bluuebunny/crossref_metadata_2025 huggingface dataset:
Empirical Evaluation of Convective Heat and Moisture Transport
Coefficients in Porous Cotton Medium
Authors: Ghali Kamel , Ghaddar Nesreen , Jones Byron
Published: July 2002

The air penetration within a porous clothing system on a moving human being is an important physical process that considerably affects the heat and moisture resistance of the textile material. This effect of the coupled convection heat and mass exchange within the clothing system is experimentally investigated and theoretically modeled to determine the heat and mass transfer coefficients between the air penetrating the void space and the solid fiber as a function of the velocity of penetrating air. Experiments were conducted inside environmentally controlled chambers to measure the transient moisture uptake of untreated cotton fabric samples as well as the outer fabric temperature using an infrared pyrometer. The moisture uptake was conducted at three different volumetric flow rates of 0.0067, 0.018 and 0.045 m3/sec/m2 of fabric area to represent airflow penetrations that could result from slow, medium, and vigorous walking, respectively. The theoretical analysis is based on a two-node adsorption model of the fibrous medium. A set of four coupled differential equations were derived describing time-dependent convective heat and mass transfer between the penetrating air and the solid fiber in terms of relevant unknown transport coefficients. The unknown model parameters were adjusted to fit the experimental data. The outer heat and mass transfer coefficients were found to increase with the air penetration flow rate.
Recent Developments in Gradient Plasticity—Part I: Formulation and Size Effects
Authors: Tsagrakis Ioannis , Aifantis Elias C.
Published: July 2002

The purpose of this two-part article, is first to give an update of recent developments of gradient plasticity as this was advanced by Aifantis and co-workers in the early eighties to address dislocation patterning and shear band problems, and then to elaborate on two specific issues of current interest: size effects and plastic heterogeneity. In Part I, a brief review of gradient dislocation dynamics as providing a direct motivation for the simplest form of gradient plasticity is given. Then, a more general phenomenological formulation of gradient plasticity is given and used to interpret size effects. In Part II, wavelet analysis is used as a potential tool to describe plastic heterogeneity at very fine scales for which experimental results are not available, as well as for providing another means to interpret size effects through the derivation of scale-dependent constitutive equations.
Mechanisms of Stiffening and Strengthening in Media-Equivalents Fabricated Using Glycation
Authors: Girton T. S. , Oegema T. R. , Grassl E. D. , Isenberg B. C. , Tranquillo R. T.
Published: July 2002

We have recently reported that glycation can be exploited to increase the circumferential tensile stiffness and ultimate tensile strength of media-equivalents (MEs) and increase their resistance to collagenolytic degradation, all without loss of cell viability (Girton et al., 1999). The glycated MEs were fabricated by entrapping high passage adult rat aorta SMCs in collagen gel made from pepsin-digested bovine dermal collagen, and incubated for up to 10 weeks in complete medium with 30 mM ribose added. We report here on experiments showing that ME compaction due to traction exerted by the SMCs with consequent alignment of collagen fibrils was necessary to realize the glycation-mediated stiffening and strengthening, but that synthesis of extracellular matrix constituents by these cells likely contributed little, even when 50 μg/ml ascorbate was added to the medium. These glycated MEs exhibited a compliance similar to arteries, but possessed less tensile strength and much less burst strength. MEs fabricated with low rather than high passage adult rat aorta SMCs possessed almost ten times greater tensile strength, suggesting that alternative SMCs sources and biopolymer gels may yield sufficient strength by compositional remodeling prior to implantation in addition to the structural remodeling (i.e., circumferential alignment) already obtained. [S0148-0731(00)00203-X]
Neck Down and Thermally Induced Defects in High-Speed Optical Fiber Drawing
Authors: Yin Z. , Jaluria Y.
Published: July 2002

The drawing speeds employed in the manufacturing of optical fibers have been rising in recent years due to growing worldwide demand. However, increasing speeds have placed stringent demands on the manufacturing process, mainly because of large temperature gradients that can generate thermally induced defects and undesirable variations in fiber characteristics. Heat transfer and glass flow that arise in drawing fibers of diameters 100–125 microns from cylindrical silica preforms of diameters 5–10 cm play a critical role in the success of the process and in the maintenance of fiber quality. This paper presents an analytical and numerical study of the optical fiber drawing process for relatively large diameter preforms and draw speeds as high as 20 m/s. The free surface, which defines the neck-down profile, is not assumed but is determined by using a balance of forces. An iterative numerical scheme is employed to obtain the profile under steady conditions. The transport in the glass is calculated to obtain the temperature, velocity and defect distributions. A zone radiation model, developed earlier, is used for calculating radiative transport within the glass. Because of the large reduction in the diameter of the preform/fiber, the velocity level increases dramatically and the geometry becomes complicated. A coordinate transformation is used to convert the computational domains to cylindrical ones. The numerical results are compared with experimental and numerical results in the literature for smaller draw speeds for validation. The effects of high draw speeds and of other physical variables on defects generated in the fiber, on the neck-down profile, and on the feasible domain for the process are determined. [S0022-1481(00)02302-1]
Skew Ray Tracing and Sensitivity Analysis of Geometrical Optics
Authors: Lin Psang Dain , Liao Te-tan
Published: July 2002

In order to improve upon the inconvenient and complicated contemporary analytic techniques employed for optical systems, this paper investigates two important optical topics: (1) the determination of light ray paths and (2) sensitivity analysis of light path parameters with respect to the light source location for occasions when light rays cross medium boundary surfaces. To this end, the traditional laws of reflection and refraction are reformulated in terms of revolution geometry. This results in a set of laws much simpler than the original, suitable for use in mathematical modeling to determine light paths and system sensitivity from location of the light source, optical component location, the equation of the optical component’s surface curve, and the refractive index. Ray tracing and sensitivity analysis of the two most popular boundary surfaces, flat and spherical, are presented as examples. In order to illustrate experimentally the integration of these boundary surfaces into optical systems, an optical measurement system for measuring surface height and orientation, containing a beam splitter and a bi-convex lens, was built. Agreement between the experimental optical system’s performance and the theoretical predictions yielded by the proposed method are excellent. [S1087-1357(00)01501-X]
Predictive Models for Flank Wear on Coated Inserts
Authors: Kwon Patrick
Published: July 2002

The purpose of this paper is to develop predictive models for flank wear that explicitly incorporate cutting temperature and the physical properties of coatings and work materials. The development of such models can minimize time-consuming machining experiments in predicting tool life by establishing flank wear models that can be applied to wide classes of coated inserts and work materials. To develop such models, a set of experiments was performed to understand the effect on flank wear due to the morphology and amount of the second phase in work materials. The plain carbon steels of AISI designation 1018, 1045, 1065, 1070, and 1095 in hot-rolled (pearlitic) and/or spherodized conditions were turned. The inserts with a single coating of TiN, TiCN, or Al2O3 were used in the cutting experiments. The temperature history at a remote location on the rake face was measured during cutting by using an infrared pyrometer with a fiber optic attachment. This temperature information was used to estimate the steady-state tool-chip interface temperatures using the inverse estimation scheme by Yen and Wright, 1986, ASME J. Eng. Ind., 108, pp. 252–263. The results were then used to predict the work-tool interface temperature using the scheme suggested by Oxley, 1989, The Mechanics of Machining: An Analytical Approach to Assessing Machinability, Wiley, New York, NY, p. 168. The results of this experiment showed that, for the spherodized steels, flank wear per sliding distance (the flank wear rate) increased with the cementite content. For the hot-rolled (pearlitic) steels, no conclusive evidence was found that correlates the flank wear rate with the cementite content. However, for pearlitic steels the wear rates, in general, were shown to increase with the flank temperature while for spherodized steels the rates decrease with the flank temperature. The reason for these trends can be explained by the microstructural difference between pearlitic and spherodized steels; therefore, the semi-empirical models of two-body and three-body wear developed by Rabinowicz (1967) and Rabinowicz et al. (1972) can be applied to describe the flank wear process. [S0742-4787(00)04501-X]
A Study of Nozzle Wear in Abrasive Entrained Water Jetting Environment
Authors: Nanduri Madhusarathi , Taggart David G. , Kim Thomas J.
Published: July 2002

Parameters that influence nozzle wear in abrasive water jetting environment are identified and classified. Regular and accelerated wear test procedures are developed to study wear under actual and simulated conditions, respectively. In addition to exit diameter growth, nozzle weight loss and bore profiles are shown to better characterize and explain the wear phenomenon. The effect of nozzle geometry on wear is investigated by means of the developed test procedures and measures of wear. [S0742-4787(00)00202-2]
Closure to “Discussion of ‘An Asperity Microcontact Model Incorporating the Transition From Elastic Deformation to Fully Plastic Flow’ ” [ASME J. Tribol., 122, No. 2, p. 479 (2000)]
Authors: Zhao, Yongwu , Marietta, and David M. , Chang L.
Published: July 2002

[S0742-4787(00)02602-3]
Effect of Two-Scale Roughness on Boundary Layer Transition Over a Heated Flat Plate: Part 2—Boundary Layer Structure
Authors: Pinson Mark W. , Wang Ting
Published: July 2002

Velocity and temperature measurements made within transitional boundary layers over a surface roughened by two roughness scales were examined. The variation of intermittency through the transition region was shown to be consistent with a smooth-wall model of transition, but the prediction of transition onset was not well represented by momentum thickness for cases with strong surface disturbances. During transition, distributed roughness was shown to reduce the growth of velocity fluctuation, possibly through stronger dissipation, and to enhance wallward transport of momentum significantly without a corresponding increase in thermal transport. The step change between the two roughness scales was shown to notably affect boundary layer behavior. Spectral analysis supported the hypothesis in Part 1 that the separated region downstream of the step shed vortices into the downstream flow. The wavelet analysis suggested that transition over rough surfaces may be in bypass mode because the disturbances were shown to be amplified in a broad spectral band. [S0889-504X(00)00302-0]
Type II PAN-based Carbon Fiber by Core Level and Valence Band XPS
Authors: Xie Yaoming , Sherwood Peter M. A.
Published: July 2002

Courtauds type II PAN-based carbon fiber surface was analyzed with both core level and valence band XPS. Compared to Du Pont and Amoco pitch-based carbon fibers with different moduli, the Courtauds type II PAN-based fiber had much more oxidized components on the surface [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc. 43, 1153 (1989); Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992).] The type II fiber had a much less graphitic structure in both the surface and the bulk than the pitch-based fibers as evidenced by both the XPS and XRD. It also had a notable nitrogen content on its surface but less than the Hercules AU4-12k and AS4-6k PAN-based fibers. However, no nitrogen was found on any of the pitch-based carbon fibers measured in our laboratory. Our previously reported work [Y. Xie and P. M. A. Sherwood, Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992)], showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra and could well be interpreted by X–α calculations with model compounds. In this work, the valence band spectrum showed that there were nitrogen and different types of oxygen species on the type II fiber surface.
Cubic Phase of Boron Nitride by AES
Authors: Simko Steven J. , Militello Maria C.
Published: July 2002

Auger electron spectra of the cubic phase of boron nitride are presented. The line shapes of the boron and nitrogen KLL transitions are characteristic for this phase of boron nitride. Therefore, cubic-boron nitride can be distinguished from other phases of boron nitride based on Auger line shapes. The powder specimen was prepared for analysis by burnishing onto a silver substrate. A single grain of boron nitride was analyzed.
Nickel(100) by XPS
Authors: Schmieg Steven J. , Belton David N.
Published: July 2002

X-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) were used to characterize a clean and highly-oriented Ni(100) single crystal. The Ni(100) crystal was cleaned and ordered with a combination of Ar-ion bombardment and annealing. There were no contaminants observed in XPS. The XPS binding energies were referenced to the Fermi edge of the clean nickel crystal.
Poly (methyl methacrylate) by XPS
Authors: Moulder J. F. , Stickle W. F. , Sobol P. E.
Published: July 2002

XPS measurements are presented for poly (methyl methacrylate). The data include the valence band region and the principal core levels.
A YBa2Cu3O7 Epitaxial Thin Film by XPS
Authors: Vasquez Richard P. , Foote Marc C. , Hunt Brian D.
Published: July 2002

X-ray photoemission spectra for the superconducting orthorhombic phase of YBa2Cu3O7 are presented. The data are from a chemically etched epitaxial thin film with the surface terminated in Cu–O planes, rather than the Ba–O termination obtained on cleaved crystals. The Cu–O termination results in a single Ba species and a Fermi edge in the valence band region which is stable in vacuum at room temperature.
A Bi2Sr2−xCa1+xCu2O8+δ Single Crystal by XPS
Authors: Vasquez Richard P. , Housley Robert M.
Published: July 2002

X-ray photoemission spectra from a chemically etched single crystal of the high temperature superconductor Bi2Sr2−xCa1+xCu2O8+δ are presented. A clear Fermi edge is observed in the valence band region, indicating a high quality surface.
Spin Cast Poly(t-butyl methacrylate) Film on Glass Substrate by XPS
Authors: Ackeret Michael , Ratner Buddy D.
Published: July 2002

X-ray photoelectron spectroscopy was used to analyze poly(t-butyl methacrylate), a pure spin cast polymer. This polymer was centrifugally spun cast onto a glass substrate and stored in an UV/ozone cleaned, O-ring sealed aluminum container. The polymer was examined at three different electron takeoff angles to verify homogeneity. Data were collected and atomic compositions calculated with a Hewlett-Packard 5950B ESCA. Measured atomic composition percentages closely matched the expected stoichiometry of the polymer.
SrTiO3 by XPS
Authors: Vasquez Richard P.
Published: July 2002

X-ray photoelectron spectroscopy measurements of the principal core levels, including the energy loss regions, for a SrTiO3(100) single crystal are presented.
P55X Pitch-based Carbon Fiber by Core Level and Valence Band XPS
Authors: Xie Yaoming , Sherwood Peter M. A.
Published: July 2002

An Amoco P55X pitched-based carbon fiber surface was analyzed with both core level and valence band XPS. Compared to Du Pont pitch-based carbon fibers with different modulus and Hercules PAN-based carbon fibers, the P55X fiber had more oxygen content on the surface than the higher modulus, pitch-based carbon fibers (e.g., Du Pont E-120 and E-75 fibers), but less than the lower modulus pitch based carbon fiber (Du Pont E-35) and PAN-based carbon fibers (Hercules AU4 and AS4). [See Y. Xie and P. M. A. Sherwood, Appl. Spectrosc. 43, 1153 (1989); Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992).] The P55X fiber also had a fairly good graphitic structure in both the surface and the bulk as evidenced by both XPS and XRD. No nitrogen was found on this P55X fiber nor on the other pitch-based carbon fiber surfaces, but it was found on the PAN-based fibers. Our previously reported work [Y. Xie and P. M. A. Sherwood, Chem. Mater. 1, 427 (1989); 2, 293 (1990); Appl. Spectrosc. 44, 797 (1990); Chem. Mater. 3, 164 (1991); Appl. Spectrosc. 44, 1621 (1990); 45, 1158 (1991); Y. Xie, T. Wang, O. Franklin, and P. M. A. Sherwood, ibid. 46, 645 (1992)], showed that XPS valence band spectra were more sensitive to chemical environment on the carbon fiber surface than core level spectra and could be well interpreted by X–α calculations with model compounds. In this work, the valence band spectrum showed that there were at least two different types of oxygen species on the P55X fiber surface. The two well separated O 2s features in the P55X fiber valence band spectrum were both more significant than those in the E-75 fiber valence band spectrum, but less than those in the E-35 fiber valence band.
Copper/Silver/Gold Alloy by XPS
Authors: Strohmeier Brian R.
Published: July 2002

The use of a sputter-cleaned copper/silver/gold (Cu/Ag/Au) alloy for calibrating the energy scale and instrument resolution (as full width at half-maximum or FWHM) of x-ray photoelectron spectrometers (XPS) was evaluated. The three component alloy material is a convenient alternative to the common practice of using three separate sputter-cleaned reference materials (i.e., Cu, Ag, and Au foils) for the calibration of XPS. The Cu 3p3/2, Cu 2p3/2, Cu L3M4,5M4,5, Ag 3d5/2, Ag M4NN, and Au 4f7/2 peaks have been recommended in the literature for calibrating XPS spectrometers. Results indicate that the Cu/Ag/Au alloy yields XPS binding energies for these peaks within reasonable experimental error (i.e., ± 0.1–0.2 eV or less) of the values obtained for pure Cu, Ag, and Au materials. In addition, the FWHM values obtained for these peaks with the Cu/Ag/Au alloy were essentially equivalent (within 0–0.03 eV) with the values obtained for pure Cu, Ag, and Au foils.
Titanium Carbide by AES
Authors: Epp June M.
Published: July 2002

The Auger electron spectra for titanium carbide are presented. The first derivative Auger electron spectrum for the C KLL line is characteristic of a carbide. The differentiated C KLL peak contains three components present at the approximate kinetic energies of 250, 260, and 270 eV, with the peak at 270 eV having a greater intensity in the positive direction than adventitious hydrocarbon. The unique shape of the differentiated C KLL Auger peak can be used to identify this carbide compound.
Second Row Transition Metals by AES
Authors: Geller Joseph D.
Published: July 2002

Auger electron spectra of second row transition metals (Ag, Cd, In, Mo, Nb, Pd, Rh, Ru, Sb, Sn, Y, and Zr) are presented. The data were taken under identical conditions (10 keV, 1 μA) in both derivative and direct (using beam brightness modulation) data collection modes.
Single Crystal 6H-SiC(0001) by AES
Authors: Bozack Michael J.
Published: July 2002

We report Auger spectra for the Si-terminated face of single crystal 6H-SiC(0001). The specimen was cut from a commercial (CREE Research) 1-in., n-doped wafer. SiC has recently attracted attention in semiconductor applications, and provides an attractive choice of material for devices operating at high temperature, high frequency, and high power. A companion submission shows XPS spectra.
Stoichiometric and Non-Stoichiometric Cu2O(111) Single Crystal Surfaces
Authors: Christiaen Anne-Claire , Abee Mark W. , Cox David F.
Published: July 2002

X-ray photoelectron spectroscopy (XPS) was used to investigate a non-polar Cu2O(111) single-crystal surface following two different preparations. The first surface, prepared by Ar-ion bombardment and annealing to 1000 K in vacuum, is nearly stoichiometric and exhibits a (1 × 1) LEED periodicity. Exposure to large doses of dissociated hydrogen gas produces the second oxygen-deficient surface which exhibits a (3 × 3) R30° LEED periodicity associated with 1/3 of an atomic layer of oxygen vacancies. There are no significant differences observed in normal emission XPS, in agreement with simulations that suggest the observed compositional changes should be smaller than the associated experimental error.
Comparison of TiO2(110) Surfaces by XPS: Effects of UV Exposure, Electron Beam and Ion Beam Damage
Authors: Baer D. R. , Xiong-Skiba P. , Shultz A. N. , Wang L.-Q. , Englehard M. H.
Published: July 2002

Many studies have been carried out on rutile TiO2 since it was discovered to be a photocatalyst with relatively high efficiency for the decomposition of water. Surface defects are believed to play an important role in dissociation of absorbed water and other small molecules. Defects created on a TiO2(110) surface by thermal annealing in vacuum, or by low-density electron beam irradiation, ultraviolet illumination, and Ar+ ion bombardment, were examined by x-ray photoelectron spectroscopy (XPS). The XPS multiplex spectra of O 1s and Ti 2p peaks were collected. The experiment was carried out in a Perkin-Elmer Physical Electronics 560 Multiprobe surface analysis system with a double pass cylindrical mirror analyzer. Nonmonochromated Mg Kα x-rays were used to generate the spectra.
UHV-Cleaved Single Crystal Cr2O3 (101¯2) by XPS and UPS
Authors: Li Xiaomei , Henrich V. E.
Published: July 2002

The oxides of chromium cover a wide stoichiometry range. There is a great deal of published x-ray photoelectron spectroscopy (XPS) data on Cr metal, where the goal is often identification of the oxide stoichiometry. In the last few years, thin Cr oxide films have also been grown epitaxially on other materials, and again the determination of stoichiometry is crucial. Presented here are Mg Kα XPS spectra taken from atomically clean, ultrahigh vacuum-cleaved, single crystal Cr2O3 (101¯2). The two largest peaks are the main Cr 2p3/2 and 2p1/2 lines, while the other features are satellites. The satellite structure is an important property of the oxide that may help to differentiate oxides of different stoichiometries. [See X. Li, V. E. Henrich, T. Saitoh, and A. Fujimori, Mater. Res. Soc. Symp. Proc. 307, 205 (1993).]
α-AlF3 by XPS and XAES Referenced by Au 4f7/2
Authors: Böse O. , Kemnitz E. , Lippitz A. , Unger W. E. S.
Published: July 2002

Powder XRD defined α-AlF3 has been investigated by XPS and XAES using the Au 4f7/2 orbital for static charge referencing. This feature originates from well-defined and chemically inert 20 nm gold particles deposited in a highly dispersed pattern on the sample surface. The particles, with a sharp particle size distribution, were obtained from a highly purified colloidal solution (Na concentration below 1 mg/l−1). This procedure allows a determination of gold-referenced XPS and XAES data sets.
Thermal Stability of Ultrathin Co/Pt(111) Films Studied by AES
Authors: Tsay Jyh-Shen , Shern Ching-Song
Published: July 2002

Rotated incommensurate Co domains are observed by LEED after applying an annealing treatment on Co/Pt(111). The thermal stability and surface composition of such a film can be obtained by monitoring the AES spectra after annealing. The specimens were ultrathin Co films grown on a Pt(111) single crystal surface at 300 K. The Pt(111) surface was clean by cycles of ion sputtering and annealing in an ultrathin vacuum chamber. All spectra were collected with a surface science instrument of VG Microtech.
Thermal Evolution of Anodized Nb by XPS
Authors: Daccà Adriana , Gemme Gianluca , Mattera Lorenzo , Parodi Renzo
Published: July 2002

XPS spectra acquired on anodized niobium during a thermal treatment from 300 to 1223 K are reported. The anodization process consists of growing a layer of oxide of known thickness on the metal surface; the sample is kept in a solution of ammonia inside an electrochemical cell and a d.d.p. is applied to the electrodes. We acquired XPS spectra by using a PHI 5600 ESCA multitechnique spectrometer with an Al Kα monochromatized source. The spherical capacitor analyzer operated in the constant energy mode at a pass energy of 5.85 eV. Measurements at two emission angles, 0° and 70°, and at temperatures between 300 and 1223 K are reported. This XPS study puts in evidence the existence of a transition on the Nb surface from Nb pentoxide to Nb pure metal during the heating phase.
Introduction to Studies of Aluminum and its Compounds by XPS
Authors: Sherwood Peter M. A.
Published: July 2002

Aluminum is a very important element because of its many practical applications, and XPS provides an attractive method for the investigation of, and distinguishing between, aluminum and its compounds. The Al 2p core XPS spectra shows a substantial shift (about 2 eV) between the metal peak and compound peaks, and the metal peak width is much less than the width of the compound peaks. This fact has been used in numerous studies where the Al 2p spectrum can be easily curve fitted to identify a percentage area due to the metal and due to aluminum compounds. Several measurements of this kind, representing aluminum metal and 11 of its compounds, have been collected in a special issue of Surface Science Spectra. This Introduction summarizes the data to be presented and provides an overview of the use of and interpretation of XPS studies of aluminum and its compounds.
HgBa2CaCu2O6+δ by XPS
Authors: Vasquez R. P. , Rupp M. , Gupta A. , Tsuei C. C.
Published: July 2002

XPS core level and valence band spectra are presented for a chemically etched epitaxial thin film of superconducting HgBa2CaCu2O6+δ (Tc = 123 K) on a SrTiO3 (100) substrate. These data exhibit lower levels of high binding energy contaminant signals in the O 1s and alkaline earth core level regions compared to studies in the literature, and a clear Fermi edge in the valence band region, evidence of a high quality surface.
Spin Dependent Electronic Structure of Doped Manganese Perovskites
Authors: Park J.-H.
Published: July 2002

The spin-resolved photoemission spectra were successfully obtained from La0.7Sr0.3MnO3 190 nm thick epitaxial film on SrTiO3(001). Well below Tc the results clearly manifest the half-metallic nature, i.e., for the majority spin, the photoemission spectrum clearly shows a metallic Fermi cut-off, whereas for the minority spin, it shows an insulating gap with disappearance of the spectral weight at ∼0.6 eV binding energy. On heating through Tc the spectra show no difference for different spins and the spectra weight at the Fermi level (EF disappears, indicating that the Mn 3d spins become disordered) and the system undergoes the ferromagnetic metal to paramagnetic non-metal transition.
Pyrocarbon and its application to reactor technology
Authors: Nickel H.
Published: July 2002

A survey of deposition methods for pyrocarbons is given, especially of the fluidized bed process for nuclear fuel kernel coating. In the fluidized bed process, it is possible to deposit isotropic pyrocarbon layers which are much more resistant to fast neutron irradiation than are anisotropic pyrocarbon layers. It has been demonstrated that the previous evaluation techniques are not sufficient to characterize isotropic pyrocarbon material. Therefore increased efforts have been made to develop new methods which are described and discussed. Also results of irradiation behavior of pyrocarbon fuel particles coatings are mentioned.
Structure and properties of arc-sprayed titanium, niobium, and molybdenum coatings
Authors: Steffens H.-D. , Müller K.-N.
Published: July 2002

Since density, ductility, and homogeneity of titanium coatings have a special significance by reason of the use of such coatings in the fabrication of chemical apparatus and equipment, metallurgical tests were conducted with a view to determining the effect of the gas atmosphere on these properties. The various tests yielded the following findings. Photographs of the structure of the coatings taken through a light-optical and electron-optical microscope reveal that arc-sprayed titanium coatings are completely dense, crack-free, and homogeneous if they have been applied in a shielding gas atmosphere of highest-purity argon. Adding reactive gases such as nitrogen to the shielding gas atmosphere causes inhomogeneous, brittle, and cracked coatings to be produced which are characterized by segregations in the direction of the temperature gradient. Examination under a scanning electron microscope and a photoemission electron microscope reveals the presence of dentritic nitrides in nitrated arc-sprayed titanium coatings. Structural examinations conducted with an x-ray diffractometer reveal that arc-sprayed titanium applied in an inert gas atmosphere does not contain foreign phases, which means that it is free from oxides and nitrides and may hence be regarded as homogeneous. By reason of the high cooling rate obtaining in thermal spraying, the transformation of the lattice structure of the titanium from the β-phase into the a-phase which, in equilibrium, occurs at 882 °C, is partially suppressed so that the spray coatings contain unstable β-titanium in addition to the stable a-titanium. As the partial pressure of the nitrogen increases the super-cooled β-phase of the titanium decreases in proportion to the increase in a-Ti stabitization. The angle shift of the diffraction reflections already noted in spraying in an atmosphere of highest-purity argon, increases with rising nitrogen content since, for one thing, the internal tensile stresses increase with increasing embrittlement of the structure and, for another, the interstitial solution of the nitrogen expands the mixed crystal. Microhardness measurements prove that the hardness of the coatings is low if gas/metal reactions are avoided, whereas the rising partial pressure of reactive gases causes the hardness to increase markedly, which is an indication of decreased ductility of the coatings. Electrochemical measurements prove that arc-sprayed coatings applied in an inert gas atmosphere exhibit the same behavior as the starting materials. The usability of such coatings as a protection against aggresive media has therefore been demonstrated.
Strengthening bulk gold–copper electrodeposits
Authors: Stoltz Daniel L. , Rahe Allan H. , Hren John J.
Published: July 2002

The effects of burnishing and chemical composition on the structure and mechanical properties of bulk gold–copper electrodeposits were studied. After developing quantitative electron microscopic methods, microstructure-calorimetric and mechanical property correlations were obtained. Burnishing was found to increase the stored energy, hardness and mechanical strength of the deposit by preventing large columnar grain growth and by creating a uniform distribution of dislocations (2.6 to 4.0×1011 cm/cm3), twins (Sν∼3×105 cm2/cm3), and subgrains (Sν=2.2 to 3.2×105 cm2/cm3). When the copper content of the burnished gold-copper deposit was increased from 3.6 to 33.2 at. %, a significant enhancement in stored energy, hardness, and mechanical strength was observed and related to the respective increase in dislocation density (∼1×1012 cm/cm3) and decrease in subgrain size (Sν=5.5×105 cm2/cm3).
Temperature determination of thin sapphire substrates
Authors: Paradis E. L. , Shuskus A. J.
Published: July 2002

A technique is presented which allows for a noncontact temperature determination of thin sapphire substrates with ordinary laboratory instrumentation. The technique utilizes the property of expansion with temperature. A calibration curve of sapphire substrate temperature vs heater temperature is deduced. This calibration scheme can be used for other substrate materials which are transparent in the visible region such as fused silica, glass, and many crystals for which thermal expansion data are known.
TaSiN thin-film pattern transfer optimization for 200 mm SCALPEL and extreme ultraviolet lithography masks
Authors: Dauksher W. J. , Resnick D. J. , Clemens S. B. , Standfast D. L. , Masnyj Z. S. , Wasson J. R. , Bergmann N. M. , Han S.-I. , Mangat P. J. S.
Published: July 2002

Optimized etch processes for the pattern transfer of TaSiN-based SCALPEL and extreme ultraviolet lithography masks have been developed. For controllability, the etch rate is very commensurate with the pattern transfer of thin films, about 140 Å/min. Furthermore, selectivity to Cr at the process of record conditions (30 W radio frequency, 375 W inductively coupled plasma, 8 mT) is greater than 50:1, a necessity for pattern transfer on membrane-based masks. Critical dimension bias is on the order of 10 nm. For the fabrication of SCALPEL masks, supporting descum and Cr etch processes were also developed and are described later. Typical intramembrane uniformity of a 12.1 mm by 1.1 mm membrane processed through the entire pattern transfer sequence was found to be 8 nm, three sigma, which is quite favorable when compared with the starting resist uniformity (7 nm, three sigma). Similarly, using a test vehicle spanning 528 membranes, the intermembrane three sigma standard deviation was found to be 9 nm (starting resist uniformity of 8 nm, three sigma).
Scaled measurements of global space-charge induced image blur in electron beam projection system
Authors: Han Liqun , Pease R. Fabian , Meisburger W. Dan , Winograd Gil I. , Takahashi Kimitoshi
Published: July 2002

Previous results on simulations of space-charge induced blur in electron projection systems indicated serious limitations on throughput particularly as minimum feature sizes (MFSs) are reduced below 100 nm. For example, a 40-cm-long 50 kV column might have a maximum throughput of only 0.2 cm2/s at MFS=50 nm [R. F. W. Pease et al., MNE, Italy, 1999]. Direct experimental verification is difficult, so we have developed a set of theory-based scaling laws for electron optics and have carried out a series of experiments for verifying these laws. Our experimental results support the earlier predictions and also confirmed that shortening the column length to the minimum allowed by the maximum practical focusing field strengths (e.g., 1 T and 107 V/m) should bring about dramatic (20- to 50-fold) improvements.
Two-dimensional spatial-phase-locked electron-beam lithography via sparse sampling
Authors: Hastings J. T. , Zhang Feng , Finlayson M. A. , Goodberlet J. G. , Smith Henry I.
Published: July 2002

We report a new mode of spatial-phase-locked electron-beam lithography based on alignment of each e-beam deflection field to a fiducial grid on the substrate. Before exposing the pattern in a given field, the fiducial grid is sparsely sampled with the electron beam at a subexposure dose. These samples form a two-dimensional moiré pattern that is analyzed to calculate field shift, scale, rotation, nonorthogonality, and trapezoidal distortion. Experimental verification of the approach was carried out with a scintillating fiducial grid quenched by interference lithography. Despite a poor signal-to-noise ratio, we achieved sub-beamstep field-stitching and pattern-placement accuracy.
Spectrophotometric Compositional Analysis of Tantalum–Aluminum Alloy Films
Authors: Huber F. , Jaffe D.
Published: July 2002

A comparative technique suitable for the rapid and reliable compositional analysis of sputtered tantalum-aluminum alloy films in the range of 0–68 at.% Al is described. The technique is based on spectrophotometric reflection measurements of anodically formed oxides of the alloys. Oxides formed at a given anodization voltage on different alloys exhibit different reflection spectra due to the compositional dependence of their refractive indexes and thicknesses. Empirical calibration curves were established between Al content (as determined independently by electron microprobe analysis) and minima of the reflection spectra. The calibration curves were linear in the range of approximately 0–55 at.% Al with regression limits (95% confidence level) of ≤±0.82 at.% Al in the range of 20–55 at.% Al.
Performance of a High-Vacuum Induction-Heated Furnace with an Integrated Dewaxing Unit for Sintering Cemented Carbides
Authors: Vollmer Helmut
Published: July 2002

This paper describes a high-vacuum induction furnace for sintering cemented carbides. The special features of this installation which are described in detail are (a) a dewaxing unit which prevents any wax condensation inside the furnace, (b) a temperature measuring device, which gives reproducible values, withstands the attack of CO and has a lifetime of more than 1000 h, (c) a cooling tower which shortens the cooling-down time by 60–80%, and (d) a newly developed automatic-control unit which permits any temperature and pressure program for sintering cemented carbides in a fully automatic manner. Hydrogen flushing is also automatic so that the furnace has only to be charged and discharged manually.
The Problem of the Compounding of Transmission Probabilities for Composite Systems
Authors: Füstöss L. , Tóth G.
Published: July 2002

A clear definition of the transmission probability depending on the flow direction in systems of varying cross sections is given. A method is shown which makes it possible to determine approximately the transmission probability of complex systems. The accuracy of the approximations is refined by proper correction factors. A descriptive concept of flow resistance is introduced. It helps to determine the validity range of the obtained formulas and the dependence of the accuracy on the parameters.
Hydrogen Pumping by a New Catalytic Pump
Authors: Murakami Yoshio
Published: July 2002

A new catalytic pump has been proposed for hydrogen pumping in high and ultra-high vacuum, and its performance is estimated from the kinetic processes involved. This pump consists of an incandescent metal filament (atomizing catalyst), a cuprous oxide layer (oxidizer), and a liquid nitrogen trap, in which molecular hydrogen is thermally dissociated into atomic hydrogen at the filament which acts upon the cuprous oxide layer to produce condensable water vapor. The speed of the pump in the molecular-flow region is, in principle, associated with the rate of formation of atomic hydrogen at the filament, which not only is a function of hydrogen pressure and filament temperature, but also depends on the filament material and the surface coverage of other chemisorbed species. From the experimental data, suitable temperatures have been determined to obtain the maximum efficiency against electric power. Iridium and rhenium are found to be good materials for the pump filament.
Ferroelectric Thin Films by Reactive Sputtering and High-Temperature Conversion
Authors: Vogel S. F. , Barlow I. C.
Published: July 2002

The composition of sputtered films can be altered to give desired ferroelectric properties by firing in an atmosphere containing the elements of the required ferroelectric film. These converted films have the pseudocubic provskite-type structure (a0 = 4.07 Å) and show the ferroelectric characteristics required for memory applications: square hysteresis loops, pulsed switching and retention of polarization.
Porous leak evaluation and application to calibration of a high-pressure ion gauge
Authors: Hultzman W. W. , Krause L. N.
Published: July 2002

Results are presented on the characteristics of a porous platinum leak, of about 10−8 liters/sec nitrogen conductance, as the basic element for the control and measurement of gas flowrate into a vacuum gauge calibration system. The leak produced free-molecule type flow for supply pressures ranging from 8 to 800 Torr, and for ten different gases whose molecular weights ranged from 2 to 131. Leak conductances were determined to within a few percent limit of error by measuring the pressure rise in a known volume downstream of the leak. Since this pressure-rise method requires less than 10 min to perform, it can be done at any convenient time during a gauge calibration. Results are also presented on the relative sensitivity of a high-pressure ion gauge for ten gases at 10−4 Torr and on the gauge's nonlinearity (for N2) in the range 10−4 to 1 Torr.
Evaporative segregation in 80% Ni–20% Cr and 60% Fe–40% Ni alloys
Authors: Gupta K. P. , Mukherjee J. L. , Li C. H.
Published: July 2002

An analytical approach is outlined to calculate the evaporative segregation behavior in metallic alloys. The theoretical predictions are based on a “normal” evaporation model and have been examined for Fe–Ni and Ni–Cr alloys. A fairly good agreement has been found between the predicted values and the experimental results found in the literature.
Granular Superconducting Films
Authors: Deutscher G. , Gershenson M. , Grünbaum E. , Imry Y.
Published: July 2002

The broadening and the decrease of the superconducting transition temperature observed in high resistivity films of granular aluminum is analyzed in terms of a critical fluctuation model. Detailed grain size measurements indicate that the enhanced transition temperature observed in lower resistivity films is due to changes in the electron-phonon coupling rather than to an excitonic mechanism.
Projection Color Television Displays
Authors: Good W. E. , True T. T.
Published: July 2002

Current projection television displays are achieved by direct projection from a small CRT or by controlling the light from a separate light source with a “light valve.” This paper briefly reviews the Swiss Eidophor three-gun color television light valve and, more fully, the recently announced single-gun color television sealed light valve developed by the General Electric Company.
Optimization of the Performance of High-Brightness Electron Guns
Authors: Ahmed H. , Munro E.
Published: July 2002

The optimization of the performance of a high-brightness electron gun requires the correct choice of material, and LaB6 has been shown to have advantages over pure metal emitters. The finely pointed tip must be accurately positioned in the grid aperture to achieve maximum brightness and the electrode positions must be maintained if the benefits of improved stability are to be realized. The brightness is measured using two apertures to define the beam and a Faraday cage to collect the current. The increased brightness is confirmed by the improved performance of the scanning electron microscope. However emission peaks have been detected under certain conditions of operation and appear to depend strongly on the position of the tip with respect to the Wehnelt. The design of this electrode has been considerably modified to a conical shape to try and achieve high brightness while suppressing some of the emission peaks. For a range of gun geometries and electrode potentials, the potential distribution near the tip and Wehnelt aperture has been computed using the finite element method. This computes the potential at points on a two-dimensional mesh, whose shape can be varied at will, which permits analysis of complex electrode configurations. Very small tip radii can be allowed for with an accurate determination of the tip field. From the tip field the electron trajectory can be computed using a “model” field near the tip and solving the paraxial ray equation from there onwards. It is observed that under certain conditions of operation a virtual crossover is obtained with pointed tip electron guns. The conditions under which Schottky enhanced emission may be present are also obtained and the emitting area of the cathode can be estimated.
Sputtering measurements with the double resonator technique
Authors: EerNisse E. P.
Published: July 2002

The double resonator technique for simultaneous thin film areal mass density and integrated lateral stress measurements will be reviewed. The technique is applied to the measurement of the sputtering yield of 45-keV Kr onto Au. The compressive stress buildup in the Au and the change in sputtering yield from 16 to 26 atoms/ion as the accumulated Kr fluence loads the Au substrate are demonstrated. The errors arising in the use of single resonator microbalances from the compressive stress buildup are shown to be of the order of 10%–25% for sputtering yield measurements at low-to-medium ion fluences where substrate loading occurs.
Centrifugal casting of misch-metal liners for the 105-mm projectile
Authors: Pfeifer W. H. , Moak D. P.
Published: July 2002

Centrifugal casting was investigated as a process to place an integral liner of misch metal within the standard 105-mm projectile body. Vacuum induction-melting equipment enabling molten misch metal to be poured into a vertically rotating projectile body that can be heated to temperatures up to ≈1600 °F was employed. Analytical solidification studies were made to help establish experimental guidelines. These included calculations of rotational velocity required to provide the desired misch-metal distribution, a simple heat balance to denote mold-heating effects from the heat content of the misch metal, and estimation of solidification times as a function of both misch metal and projectile-body temperatures. Both the misch metal employed and the as-received projectile bodies were thoroughly characterized to provide baseline data, and an annealing study of the AISI Type 1018 steel projectile body was made to determine the temperature at which serious degradation of the yield strength (provided by extensive cold working) occurs. Casting experiments were conducted to establish process parameters and demonstrate feasibility of the centrifugal casting technique. Most castings were destructively examined to determine the liner quality, the bond between the liner and projectile body, and the final properties of the projectile body. These experiments revealed that projectile-body temperatures of 1100–1150 °F are critical in effecting a compromise between retention of the cold-worked properties of the steel and attainment of the desired casting profile and liner-projectile body bonding.
Vacuum heat treatment today
Authors: Westeren Herbert W.
Published: July 2002

Vacuum heat-treating equipment is defined as “controlled-atmosphere” equipment—controlled in quality and in quantity with special emphasis on partial pressures as well as total pressures. This concept is substantiated by a brief review of vacuum heat-treating equipment from pioneer studies by a leading vacuum furnace manufacturer, the development of fibrous graphite furnaces, vacuum oil-quench equipment, and vacuum water-quench through vacuum carburizing equipment.