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1 Feb 1967

Volume 38, Issue 2, pp. 425-912

Page 2 of 5 Pages Previous Page Next Page | Jump to Page

Structure of Martensite

M. Ron, A. Kidron, H. Schechter, and S. Niedzwiedz

J. Appl. Phys. 38, 590 (1967); http://dx.doi.org/10.1063/1.1709379 (5 pages) | Cited 17 times

Online Publication Date: 29 December 2004

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X‐ray measurements cannot give a complete microscopic interpretation of the structure of carbon—iron martensite because of the broad diffuse diffraction lines. They show that the iron martensite has a body‐centered tetragonal lattice on the average, but cannot give an exact picture of the distortion centers around the carbon atoms.
Several samples of martensite were studied by means of the Mössbauer effect to separate the octahedra occupied by carbon atoms from the rest of the lattice. The iron atoms around each octahedron gave two extra different hyperfine fields, with an isomer shift relative to Armco iron. The strength of the new fields coupled with the intensity ratio of the absorption lines leads to the interpretation that the distortion around a carbon atom is local, and that most of the crystal has an almost bcc structure, probably with a small strain field centered at the carbon atom.

Interactions of Point Defects and Elastic Inclusions

Francis C. Moon and Yih‐Hsing Pao

J. Appl. Phys. 38, 595 (1967); http://dx.doi.org/10.1063/1.1709380 (7 pages) | Cited 8 times

Online Publication Date: 29 December 2004

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Using a continuum model for crystal defects and inclusions, the interaction energies are calculated for one defect with several inclusions and for several defects with a single inclusion. The special cases of the interaction of a center of dilatation and a doublet with a spherical inclusion are discussed. The center of dilatation may be attracted to or repelled from the inclusion depending on the rigidity of the inclusion and of the matrix material.

Temperature Dependence of the Elastic Constants of Molybdenum

J. M. Dickinson and P. E. Armstrong

J. Appl. Phys. 38, 602 (1967); http://dx.doi.org/10.1063/1.1709381 (5 pages) | Cited 30 times

Online Publication Date: 29 December 2004

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The elastic properties of molybdenum single crystals have been measured using thin‐rod resonance techniques as a function of temperature from −198° to over +650°C. Molybdenum behaves in a normal manner over this temperature range. Its elastic stiffness coefficients, with the exception of C12 which increased 3%, decreased in a nearly linear manner. The decrease was 8% for C44, 11% for C11, and 18% for C′. From these data the temperature dependence of the bulk modulus, the shear coefficient C′, the anisotropy ratio, and the Young's and shear modulus of isotropic polycrystalline molybdenum were calculated.

Correlating Devices and Their Estimation Errors

J. B. Knowles and H. T. Tsui

J. Appl. Phys. 38, 607 (1967); http://dx.doi.org/10.1063/1.1709382 (6 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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Several special‐purpose devices capable of performing correlation measurements have been described in the literature over the past few years. While the expected outputs of these devices have been shown to equal the required correlation function, their intrinsic sampling errors have apparently not been investigated. Two such important devices are the modified relay and polarity‐coincidence correlators. Variances for their measurement errors are derived in this paper. The dependence of the sampling error on the information content of the input processes and on the type of auxilliary signal is also considered. The analysis is confirmed by the experimental results.

Hall Effect in Dielectric Media: Microwave X‐Band Faraday Rotation of Water Adsorbed on Hemoglobin

Soo‐Young Chai and Paul O. Vogelhut

J. Appl. Phys. 38, 613 (1967); http://dx.doi.org/10.1063/1.1709383 (6 pages) | Cited 5 times

Online Publication Date: 29 December 2004

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The structure of bound water molecules in crystalline, bovine hemoglobin powder is investigated with a microwave technique of Faraday rotation at a frequency of 9.36 Gc∕sec. An expression for the Faraday rotation due to displacement‐current Hall field is derived in terms of dipole concentrations of free water molecules and is applied to measure the changes from free water to bound water molecules on hemoglobin with variable amounts of adsorbed water. In agreement with the theory, the experimental result shows a linear relationship between the angle of rotation and the concentration of free water dipoles up to the hydration level of 0.13 g of water per gram of dry hemoglobin. Above this hydration level, the formation of icelike structures on the surface of hemoglobin is discussed based on our experimental results.

The Martensitic Transformation in Cobalt

R. T. Johnson and R. D. Dragsdorf

J. Appl. Phys. 38, 618 (1967); http://dx.doi.org/10.1063/1.1709384 (9 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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The properties of the fcc to hcp transformation in cobalt single‐crystal whiskers have been determined. Studies of the crystallographic properties and dislocation structure using optical, standard x‐ray diffraction, and high‐resolution x‐ray diffraction topographic techniques are herein reported. It is shown that the atomic movements associated with the transformation in cobalt initiate at the most highly strained regions in the crystal. The strain configuration and the crystal boundaries act as a combined mechanism restricting the transformation to a particular set of {111} planes. When the strain distribution is nonuniform throughout the crystal, localized regions within the crystal utilize different sets of {111} transformation planes. The transformation from the fcc to hcp phase is accomplished by the glide of Shockley partial dislocations through the lattice. Frank partial dislocations remain pinned in the lattice. These partials are formed from the extension of total dislocations. Martensitic platelets result from either the glide of Shockley partial dislocations which have different slip vectors in parallel and adjacent sections of the crystal or the pinning of Frank partial dislocations which form the boundary of faulted regions. The platelets intersecting the crystal surfaces produce observable slip bands.

Electrical Breakdown between Metal Electrodes in High Vacuum. I. Theory

Francis M. Charbonnier, Carol J. Bennette, and Lynwood W. Swanson

J. Appl. Phys. 38, 627 (1967); http://dx.doi.org/10.1063/1.1709385 (7 pages) | Cited 50 times

Online Publication Date: 29 December 2004

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A theoretical description of electrical breakdown across narrow gaps in high vacuum is presented under conditions for which surface cleanliness, work functions, gap geometry, and cathode surface roughness are well defined. Two basic initiating mechanisms are considered: (1) thermal processes initiated at both the anode and the cathode by the prebreakdown field‐emitted electron current, and (2) mechanical processes resulting from yield of one of the electrode surfaces under the action of electrostatic stress produced by the electric field in the gap. In the case of thermal breakdown initiation, there exists a boundary between an anode and a cathode‐initiated arc which can be expressed in terms of the factor γ by which the gross field in the gap is enhanced at the tip of microscopic cathode protrusions. Solution of the heat conduction equation is given for the general case of dc or pulsed gap voltages. This leads to a distinction between three ranges of pulse duration, and for each region, a simple analytical expression is given for the boundary value γ0 which separates cathode‐ and anode‐initiated breakdown. Based on the considerations presented here, some practical limitations of several electrode materials are given.

Electrical Breakdown between Metal Electrodes in High Vacuum. II. Experimental

Carol J. Bennette, Lynwood W. Swanson, and Francis M. Charbonnier

J. Appl. Phys. 38, 634 (1967); http://dx.doi.org/10.1063/1.1709386 (7 pages) | Cited 30 times

Online Publication Date: 29 December 2004

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Experiments were performed in order to test the validity of the theory outlined in I. Significant theoretical parameters varied experimentally included electrode material, electrode geometry, and applied voltage pulse length. Electrode materials chosen included W, Mo, Cu, and Al. Gap spacings varied from a few tenths to a few thousandths of a centimeter at gap voltages up to 30 kV applied either continuously or in single pulses of 1 to 100 μsec duration. For all electrode materials except Al, thermal processes are the primary initiation mechanism, and experimental observations agree with the theoretical predictions of I. With electrode materials of low tensile strength such as Al, the primary cause of electrical breakdown is due to the electrostatic stress produced by the high electric field.

Recovery of Ultrasonic Attenuation in Copper Single Crystals Following Small Plastic Deformation

Julius Frankel and L. V. Meisel

J. Appl. Phys. 38, 641 (1967); http://dx.doi.org/10.1063/1.1709387 (6 pages) | Cited 4 times

Online Publication Date: 29 December 2004

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Migration of deformation‐produced defects to dislocations was studied by means of an ultrasonic technique. Copper single crystals of 3N and 4N nominal purity were deformed about 0.3% in tension at temperatures between 40° and 90°C. After deformation the stress was released and the change in ultrasonic attenuation was measured continuously at the deformation temperature. The recovery of the ultrasonic attenuation fits the predictions of the Granato, Hikata, and Lücke theory. This indicates the validity of the Cottrell—Bilby ``t2∕3'' strain‐aging law for stress‐assisted diffusion of point defects to dislocations in copper. A single mobile defect was detected, and its migration energy was measured as 0.67±0.06 eV. The defect was identified as the divacancy. The divacancy concentration after about 0.3% deformation was estimated as 5×10−8.

Thermal Expansion and Elastic Constants of β′‐AgMg. I. The Coefficient of Thermal Expansion from 77° to 800°K

J. P. Neumann and Y. A. Chang

J. Appl. Phys. 38, 647 (1967); http://dx.doi.org/10.1063/1.1709388 (3 pages) | Cited 3 times

Online Publication Date: 29 December 2004

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The linear coefficient of thermal expansion of β′‐AgMg has been determined from 77° to 800°K by means of lattice‐parameter measurements below room temperature and dilatometric measurements at higher temperatures. At room temperature, the linear coefficient of thermal expansion was found to be 21×10−6 per °C. The Grüneisen parameter derived from the coefficient of thermal expansion obtained here and from other thermal data available in the literature is essentially constant (γ≃1.8) above the Debye temperature, but increases at lower temperatures. Using Slater's formula, a value of 2.2 was obtained for the Grüneisen parameter at 0°K.

Thermal Expansion and Elastic Constants of β′‐AgMg. II. Single‐Crystal Elastic Constants from 77° to 750°K

Y. A. Chang, L. Himmel, and J. P. Neumann

J. Appl. Phys. 38, 649 (1967); http://dx.doi.org/10.1063/1.1709389 (4 pages) | Cited 9 times

Online Publication Date: 29 December 2004

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The single‐crystal adiabatic elastic constants of stoichiometric β′‐AgMg have been determined from 77° to 750°K using the ultrasonic pulse‐echo technique. The values obtained at 300°K are: c11=0.8380, c12=0.5635, c44=0.4755 (all in units of 1012 dyn∕cm2).
A relationship between the elastic constants and the lattice parameters of the two β′‐structures AgMg and CuZn was found. A similarity of the temperature dependence of the elastic constants was also observed. From the extrapolated values of the elastic constants at 0°K, a Debye temperature of 287°K was obtained. Finally, using the elastic constant data, specific heat of β′‐AgMg at constant volume was calculated and found to compare favorably with the classical value 3R at high temperature.

Reflection and Refraction of Electromagnetic Waves by a Moving Dielectric Medium

V. P. Pyati

J. Appl. Phys. 38, 652 (1967); http://dx.doi.org/10.1063/1.1709390 (4 pages) | Cited 36 times

Online Publication Date: 29 December 2004

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The problem of reflection and refraction of a plane electromagnetic wave by a semi‐infinite dielectric medium moving uniformly parallel to its surface is analyzed. The scope of this paper is wider than earlier ones in that the orientation of the plane of incidence is arbitrary.
Certain interesting features are revealed. First, Snell's law is modified. Secondly, the resultant reflected and transmitted E and H vectors are not parallel (or antiparallel) to the incident E and H. Furthermore, when the incident wave is polarized with its electric field parallel to the plane of incidence, there is no angle of incidence (Brewster's angle) for which the reflected wave vanishes. An exception to these results occurs when the plane of incidence is parallel to the velocity. In this case, there is a strong resemblance to the nonmoving case.

Theory of Anomalous Infrared Attenuation in Neutron‐Irradiated Compound Semiconductors

J. L. McNichols and W. S. Ginell

J. Appl. Phys. 38, 656 (1967); http://dx.doi.org/10.1063/1.1709391 (5 pages) | Cited 12 times

Online Publication Date: 29 December 2004

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It is proposed that the anomalous infrared attenuation observed in neutron‐irradiated compound semiconductors is the result of an induced local phase change to a metallic‐like state. The total infrared scattering and absorption for a distribution of small metallic inhomogeneities in an otherwise uniform nonmetallic crystal is shown to produce attenuation which is proportional to the square of photon energy in the band gap. Application is made to fast‐neutron‐irradiated GaAs and agreement with reported data is found to be excellent. It is suggested that further investigation of the anomalous, structureless infrared attenuation observed for some irradiated compound semiconductors may lead to more quantitative understanding of spike phenomena in these materials.

Improved Room‐Temperature Laser Performance in GaAs Diffused‐Junction Diodes

R. O. Carlson

J. Appl. Phys. 38, 661 (1967); http://dx.doi.org/10.1063/1.1709392 (8 pages) | Cited 9 times

Online Publication Date: 29 December 2004

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Significant reduction in room‐temperature laser threshold and stimulated emission delay is obtained in diodes made from zinc‐diffused wafers (850°C—3 hours in Zn☒As atmosphere) if the single‐diffusion process is modified with multiple diffusions, or, more controllably, by the addition of a post‐annealing step (∼900°C in As atmosphere) following the initial diffusion. Incremental sheet‐conductivity measurements show the zinc concentration gradient is reduced and etching studies show a lowered dislocation density near the junction after annealing. Without an annealing step, diffused‐junction diodes show consistently larger emission delays (observed above ∼200°K) than epitaxial‐junction diodes made from the same n‐type substrates. The deliberate in‐diffusion of high copper concentrations causes large delays even at 77°K. However, copper is probably not the center causing delays near room temperature because a mass spectrographic analysis did not reveal higher copper concentrations in diffused‐junction wafers than in epitaxial‐junction wafers when there was no deliberate copper doping.

Light Holes in Bismuth‐Tin Alloys

Laird C. Towle, Alex Cybriwsky, and Ralph E. Stajdohar

J. Appl. Phys. 38, 668 (1967); http://dx.doi.org/10.1063/1.1709393 (5 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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Galvanomagnetic measurements have been made on several polycrystalline bismuth alloys containing up to 0.15 at.% tin. Data obtained at 77.4°K have demonstrated the existence of a light‐hole band in the bismuth band structure. The effective mass of the new carriers is ∼0.002m0.

Growth of the Close‐Packed (111) Plane of Gold Single Crystals

Richard L. Schwoebel

J. Appl. Phys. 38, 672 (1967); http://dx.doi.org/10.1063/1.1709394 (9 pages) | Cited 1 time

Online Publication Date: 29 December 2004

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The structure of the (111) plane of gold single crystals growing from the vapor, deposited at a rate equivalent to 0.026±0.005 monolayers∕second, has been studied using carbon replicas and electron microscopy, electron and x‐ray reflection diffraction. Below a temperature of 750°K, crystallites of gold develop on the surface, sometimes with preferred orientation. Somewhat above this temperature, extensive surface step systems and oriented trigonal growth centers are observed. The crystallographic orientation of the steps and growth centers, as well as reflection x‐ray diffraction patterns from these surfaces, are evidence that the deposited gold atoms participate in growth of the substrate crystal at temperatures above 750°K. Development of these trigonal growth centers is described in terms of a simple model in which diffusing atoms are preferentially incorporated into growth centers at sites with particular coordination arrangements, i.e., such that the growth centers preferentially expose particular facets. Existence of oriented step systems and growth centers implies that adsorbed gold atoms diffusing on the surface are reversibly captured at steps under these growth conditions. Consequently, the activation energy for surface diffusion includes the energy for dissociation of atoms from steps to adsorbed positions on an atomically smooth portion of the surface. An upper bound for the activation energy for surface diffusion is concluded to be approximately 1.7 eV for atoms adsorbed on the (111) plane. The activation energy for motion of an atom along a step is estimated to be approximately equal to or greater than 0.7 eV.

Effects of Strain, Preferred Orientation, and Local Crystallite Size Variation on Néel and Cross‐Tie Domain Walls

G. A. Walker and C. O. Heinzel

J. Appl. Phys. 38, 680 (1967); http://dx.doi.org/10.1063/1.1709395 (5 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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The effects on shape and coercive force, Hc, of Néel and cross‐tie domain walls due to variation in crystallite size, strain, and preferred orientation have been studied. Experiments were designed to try to separate the different effects in order to better understand their respective contribution to domain wall motion. The breaking or joining of domain walls during motion has been shown to be caused either by crystallite size variation greater than 50 Å, or by local areas of preferred orientation plus strain. In order to assess the effects of strain or preferred orientation in these films, it is imperative to eliminate crystallite size effects. Once this is done, anisotropy terms are used to describe the experimental results. A crystallite size variation of 200 Å is shown to make a difference of 0.9 Oe in Hc. Preferred orientation plus strain in our films has been shown to reduce Hc by 2.6 Oe. The possible effects of intrinsic and extrinsic stacking faults are indicated.

Diffusion Lengths of Electrons and Holes in GaAs

L. W. Aukerman, M. F. Millea, and M. McColl

J. Appl. Phys. 38, 685 (1967); http://dx.doi.org/10.1063/1.1709396 (6 pages) | Cited 31 times

Online Publication Date: 29 December 2004

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The short‐circuit current of both diffused and n‐type metal semiconductor junctions during 2‐MeV electron irradiation was measured. The results indicate that electron diffusion length in the Zn‐diffused p‐type region is proportional to the reciprocal of the square root of the donor concentration. The electron‐diffusion length ranges from 20 μ for lightly doped diodes to 2 μ for heavily doped diodes. The hole‐diffusion lengths are less than 1.0 μ in heavily doped surface barrier diodes. The thickness of the active radiative recombination region for diffused diodes under forward bias was measured and compared with the short‐circuit current results. These results suggest that the pre‐irradiation electron lifetime is ≈ (10−9 ND)−1, where ND is the substrate donor concentration. This behavior is consistent with radiative recombination between donors and free holes.

Magnetic Susceptibility of Sodium—Ammonia Solutions

Rudolf G. Suchannek, Sam Naiditch, and Olgierd J. Klejnot

J. Appl. Phys. 38, 690 (1967); http://dx.doi.org/10.1063/1.1709397 (5 pages) | Cited 8 times

Online Publication Date: 29 December 2004

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Magnetic susceptibilities of sodium—ammonia solutions with concentrations ranging from 0.36 to 3.85 mole∕liter have been measured at room temperature using Gouy's force method. At the low concentration end, atomic susceptibilities of sodium derived from the measurements fit Hutchison and Pastor's data which were measured at lower molarities. The general trend of the atomic susceptibility as a function of concentration indicates a transition in the electronic structure at a critical interatomic distance dm of 15 Å. This transition is discussed in relation to the transition from the nonmetallic to the metallic state which has been predicted by Mott for crystalline arrays of hydrogen‐like atoms. At concentrations c above 2.0 mole∕liter, the atomic susceptibility exhibits a c−2∕3 dependence as expected for Pauli's paramagnetism of a degenerate electron gas. Observed deviations of metal—ammonia solutions from Curie's law can be accounted for by a temperature dependence of dm.

Generalized Physical Optics Approximation for the Scattering of Electromagnetic Radiation from Imperfect Conductors of Irregular Shape

Oldwig Von Roos

J. Appl. Phys. 38, 694 (1967); http://dx.doi.org/10.1063/1.1709398 (4 pages)

Online Publication Date: 29 December 2004

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Show Abstract
The scattering of electromagnetic waves from plasmas of arbitrary shape (underdense and absorptive, overdense and∕or collision‐dominated) is calculated in the physical optics limit (wavelength short compared to a radius of curvature of the surface of the body). For infinitely conducting plasmas, the results for perfect conductors are recovered, and it is shown that the radar cross section for plasmas with a finite conductivity is, in general, polarization dependent, in contrast to the case of a perfect conductor.

Surface Self‐Diffusion and Surface Energy of Nickel

P. S. Maiya and J. M. Blakely

J. Appl. Phys. 38, 698 (1967); http://dx.doi.org/10.1063/1.1709399 (7 pages) | Cited 79 times

Online Publication Date: 29 December 2004

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The relaxation to flatness of sinusoidal single‐crystal nickel surfaces produced by a photoetching technique has been measured under high‐vacuum conditions. Results are presented on the variation of the surface diffusion coefficient Ds with temperature, orientation, and direction on certain low‐index planes. In the temperature range studied, the diffusion coefficient is found to vary only by a factor of about two for orientations close to (100), (111), and (110). For the (110) plane, Ds is anisotropic with Ds (110)[001]> Ds(110)[110]. From surface relaxation measurements in the wavelength range where volume diffusion contributes significantly, the surface free energy has been determined for the (100) and (110) planes. The values are 1821±182 erg∕cm2 and 1900±190 erg∕cm2, respectively.

Effect of Grip Stresses on Dislocation Configuration after Plastic Deformation

R. K. MacCrone

J. Appl. Phys. 38, 705 (1967); http://dx.doi.org/10.1063/1.1709400 (10 pages)

Online Publication Date: 29 December 2004

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Berg—Barrett x‐ray micrographs of strained single crystals of aluminum have revealed that the macroscopic dislocation configuration is inhomogeneous. Two kinds of inhomogeneity are recognised: short‐range inhomogeneity in any one ``small'' area due to dislocation subboundary formation and long‐range inhomogeneity in which both subboundary type and density depend upon the position along the specimen gauge length and also on the position within the cross‐sectional area.
The experimental results are interpreted in terms of the effects of grip stresses on dislocation motion.

The Oxide—Metal Interface of Electropolished Aluminum

H. A. Francis

J. Appl. Phys. 38, 715 (1967); http://dx.doi.org/10.1063/1.1709401 (11 pages) | Cited 2 times

Online Publication Date: 29 December 2004

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Replica and transmission electron microscopy were used to study the ordered topography of the amorphous oxide film on electropolished aluminum. The symmetry, periodicity, and amplitude of the oxide film thickness variation constituting the regular topography were investigated as a function of substrate orientation. The results are consistent with previously reported data and have enabled the dislocation model proposed by Doherty and Davis for the oxide—aluminum interface to be amplified and the nature of the interface to be more precisely defined. The model postulates that the first oxide to form has long‐range lattice symmetry identical to that of the substrate, resulting in a regular network of interfacial dislocations. The amorphous oxide subsequently grown by cation transport is thinnest over the dislocations, as the interface is the rate‐controlling barrier. No correlation was observed between the existence of ordered topography and epitaxy of the high‐temperature crystalline oxide which nucleates heterogeneously on the ordered oxide surface originally in contact with the metal. It is concluded that, for the range of orientations over which ordered topography exists, the dislocation cores are wide, i.e., almost a pure vernier. The observed defects in the long‐range order of the various topographies may be accounted for by corresponding defects in the ordered oxide adjacent to the interface. The dependence of the existence and periodicity of the topographies on electropolishing temperature and voltage was investigated and may be explained by the difference in thermal expansion of the substrate and the ordered oxide at the interface. It is concluded from these data that the lattice parameter of the ordered overgrowth is 6.0% larger than that of the substrate, and that, when the first layer of oxide is formed, the temperature of the metal surface may be considerably greater than the electrolyte temperature. The absence of ordered topography for surface treatments other than electropolishing suggests that the minimum surface temperature for the formation of interfacial dislocations is greater than room temperature.

Residual Strains in Phosphorus‐Diffused Silicon

M. L. Joshi, C. H. Ma, and J. Makris

J. Appl. Phys. 38, 725 (1967); http://dx.doi.org/10.1063/1.1709402 (10 pages) | Cited 10 times

Online Publication Date: 29 December 2004

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An x‐ray line‐broadening method is used to determine the residual strain level in a single‐crystal silicon slice diffused with high amounts of phosphorus (surface concentration >1021 atoms∕cm3). The strain level was found to be higher than that from the Prussin model. This is shown to be due to insufficient penetration of the diffusion‐induced dislocations inside the diffused layers. Moreover, the strains along 〈220〉 directions were found to be considerably higher than those along other directions. This is interpreted as additional broadening along the Burgers vector direction.

Mössbauer Studies of Ordered and Cold‐Worked Fe☒Al Alloys Containing 30 to 50 at. % Aluminum

G. P. Huffman and R. M. Fisher

J. Appl. Phys. 38, 735 (1967); http://dx.doi.org/10.1063/1.1709403 (8 pages) | Cited 79 times

Online Publication Date: 29 December 2004

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Fe☒Al alloys containing 30 to 50 at. % Al were investigated by Mössbauer spectroscopy. Both ordered alloys, having the CsCl or B2 structure, and alloys severely cold‐worked by crushing were studied. At room temperature, all of the ordered alloys exhibit only paramagnetic lines, whereas the crushed alloys exhibit both paramagnetic and ferromagnetic lines, the intensity of the former increasing from 0% to 100% as the Al concentration increased from 30% to 50%. The results can be explained by considering the nearest neighbor configurations of Fe atoms in the ordered and deformed alloys, with slight corrections for next‐nearest neighbors. Plastic deformation induces ferromagnetism by creating large numbers of antiphase boundaries across which the number of Fe☒Fe nearest‐neighbor bonds is significantly greater than in the ordered alloy. The observed percentages of paramagnetic and ferromagnetic material and the average effective field values in the crushed alloys indicate that the average linear dimensions of the antiphase domains are about six atomic distances. In addition, the effects of antiphase boundaries and short‐range order produced by heat treatment have been observed in alloys of the DO3 structure (BiF3 type) having less than 25% Al.
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