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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

First principles based multiscale modeling of single crystal plasticity application to BCC tantalum /

Wang, Guofeng. Goddard, William A., Johnson, W. L. January 2002 (has links)
Thesis (Ph. D.)--California Institute of Technology, 2010. PQ #3052851. / Advisor names found in the Acknowledgements pages of the thesis. Title from home page. Viewed 01/13/2010. Includes bibliographical references.
2

Electronic structure calculations of localized states of transition-element impurities in ionic crystals

Harrison, Joseph Gillis. January 1981 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1981. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
3

Laser spectroscopy of defect chemistry in conducting materials

Mho, Sun-Il. January 1983 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 289-297).
4

The crystal structures of malonamide, cyanoacetamide, a compound C₂₀H₃₃N₃, and acetyltriphenylsilane

Chieh, Peter Chung January 1969 (has links)
Supervisor: Professor James Trotter The crystal structures of malonamide, cyanoacetamide, a methiodide derivative of a compound, C₂₀H₃₃N₃, and acetyltriphenylsilane have been determined by single crystal X-ray diffraction methods. The first three are organic compounds and the fourth is an organometallic compound. A summary of the crystal data is given below:[data omitted] The cell dimensions and space groups of all the crystals were determined from rotation, Weissenberg and precession photographs and on the General Electric Spectrogoniometer. The intensities of the reflexions of these compounds, except the compound C₂₀H₃₃N₃3, were collected on a General Electric XRD-6 Automatic Spectrogoniometer with scintillation counter, Mo-K∝ or Cu-K∝ radiation and a θ-2θ scan. The intensity data for C₂₀H₃₃N₃ were collected on a G. E. XRD-5 Spectrogoniometer. The crystal structure of malonamide was solved by direct methods. The signs of 158 reflexions with ∣E|≥ 1.50 were derived using the symbolic addition method. The fourteen highest peaks on the three-dimensional E-map corresponded to two molecules of malonamide in the asymmetric unit. With these coordinates, the discrepancy factor, R, was 0.38. The hydrogen atoms were located on a difference Fourier at R=0.12. With all nonhydrogen atoms anisotropic, the refinement was complete at R=0.05, using block-diagonal least-squares methods. The two symmetry-unrelated molecules have different orientations but similar conformations. The amide groups are rotated out of the central C-C-C plane, one by 65° and the other 40°. The mean bond distances are C-C, 1.506A;C-N, 1.317A, C=0, 1.242A, and after correcting for thermal libration, C-N, 1.334A; C=O, 1.254A. The molecules are held together by hydrogen bonds involving all eight amino hydrogens, with each oxygen accepting two hydrogen bonds. The structure of cyanoacetamide was solved by Patterson methods combined with information from electron spin resonance measurements and with considerations of possible hydrogen-bond formation. The structure contains layers of molecules and this reduces the three-dimensional Patterson to a two-dimensional one. The trial structure had a discrepancy of 0.50 and refined to 0.089. Through hydrogen-bonding of the amide group, the two symmetry-unrelated molecules form dimers, which can be considered as packing units, and other units are generated by a screw axis, 2₁. The dimers are bonded to each other by a weak hydrogen bond of the type N-H⃛N≡C. The layers are related to each other by a centre of symmetry. The structures of C₂₀H₃₃N₃•CH₃I and acetyltriphenylsilane were solved by the heavy atom method. The positions of the heavy atoms were obtained from the Patterson functions, and other atoms from consecutive Fourier maps. The compound C₂₀H₃₃N₃ of unknown structure was obtained in an attempted laboratory synthesis of the alkaloid matrine. The structure of the compound was derived by single crystal X-ray structure analysis. Features of the structure are described. In acetyltriphenylsilane the acetyl and three phenyl groups are arranged tetrahedrally around the silicon atom. The phenyl rings are orientated in a propeller fashion and the features of the structure are compared with the germanium analogue. / Science, Faculty of / Chemistry, Department of / Graduate
5

Computational studies of bioceramic crystals & related materials

Rulis, Paul Michael, Ching, Wai-Yim. January 2005 (has links)
Thesis (Ph. D.)--Dept. of Physics and School of Computing and Engineering. University of Missouri--Kansas City, 2005. / "A dissertation in physics and computer networking." Advisor: Wai-Yim Ching. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed March 12, 2007. Includes bibliographical references (leaves 256-267). Online version of the print edition.
6

EFFECTS OF CERTAIN PROCESSING VARIABLES ON STACKING FAULT FORMATION IN SILICON CRYSTALS

Chang, Yang-Ming, 1937- January 1977 (has links)
No description available.
7

STRIATIONS, SWIRLS, AND STACKING FAULTS IN CZOCHRALSKI-GROWN SILICON

Rao, Kalipatnam Vivek January 1981 (has links)
In this investigation, controlled thermal annealing and oxidation treatments were carried out on wafers obtained from seed-end and tang-end regions of (100)-oriented, 75 mm-diameter, Czochralski-grown, "typical" silicon single crystals. The radial variation of resistivity was characterized with four-point probe and spreading resistance probe measurements. The defects were studied by preferential etching and optical microscopy, using Wright etch for characterizing the individual etch figures, whereas the overall distribution of defects was obtained by using a modified form of Sirtl etch. The preferential etching was carried out in a Teflon barrel under controlled conditions. Transmission electron microscopy (TEM) was carried out on selected samples to study the defect structure in the as-grown crystal as well as after specific thermal treatments. In the p-type as well as n-type crystals studied in this work, the relative radial gradient as well as the magnitude of resistivity are greater at the seed-end than at the tang-end. An annealing treatment at 650°C for 100 min on seed-end wafers stabilized the resisitivity by destroying oxygen-donor complexes. Such an annealing treatment on tang-end wafers has a minor effect on the resistivity of the sample, which was uniform initially. The "swirl" patterns, as revealed by preferential etching, showed that they are more pronounced in seed-end wafers and are almost absent in tang-end wafers. A pre-annealing treatment at 650°C in argon for 100 min followed by a high-temperature (≥800°C) treatment precipitates the swirl pattern much more intensely, in comparison to just the high temperature treatment without any preanneal at 650°C. For comparable oxide thicknesses (0.5 μm) for thermal oxidation in steam at three different temperatures (900°C, 1050°C, 1200°C), it was found that the swirl pattern was most severe at 900°C and the dissolution of the defect structure progressively increased with increasing temperature. It was found in this investigation that bulk-type stacking faults are generated after argon annealing at 1050°C. This is in contrast to the generally prevailing confusion that thermal oxidation is essential for generation of stacking faults in silicon. It must be distinguished here that the formation of surface-type stacking faults requires thermal oxidation, whereas bulk-type stacking faults nucleate at individual swirl defects due to precipitation of dissolved oxygen. TEM work done in this investigation showed that as-grown CZ silicon defect structure consists of an assortment of precipitates, small dislocation lines, and a helical type of long (∼24 μm) dislocation line, and another long linear defect with periodically spaced nodes. The annealing treatment at 650°C as well as thermal oxidation at 900°C produce a spectrum of precipitates and small dislocations.
8

AN INVESTIGATION OF DYNAMIC DISLOCATION PHENOMENA IN IONIC CRYSTALS

Kreyns, Pieter Hollenbeck, 1937- January 1965 (has links)
No description available.
9

Dislocation substructure in quenched aluminum single crystals

Strudel, J. L. January 1963 (has links)
Thesis (Master's)--University of California, Berkeley, 1963. / "UC-25, Metals, Ceramics and Materials" -t.p. "TID-4500 (19th Ed.)" -t.p. Includes bibliographical references (p. 18-19).
10

Control of alignment for liquid crystal on inhomogeneous substrate /

Lee, Fuk Kay. January 2005 (has links)
Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 125-132). Also available in electronic version.

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