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1 Feb 1963

Volume 34, Issue 2, pp. 241-444

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A Radiographic Study of Shock‐Loaded Iron

A. S. Balchan

J. Appl. Phys. 34, 241 (1963); http://dx.doi.org/10.1063/1.1702591 (5 pages) | Cited 8 times

Online Publication Date: 9 June 2004

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A study of shock‐loaded Armco iron has been made using a flash radiographic technique. Oblique shock waves were produced in iron samples by the collision of an explosively loaded driver. Details in the radiograph were compared qualitatively with the shock configuration to be expected from the Hugoniot curve of iron. The double shock structure of iron and the rarefaction shock were observed.

Ion Drag Pumping. I. Theory

William F. Pickard

J. Appl. Phys. 34, 246 (1963); http://dx.doi.org/10.1063/1.1702592 (5 pages) | Cited 34 times

Online Publication Date: 9 June 2004

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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

William F. Pickard

J. Appl. Phys. 34, 251 (1963); http://dx.doi.org/10.1063/1.1702593 (8 pages) | Cited 20 times

Online Publication Date: 9 June 2004

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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.

Field Emission in Rutile Diodes

O. E. Wagner and W. W. Happ

J. Appl. Phys. 34, 259 (1963); http://dx.doi.org/10.1063/1.1702594 (2 pages)

Online Publication Date: 9 June 2004

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Tunnel field emission is here proposed as a model for rectification in rutile diodes. This model has been previously applied by Mead [C. A. Mead, J. Appl. Phys. 23, 646 (1961)] to rectification phenomena observed with tantalum and aluminum oxides. In the case of rutile diodes it was found that the forward characteristics were explained by the tunnel field emission mechanism.

Theory of Flow Properties of Attapulgite Suspension in Water. A Method for Determining the Relaxation‐Time Parameter β

A. F. Gabrysh, Henry Eyring, Michie Shimizu, and Jeanette Asay

J. Appl. Phys. 34, 261 (1963); http://dx.doi.org/10.1063/1.1702595 (5 pages) | Cited 5 times

Online Publication Date: 9 June 2004

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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
math
, 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

Emmanuel P. Papadakis

J. Appl. Phys. 34, 265 (1963); http://dx.doi.org/10.1063/1.1702596 (5 pages) | Cited 6 times

Online Publication Date: 9 June 2004

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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.

High‐Field Superconducting Properties of Ti‐Mo Alloys

R. R. Hake and D. H. Leslie

J. Appl. Phys. 34, 270 (1963); http://dx.doi.org/10.1063/1.1702597 (7 pages) | Cited 11 times

Online Publication Date: 9 June 2004

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Critical current densities Jc for restoration of detectable resistance have been measured for super‐conducting Ti‐Mo alloys at 1.2°K in steady magnetic fields up to 30 kG, and for approximate Mo concentrations of 6, 9, and 16 at. %. Cold‐rolling is observed to increase the Jc values considerably and, in the case of Ti‐16 at. % Mo, to result in a marked ``anisotropy'' of Jc similar to that observed in many other cold‐rolled alloy superconductors: at high fields Jc is essentially a maximum or minimum when the applied transverse magnetic field (H⊥J) is, respectively, parallel or perpendicular to the rolling plane, apparently independent of specimen geometry. This suggests that Jc is very sensitive to the relative orientation of the field and an anisotropic defect structure normally introduced during cold‐rolling. The Jc anisotropy does not appear to be critically dependent upon the angle between the current and the rolling direction for current directions in the rolling plane and can apparently be suppressed by martensitic transformation during cold‐rolling. Although an explanation of Jc anisotropy in cold‐worked alloys does not fall within the scope of homogeneous alloy‐negative surface energy theories, the ``upper'' resistive critical fields [Hr(J=1A∕cm2)] for these alloys, ranging from 26.5 to 64 kG, are in fair agreement with predictions of the Ginzburg‐Landau‐Gor'kov‐Abrikosov theory.

Arc Cathode Emission Mechanisms at High Currents and Pressures

Peter W. Neurath and Thomas W. Gibbs

J. Appl. Phys. 34, 277 (1963); http://dx.doi.org/10.1063/1.1702598 (7 pages) | Cited 4 times

Online Publication Date: 9 June 2004

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Cathode emission was studied at over 1 atmosphere pressure into He and A plasmas at 100‐ to 500‐A total current. The cathode spot temperature and current density were measured by a high speed photometric method developed for this purpose. A low vacuum thermionic work function was found to be a most important criterion for long cathode life. Emission current densities of the order of 100 to 200 A∕mm2 were found to be independent of total current; surface temperature, typically, increased 300°C for the 5‐fold increase in current and was approximately 2500°C in argon for a thoriated W cathode. Calcium‐barium‐aluminate‐impregnated W cathodes operated well in such an arc, remaining at very low temperatures, confirming the results obtained with the thoriated W.

Ferroelectric Switching and the Sievert Integral

P. H. Fang and Irene A. Stegun

J. Appl. Phys. 34, 284 (1963); http://dx.doi.org/10.1063/1.1702599 (3 pages) | Cited 1 time

Online Publication Date: 9 June 2004

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A connection between some ferroelectric switching functions and the Sievert integral is established. Switching functions of Landauer et al. and of Franklin are computed and discussed.

Electrical Resistivity of Scandium

R. V. Colvin and Sigurds Arajs

J. Appl. Phys. 34, 286 (1963); http://dx.doi.org/10.1063/1.1702600 (5 pages) | Cited 2 times

Online Publication Date: 9 June 2004

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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.

Tables of the Conductivity Coefficients in Transverse Magnetic Fields K(γ) and L(γ)

Peter V. Gray

J. Appl. Phys. 34, 291 (1963); http://dx.doi.org/10.1063/1.1702601 (3 pages) | Cited 1 time

Online Publication Date: 9 June 2004

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Tables of K(γ) and L(γ) as defined by Willardson et al. are given over the range in which simple (high and low field) approximations are not valid. The tables permit easy multi‐band calculation of the transverse magnetoresistance and isothermal Hall coefficient as a function of magnetic field in nondegenerate semiconductors in the lattice scattering range.

Identification of Precipitates on Grown‐In Dislocations in MgO

John D. Venables

J. Appl. Phys. 34, 293 (1963); http://dx.doi.org/10.1063/1.1702602 (5 pages) | Cited 16 times

Online Publication Date: 9 June 2004

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It has been shown through means of transmission electron microscopy that precipitate particles decorate grown‐in dislocations in commercially available single crystal MgO. It has now been possible to show by means of electron diffraction that these precipitate particles are ZrO2 and that they are formed even when the Zr concentration in the MgO is as low as 1 ppm.

Effect of Prior Deformation and Recovery on the Defect Concentration Increase During Plastic Deformation

H. R. Peiffer

J. Appl. Phys. 34, 298 (1963); http://dx.doi.org/10.1063/1.1702603 (5 pages) | Cited 7 times

Online Publication Date: 9 June 2004

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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

O. S. Oen, D. K. Holmes, and Mark T. Robinson

J. Appl. Phys. 34, 302 (1963); http://dx.doi.org/10.1063/1.1702604 (11 pages) | Cited 44 times

Online Publication Date: 9 June 2004

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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.

Piezoresistive Properties of Silicon Diffused Layers

O. N. Tufte and E. L. Stelzer

J. Appl. Phys. 34, 313 (1963); http://dx.doi.org/10.1063/1.1702605 (6 pages) | Cited 68 times

Online Publication Date: 9 June 2004

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The piezoresistive properties of n‐ and p‐type layers formed by the diffusion of impurities into silicon have been investigated. The values of the three piezoresistance coefficients and the temperature dependence of the large coefficients have been measured on layers having surface concentration values from 1018 to 1021 cm−3. The piezoresistance effect in p‐type diffused layers follows qualitatively the behavior expected in a degenerate semiconductor. n‐type layers having high surface concentration values show a change in the symmetry of the piezoresistance effect at room temperature and a decrease in the coefficient π11 at lower temperatures. A discussion of the piezoresistance effect in diffused layers and its relation to the piezoresistance effect in uniformly doped material is also given.

Effects of Glass Contamination and Electrode Curvature on Electrical Breakdown in Vacuum

E. E. Donaldson and M. Rabinowitz

J. Appl. Phys. 34, 319 (1963); http://dx.doi.org/10.1063/1.1702606 (4 pages) | Cited 12 times

Online Publication Date: 9 June 2004

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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.

Morphological Stability of a Particle Growing by Diffusion or Heat Flow

W. W. Mullins and R. F. Sekerka

J. Appl. Phys. 34, 323 (1963); http://dx.doi.org/10.1063/1.1702607 (7 pages) | Cited 663 times

Online Publication Date: 9 June 2004

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The stability of the shape of a spherical particle undergoing diffusion‐controlled growth into an initially uniformly supersaturated matrix is studied by supposing an expansion, into spherical harmonics, of an infinitesimal deviation of the particle from sphericity and then calculating the time dependence of the coefficients of the expansion. It is assumed that the pertinent concentration field obeys Laplace's equation, an assumption whose conditions of validity are discussed in detail and are often satisfied in practice. A dispersion law is found for the rate of change of the amplitude of the various harmonics. It is shown that the sphere is stable below and unstable above a certain radius Rc, which is just seven times the critical radius of nucleation theory; analogous conclusions are obtained for the solidification problem. The results for the sphere are used to discuss the stability of nonspherical growth forms.

Metal—Semiconductor Barrier Height Measurement by the Differential Capacitance Method—One Carrier System

Alvin M. Goodman

J. Appl. Phys. 34, 329 (1963); http://dx.doi.org/10.1063/1.1702608 (10 pages) | Cited 222 times

Online Publication Date: 9 June 2004

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The differential capacitance measurement for determining the height of a Schottky barrier at a metal—semiconductor contact is based upon a number of assumptions. In practice, one or more of these assumptions may not be valid. Some of these deviations from the ``ideal case'' are examined in order to determine the effects of each upon the interpretation and validity of measurements on such contacts. Specifically, the effects of each of the following are considered: series resistance, traps in the depletion layer, effective contact area variation with depletion layer width, an insulating interfacial layer between the metal and semiconductor, semiconductor surface charge variation with bias voltage, and the reserve layer at the edge of the barrier. Experimental data for gold plated contacts to conducting cadmium sulfide single crystals are given to illustrate some of the results.

Polar Properties of BeO Single Crystals

S. B. Austerman, D. A. Berlincourt, and H. H. A. Krueger

J. Appl. Phys. 34, 339 (1963); http://dx.doi.org/10.1063/1.1702609 (3 pages) | Cited 37 times

Online Publication Date: 9 June 2004

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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.

Frictional Properties of Polyvinyl Chloride

C. L. Sieglaff and M. E. Kucsma

J. Appl. Phys. 34, 342 (1963); http://dx.doi.org/10.1063/1.1702610 (6 pages) | Cited 5 times

Online Publication Date: 9 June 2004

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The frictional properties of rigid and plasticized PVC have been measured as a function of temperature, speed of test, applied load, and plasticizer content. It was found that the data could be correlated by the simple equation
math
, where F is the frictional force, F* is a limiting frictional force dependent upon temperature and composition, and f is the applied normal force. The constants F* and k could be correlated with the tensile strength and the bulk modulus, respectively. A mechanism of polymer frictional behavior is proposed.

Stress Anisotropy in Silicon Oxide Films

J. Priest, H. L. Caswell, and Y. Budo

J. Appl. Phys. 34, 347 (1963); http://dx.doi.org/10.1063/1.1702611 (5 pages) | Cited 19 times

Online Publication Date: 9 June 2004

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The residual stress in films formed by vacuum sublimation of bulk silicon monoxide has been studied as a function of the angle of incidence of the evaporant. Using a source temperature of 1350–1400°C and a system total pressure of ∼2×10−6 Torr, a pronounced dependence of stress on angle of incidence and a distinct stress anisotropy was observed. The stress in the x direction (i.e., perpendicular to the direction of the evaporant irrespective of substrate orientation) increases from 4×108 dyn∕cm2 for normal incidence to 14×108 dyn∕cm2 for an incident angle of ∼50° and then decreases to 4×108 dyn∕cm2 for an incident angle of 80°. The stress in the y direction (i.e., perpendicular to the x direction) is peaked at ∼30° at a value of 13×108 dyn∕cm2 and then decreases to ∼0.5×108 dyn∕cm2 at 80°. Films formed at normal incidence are quite stable and not susceptible to the effects of water vapor. However, films formed by depositing at grazing incident angles (>30°) are very unstable and invariably buckle and rupture when exposed to atmospheres of water vapor. Substrate temperature, film thickness, and inert residual gases were found to have little effect on the stress and stability of films deposited at an angle of incidence of 45°. When a lower source temperature (<1200°C) is used and a high partial pressure (10−4 Torr) of water vapor is present during deposition, the resulting highly oxidized films show a compressive stress (∼2×108 dyn∕cm2) and very little dependence on the angle of incidence. These films are stable when exposed to higher partial pressures of water vapor.

Use of Induction Heating for Floating Zone Melting above 2000°C

Robert W. Johnson

J. Appl. Phys. 34, 352 (1963); http://dx.doi.org/10.1063/1.1702612 (4 pages) | Cited 7 times

Online Publication Date: 9 June 2004

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The method described uses an eddy current concentrator to focus the energy of an rf magnetic field on a small part of a ¼‐in.‐diam rod. Zone melting has been carried out at temperatures above 2600°C, and can probably be extended to temperatures above 3000°C. The advantages of this method over some others used in the same temperature range are that it can be carried out under an inert gas atmosphere instead of a vacuum, and uses for its power supply conventional 450‐kc induction heating equipment.

Noise on a Drifting Maxwellian Beam

Stanley Bloom and Bayram Vural

J. Appl. Phys. 34, 356 (1963); http://dx.doi.org/10.1063/1.1702613 (8 pages) | Cited 3 times

Online Publication Date: 9 June 2004

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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.

Elastic‐Plastic Properties of Iron

John W. Taylor and Melvin H. Rice

J. Appl. Phys. 34, 364 (1963); http://dx.doi.org/10.1063/1.1702614 (8 pages) | Cited 71 times

Online Publication Date: 9 June 2004

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Smooth bore cannons were used to produce plane collisions between plates of Armco iron. Projectile velocities ranged from 60 to 400 m∕sec. Time resolved measurements of the target free‐surface velocities indicate that the dynamic yielding process is time dependent on a submicrosecond time scale. The shape of the Hugoniot curve in the pressure‐volume plane up to 80 kbars shows that true hydrostatic equilibrium has not yet been established behind the elastic wave. On the other hand the substantially constant free‐surface velocities behind the plastic front indicate that the material cannot be far from equilibrium after a short time. Some data on the rarefaction sound speed in the high pressure region are interpreted to imply a value very near 6 km∕sec.

Development of Substructure in Polycrystalline Aluminum During Constant‐Strain Fatigue

J. C. Grosskreutz

J. Appl. Phys. 34, 372 (1963); http://dx.doi.org/10.1063/1.1702615 (8 pages) | Cited 15 times

Online Publication Date: 9 June 2004

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Transmission electron microscopy and microbeam x‐ray techniques were used to study the substructure developed in pure, polycrystalline aluminum during constant strain fatigue. A complete study was made at strain amplitude ±0.002 over the cycle range 0–100 000 cycles. During the first several thousand cycles, the substructure varies considerably from grain to grain, depending on orientation. In general, dislocations initially cluster along {111} glide planes during the first few hundred cycles. By 2000–3000 cycles subgrain boundaries have formed along {111}, {100}, and {110} planes. Large numbers of dislocation loops are seen in and near the boundaries. As cycling proceeds to fracture, the dislocation density in these boundaries and the misorientation between the subgrains increases. The average subgrain volume decreases from ∼25 μ3 at 5000 cycles to ∼8 μ3 at 100 000 cycles. Subgrains were formed at all strain levels which were investigated, the lowest being ±0.0005; however, the rate of formation decreases rapidly as the strain is lowered. A model of fatigue hardening is proposed based on these observations, and the relation to fatigue fracture is discussed briefly.
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