these parameters in terms of the experimental data are described in detail.
Effect of Some Rare-Earth Elements on the hcp-bcc Transformation of Zirconium
Authors: Ianniello L. , Burr A.
Published: April 2005

Thermal dilation measurements through the temperature of transformation of some zirconium—rareearth alloys were utilized to compare the effect of the elements Nd, Y, Dy, Ho, and Er on the hcp-bcc transformation temperature of Zr. Binary alloys were vacuum arc melted and concentrations of the individual rare earths were varied up to slightly beyond their solubility limits. All the elements investigated raised the transformation temperature similarly per atomic percent. Electrical resistivity measurements at room temperature and below also showed the same trend of equal change in property, irregardless of the alloying element at least up to the solubility limit.
Friction and Wear of Single-Crystal Sapphire Sliding on Steel
Authors: Duwell E. J.
Published: April 2005

The friction and wear of spherical single crystals of sapphire (α-Al2O3) sliding on a wet steel surface were observed. As a result of changing only the crystal orientation of the single-crystal sphere, the rate of wear varied by more than three orders of magnitude, and the coefficient of friction varied by a factor of three. The rate of wear of the sapphire was greatest when the crystal structure offered least resistance to shear parallel to the sliding surface and in the direction of slide. It is concluded that wear of sapphire sliding on steel proceeds by shear through the sapphire, although interface adhesion may involve the formation of chemical bonds.
Swirls Produced in a ``Crowbarred'' Rotating Plasma
Authors: Wilcox John M. , Cooper William S. , DeSilva Alan W. , Spillman George R. , Boley Forrest I.
Published: April 2005

Hydromagnetic swirls develop in a rotating, gaseous plasma subjected to an electromagnetic braking action. Observations of these swirls and the effect of a conducting grid upon them are discussed.
Electrical and Thermal Properties of Materials in the System As2Te3-Tl2Te-As2Se3
Authors: Uphoff H. L. , Healy J. H.
Published: April 2005

Seven compositions were prepared in the system As2Te3-Tl2Te-As2Se3. Some of the samples were amorphous while others were diphasal including both amorphous and crystalline phases. The electrical and thermal properties of the samples were structure dependent. At room temperature the resistivity values ranged from 4.7×10−3 to 1.8×105 Ω-cm, Seebeck coefficient values were 40 to 1210 μV/°K and thermal conductivity values were 18.1 to 2.2 mW/cm-deg.
Diffusion Theory of the Electrodeless Ring Discharge
Authors: Eckert Hans U.
Published: April 2005

The Schottky theory of the positive column is applied to the inductive type of a high frequency discharge for cases where the electron collision frequency νc is large compared to the field frequency ω. Simultaneous solutions of the equations for the induced field and for the electron balance are obtained under the following assumptions: (1) Mobilities of electrons and ions in the discharge volume are constant; (2) the distributions of ionization rate and diffusion coefficient across the discharge tube are determined by the absolute value of the induced electric field at the inner tube radius |ER| and by its gradient at the same position; (3) the distribution of E can be obtained on the basis of an equivalent uniform conductivity σ̄ which yields the same impedance for the discharge as the actual σ distribution. The characteristic equation relating |ER| to tube radius R contains (compared to the positive column) an extra term which takes into account the nonuniformity of |E|. This term is expressed as a function of the parameter ρR≡2R/δ, where δ is the skin depth. Solving for R with assumed values of |ER| and ρR thus yields δ and by the known value of ω also σ̄. From the impedance relationship one then determines the value of the magnetic field HR that must be applied to produce particular values of σ̄ and |ER| with given ω and R. The distribution of electron density n is obtained in relation to the undetermined value at the tube axis n0. On the basis of constant electron mobility a relationship between σ̄ and n0 is obtained from the impedance equivalence which allows one to calculate absolute distributions of σ and n. These distributions are compatible with the |E| distribution for cases where ρR≤1.4. The method is illustrated by examples for hydrogen, where empirical data for νc, electron energy, ionization, and diffusion rates are used. The results are generalized in the way common for glow discharges by introduction of gas pressure p as similarity parameter. They indicate that the maximum obtainable electron density depends primarily upon the product ωHR, only moderately upon p and not upon R.
Observation of Slip In Nylon 66 and 610 and Its Interpretation in Terms of a New Model
Authors: Zaukelies D. A.
Published: April 2005

Crystalline slip has been observed in singly and doubly oriented nylon 66 and 610 by deformation of bristles in compression parallel to their orientation direction to form kink bands. The angles of the bands correspond to two and three (010) planes acting in unison as lamella in the kinking process. Slip was also manifested along a unique crystallographic plane (010) and a unique crystallographic direction ([1,3,14] and [1,3,18] in nylon 66 and 610) during fracture experiments on doubly oriented bristles. To account for this behavior a model of the structure of these oriented polymers is proposed in which the material is considered essentially completely crystalline with many vacancies and dislocations within the lattice. The dislocations and their motions which account for the observed deformations are illustrated. The difference between observed values of density and the theoretical density of nylon 66 is attributed to vacancies. The so-called amorphous background in x-ray diffraction patterns of these nylons is attributed to the vacancies and dislocations in the crystal structure.
Theory of Alkali Halide Solid Solutions
Authors: Dick B. G. , Das T. P.
Published: April 2005

Dilute solid solutions of the system NaCl-NaBr are considered. The displacements of the nearest, next-nearest, and third-nearest neighbors are dealt with microscopically and the rest of the medium is regarded as a continuous elastic medium. Heats of solution and changes in lattice constants are calculated and compared with experiment. Because of the distortion of the crystal around the impurity, appreciable field-gradients appear at the nuclei in the neighborhood of the impurity. These field gradients are calculated and compared with some available experimental results obtained from nuclear magnetic resonance studies of these solid solutions.
A Sum Rule Concerning the Inhomogeneous Demagnetizing Field in Nonellipsoidal Samples
Authors: Schlömann Ernst
Published: April 2005

It is shown that the inhomogeneous demagnetizing field occurring in uniformly magnetized, nonellipsoidal samples can be described by a generalized demagnetizing factor. The demagnetizing factor is a tensor and, in general, is different in different parts of the sample. The diagonal sum of this tensor field is unity at all points inside the sample and zero at all points outside the sample.
Electrical Properties of Single Crystals of Indium Oxide
Authors: Weiher R. L.
Published: April 2005

An investigation of electrical properties of indium oxide single crystals has been made. Indium oxide has been found to be a n-type excess semiconductor over a wide temperature range. The electrical conductivity at room temperature is of the order of 10 Ω cm−1 and the mobility is approximately 160 cm2 V-sec−1. The temperature dependence of the mobility has been quantitatively interpreted in terms of lattice and ionized impurity scattering. The donor ionization energy has been found to decrease with increasing impurity concentrations. High ``apparent intrinsic'' conductivity with an activation energy of 1.55 eV has been observed at elevated temperatures.
Velocity of Propagation and Nature of Luminosity Fluctuations in a Plasma Jet
Authors: Freeman Mark P. , Li Sik U. , Von Jaskowsky W.
Published: April 2005

The velocity of propagation of the luminous detail in a plasma jet was determined by the time required for transit between photomultiplier stations at different axial positions of an expanded plasma jet. The measurements were synchronized with power supply ripple to eliminate this as a random perturbation.

It is found that the luminous fluctuations travel at two velocities. The slower fluctuations move with nearly the calculated speed of the jet and may therefore be ascribed to temperature or possibly composition fluctuations while the (much) faster fluctuations travel with jet speed plus local sonic velocity and are evidently pressure waves.
Thermal Oxidation of Silicon
Authors: Yeh T. H.
Published: April 2005

The results of a laboratory investigation of silicon—silicon dioxide film produced by high-temperature thermal oxidation of silicon in water vapor shows that (1) the oxidation rate in steam is dependent on the doping impurity concentration of the crystal, and (2) the oxidation in steam at 970°C for various lengths of time of phosphorus-diffused wafers with surface concentration of 2×1021 cm−3 results in an impurity pile-up region near the silicon surface. On the other hand, boron-diffused wafers with surface concentration in the order of 5×1018 cm−3 deplete their impurity concentration near the silicon surface.
Effect of Initial Straining and γ Irradiation on Strength of Polyethylene
Authors: Hsiao C. C. , Yang J. W.
Published: April 2005

Uniaxially and biaxially oriented samples of polyethylene irradiated by γ rays have been investigated at room temperature. Both the tensile strength and the modulus of elasticity are found to increase as the degree of orientation induced by homogeneous deformation increases. But the tensile strength decreases as the dose of γ irradiation increases while the modulus of elasticity increases. The combined effects seem to indicate that the γ irradiation essentially destroys the macromolecular orientation and thus reduces the tensile strength to that of unoriented solid, but with relatively higher elastic modulus as a result of the occurrence of crosslinking.
Thermal Bleaching of Additively Colored KCl
Authors: Penley James C. , Witte Robert S.
Published: April 2005

The rate of thermal formation of colloids in additively colored KCl has been studied in an attempt to understand the mechanism of precipitation of the excess potassium. It is found that the process is best described as a dislocation induced precipitation, the end product being an equilibrium between the remaining F centers and the precipitated potassium. Analysis of the rate data leads to a diffusion constant of the diffusing entity of the order of 10−9 cm2 sec−1 to 10−13 cm2 sec−1. The model postulated for the formation of the colloids is the diffusing of F centers to a nucleation site where they combine with lattice potassium ions to form atomic potassium.
Dislocation Damping in Copper at Kilocycle and Megacycle per Second Frequencies
Authors: Granato A. V. , Stern Richard
Published: April 2005

A recent conclusion that the vibrating string model of dislocation motion cannot account for the magnitude of the observed amplitude-independent damping at kilocycle per second frequencies is shown to be not generally valid. In fact, it is shown that there are specimens for which the extrapolated values of the decrement from megacycle frequencies to 15 kc are higher than any previously measured values at 15 kc. This result shows that the model can easily account for the magnitudes observed in the kilocycle region, and contributes a substantial fraction, if not all, of the component of the damping at 15 kc, which can be removed by irradiation. Since it has been demonstrated for the megacycle measurements that the source of the damping is the dislocation-phonon interaction, the evidence is strong that the same mechanism contributes to the damping observed at 15 kc. The argument given does not depend on assumed values for dislocation parameters, but only on experimentally established relations. A critical experiment would now be a measurement of the frequency dependence in the kilocycle range of the component of the damping which can be removed by irradiation. Such a measurement, if feasible, should show whether or not other as yet unknown mechanisms also contribute to the damping at 15 kc.
X-Ray Diffraction Line Shifts in the Debye-Scherrer Pattern from Wire Specimens with Preferred Orientation
Authors: Otte Henry M.
Published: April 2005

In solid metal samples which have a strong texture, certain planes will favor the diffraction of the vertically divergent rays of the x-ray beam more than the parallel rays. In extreme cases this will produce a diffraction peak shift. The direction and magnitude of the shift obtained from a specimen with a prominent 〈001〉 wire texture is in good agreement with the theoretical calculations of Pike (1957).
Ion Drag Pumping. I. Theory
Authors: Pickard William F.
Published: April 2005

The ion-drag pumping problem is re-examined. New theoretical results are presented for both the static and dynamic cases: in particular, the phenomena of ``cut-in'' voltage and hydrodynamic instability are shown to behave in a fashion different from that previously believed. The predictions of the theory are evaluated in the light of the published experimental evidence.
Ion Drag Pumping. II. Experiment
Authors: Pickard William F.
Published: April 2005

The problem of the electrical pumping of a dielectric liquid along lines of the applied field is considered experimentally. The pressure generated by typical pumps are studied in detail, often in novel fashions; e.g., by varying the liquid flow velocity, the electrode spacing, or the liquid temperature while the applied field is held constant. It is shown that the experimental data are consistent with an ion emission model of the phenomenon, but that the emission is not necessarily space-charge-limited; photomicrographs are presented to show the effects of the emission process on the electrodes.
Theory of Flow Properties of Attapulgite Suspension in Water. A Method for Determining the Relaxation-Time Parameter β
Authors: Gabrysh A. F. , Eyring Henry , Shimizu Michie , Asay Jeanette
Published: April 2005

In two previous papers the stress-strain-time relations with respect to variables of temperature, concentration, and pH were given for attapulgite suspension in water, in terms of rheopexy (dilatancy) and thixotropy. Stress relaxation and script S-like curves showing both thixotropy and rheopexy were determined at various temperatures. Yield-point viscosities for the rheopectic and thixotropic curves showed activation energies of about 1 and 2 kcal, respectively. In the present paper Eyring's rate theory of viscosity is briefly discussed in terms of the well known generalized-viscosity equation η= ∑ i=1iXiβiαisinh−1βiṡβiṡ, which is applied successfully to given flow curves. A new method for determining the parameter βi is discussed.
Rayleigh and Stochastic Scattering of Ultrasonic Waves in Steel
Authors: Papadakis Emmanuel P.
Published: April 2005

The ultrasonic attenuation in SAE 4150 steel has been measured from 5 to 100 Mc at various stages in its heat treatment. The attenuation is changed by changes in grain diameter and anisotropy. The anisotropy of grains transformed to martensite is lower than pearlite, while martensite itself becomes less anisotropic upon tempering. The dependence of the attenuation upon frequency f, grain diameter D, and anisotropy μ agrees well with the theory of Lifshits and Parkhomovskii, who predict Rayleigh scattering proportional to μ2D3f4 for λ > 2πD and another type proportional to μ2Df2 for λ<2πD. The anisotropy factor μ2 is lower by a factor of 10 for hardened, tempered steel than for iron.
Electrical Resistivity of Scandium
Authors: Colvin R. V. , Arajs Sigurds
Published: April 2005

Electrical resistivity of polycrystalline scandium has been studied between 1.38° and 358.8°K. The measurements show a step-type anomaly in the resistivity between 4 and 5°K and possibly a very small minimum at 9.5°K. Considerable hysteresis in the electrical resistivity exists at low temperatures, depending upon the previous thermal history of the sample. It is very likely that these anomalies may be associated with a super-conductive substructure resulting from the presence of small amounts of tantalum as an impurity. However, the possibility that the anomalous behavior is due to the occurrence of some cooperative magnetic states at low temperatures cannot be completely eliminated at the present time. Between about 80° and 360°K the intrinsic resistivity of scandium is describable by the Bloch-Grüneisen formula with Debye θ of 275°K. At lower temperatures the temperature dependence of the intrinsic resistivity is consistent with expectations derived from the interband electron-phonon scattering. Ziman's reduced electrical resistivity at 300°K is calculated to be 50.8.
Effect of Prior Deformation and Recovery on the Defect Concentration Increase During Plastic Deformation
Authors: Peiffer H. R.
Published: April 2005

The increase in the concentration of lattice defects during deformation of copper is shown to have a power law dependence on strain, i.e., Δρ=cΔεn, where Δρ is the change in electrical resistivity at 78°K following an elongation strain increment Δε, and c and n are constants. It is further shown that the initial internal condition of the metal affects the subsequent defect deformation in the metal. Finally it is shown that following room temperature anneal the production of defects is enhanced.
Ranges of Energetic Atoms in Solids
Authors: Oen O. S. , Holmes D. K. , Robinson Mark T.
Published: April 2005

The ranges in solids of atoms having energies from 1 to 100 keV have been calculated using Monte Carlo techniques. The model assumes that the moving atom loses all of its energy through binary elastic collisions with the atoms of the solid. The potential of interaction, principally studied, is an exponentially screened Coulomb (Bohr) potential, and the scattering angles are calculated explicitly. It is found that neither the hard sphere approximation nor the inverse r-squared approximation to the Bohr potential is particularly good. To obtain correspondence with experimental results it is found that the Bohr screening length must be increased as the atomic number of the interacting atoms increases.
Effects of Glass Contamination and Electrode Curvature on Electrical Breakdown in Vacuum
Authors: Donaldson E. E. , Rabinowitz M.
Published: April 2005

It has recently been found that particles of contamination reside on surfaces inside vacuum systems as a result of thermal decomposition of glass. These particles contain at least Na, K, and B as well as traces of Al and Si. They may well have been important in many clean surface experiments. Our investigation has shown that these particles have a strong influence in reducing the breakdown voltage in vacuum. Breakdown voltages for Al, Cu, and stainless steel electrodes with radii of curvature of 12.7, 25.4, 50.8, and 101.6 mm were determined under clean and contaminated conditions at 10−5 Torr. It was found that under clean conditions the electrodes of smaller radii of curvature have higher breakdown voltages than the more nearly plane electrodes.
Polar Properties of BeO Single Crystals
Authors: Austerman S. B. , Berlincourt D. A. , Krueger H. H. A.
Published: April 2005

Piezoelectric, dielectric, and pyroelectric measurements were made on hexagonal BeO crystals grown in molten lithium molybdate flux. The piezoelectric constant d33∼0.24×10−12 C/N, ε33T/ε0∼7.6, and the average free pyroelectric constant in the range −196° to 25°C is −3.4×10−10 C/cm2 °C. The sound velocity perpendicular to the polar axis is 12 000 m/sec. Although no absolute identification of crystal planes was made, it was concluded from the sign of the piezoelectric constant d33 that the oxygen side of the closely coupled Be—O layer is that of principal growth and etch. Polarity of the crystal structure is reflected in typical crystal growth habits and in characteristic etch patterns which are described.
Noise on a Drifting Maxwellian Beam
Authors: Bloom Stanley , Vural Bayram
Published: April 2005

The problem of noise- (and, as a special case, signal-) wave propagation along a drifting, one-dimensional electron stream with a half-Maxwellian velocity distribution is analyzed. The integral equation resulting from the linearized Boltzmann equation is intractable in its exact form and so, heretofore, has succumbed only to machine computation. In this paper closed-form solutions are obtained through the use of a simplified kernel. This approximation, although it limits the analysis to beams with small relative velocity spreads and small ratios of plasma frequency to operating frequency, is yet innocuous enough not to mask the main effects.

The noise current and voltage are found to consist of three wave terms: a ballistic wave describing the injected noisy ``test particle,'' a slow space-charge wave and an aggregate of fast space-charge ``waves'' which decays, en masse, with distance because of phase mixing. This aggregate is approximately representable by a single fast wave with exponential damping. Far downstream the noise power spectra (ψ,Φ,Π,S) lose their familiar sinusoidal pattern and settle to constant values. Along the entire beam the positive rf noise power, S+Π, is invariant.
Direct Observation of Charge Storage in the Surface States of Silicon
Authors: Harman G. G. , Raybold R. L. , Meyer Owen L.
Published: April 2005

A new method of studying the surface states of silicon is described. Essentially it involves applying porous graphite contacts to p-type silicon and exposing the samples to various inversion-layer producing gaseous ambients. A voltage pulse is applied to the sample and the resulting current pulse is a measure of the density of charge states. From such data it was found that the number of water-vapor-induced surface states on p-type silicon was 5×1012/cm2. For any sample this value was reduced ∼50% by using ammonia instead of water vapor. Tests using widely differing electrode particle sizes resulted in no change in the measured density of states. By applying a small dc bias (∼1 V at <1 mA) to control the surface potential it is possible to continuously extend the current envelope or reduce it to a small capacitive spike. The total charge, at fixed bias, is a constant, independent of applied voltage amplitude.
End Losses in Magnetohydrodynamic Channels with Tensor Electrical Conductivity and Segmented Electrodes
Authors: Sutton George W.
Published: April 2005

End losses of an inviscid magnetohydrodynamic channel having tensor conductivity and segmented electrodes have been calculated for a magnetohydrodynamic power generator of this geometry. It was found that the constant-current configuration is more efficient than the constant potential difference case. The efficiencies increase with increasing Hall effect, but constant magnitude extensions to the magnetic field have very little effect. The theoretical efficiency for an aspect ratio of 10 and ωτ=2 is only 74%.
Cd and Te Dislocations in CdTe
Authors: Inoue Morio , Teramoto Iwao , Takayanagi Shigetoshi
Published: April 2005

It seems probable that two types of 60° edge dislocation exist in CdTe because of the geometrical polarity. In fact, such types of dislocations can be made visible as different etch pit figures with two kinds of etches. Two types of bendings were applied for the introduction of either excess-Cd or excess-Te dislocations. On each bending two types of dislocations were simultaneously brought about with a minimum in density near the neutral plane. However, annealing at high temperature resulted in a uniform distribution of dislocations and a polygonization of the crystal. Furthermore, it was found that dislocations of the correct sign, necessary to produce the required configuration of bending, were predominantly conserved while unexpected dislocations were thermally annihilated during the polygonization process.