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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.
11

Syntheses, structural studies and photophysical properties of mono, di and polynuclear d10-metal complexes with bulky and electron-rich phosphine ligands /

Tse, Man-chung. January 1999 (has links)
Thesis (Ph. D.)--University of Hong Kong, 2000. / Includes bibliographical references (leaves 404-431).
12

Processing of bulk hierarchical metal-metal composites

Kelly, Aoife January 2011 (has links)
Spray forming with eo-injection of a solid particulate phase to form a metal-metal composite has been studied as a new route for manufacture. Two Al-based matrices were investigated: AI-12Si for testing the feasibility of the new manufacturing route and Al-4Cu for providing better mechanical performance. For both composite types, Ti was chosen as the particulate phase and the processing-microstructure-property relationships then studied. At Peak Werkstoff GmbH, Germany 12 wt%Ti particles were eo-injected into an atomised Al alloy droplet spray and eo-deposited to form a rv300 kg billet. The microstructure comprised refined equiaxed a-AI grains (rv5fLm), spherical Si particles (rv5fLm) and uniformly distributed Ti particles (rv80fLm). Sections of the billet were extruded under a range of conditions into long strips 20mm wide and 6mm, 2.5mm and 1mm thickness. At high strains, the Ti particles were deformed into continuous fibres of a few microns in thickness. Accumulative roll bonding was then performed to higher total strains, while maintaining a constant cross-section, reducing the Ti fibres to sub-micron thickness. The fibres were studied by extraction after selective dissolution of the a-AI matrix. There was no interfacial reaction between a-AI and Ti or any measurable oxide formation, thus providing encouragement for the manufacture of metal-metal composites by eo-spray forming. A powder injection pump was successfully integrated and commissioned on the spray forming facility at Oxford University. The pump was calibrated to optimise powder flow rates. Three AI-4Cu+ Ti composite billets were processed with each containing Ti powder with a different processing history. Up to 20vol%Ti was successfully incorporated, however due to the cooling effect from powder injection, porosity was significant. The quenching effect provided a finer AI-4Cu grain structure in the region of Ti injection, and also promoted precipitation of O'-AbCu precipitates. A Ti/ Al-4Cu interfacial reaction was more prominent in the billet spray formed at 850°C than those spray formed at 750°C. Angular Ti processed by a hydride-dehydride route had better deformation characteristics than spherical gas atomised Ti. Deformation processing by extrusion and rolling was investigated for Al-4Cu+20vol%Ti using SEM, EBSD and FIB. After extrusion to a strain of 5, the composite contained elongated reinforcing fibres characteristic of metal-metal composites. The microstructure studied by EBSD revealed equiaxed polygonal Al-4Cu matrix grains. Rolling was not as efficient as extrusion in producing elongated Ti fibres and was attributed to a lower deformation processing temperature. The rolled composites consisted of elongated Al-4Cu grains 1-5J1m in thickness. An UTS of 339MPa at a strain of 3 was attributed to texture strengthening in the Q- AI.
13

Synthesis and structural characterization of some metal complexes containing betaine and pseudohalide ligands.

January 1992 (has links)
by Mok-Yin Chow. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1992. / Includes bibliographical references (leaves 55-58). / Acknowledgement --- p.1 / Abstract --- p.2 / Contents --- p.3 / List of Figures --- p.4 / List of Tables --- p.5 / Chapter 1. --- Introduction --- p.6 / Chapter I. --- Chemistry of pseudohalides --- p.6 / Chapter II. --- Infrared spectroscopy of pseudohalides --- p.8 / Chapter III. --- Chemistry of metal carboxylates --- p.10 / Chapter IV. --- Infrared spectroscopy of carboxylates --- p.13 / Chapter V. --- Chemistry of betaine ligands --- p.14 / Chapter VI. --- Objectives of this research --- p.15 / Chapter 2. --- Experimental --- p.17 / Chapter I. --- Preparation --- p.17 / Chapter II. --- X-ray crystallography --- p.21 / Chapter 3. --- Results and discussion --- p.23 / Chapter I. --- "Isostructural complexes Co2(bet)2(N3)4 1,Zn2(bet)2(N3)42, Cd2(bet)2(N3)4 3, and Cd2(bet)2(NCO)4 4" --- p.23 / Chapter II. --- Copper(II) complex Cu2(bet)2(N3)2(N03)2 5 --- p.29 / Chapter III. --- Cadmium(II) complexes Cd3(bet)4(SCN)6(H20)2 6 and Cd(prbet)(NCS)2 7 --- p.34 / Chapter IV. --- Barium(II) complex Ba(pybet)2(NCS)2 8 --- p.43 / Chapter V. --- Cobalt(II) complex [Co(pybet)2(NCS)(H20)3]2[Co(NCS)4] 9 --- p.49 / Chapter VI. --- Conclusion --- p.53 / References --- p.55 / Publications based on work reported in this thesis --- p.59 / Appendix --- p.60
14

Synthesis of non-bridged rhodium and iridium metal-metal bonded dimers. / CUHK electronic theses & dissertations collection

January 2000 (has links)
by Maoqi Feng. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.
15

Synthesis, structural characterization and reactivity of binuclear and polynuclear transition metal complexes containing bridging pyridylphosphine ligands. / CUHK electronic theses & dissertations collection

January 1998 (has links)
by Shan-Ming Kuang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (p. 135-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.
16

Structure and reactivity of dinuclear complexes of iridium /

Fine, David Andrew, January 1996 (has links)
Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [165]-173).
17

Synthesis and reactivity of multiply bonded tungsten dimers

Sturgeoff, Lynda Gail. January 1982 (has links)
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 1982 / Includes bibliographical references. / by Lynda Gail Sturgeoff. / Ph. D. / Ph. D. Massachusetts Institute of Technology, Department of Chemistry
18

Synthesis, optical and luminescence studies of rhenium(I) diimine alkynyl complexes and their utilization as building blocks for theassembly of multinuclear and mixed-metal complexes

Lam, Chan-fung., 林親鳳. January 2005 (has links)
published_or_final_version / abstract / Chemistry / Doctoral / Doctor of Philosophy
19

Carboxylato compounds of chromium, copper, rhodium and molybdenum and new advances in the chemistry of V2(NXN)4

Hillard, Elizabeth Anne 30 September 2004 (has links)
This dissertation comprises the investigation of two subjects in the field of dimetal paddlewheel-type compounds containing metal-metal bonds: unsolvated transition metal carboxylates and triply bonded divanadium compounds. The first subject is very mature; dichromium tetraacetate was first synthesized in 1844, and hundreds of dimetal tetracarboxylates have been structurally characterized to date. A general question concerning the complexes of the type M2L4-Xn (where n = 0 to 2) is the extent to which the M-M distances are influenced by the presence of axial ligands, X. However, virtually none of the carboxylato complexes crystallize without axial ligands. In the solid state, in the absence of a coordinating solvent, the dimetal units often act as axial ligands to one another. In order to exclude axial coordination, both from donor solvent molecules, and from the aggregation of M24+ units, we have successfully used the bulky 2,4,6-triisopropylbenzoate ligand to bridge the dimetal core. We have investigated the triisopropylbenzoato complexes of some metals which are known for their ability to form a vast array of tetracarboxylato complexes, namely chromium, copper, molybdenum, and rhodium, and have found that these novel compounds display some interesting structural and chemical properties. The second subject of this dissertation is much more contemporary. Although compounds containing multiple bonds between metal atoms have been known since 1964, the first triply-bonded divanadium compound was not synthesized until 1992, and only two additional compounds of this type have been made in the intervening ten years. In order to extend this chemistry, several additional compounds containing a triply bonded V24+ core have recently been characterized. In our study of these compounds, we have discovered the first example of a stable paddlewheel-type compound with a M23+ core.
20

On the nature of the electronics structure of metal-metal quadruply bonded complexes

D'Acchioli, Jason S., January 2005 (has links)
Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xii, 286 p.; also includes graphics (some col.). Includes bibliographical references (p. 273-286). Available online via OhioLINK's ETD Center

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