| Strain Characterization of AsH3 Induced Exchange Reactions in InP Grown by OMVPE |
APR 96 |
8 pages |
| Authors:
A. R. Clawson; C. M. Hanson; NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
|
 | Behavior of As-P intermixing in heterojunctions of As-compounds grown on InP (001) has been inferred from strain of very thin mis-matched layers inserted periodically in InP to form multilayer superlattice structures. Strain components are observed for both As-P exchange in the InP and from inserted layer growth. The data suggest that for As-compounds grown on an InP surface the availability of As for both layer growth and As-P exchange is ... |
|
| Research Progress on Growth of UV Nonlinear Optical Borate Crystals |
APR 96 |
24 pages |
| Authors:
Tang Dingyuan; NATIONAL AIR INTELLIGENCE CENTER WRIGHT-PATTERSON AFB OH
|
| In this paper, a description of research advance on the growth of some important uv nonlinear optical crystals, such as BBO LBO and KBBF etc., which were first invented and developed by our institute during the past decade is given. The review consists of the following contents: the choice of method for the crystal growth; the technique of the crystal growth and the development; the choice of the flux; the ... |
|
| Measurement and Analysis of Electro-Optical Materials and Devices |
APR 96 |
182 pages |
| Authors:
J. A. Adamski; A. F. Armington; J. H. Bloom; D. R. Gabbe; W. Higgins; PARKE MATHEMATICAL LABS INC LOWELL MA
|
| A description is given of the research and experimental work accomplished on the injection of phosphorus into an indium melt. Two crystal growing techniques were used to produce single crystals of InP. Three little used crystal growth techniques are discussed for growing nonlinear optical materials. Device processing techniques covering the use of an ultra high vacuum deposition system for evaporating a dielectric layer of silicon monoxide is described. Nonlinear materials ... |
|
| Development of Compact 1.06 and 2.1 Micron Lasers |
31 MAR 96 |
3 pages |
| Authors:
Vikram S. Kushawaha; HOWARD UNIV WASHINGTON DC
|
| During the project period, extensive studies of the laser performance of a Nd: and Ho:Tm ions doped in YAG (Y 3Al5O12), KGW (KGd (WO4)2) host crystals pumped by diode lasers operating in continuous wave or pulsed modes of operation. The diode lasers were temperature tuned to select the appropriate wavelengths to pump the Nd-ions at 785 nm. The laser action from these ions was observed at 1.06 and 2.1 micron, ... |
|
| Kinetics of Growth Phenomena at Semiconductor Surfaces |
19 MAR 96 |
13 pages |
| Authors:
Horia Metiu; CALIFORNIA UNIV SANTA BARBARA DEPT OF CHEMISTRY
|
| Our research is directed towards understanding the processes taking place during epitaxial growth of solid surfaces, with a view to potential control of growth. We use computer simulations and, when possible, simple models that are tested by simulations and by comparison with experiments. Issues include movement of atoms and of vacancies; nucleation processes, aggregation, and density; and the evolution of island shape. To take one example, we have studied, using ... |
|
| Materials for Adaptive Structural Acoustic Control. Volume 1 |
13 MAR 96 |
|
| Authors:
L. E. Cross; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
 | This report documents work carried forward over the fourth year of a five year ONR sponsored University Research Initiative (URI) entitled 'Materials for Adaptive Structural Acoustic Control.' The program has continued to underpin the development of new electroceramic, single crystal and composite materials combinations for both the sensing and actuation functions in adaptive structures. For the lead based perovskite structure relaxor ferroelectric electrostrictors, new experimental and theoretical studies have underscored ... |
|
| Growth, Characterization and Device Development in Monocrystalline Diamond Films |
MAR 96 |
34 pages |
| Authors:
R. F. Davis; R. J. Nemanich; Z. Sitar; S. P. Bozeman; M. T. McClure; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| A combination of in-situ microprobe sampling and detailed chemical kinetic modeling has been employed to provide insight into the mechanisms of nucleation and growth of high quality diamond films in combustion flame CVD. Growth of high quality diamond with large area uniformity has been accomplished. The effects of substrate temperature and gas ratio on morphology and quality are reported. In-situ measurements of gas phase species are described. Calculations were performed ... |
|
| Environmental Effects of Dredging. Grain Size and Total Organic Carbon Effects on Benthic Organisms |
MAR 96 |
10 pages |
| Authors:
Jerre G. Sims; ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
|
| The purpose of this technical note is to document the effects of grain size and total organic carbon (TOC) on benthic organisms and evaluate those effects in terms of their potential to confound the results of dredged material bioassays. Sediment toxicity tests must be able to assess the effects of sediment-associated contaminants without the influence of nontreatment factors (that is, sediment, grain size, sediment TOC, ammonia toxicity, etc.). While nontreatment ... |
|
| Epitaxial Quality of Thin Ag Films on GaAs(100) Surfaces Cleaned with Various Wet Etching Techniques |
MAR 96 |
17 pages |
| Authors:
K. E. Mello; S. R. Soss; S. P. Murarka; T. M. Lu; S. L. Lee; ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS
|
| Two theta scans and pole figure X-ray analyses have been used to examine the crystal structure and orientation of Ag films deposited on GaAs(100) substrates cleaned by a variety of wet etches. Where epitaxy was observed, it was of the type Ag(110)GaAs(100). The H3PO4/HCl sequential etch yielded the film with the highest degree of preferred orientation, with the H2SO4/HCl, NH4OH, and HF etches producing films of decreasing quality in the ... |
|
| Preparation and Evaluation of Single-Crystal Yttrium Titanate-Based Monofilaments |
MAR 96 |
43 pages |
| Authors:
J. H. Sheehan; R. J. Prince; G. H. Reynolds; J. S. Haggerty; J. Sigalovski; MSNW INC SAN MARCOS CA
|
| This SBIR Phase I research produced and characterized single-crystal monofilaments of Y2Ti2O(z) for preliminary evaluation as reinforcement. These Experiments were initiated without benefit of prior experience with the material because no crystal growth citations were identified and equilibrium phase relationships were incomplete. |
|
| Electronic Characterization of Defect Sites on Si(OOl)-(2x1) by STM |
27 FEB 96 |
31 pages |
| Authors:
V. A. Ukraintsev; Z. Dohnalek; J. T. Yates Jr; PITTSBURGH UNIV PA SURFACE SCIENCE CENTER
|
| A study of the defect sites on Si(OOl)-(2x1) was undertaken by employing Comparative Scanning Tunneling Spectroscopy (CSTS). Ni induced defects, the A, B, and C defects, and the A and B steps were studied. The STM tip induced band bending significantly affects tunneling spectra. This is evident from comparison of LDOS and local surface potentials obtained for high (10 Ohm-cm) and low (100 Ohm-cm) doped Si(001) crystals. Decay in the ... |
|
| Thermoluminescence Radiation Dosimetry Using Transparent Glass Containing Nanocrystalline Phosphor. |
08 FEB 1996 |
25 pages |
| Authors:
Brian L. Justus; Alan L. Huston; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| Radiation is detected using a light transparent thermoluminescent dosimeter that comprises a nanocrystalline phosphor dispersed in a light transparent glassy matrix, such as Vycor glass. The dosimeter is placed in an environment in which radiation is present for a period of time, removed from the environment and then heated to emit light, the intensity of which is indicative of the radiation dose. The method of the invention is useful for ... |
|
| Gas-Surface Interactions Near Dissociation Threshold. |
FEB 1996 |
6 pages |
| Authors:
Hanna Reisler; Curt Wittig; UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF CHEMISTRY
|
| Two aspects of molecular decomposition on MgO(100) surfaces were explored. Nitrogen dioxide entrained in a molecular beam was photoexcited and directed at a crystal surface. Following collision, it had enough internal plus translational energy to undergo dissociation. The NO products, which were detected with state and angular resolution, were scattered preferentially in the specular direction and their internal energies were analyzed The results showed that the collisional dissociation was rather ... |
|
| Nucleation Growth and Defect Engineering in Diamond Thin Films |
FEB 96 |
5 pages |
| Authors:
Jagdish Narayan; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| We studied the chemical nature of the substrate and the role of buffer layers on nucleation and growth of diamond during chemical vapor deposition (hot-filament). The transition metals with partially filled d-atomic orbitals are found to stabilize SP2 bonding which leads to enhanced precipitation of SP2 bonded non-diamond carbon phases such as graphite, amorphous and glassy carbon films. We have shown that by alloying these metals with electron donating elements, ... |
|
| Low Temperature Materials Growth and Processing Development for Flat Panel Display Technology Applications |
FEB 96 |
11 pages |
| Authors:
OREGON GRADUATE INST BEAVERTON
|
| This report is a collection of documents pertaining to low temperature materials growth and processing development for flat panel display technology applications. Topics include: (1) field emitter flat panel results, (2) modeling of a-Si TFTs for liquid crystal display applications, and (3) electroluminescent displays. |
|
| Development of a Liquid Crystal Smart Reflector |
23 JAN 96 |
19 pages |
| Authors:
Robert B. Meyer; BRANDEIS UNIV WALTHAM MA DEPT OF PHYSICS
|
| We present results concerning the development of liquid crystal smart reflectors, consisting of a cholesteric liquid crystal with temperature sensitive helix pitch, in combination with a light absorbing dye. Light entering the liquid crystal is absorbed by the dye, generating heat which raises the temperature of the liquid crystal. The resulting change in the helix pitch of the cholesteric causes an increase in its reflectivity, reducing the intensity of light ... |
|
| Germanate Glass Ceramic. |
23 JAN 1996 |
|
| Authors:
John M. Jewell; Barry B. Harbison; Ishwar D. Aggarwal; Shyam S. Bayya; DEPARTMENT OF THE NAVY WASHINGTON DC
|
| A germanate glass ceramic article which has better thermal and physical properties than the competing materials of zinc sulfide, spinel, and sapphire is made by mixing germanate ceramic glass components; melting the components to form a molten mass; cooling the molten mass to form a solid glass article; nucleating the solid article by heating it in the range of about 630 deg-790 deg C. for about 1-16 hours to develop ... |
|
| Structural, Magnetic and Electrical Properties of the New Ternary CePdIn2 |
12 JAN 96 |
29 pages |
| Authors:
Y. Ijiri; F. J. DiSalvo; H. Yamane; CORNELL UNIV ITHACA NY DEPT OF CHEMISTRY
|
| CePdIn2 is found to crystallize in the orthorhombic space group Cmcm (Z=4) with a = 4.6210(9) A, b = 10.694(2) A, and c = 7.455(2) A. Single crystal X- ray data were refined to R = 0.0459 (wR2 = 0.0666), with 255 independent reflections and 16 variables. The structure adopts the BRe3 structure type and is the first known Ce-containing member. Magnetic measurements indicate that CePdIn2 undergoes a ferromagnetic phase ... |
|
| Electric and Magnetic Behavior of Ce8Pd24M Compounds with M = (Ga, In, Sn, Pb, Sb and Bi) |
12 JAN 96 |
34 pages |
| Authors:
R. A. Gordon; C. D. Jones; M. G. Alexander; F. J. DiSalvo; CORNELL UNIV ITHACA NY DEPT OF CHEMISTRY
|
| We have prepared and examined the resistivity and magnetic susceptibility of a series of ternary compounds with composition Ce8Pd24M, where M is one of Ga, In, Sn, Sb, Pb or Bi and the related composition La8Pd24In. All members of this series are cubic with effective cerium moments consistent with tri-valent cerium. The lanthanum compound behaves as a simple metal in resistivity and has a small, negative susceptibility at 295K. All ... |
|
| Crystal Structure, Electric and Magnetic Behavior of Ce2Pd9Sb3. |
12 JAN 1996 |
23 pages |
| Authors:
Robert A. Gordon; Francis J. DiSalvo; Rainer Poettgen; Nathaniel E. Brese; CORNELL UNIV ITHACA NY DEPT OF CHEMISTRY
|
| A new ternary compound in the Ce-Pd-Sb system has been observed and studied by single crystal diffraction, magnetic susceptibility and resistivity. This new compound, Ce2Pd9Sb3, was determined to crystallize in the Y2Co3Ga9 structure type: Cmcm, a = 13.769(2)A,b = 8.0412(8)A, c= 9.348(1)A,wR2 = 6.7%, 709F( sup 2) values, and 42 variables. An anti-site relationship exists between the p-block and transition elements relative to the parent structure type. The magnetic susceptibility ... |
|
| Photorefractive Tungsten Bronze Crystals for Optical Limiters and Filters. |
JAN 1996 |
134 pages |
| Authors:
Ratnakar R. Neurgaonkar; ROCKWELL INTERNATIONAL THOUSAND OAKS CA SCIENCE CENTER
|
| The photorefractive tungsten bronze SBN:6O and BSKNN-2 crystals were investigated for sensor protection applications with considerable success. Our best photorefractive crystals exhibit response times of approximately 10 microseconds with coupling > 25/cm. This fast response was achieved using suitable dopant combinations, external field and focusing the incoming 1W/sq cm laser beam. Prototype limiters based on these photorefractive crystals have been tested at the University of Arkansas and their overall performance ... |
|
| Fabrication of Nanostructures in Group IV Semiconductors |
JAN 96 |
140 pages |
| Authors:
Jason Xu; Andrew J. Stecki; CINCINNATI UNIV OH NANOELECTRONICS LAB
|
| The objectives of this work combine a study of the fundamental mechanisms of light emission from porous silicon (PoSi) with the development of techniques for fabricating PoSi-based light emitting structures and devices. The incubation time of PoSi formation was found to have a strong dependence on the substrate doping type and concentration. Utilizing the incubation time difference and Ga+ FIB implantation a process was successfully developed to fabricate selective light ... |
|
| Raman Spectra of Inorganic Compounds Related to Solid State Tribochemical Studies |
JAN 96 |
76 pages |
| Authors:
Jeffrey S. Zabinski; Neil T. McDevitt; WRIGHT LAB WRIGHT-PATTERSON AFB OH
|
| The accomplishments of this research program were twofold: (a) establish a basic Raman spectral library for materials related to solid-state tribological studies, and (b) develop a usable analytical approach for this technology in the Materials Directorate. The research was concerned with the characterization of the Raman spectra and how observed changes in these data may reflect the stress placed on a crystal structure during wear testing. This type of study ... |
|
| Stimulated Emission without Cavity in Powders and Single Crystals of Nd Doped Materials |
96 |
9 pages |
| Authors:
M. A. Noginov; N. E. Noginova; H. J. Caulfield; P. Venkateswarlu; T. T. Thompson; ALABAMA A AND M UNIV NORMAL
|
| Short (>300 ps) pulses of stimulated emission were found from powders of NdAl3(BO3)4, NdSc3(BO3)4, and Nd:Sr5(PO4)3F laser crystals under 532 nm and 805 nm excitation. Study of stimulated emission in the mixture of two powders has shown that different components influenced each other. The main feature of experimentally observed stimulated emission described with a simple model accounting for (4)F3/2 excited state concentration and emission energy density. |
|
| 3RD European Symposium on X-Ray Topography and High Resolution Diffraction, X-TOP '96, Palermo, Italy, Hotel Torre Normanna, 22-24 April 1996. (Abstracts) |
96 |
221 pages |
| Authors:
CONSIGLIO NAZIONALE DELLE RICERCHE ROME (ITALY)
|
| The third European symposium was held at the hotel Torre Normanna, Italy on 22-24th of April 1996. The purpose of this symposium is to discuss advanced X ray Topography methods and high resolution diffraction. The symposium also emphasizes instrumental developments, theoretical models and applications to crystal growth, surface and interfaces. |
|
| High Pressure Science & Technology: Proceedings of the Joint XV AIRAPT and XXXIII EHPRG International Conference Warsaw, Poland, September 11-15, 1995 |
96 |
|
| Authors:
Witold A. Trzeciakowski; POLISH ACADEMY OF SCIENCES WARSAW
|
| This conference has been organized by High Pressure Research Center (UNIPRESS), Polish Academy of Sciences and Institute of Experimental Physics at Warsaw University. This international conference was held in Warsaw University, Poland from 11-15th of September 1995. The proceedings served as a through review of high pressure research all over the world. Best of all, the conference also brought together participants from all important centers of high pressure research. ... |
|
| Proceedings of the International Conference (9th) on Molecular Beam Epitaxy Held in Malibu, California, USA on 5-9 August 1996. Part I, Sections I- VIII |
96 |
705 pages |
| Authors:
Y. C. Kao; ELSEVIER SCIENCE PUBLISHERS LTD BARKING(UNITED KINGDOM)
|
| In MBE-IX, 265 papers, including 14 invited talks, were selected from 400 abstract submissions. The percentage of papers being selected is the lowest as compared to previous International MBE conferences, indicating strong interest and growth in MBE development. MBE is now of fundamental importance in the creation of advanced new materials and device structures for electronics, optoelectronics, and photonics applications. MBE has progressed to the point that it is now ... |
|
| Proceedings of the International Conference (9th) on Molecular Beam Epitaxy Held in Malibu, California, USA on 5-9 August 1996. Part 2, Sections IX- XVIII |
96 |
|
| Authors:
Y. C. Kao; ELSEVIER SCIENCE PUBLISHERS LTD BARKING(UNITED KINGDOM)
|
|
| Amphiphilic Linear-branched Copolymers and Their Fluorinated Dendritic Analogs |
1996 |
3 pages |
| Authors:
Dong Yu; Jean M. Frechet; CALIFORNIA UNIV BERKELEY DEPT OF CHEMISTRY
|
| Copolymers of PEG and analogs of second generation dendrimer have been synthesized and characterized. Normal polyether dendrimers can be replaced by other branched structures with similar physical properties. Incorporation of fluorinated chains enhance the hydrophobicity of the dendrimer. Attachment of long alkyl chains to dendrimers to achieve the same goal is under investigation and applications of the amphiphilic copolymers are being explored. |
|
| Photoreflectance for the In-Situ Study and Characterization of Semiconductor Growth and Processing |
31 DEC 1995 |
10 pages |
| Authors:
Fred H. Pollack; BROOKLYN COLL NY DEPT OF PHYSICS
|
| The objective of this program was to utilize photoreflectance for the in-situ and ex-situ study of a number of fundamental as well as applied properties of semiconductors, semiconductor microstructures, semiconductor surfaces/interfaces as well as actual device structures. These include: (a) the determination of the substrate temperatures and alloy composition during actual growth at elevated temperatures, (b) a detailed in-situ study of Fermi level pinning, passivation, and Schottky barrier formation as ... |
|
| Reactions of Phenylaluminium Compounds with E(SiMe3)3 (E = P or As): X- Ray Crystal Structures of Ph3Al.E(SiMe3)3 (E = P or As) and Ph2(Cl)Al.P(SiMe3)3 |
20 DEC 95 |
31 pages |
| Authors:
Janeen A. Cooke; Hamid Rahbarnoohi; Andrew T. McPhail; Richard L. Wells; Peter S. White; DUKE UNIV DURHAM NC DEPT OF CHEMISTRY
|
| The independent reactions of Ph3Al with E(SiMe3)3 (E = P or As) in 1:1 mole ratios afforded the adducts Ph3Al.E(SiMe3)3 (E = P (I) and As (II), respectively). The attempted dehalosilylation reactions between Ph2AlCl and E(SiMe3)3 (E = P or As) in 1:1 mole ratios yielded only the adducts Ph2(Cl)Al. E(SiMe3)3 (E = P (III) and As (IV)). The adduct Ph(Cl)2Al.P(SiMe3)3 (V) was isolated from the reaction of equimolar amounts ... |
|
| Synthesis, Characterization and Immobilization of Nanocrystalline Binary and Ternary III-V (13-15) Compound Semiconductors |
20 DEC 95 |
24 pages |
| Authors:
Lara I. Halaoui; Shreyas S. Kher; Michael S. Lube; Steven R. Aubuchon; Carolynne R. Hagan; DUKE UNIV DURHAM NC DEPT OF CHEMISTRY
|
| Two synthetic routes to nanocrystalline III-V (13-15) materials are discussed. The first employs dehalosilylation reactions between Group III trihalides and E(SiMe3)3 (E = P, As) in hydrocarbon solvents affording nanocrystalline III-V semiconductors or their precursors. The second involves reactions of MX3 (M = Ga, X = Cl, I; M = In, X = Cl, I) in glymes with in situ synthesized (Na/K)3E (E = P, As, Sb) in aromatic solvents, ... |
|
| Synthesis and Structural Characterization of Alkyl, Gallium-Phosphorus Compounds, X-Ray Crystal Structures of (Me3CCH2)2(Cl)Ga.P(SiMe3)3, R2GaP(SiMe3) 2GaR2Cl(R=Me3CCH2 and Me3SiCH2), and ((R)(X)GaP(SiMe3)2)2 (R=Me3CCH2, X=Cl; R=Me3CCH2, X=Me3CCH2; R=Me3S |
20 DEC 95 |
35 pages |
| Authors:
Richard L. Wells; Ryan A. Balwin; Peter S. White; William T. Pennington; Arnold L. Rheingold; DUKE UNIV DURHAM NC DEPT OF CHEMISTRY
|
| Continued activity in the development of single-source precursors to 13-15 semiconductor materials has motivated our laboratory to investigate the synthesis of novel organogallium phosphorus compounds which might serve as potential precursors to GaP. Recently, our efforts to produce the gallium- phosphorus bond have led to the formation of interesting ring compounds and simple adducts. |
|
| Reactions of Trimethylaluminum with Secondary Arsines: Synthesis and Characterization of Phenyl(trimethylsilylmethyl)arsine, Ph(Me3SiCH2)AsH, and the X-Ray Crystal Structures of the Trimers, Me2AlAsPh2!3.(C7H8)2 and Me2AlAs(CH2SiMe3)Ph3 |
20 DEC 95 |
33 pages |
| Authors:
Janeen A. Cooke; Andrew P. Purdy; Richard L. Wells; Peter S. White; DUKE UNIV DURHAM NC DEPT OF CHEMISTRY
|
| The reactions of trimethylaluminum with diphenylarsine, Ph2AsH, and phenyl(trimethylsilylmethyl)arsine, Ph(Me3SiCH2)AsH, in 1:1 mole ratios afford the trimeric compounds Me2AlAsPh23.(C7H8)2 (1) and Me2AlAs(CH2SiMe3)Ph3 (2), respectively. Compounds 1 and 2 are the first Al-As six-membered ring compounds to be structurally characterized by single-crystal X-ray crystallography, as well as 1H and 13C solution NMR spectroscopy. X-ray crystallographic analysis revealed that trimer 1 is a toluate which crystallizes in the monoclinic space group P ... |
|
| Nanocrystalline Systems For Protection, Detection and Demilitarization |
19 DEC 95 |
24 pages |
| Authors:
Michael Graetzel; ECOLE POLYTECHNIQUE FEDERALE DE LAUSANNE (SWITZERLAND) INST DE CHIMIE PHYSIQU E
|
| Ferritin, an ubiquitous biological iron-storage protein molecule, consists of 24 symmetrically related protein subunits forming a near-spherical hollow shell, apoferritin. The central cavity of the apoferritin shell is occupied by an iron core of ferrihydrite or 5Fe2 03. 9 H2O varying in crystallite structure (amorphous or crystalline) depending on the source of the ferritin which is widely distributed in nature (e.g., mammalian spleen, liver, heart or bacterial, plant or fungal ... |
|
| Growth, Characterization and Device Development in Monocrystalline Diamond Films |
DEC 95 |
18 pages |
| Authors:
R. F. Davis; R. J. Nemanich; Z. Sitar; NORTH CAROLINA STATE UNIV AT RALEIGH DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| X-ray photoelectron spectroscopy (XPS) has been conducted on a TiC(111) substrate to understand bias-enhanced nucleation (BEN) of CVD diamond. The data revealed two important results: i) the C:Ti ratio of the substrate decreases after an initial exposure to the biasing procedure, and ii) the C-C bonding signal is consistent with the formation of island-like deposition of an overlayer. The decrease in the C-Ti bonding signal suggests that BEN causes C ... |
|
| Atomic Layer Epitaxy of Group IV Materials: Surface Processes, Thin Films, Devices and Their Characterization |
DEC 95 |
29 pages |
| Authors:
R. F. Davis; S. Bedair; N. A. El-Masry; Z. Sitar; A. H. Morshed; NORTH CAROLINA STATE UNIV AT RALEIGH
|
| A seeding multi-step deposition process has been developed to nucleate and grow oriented diamond films on both (100) and (111) Ni substrates without graphite codeposition, as shown by SEM and micro Raman spectroscopy. Cross-sectional TEM and XRD confirmed the presence of a polycrystalline Ni4C interlayer between single crystal Ni and the oriented diamond crystals. The key to the process is a molten Ni-C-H surface layer that promotes the nucleation of ... |
|
| High Order Parametric X-Radiation from Silicon and Lithium Fluoride Crystal Monochromators |
DEC 95 |
159 pages |
| Authors:
Joseph R. Thien; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| This thesis examines parametric x-radiation (PXR) generated by Silicon and Lithium Fluoride monochromators, including the first observation of PXR from Lithium Fluoride. Parametric x-radiation may be described as the Bragg scattering of virtual photons associated with relativistic electrons as they pass through single crystal monochromators. As the photons interact with the crystal lattice they produce x-rays which meet the Bragg condition lambda = 2dsintheta sub B, where theta sub B ... |
|
| Assessment of Grain Refinement by Microtexture Analysis in Thermomechanically Processed Al 2519 Alloy |
DEC 95 |
67 pages |
| Authors:
Steven L. Stancy; NAVAL POSTGRADUATE SCHOOL MONTEREY CA
|
| The first part of this study involved determining the mechanism by which elevated-temperature deformation occurred for selected tensile specimens from previous research on thermomechanically processed Al2519 alloy. Microtexture information in the form of discrete pole figures indicated that the most highly superplastic material had completely recrystallized and deformed via grain boundary sliding, whereas material that did not display superplastic behavior deformed via slip. The second part of the study was ... |
|
| X-Ray Crystallographic Studies on Acetylcholinesterase and on its Interaction with Anticholinesterase Agents |
DEC 95 |
73 pages |
| Authors:
Israel Silman; Joel Sussman; WEIZMANN INST OF SCIENCE REHOVOT (ISRAEL)
|
| The objective of this project was to solve, for the first time, by X- ray crystallography, the three-dimensional structure of acetylcholinesterase (AChE) and to learn from this structure the reaction mechanism, inhibition modes and other structural and functional properties of the enzyme. The principal objectives of the current project included: (1) Attempts to obtain crystals of cholinesterases other than T. californica AChE, in particular of AChE of human origin. (2) ... |
|
| Electrical Characterization of 4H-Silicon Carbide P-N Junction Diodes |
DEC 95 |
101 pages |
| Authors:
Michael E. Dunn; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| The current conduction mechanisms of 4H-SiC p+n mesa diodes were studied using current-voltage-temperature (I-V-T), capacitance-voltage- temperature (C-V-T), deep level transient spectroscopy (DLTS), optical observations, and reverse breakdown measurements. Temperature and voltage dependencies of diffusion, recombination, and tunneling current processes are shown to be consistent with Sah-Noyce-Shockley theory. Recombination currents having an ideality factor of A=1.85-2.1 yielded an activation energy of E sub A=1.56 eV, whereas for ideal recombination, A=2 and ... |
|
| Recovering Elastic Moduli of Nonlinear Anisotropic Annular Membranes from Interior Measurements of Deformation and Pressure |
DEC 95 |
54 pages |
| Authors:
Arthur D. Cummings; AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
|
| We investigate the problem of inferring elastic moduli of nonlinearly elastic membranes from interior measurements of deformation and pressure. We begin by formulating a model of membrane deformation under a vertical force where the geometry of the membrane is star-like. The model makes no specification of the constitutive law by which stresses are calculated from applied strains. Under appropriate choice of the constitutive law and simplification of the geometry, we ... |
|
| Radiation Effects and Defects in Solids. Proceedings of the Seventh Europhysical Conference on Defects in Insulating Materials Eurodim 94, Lyon 1 - University July 5-8, 1994. Part III. Volume 136, Number 1-4 |
DEC 95 |
|
| Authors:
Jochen P. Biersack; M. G. Blanchin; J. Davenas; B. Moine; C. Pedrini; LYON UNIV (FRANCE)
|
| Radiation Effects and Defects in Solids publishes experimental and theoretical papers of both a fundamental and applied nature that contribute to the understanding of either phenomena induced by the interaction of radiation with condensed matter or defects in solids introduced not only by radiation but also by other processes. Papers are categorized in three groups. Section A. Radiation Effects - Suitable topics include, but are limited to, atomic collisions, radiation ... |
|
| Radiation Effects and Defects in Solids: Proceedings of the Seventh Europhysical Conference on Defects in Insulating Materials Eurodim 94, Lyon 1 - University July 5-8, 1994. Part II. Volume 135, Numbers 1-4 |
DEC 95 |
|
| Authors:
Jochen P. Biersack; M. G. Blanchin; J. Devenas; B. Moine; C. Pedrini; LYON UNIV (FRANCE)
|
| Radiation Effects and Defects in Solids publishes experimental and theoretical papers of both a fundamental and applied nature that contribute to the understanding of either phenomena induced by the interaction of radiation with condensed matter or defects in solids introduced not only by radiation but also by other processes. Papers are categorized in three groups. Section A: radiation Effects - Suitable topics include, but are limited to, atomic collisions, radiation ... |
|
| Protein-Based Polymers |
30 NOV 95 |
17 pages |
| Authors:
David A. Tirrell; MASSACHUSETTS UNIV AMHERST DEPT OF POLYMER SCIENCE AND ENGINEERING
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| This contract supported synthetic and structural investigations of two classes of protein-based polymers: (1) alanylglycine-rich polymers related to the silks and capable of forming well-defined beta-sheets; and (2) alpha- helical polymers of uniform chain length capable of forming liquid crystalline phases. jg |
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| Strengthening of NiAl Matirix Composites |
30 NOV 95 |
51 pages |
| Authors:
R. J. Arsenault; MARYLAND UNIV COLLEGE PARK
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| A detailed mechanism has been developed which will predict the formation of vacancy-producing jogged-screw dislocations. The motion of these screw dislocations is the thermally-activated rate-controlling mechanism for both the matrix and the NiAl matrix composites. With the exception of very small subgrain or grain sizes and Al2O3 particle size (0.5 micrometer), the internal stress is independent of stress and temperature. The increase in the internal stress caused by the reinforcement ... |
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| Nucleation and Growth of Semiconductor-Metallic Superlattices |
30 NOV 95 |
12 pages |
| Authors:
P. I. Cohen; MINNESOTA UNIV MINNEAPOLIS DEPT OF ELECTRICAL ENGINEERING
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| An investigation of the nucleation and growth as well as magnetic properties of epitaxial FeAl on AlAs/GaAs(100) is reported. These are the first real space studies of the nucleation, growth and properties of so-called thermodynamically stable films. In-situ RHEED and the first UHV STM measurments were used to characterize the surface. Ex-situ MOKE measurements were used to characterize the magnetic properties. FeAl was found to have an unusual incubation effect ... |
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| Lattice Gas Dynamics, Volume 1. Viscous Fluids |
09 NOV 95 |
222 pages |
| Authors:
Jeffrey Yepez; AIR FORCE RESEARCH LAB HANSCOM AFB MA
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| The theory and computation of lattice gas dynamics for viscous fluid hydrodynamics is presented. Theoretical analysis of these exactly conserved, discrete models is done using the Boltzmann approximation, a mean-field theoretical treatment. Theoretical results are then compared to numerical data arrived by exactly computed simulations of simple lattice-gas systems. The numerical simulations presented were carried out on a prototype lattice-gas machine, the CAM-8, which is a virtual finegrained paralled mesh ... |
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| Structural Characterization of Epitaxial Layers for Infrared Detectors |
02 NOV 95 |
12 pages |
| Authors:
D. W. Greve; CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF ELECTRICAL AND COMPUTER ENGINEERIN G
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| UHV/CVD is a growth technique highly suitable for deposition of Ge(x) Si(1-x) heterostructures for long-wavelength infrared detectors. We have used transmission electron microscopy to determine favorable conditions for the growth of these structures. Multiple quantum well structures can be grown with excellent quality without any evidence of nonplanar growth while heterojunction internal photoemission structures incorporated thicker Ge(x)Si(1-x) layers do exhibit nonplanar growth. A modest decrease in growth temperature to 550 ... |
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| Optical Stress Gauge Development for Very High Stresses Piezoraman Measurements and Analysis |
01 NOV 95 |
235 pages |
| Authors:
Yogendra M. Gupta; WASHINGTON STATE UNIV PULLMAN DEPT OF PHYSICS
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| Experiments and analyses were carried out to demonstrate the use of diamond crystals as very high stress, optical transducers under shock loading. Experimental methods were developed to routinely permit time-resolved measurements (10 ns resolution) of stress induced frequency shifts of the Raman line in shocked diamonds. Plate impact experiments were conducted to achieve peak stresses to 500 kbar for uniaxial strain compression along the 110 and 100 orientations. Over the ... |
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Crystallography
