| Liquid Crystalline Dendrimers: 2. Synthesis of Four Generations of Carbosilane LC Dendrimers with Terminal Methoxyphenylbenzoate Groups. Study of Phase Behaviour Structure and Mobility of meso |
07 JUL 1998 |
3 pages |
| Authors:
V. P. Shibaev; N. I. Boiko; A. M. Muzafarov; E. A. Rebrov; S. A. Ponomarenko; MOSCOW STATE UNIV (USSR) DEPT OF CHEMISTRY
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 | Carbosilane LC dendrimers of generation 1-4 with 8, 16, 32 and 64 terminal phenyl benzoate mesogenic groups were synthesized all LC dendrimers with methoxyphenyl benzoate mesogenic groups of generation first to four the included are crystallized as opposite to the ones with the cyanobiphenyl groups. Small angle X-ray scattering (SAXS) of LC dendrimers with cyanobiphenyl groups of generations first to fourth revealed disordered or thogonol or ... |
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| Hexagonal II-VI Structures by Substrate Bandgap Engineering |
JUL 1998 |
3 pages |
| Authors:
Brian J. Fitzpatrick; Maria C. Tamargo; OPTICAL SEMICONDUCTORS INC PEEKSKILL NY
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| This is the third report on Contract NOOOl4-97-C-0367, "Hexagonal II- VI Structures by Substrate Bandgap Engineering". |
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| Three-Dimensional Structure Determination of Botulinum Toxin |
JUL 1998 |
60 pages |
| Authors:
Ray C. Stevens; CALIFORNIA UNIV RIVERSIDE
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| The immediate goals of the contract on the structure and function relationship of botulinum neurotoxin are: 1) Determine the three-dimensional structure of botulinum neurotoxin at atomic resolution by x-ray crystallography. 2) Based on the structure of the neurotoxin, understand the toxins mechanism of action. We have accomplished the first goal of determining the three-dimensional structure of the 150 kD botulinum neurotoxin serotype A. The toxin is Y-shaped, ... |
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| Instrumentation for Real-Time Information Extraction from RHEED and Correlation Using Scanning Probe Microscopy: Applications to Si-Nano- Electronics |
JUL 1998 |
8 pages |
| Authors:
M. Krishnamurthy; D. J. Swenson; T. J. Schulz; MICHIGAN TECHNOLOGICAL UNIV HOUGHTON
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| This project involved the procurement and installation of enhancements to Michigan Technological University's Molecular Beam Epitaxy (MBE) facility. MBE is a thin film deposition technique that permits precise control of multiple element fluxes to a surface, permitting alloy layers as thin as one monolayer to be prepared under carefully controlled conditions of vacuum and temperature. Unlike most other thin film preparation techniques, the deposition conditions for MBE can be far ... |
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| Processing of Nanocrystalline Nitrides and Oxide Composites |
30 JUN 1998 |
4 pages |
| Authors:
Jackie Y. Ying; Martin L. Panchula; MASSACHUSETTS INST OF TECH CAMBRIDGE DEPT OF CHEMICAL ENGINEERING
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| The direct synthesis of nanocrystalline AlN in the forced flow reactor is described, along with initial characterization and chemical analysis results. The AlN has a surface area in excess of 100 square meters per gram and a volume average crystallite size of 40 nm. The particles are not entirely spherical and show some faceting and elongation, which explains the discrepancy between the high surface area and the XRD determined crystallite ... |
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| Liquid Crystalline Dendrimers. 1. Synthesis of Five Generations of Carbosilane Liquid Crystalline Dendrimers with Terminal Cyanobiphenyl Groups |
30 JUN 1998 |
3 pages |
| Authors:
V. P. Shibaev; N. I. Boiko; A. M. Muzafarov; E. A. Rebrov; S. A. Ponomarenko; MOSCOW STATE UNIV (USSR) DEPT OF CHEMISTRY
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| Using the controlled layer by layer experimental technique via reiterative sequence of chemical reactions carbosilane LC dendrimers with terminal cyanobiphenyl mesogenic groups of generations 1 - 5 were synthesized. Molecular structure and purity of all new compounds were characterized by 1H-NMR spectroscopy and GPC analysis. Thermal behavior of LC dendrimers was investigated by means of polarizing optical microscopy and DSC methods. All LC dendrimers synthesized ... |
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| Structural Aspects of Protein-Metal Recognition and Discrimination |
30 JUN 1998 |
5 pages |
| Authors:
David W. Christianson; PENNSYLVANIA UNIV PHILADELPHIA DEPT OFCHEMISTRY
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| This project utilized the zinc enzyme human carbonic anhydrase II (CAII) as a paradigm for dissecting and understanding the structural basis of protein-transition metal recognition and discrimination. We have successfully redesigned the zinc binding site of CAII so that protein-metal affinity can be modulated by design, by factors of 10 from micromolar to femtomolar affinity. We have explored the binding of zinc and copper to engineered ... |
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| Multi-Wavelength, Efficient Mid-Infrared Laser System |
15 JUN 1998 |
72 pages |
| Authors:
Hanna Hoffman; Hans Jennsen; LASERGENICS CORP SAN JOSE CA
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| The objective of this project was to investigate the feasibility of producing radiation at multiple wavelengths from a single solids state laser medium. We investigated holmium doped YLF and BYF. Both the growth of boules and single crystal fiber growth were investigated. Laser quality boules of high Ho concentration were grown. Although single crystal fibers were grown, they were not of laser quality due to oxygen ... |
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| Development of Novel, Band-Gap Engineered Photorefractive Semiconductors CdMnTe:V For Real Time Optical Processing |
JUN 1998 |
34 pages |
| Authors:
S. B. Trivedi; G. V. Jagannathan; S. W. Kutcher; K. Grasza; Z. Yu; R. D. Rosemeier; R. Scheerer; BRIMROSE CORP OF AMERICA BALTIMORE MD
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| During this project, we have developed and produced application quality photorefractive Cd(1-x)Mn(x)Te:V crystals with compositions x= 0.15, 0. 45, and 0.60. These crystals are useful for applications in the wavelength range of 0.7 to 1.3mm. These crystals were obtained through the following material processing steps: (1) extensive purification of the starting elements (cadmium, manganese and tellurium) and purification if the compound (Cd(1-x)Mn(x)Te); (2) crystal growth from the melt under controlled ... |
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| Electron Saturated Velocities in Silicon Carbide Polytypes for Drift Direction Along Crystal Axis |
JUN 1998 |
4 pages |
| Authors:
V. I. Sankin; A. A. Lepneva; RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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| The saturated drift velocity is a very important parameter of semiconductor crystals. It determines frequency limitation of semiconductor devices and consequently the range of the most effective application. Silicon carbide polytypes are not exclusion, Up to the present such velocities have been determined for two polytypes 4H and 6H SiC for direction perpendicular to crystal axis. |
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| Control of the Quantum Dot Energy by a Photon: Observation of Two-Exciton and Three-Exciton States in Quantum Dots |
JUN 1998 |
4 pages |
| Authors:
Yasuaki Masumoto; Michio Ikezawa; TSUKUBA UNIV IBARAKI (JAPAN) INST OF PHYSICS
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| Antibonding two-exciton and three-exciton states were observed in CuCl quartum dots. This observation demonstrates the controlability of the quartum dot energy by a photon. |
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| Vertical Correlations and Anti-Correlations in Multi-Layered Arrays of 2D Quantum Islands |
JUN 1998 |
4 pages |
| Authors:
V. A. Shchukin; V. G. Malyshkin; N. N. Ledentsov; D. Bimberg; RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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| A remarkable feature of multi-sheet arrays of 3D islands is that the buried islands in successive sheets are spatially correlated. At the surface, new islands were observed to be formed directly above buried islands. The existing theory explaining well the correlation accounts the strain created by buried islands and shows that energetically preferred sites for nucleation of islands of the second sheet occur above buried islands, buried islands were approximated ... |
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| Self-Assembled Formation of Quantum Dots During InGaAlAs Quantum Well Growth |
JUN 1998 |
3 pages |
| Authors:
I. L. Krestnikov; A. V. Sakharov; N. N. Ledentsov; I. P. Soshnikov; Yu G. Musikhin; RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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| We demonstrate that InGaAlAs layers with very low average indium composition effectively decompose to In-rich nanoscale domains during epitaxial growth. The resulting quantum dots have significant localization energies as follows from temperature dependencies of the corresponding PL lines. |
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| Equilibrium Composition-Modulated Structures in Epitaxial Films of Semiconductor Alloys |
JUN 1998 |
4 pages |
| Authors:
V. A. Shckukin; A. N. Starodubtsev; RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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| Here we study the thermodynamic stabllity of an alloy A(1-cB(c)C in the epitaxial film against fluctuations of alloy composition. We consider a film on the (001)-substrate of a cubic crystal and we focus on the situation where the homogeneous alloy with the compostion c=c-bar is lattice matched to the substrate. Both the substrate and the epitaxial film are elastically anisotropic cubic crystals having equal elastic modulus tensors. |
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| Enhanced Two-Dimensional Precipitation of Excess As in LT-GaAs Delta-Doped with Sb |
JUN 1998 |
4 pages |
| Authors:
N. A. Bert; V. V. Chaldyshev; A. A. Kosogov; A. A. Suvorova; V. V. Preobrazhenskii; RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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| We have used, for the first time, isovalent delta-doping with antimony instead of indium to produce two-dimensional sheets of arsenic nano-clusters in GaAs films grown by molecular beam epitaxy (MBE) at low (200 C) ten%peratuw. The precipitation kinetics at Sb delta-layers is found to be enhanced as compared to that for In delta-doping. It provides an opportunity to improve the cluster spatial ordering. In addition, at early precipitation stages, the ... |
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| Correlation Between Structural and Optical Properties of Nanocrystal Particles Prepared at Low Temperature Plasma-Enhanced Chemical Vapor Deposition |
JUN 1998 |
4 pages |
| Authors:
D. Milovzorov; T. Inokuma; Y. Kurata; S. Hasegawa; KANAZAWA UNIV (JAPAN)
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| We have synthesized poly-Si films with controlled size distribution of nanocrystals and sufficient luminescent properties. The correlation between structural and optical properties of the poly-Si films allows us to determine the optimal deposition conditions for preparation films with high PL response with narrow width of energy. |
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| Surface Relief Influence on Rheed Oscillations Shape During MBE Growth |
JUN 1998 |
4 pages |
| Authors:
I. G. Neizvestny; N. L. Shwartz; Z. S. Yanovitskaya; RUSSIAN ACADEMY OF SCIENCES NOVOSIBIRSKINST OF SEMICONDUCTOR PHYSICS
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| The Formation of Copper Nanoclusters in SiO2: An X-ray Absorption Study |
JUN 1998 |
4 pages |
| Authors:
A. V. Kolobov; H. Oyanagi; S. A. Gurevich; V. V. Horenko; K. Tanaka; RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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| Results on Cu K-edge x-ray absorption study of copper dispersed in SiO2 are reported. Randomly distributed in as-made samples at low concentration, copper atoms tends to form clusters at larger concentrations. The cluster size reaches a size of 20 to 50 A after which the cluster growth stops. Only the first-neighbour peak is observed in as-made samples indicating either a very strong disorder in clusters or their low-dimensionality. Annealing results ... |
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| Atomic Force Microscopy and Structural Studies of MBE-Grown CdF2 Layers on CaF2(111) |
JUN 1998 |
4 pages |
| Authors:
M. M. Moisseeva; N. S. Sokolov; S. M. Suturin; R. N. Kyutt; Yu V. Shusterman; RUSSIAN ACADEMY OF SCIENCES SAINT PETERSBURG IOFFE PHYSICAL-TECHNICAL INST
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| The possibility of epitaxial CdF2 growth on CaF2 (1-bar,1,1) substrates in a wide growth temperature range of 100 - 500 C has been demonstrated, It is found that there are pyramidal mounds on CdF2 with a typical lateral size 30-60 nm at 100 C and 100-150 nm at 300 C. The angle between its facets and the growth plane is about 10 deg. At higher growth temperatures, the surface morphology ... |
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| Raman Study of Optical Vibrations in InAs/GaAs Self-Assembled Quantum Dots |
JUN 1998 |
1 pages |
| Authors:
Yu. A. Pusep; G. Zanelatto; J. C. Galzerani; S. W. Da Silva; P. P. Gonzalez-Borrero; RUSSIAN ACADEMY OF SCIENCES NOVOSIBIRSKINST OF SEMICONDUCTOR PHYSICS
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| Raman Scattering in Strained Highly-Doped P-Type GaAs/GaAsP Epitaxial Layers |
JUN 1998 |
3 pages |
| Authors:
A. V. Subashiev; V. Y. Davydov; I. N. Goncharuk; A. N. Smirnov; O. V. Kovalenkov; SAINT PETERSBURG STATE TECHNICAL UNIV (RUSSIA)
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| Mechanism of Photoluminescence from Sl-Nanocrystals Fabricated in SiO2 -Matrix |
JUN 1998 |
4 pages |
| Authors:
K. S. Zhuravlev; A. M. Gilinsky; A. Y. Kobitsky; RUSSIAN ACADEMY OF SCIENCES NOVOSIBIRSKINST OF SEMICONDUCTOR PHYSICS
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| The luminescence properties of silicon nanocrystals formed by Si ion implantation into SiO2 matrix and a subsequent thermal annealing have been studied. For identification of PL mechanism the dependencies of cw PL on temperature and excitation power density, and time-resolved PL have been investigated. Expenmental results point to the mechanism of recombination via the levels of centers which are localized on the silicon nanocrystal-silicon dioxide boundary |
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| Adaptive and Parallel Computational Techniques in Materials Science |
31 MAY 1998 |
6 pages |
| Authors:
Joseph Flaherty; RENSSELAER POLYTECHNIC INST TROY NY DEPT OF COMPUTER SCIENCE
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| This Augmentation Award for Science and Engineering Research Training (AASERT) supported research students to work 0 adaptive and parallel computational techniques associated with crystal growth processing. This grant accompanied the AFOSR Multidisciplinary University Research Initiative (MURI) in crystal growth which is centered at the State University of New York at Stony Brook. Students conducted research on the following topics. Systems integration tools to enable the various ... |
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| Synthesis and Characterization of Sterically Hindered Alkylaluminum- Phosphorus and -Arsenic Compounds. X-Ray Crystal Structures of (Me3ECH2)3Al E'(SiMe3)3 (E = Si, E' = As; E = C, E' = P, As), (Me3SiCH2)2(Br)Al P(SiMe3)3, and (Me3SiCH2)(X)AlE(SiMe3)22 (X |
23 MAY 1998 |
37 pages |
| Authors:
R. L. Wells; J. E. Foos; A. L. Reheingold; G. Y. Yap; L. M. Liable-Sands; DUKE UNIV DURHAM NC DEPT OF CHEMISTRY
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| Reaction of (Me3SiCH2)3Al with E(SiMe3)3 (E = P, As) in a 1:1 mole ratio affords the Lewis acid-base adducts (Me3SiCH2)3Al.P(SiMe3)3 (1) and (Me3SiCH2)3Al.As(SiMe3)3 (2). Similarly, the 1:1 mole ratio reaction of (Me3CCH2)3Al with E(SiMe3)3 (E = P, As) leads to the isolation of (Me3CCH2)3Al. P(SiMe3)3 (3) and (Me3CCH2)3Al.As(SiMe3)3 (4). The adduct (Me3SiCH2)2(Br)Al. P(SiMe3)3 (5) was obtained from the 1:1 mole ratio reaction of (Me3SiCH2)2AlBr with P(SiMe3)3. The dimers (Me3SiCH2)(Br)AlP(SiMe3)22 (6) ... |
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| Reactions of H3Al NMe3 with E(SiMe3)3 (E = P, As). Structural Characterization of the Trimer H2AlP(SiMe3)23 and Base-Stabilized Adduct H2AlAs(SiMe3)2 NMe3, and Their Thermal Decomposition Toward Nanocrystalline AlP and AlAs, Respectively |
23 MAY 1998 |
28 pages |
| Authors:
J. F. Janik; R. L. Wells; P. S. White; DUKE UNIV DURHAM NC DEPT OF CHEMISTRY
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| Dehydrosilylation reactions in diethyl ether between H3Al.NMe3 and E(SiMe3)3 afforded for E = P a high yield of the trimer H2AlP(SiMe3)23 (1) while for E = As a monomeric base-stabilized adduct H2AlAs(SiMe3)2.NMe3 (2) as well as its degradation solid product were obtained. No reaction occurred for E = N. The single-crystal X-ray structure determination for 1 yielded a planar six-membered ring of alternating four-coordinated Al and P centers. The structural ... |
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| Lithium Pnictidoaluminates (Et2O)2LiMU-E(SiMe3)22AlH2 (E = P, As) - New Mixed-Metal Pnicogen-Bridged Four-Memhered Ring Compounds |
23 MAY 1998 |
22 pages |
| Authors:
J. F. Janik; R. L. Wells; P. S. White; DUKE UNIV DURHAM NC DEPT OF CHEMISTRY
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| The lithium pnictidoaluminates, (Et2O)2LiMU-E(SiMe3)22AlH2, E = P (1) , As (2), were obtained from the reactions between LiAlH4 and E(SiMe3)3 in diethyl ether following dehydrosilylation chemistry described earlier by us for related gallium derivatives. No reaction was detected for E = N. Single-crystal X-ray diffraction studies for 1 and 2 provided the isomorphous structural solutions featuring the planar four-membered (LiMU-E2Al) cores. |
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| Acoustic Transduction - Materials and Devices, Period 31 July 1996 to 31December 1997, Annual Report. Volume I |
01 MAY 1998 |
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| Authors:
Kenji Uchino; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
 | In Material Studies, undoubtedly major breakthroughs have occurred in the ultra- high strain relaxor ferroelectric systems. Earlier reports of unusual piezoelectric activity in single crystal perovskite relaxors have been amply confirmed in the lead zinc niobate : lead titanate, and lead magnesium niobate : lead titanate systems for compositions of rhombohedral symmetry close to the Morphotropic Phase Boundary (MPB) in these solid solutions. Analysis of the unique ... |
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| Acoustic Transduction - Materials and Devices, Period 31 July 1996 to 31December 1997, Annual Report. Volume II |
01 MAY 1998 |
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| Authors:
Kenji Uchino; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
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| In Material Studies, undoubtedly major breakthroughs have occurred in the ultra- high strain relaxor ferroelectric systems. Earlier reports of unusual piezoelectric activity in single crystal perovskite relaxors have been amply confirmed in the lead zinc niobate : lead titanate, and lead magnesium niobate : lead titanate systems for compositions of rhombohedral symmetry close to the Morphotropic Phase Boundary (MPB) in these solid solutions. Analysis of the unique ... |
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| Acoustic Transduction - Materials and Devices, Period 31 July 1996 to 31December 1997, Annual Report. Volume 3 |
01 MAY 1998 |
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| Authors:
Kenji Uchino; PENNSYLVANIA STATE UNIV UNIVERSITY PARK MATERIALS RESEARCH LAB
|
| In Material Studies, undoubtedly major breakthroughs have occurred in the ultra- high strain relaxor ferroelectric systems. Earlier reports of unusual piezoelectric activity in single crystal perovskite relaxors have been amply confirmed in the lead zinc niobate : lead titanate, and lead magnesium niobate : lead titanate systems for compositions of rhombohedral symmetry close to the Morphotropic Phase Boundary (MPB) in these solid solutions. Analysis of the unique ... |
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| Characterization of Molecular Crystalline Thin Films on Substrates |
15 APR 98 |
109 pages |
| Authors:
Jeff T. Stricker; MINNESOTA UNIV MINNEAPOLIS
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| In the past few decades, there has been significant progress in developing an understanding of the role that non-covalent interactions have on the self-assembly and structural order of molecular crystals. This understanding has led to the development of crystal engineering, which is a promising approach to manipulate solid-state structures at the molecular level. Modification of the topochemical nature of the constituent molecules can enhance the ability to manipulate the solid-state ... |
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| Development of Novel Photoconductive Liquid Crystals for Large Area Photodetectors |
APR 1998 |
4 pages |
| Authors:
Steven K. Pollack; HOWARD UNIV WASHINGTON DC
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| Attempts were made to develop liquid crystals based on the Pd/Cu- mediated cyclization of o-iodo-trimethylethynylbenzenes. We found that the palladation of the triazene protected intermediate led to a stable organo- palladium complex, frustrating further reaction. An alternative route, using the dehydrofluorination of triazene functional trifluorostryenes led to the desired building block. Unfortunately, cyclization proved unsuccessful. |
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| High Temperature Deformation and Fracture Resistance of Single Crystals of NiAl and NiAl-Based Intermetallic Alloys |
31 MAR 1998 |
28 pages |
| Authors:
William D. Nix; Reinhold H. Dauskardt; STANFORD UNIV CA DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| The main objective of this research has been to develop a fundamental understanding of the high temperature deformation, fracture, and fatigue crack growth resistance of single crystals of NiAl and NiAl-based intermetallic alloys. The approach we have taken involves high resolution mechanical property studies of well-characterized and well-oriented single crystals of NiAl containing various alloying elements (Ti, Fe, Zr) in the form of both solid solutions and two phase alloys. ... |
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| Computer Simulations of Growth Phenomena on Solid Surfaces |
10 MAR 1998 |
9 pages |
| Authors:
Horia Metiu; CALIFORNIA UNIV SANTA BARBARA
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| Our work provides an understanding of epitaxial growth at the atomic level and develops new phenomenological theories describing epitaxy on large space and time scales. It is hoped that a better understanding of crystal growth will allow us to optimize performance of solid state electronic devices and perhaps suggest how to grow new structures with new functions. During this funding period we have focused our efforts on understanding two-dimensional growth ... |
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| Anisotropic Grain Noise in Eddy Current Inspection of Noncubic Polycrystalline Metals |
02-Mar-1998 |
4 pages |
| Authors:
Mark Blodgett; Peter B Nagy; AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH
|
| This letter discusses the role electrical anisotropy plays in the structural integrity assessment of polycrystalline titanium alloys from the standpoint of fatigue crack detection and the related issue of microstructural noise. In eddy current inspection of noncubic crystallographic classes of polycrystalline metals the electric anisotropy of individual grains produces an inherent microstructural variation or noise that is very similar to the well-known acoustic noise produced by the elastic anisotropy of ... |
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| Growth, Characterization and Device Development in Monocrystalline Diamond Films |
MAR 1998 |
37 pages |
| Authors:
R. F. Davis; R. J. Nemanich; Z. Sitar; NORTH CAROLINA STATE UNIV AT RALEIGH
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| Surfaces of diamond and GaN have been characterized using UV photoemission spectroscopy (UPS), position dependent field emission and photo- electron emission microscopy (FEEM and PEEM). Electron affinity is a critical limiting aspect for field emission from conducting p-type diamond and Si doped GaN. Emission from p-type diamond originates from the valence band of the material; field emission from Si-doped GaN originates from electrons in the conduction band. Particle detectors for ... |
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| Defects and Impurities in 4H- and 6H-SiC Homoepitaxial Layers: Identification, Origin, Effect on Properties of Ohmic Contacts and Insulating Layers and Reduction |
MAR 1998 |
17 pages |
| Authors:
R. F. Davis; M. O. Aboelfotoh; B. J. Baliga; R. J. Nemanich; NORTH CAROLINA STATE UNIV AT RALEIGH
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| A hot wall chemical vapor deposition system has been constructed to deposit thin films of 4H- and 6H-SiC and AlN. The design incorporates a separate load lock from which the growth chamber and a RHEED chamber are attached. Operation awaits the completion of the laboratory upfitting to address the safety requirements necessary to use silane. Characteristics of high voltage, planar, PN junction diodes fabricated on 4H-SiC using field plate as ... |
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| Acoustic Microsensors III. Direct Detection of Staphylococcal Enterotoxin B Employing a Piezoelectric Crystal Immunosensor with a Flexible Carboxylated Dextran Matrix as the Biochemical Interface |
MAR 1998 |
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| Authors:
J. L. Harteveld; PRINS MAURITS LABORATORIUM TNO RIJSWIJK(NETHERLANDS)
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| Within the framework of the project 'Acoustic Microsensors' (A93KL448) the possibilities of a biosensor system based on an immunological reaction on a piezoelectric crystal sensor are investigated at the TNO Prins Maurits Laboratory (TNO-PML). The results described are a continuation of previous reported work in which the toxin Staphylococcal Enterotoxin B (SEB) was detected in a competition assay with a preincubation period of at least 20 minutes and a detection ... |
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| Studies of Silicon Nanocrystals |
28 FEB 1998 |
28 pages |
| Authors:
Raphael Tsu; NORTH CAROLINA UNIV AT CHARLOTTE
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| Quantum mechanical devices utilize the wave nature of electrons for their operations whenever the electron mean-free-path exceeds the appropriate dimensions of the device structure. Some of the issues such as the tunneling time, the reduction of the dielectric constant and the drastic increase in the binding energy of dopants were studied. In the past several years, certain schemes appeared which may facilitate the realization of silicon quantum devices, such as ... |
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| Correlation of Substitutional Hydrogen to Refractive Index Profiles in Annealed Proton-Exchanged Z- and X-Cut LiNbO3 |
20 FEB 1998 |
52 pages |
| Authors:
J. M. Zavada; H. C. Casey; R. J. States; s. W. Novak; A. Loni; DUKE UNIV DURHAM NC DEPT OF ELECTRICALENGINEERING
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| The goal of this project was to investigate waveguiding in optoelectronic crystals. Studies of the correlation between hydrogen (H) concentration and the extraordinary refractive index n sub e in proton-exchanged lithium niobate (LiNbO3) were resolved by partitioning the total H into optically active substitutional H and optically inactive interstitial H. These results were summarized in two publications: Applied Physics Letters, 63, 718 (1993) and Journal of Applied Physics, 77, 2697 ... |
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| Growth and Characterization of Reduced Dimensionality Superconductor- Related Phases by Molecular Beam Epitaxy |
FEB 1998 |
329 pages |
| Authors:
Darrell G. Schlom; PENNSYLVANIA STATE UNIV UNIVERSITY PARK
|
| This contract played a major role in enhancing the understanding and capabilities of reactive molecular beam epitaxy (MBE) to assemble oxide heterostructures with unit cell layering precision. The specific compounds grown under its support included (Ba,K)BiO3, YBa2Cu3 O(7-delta), SrTiO3, PbTiO3, Bi4Ti3O12, and superlattices of these compounds. Several of these materials had never before been grown by MBE and in addition to achieving an enhanced understanding ... |
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| Crystallization and Microstructural Control of Ferroelectric Thin-Films and Glass-Ceramics |
31 JAN 98 |
13 pages |
| Authors:
Michael J. Haun; COLORADO SCHOOL OF MINES GOLDEN DEPT OF METALLURGICAL ENGINEERING
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| Research on solution-derived ferroelectric thin-films and melt- derived ferroelectric glass-ceramics was conducted in parallel with considerable overlap in the compositions studied and the evaluations of the crystallization behavior, microstructural development, and resulting properties. Lead germane based ferroelectric thin films were developed with a room temperature pyroelectric coefficient over 90% of the single crystal value, and a pyroelectric figure of merit exceeding the highest reported value for oriented lead titanate films. ... |
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| Defects in SiC Single Crystals and their Influence on Device Performance |
26 JAN 1998 |
5 pages |
| Authors:
Michael Dudley; STATE UNIV OF NEW YORK AT STONY BROOK DEPT OF MATERIALS SCIENCE AND ENGINEERING
|
| This project constituted an extensive program of research aimed at applying the techniques of Synchrotron White Beam X-ray Topography (SWBXT), Nomarski Optical Microscopy, Stereo Transmission Optical Microscopy and Scanning Electron Microscopy to the detailed analysis of defect structures in SiC crystals of various polytypes, and to determine how these defect structures can influence the performance of various kinds of device manufactured therein. It has served to establish a heightened awareness ... |
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| High Frequency Investigations of Lateral Superlattice Structures |
26 JAN 1998 |
11 pages |
| Authors:
M. Pepper; CAMBRIDGE UNIV (UNITED KINGDOM) CAVENDISH LAB
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| A description is given of work on the controlled movement of single electrons induced by a Surface Acoustic Wave in GaAs heterostructures and the formation of mini-gaps induced by a potential from patterned gates. |
|
| Nineteenth International Conference of Defects in Semiconductors |
23 JAN 98 |
376 pages |
| Authors:
AVEIRO UNIV (PORTUGAL)
|
| Emphasis will be given on the properties of wide-bandgap materials, including quantum enhancement of effective bandgaps, semiconductors (silicon and lll-V materials), plus radiation effects on detector materials. Topics will also include: GaN. Nanostructures, Large bandgap materials, defects In Epitaxial growth. selforganizing rare earth, metastable defects, pairs and complexes, defect reactions, radiation effects on detector material. |
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| Diorganogallium Beta-Diketonates and Their Lewis Acid-Base Adducts. Crystal and Molecular Structures of Mes2Ga(hfac) and Me2Ga(hfac).NC5H5 |
22 JAN 98 |
33 pages |
| Authors:
O. T. Beachley; James R. Gardinier; Melvyn R. Churchill; Laurence M. Toomey; STATE UNIV OF NEW YORK AT BUFFALO DEPT OF CHEMISTRY
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| Compounds of the type R2Ga(bdk) (R=Me, Et, Mes (mesityl); bdk=2,4- pentanedionato-(acac), 1,1,1,-trifluoro-2,4-pentanedionato-(tfac), 1,1,1,5,5,5,- hexafluoro-2,4-pentanedionato-(hfac), 2,2,6,6,-tetramethyl-3,5-heptanedionato- (tmhd) have been prepared by multiple routes including hydrocarbon elimination, metathesis and ligand redistribution reactions and fully characterized by elemental analyses, cryoscopic molecular weight studies in benzene, and IR and multinuclear NMR spectroscopic studies. An X-ray structural study of Mes2Ga(hfac) demonstrated four coordinate gallium with sigma bonds to the two mesityl rings and to the ... |
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| Scale-up Equipment for Nanosize Particle Synthesis |
22 JAN 98 |
4 pages |
| Authors:
Gary L. Messing; PENNSYLVANIA STATE UNIV UNIVERSITY PARK
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| The goal of the ARPA/AFOSR supported research program is to establish a scientific foundation for the low cost preparation of bulk single crystal quality materials by templated grain growth (TGG); a process in which solid phase epitaxy is used to initiate solid state grain growth of a specific orientation in a polycrystalline matrix. We are investigating two classes of TGG; surface TGG in which a single ... |
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| Vibrational and Electronic Dynamics of Tetravalent Chromium Ions in Dielectric Crystals |
22 JAN 1998 |
7 pages |
| Authors:
R. R. Alfano; Dana M. Calistru; S. G. Demos; V. Kremerman; V. Petricevic; M. Lax; CITY COLL NEW YORK
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| The research program demonstrated that the overall nonradiative deexcitation' taking place in impurity-doped laser crystals can be broken down into three distinct steps: generation of local mode population due to transition through electronic bottleneck, energy transfer from local into select phonon modes via local-phonon mode coupling and return of the system to thermal equilibrium via interaction of the active phonons with the phonon bath. The mechanism of the nonradiative decay ... |
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| Modeling of Defects in Ceramic Oxides YAG |
18 JAN 98 |
31 pages |
| Authors:
Ravi Pandey; MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF PHYSICS
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| Native point defects in Y3Al5O12 (YAG) were studied in the framework of the pair-potential approximation coupled with the shell model description of the lattice ions. For the perfect lattice, a new set of potential parameters were obtained which reproduce structure, elastic and dielectric constants of YAG very well. The calculated formation energies for native point defects predict that the antisite disorder is preferred over the Frenkel and Schottky like disorder ... |
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| Deposition of Gallium Nitride Epilayers by OMVPE |
14 JAN 98 |
11 pages |
| Authors:
M. Skowronski; CARNEGIE-MELLON UNIV PITTSBURGH PA DEPT OF MATERIALS SCIENCE AND ENGINEERING
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| Gallium nitride films have been deposited on sapphire substrates by organometallic vapor phase epitaxy and their structural quality assessed by Transmission Electron Microscopy and high resolution x-ray diffraction. The dominant type of threading dislocation was determined to be pure edge with Burgers vector 1/3 . Dislocations are arranged into arrays corresponding to low angle twist grain boundaries with typical in-basal-plane misorientations of about 1 degree. The granular structure of the ... |
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| High Temperature, High Rate, Epitaxial Synthesis of Diamond in a Laminar Plasma |
06 JAN 1998 |
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| Authors:
Keith A. Snail; DEPARTMENT OF THE NAVY WASHINGTON DC
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| A method for synthesizing large, single crystal diamond comprising mixing carbon source and a hydrogen source to form a mixture. The mixture is excited and reacted to form a reactive species in a laminar plasma plume. A substrate having a diamond seed crystal is disposed in the laminar plasma plume while maintaining the diamond seed crystal at a growth temperature between 1100 and 1700 degrees C. for the deposition of ... |
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Crystallography
