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Babilas, Rafał. "Badania i modelowanie struktury amorficznej wybranych szkieł metalicznych typu metal-niemetale oraz metal-metale." Praca habilitacyjna, Wydawnictwo Politechniki Śląskiej, 2015. https://delibra.bg.polsl.pl/dlibra/docmetadata?showContent=true&id=68438.
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Clegg, Richard Edward. "Liquid-metal embrittlement of metals and alloys." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.260608.
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Miljana, Prica. "Efekti primene različitih postupaka remedijacije na imobilizaciju teških metala u sedimentu." Phd thesis, Univerzitet u Novom Sadu, Prirodno-matematički fakultet u Novom Sadu, 2009. https://www.cris.uns.ac.rs/record.jsf?recordId=73282&source=NDLTD&language=en.
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Predmet izučavanja ove disertacije, osim poređenja različitih metoda procene rizika na osnovu karakterizacije kvaliteta sedimenta vodotokova Vojvodine, bilo je i ispitivanje mogućnosti imobilizacije teških metalau sedimentu primenom različitih remedijacionih tehnika kao i određivanje njihove efikasnosti (npr. solidifikacija/stabilizacija silikatnim materijalima, portland cementom, kalcijum-oksidom itd.) u zavisnosti od brojnih faktora. Osim pseudo-ukupnog sadržaja metala određene su i specifičnije frakcije metala sa posebnimosvrtom na određivanje potencijalno biodostupnih frakcija.Rezultati su ukazali da je naosnovu holandskih preporuka sediment pojedinih vodotokova Vojvodine (Begej, DTD-kanal,Nadela, Sava-Šabac) zagađen metalima (klasa 4) i da je neohodno izmuljivanje i remedijacija. Prema USEPA i kanadskim preporukama, neki uzorci su potencijalno toksični, ali nije zabeležena akutna toksičnost za test vrste u pornoj vodi. Za neke uzorke, i pored visoke pseudo-ukupne koncentracije (klasa 4), nije potvrđena potencijalna toksičnost na osnovu odnosa kiselog volatilnog sulfida i simultano ekstrahovanih metala. Dok se ne primene skuplje metode remedijacije i tretmana sedimenta, najbolje rešenje je izolovano skladištenje na specijalnim deponijama. Naredni koraci bi trebali da budu usresređeni na kontrolu i sprečavanje zagađenja kako bi se obezbedilo da revitalizacija ovih vodotoka ima trajni pozitivan uticaj na životnu sredinu i nesmetanu i bezbednu plovidbu, kao i na primenu određenih remedijacionih metoda. Poređenje rezultata koji su dobijeni različitim procenama kvaliteta sedimenta pokazalo je da ponekad nije dovoljan jedan pristup i da je potrebno je uključiti metode procene biodostupnosti, biotestove i aspekt radioaktivnosti. U uzorku sedimenta koji je korišćen za ispitivanje efikasnosti remedijacionih tretmana, pokazano je da cink, nikal i olovo imaju visok rizik po okolinu, jer seprocenat metala u izmenljivoj i karbonatnoj fazi kretao od 40.1 do 45.2%. Cr i Cd imaju umeren rizik, dok je bakar prisutan u ovim frakcijama u koncentraciji koja predviđa nizak rizik (5.3%). Ovo je u skladu i sa rezultatima analize porne vode i simultano ekstrahovanih metala i kiselog volatilnog sulfida.Istraživanje prikazano u radu je dalo odgovor na pitanje da li remedijacija može uspešno da ukloni zagađenje, u smislu imobilizacije metala u stanje kada oni više neće biti opasnost po okolinu. Svi primenjeni tretmani doveli su dosmanjenja procenta kumulativno izluženih metala iz S/S smeša, ali nijedna smeša tretiranog sedimenta i ispitivanih imobilizacionih agenasa ne pripada grupi inertnog otpada ukoliko se kumulativne izlužene koncentracije metala porede sa koncentracijama koje za otpad propisuje Evropska Unija (2003/33/EC). Ukoliko nam je cilj dobijanje nehazardnog otpada onda moramo primeniti u tretmanu sedimenta kontaminiranog metalima najmanje 30% imobilizaconih agenasa (cementa, kalcijum-oksida). Najveća efikasnost u imobilizaciji metala postignuta je korišćenjem cementa i kalcijum-oksida u smeši (30% cementa i 10% kalcijum-oksida) i primenom termičkog tretmana na višoj temperaturi (11000C) sa glinom (20% gline) što je zaključeno na osnovu koeficijenata difuzije i indeksa izlužljivosti. Dominantan mehanizam izluživanjametala iz ovih smeša je difuzija.This work is concerned with the comparison of the different methods of metal risk assessment in sediments based on examination of the qualityof water courses in Vojvodina. Besides, it deals with the possibility of applying remediation treatments of contaminated sediment and with the efficiency of the different methods, that is the techniques, for immobilization of sediment heavy metals by applying S/S and thermal treatments. A dominant mechanism is proposed for the process of leaching ofthe metals from treated mixtures.Comparison of the results obtained by the different methods of sediment quality assessment showed that in some cases one approach to solving this problem is not sufficient. Metal concentrations in particular sediment samples (the Begej, the DTD Canal, the Nadela, the Sava at Šabac) indicate the presence of contamination, the analyzed samples being of Class 4. According to the Dutch regulations, a sedimentof Class 4 is of unacceptable quality and requires urgent intervention in the sense of sediment dredging, disposal into special depots, and, if possible, remediation. For some samples, despite a high pseudo-total concentration (Class 4), no potential toxicity was confirmed onthe basis of the ratioof the acidic volatile sulfide and simultaneously extracted metals. The results showed that, apart from chemical analyses, biological tests are also necessary, but also sequential extraction analysis, which can more clearly define the way of metal binding to the particular sediment fractions, to allow a more reliable prediction of metal mobility, potential toxicity and bioavailability. In the analysis of sediment quality it is also necessary toinclude the aspect of radioactivity, as it has been shown that the results of this analysis can, not only confirm some of the results of the other analyses, but also indicate the sediment age, origin of contamination and potential toxicity.The subsequent steps should be directed to the control and prevention of contamination, in order to ensure that the water course reviatalization has a lasting positive effect on the environment, an unimpared and safe navigation and application of remediation methods.In the sediment sample (Class 4) that was usedfor the examination of the efficiency of it appeared that zinc, nickel and lead exhibit a high risk, as the percentages of these metals in the exchangeable and carbonate phases were in the range from 40.1 to 45.2%. On the other hand, chromium and cadmium exhibited a moderaterisk, whereas copperin these fractions was present at the levels corresponding to a low risk (5.3%). This is alsoin agreement with the results of pore water analysis and simultaneously extracted metals and acid volatile sulphide examinations.The investigations presented in this work provided an answer to the question whetehr the remediation can successfully remove the contamination in the sense of the immobilization of metals in a state that will not be harmful tothe environment. All the treatments applied yielded a decrease of the percentage of cumulatively leached metals from the S/S mixtures, but none of the mixtures of treated sediments with the tested immobilization agents belongs to the group of inert materials if the cumulative leached concentrations are compared with the concntrations for the wastes given by the EU legislation (2003/33/EC). Ifthe goal is to obtain a non-hazardous material it is necessary to treat the contaminatedsediment with at least 30% of the immobilizing agent (cement or calcium oxide). Based on the diffusion coefficients and leachability index, the highest immobilization efficiency was achieved using a mixture of cement and calcium oxide (30% of cement and 10% of CaO) and by applying thermal treatment at a higher temperature (11000C) with clay (20%). A dominant mechanism of leaching metals from these mixtures is diffusion.
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Zwigl, Peter 1963. "Transformation-superplasticity of metals and metal matrix composites." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/49665.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1998.Includes bibliographical references (p. 156-162).
The work covers transformation superplasticity of metals, alloys and metal matrix composites. Fundamental studies of transformation superplasticity in unreinforced metals, which either deform plastically or by creep, form the basis of further investigations in metal matrix composites. Experiments and analytical modeling are complemented by numerical analysis. The transformation superplastic behavior is related to microstructure and chemical composition. Based on an existing linear theory, a non-linear model is developed and applied to the experimental data. Numerical methods are used to model the stress-, strain and temperature evolution during the phase transformation. The results are in good agreement with the experiment and analytical predictions. First, transformation superplasticity of iron and iron-TiC composites is demonstrated with strains of 450% and 230% respectively. The reduction of the transformation superplasticity in the composites is attributed to the dissolution of TiC in iron and effect which is shown for iron-carbon alloys. Effects of transient primary creep, ratchetting and partial transformation through the ferrite-austenite phase field are examined. Second, transformation superplasticity of zirconium is demonstrated for the first time with a strain of 270% without fracture. Partial transformation resulting from high cycle frequencies is analyzed and related to material properties and cycle characteristics. Finally, nickel aluminide with unstabilized zirconia particulates shows significant higher strain rates upon thermal cycling as compared to the unreinforced matrix. Although, the fracture strain of 23% is below the superplastic limit, the composite shows a high strain rate sensitivity of m = 0.71, which is a necessary characteristic of transformation superplasticity.
by Peter Zwigl.
Ph.D.
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Humphrey, Elizabeth Rebecca. "Tris(pyrazolyl)borate metal complexes : new ligands and metal-metal interactions." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340301.
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SOFFRITTI, Chiara. "On the tribological behaviour of metal/ceramic and metal/metal couplings." Doctoral thesis, Università degli studi di Ferrara, 2011. http://hdl.handle.net/11392/2388832.
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Corrosion, wear or the combined effects of these failure modes cost the industrial economies
hundreds of billions of euros each year. One of the more effective ways to reduce damage due
to corrosion and wear is to treat, or “engineer” the surface, so that it can perform functions
that are distinct from those required by most materials. For example, steel is a very popular
material, because it is inexpensive, strong and easily manufactured. Unfortunately, it is highly
susceptible to corrosion in many environments and therefore needs to be coated in order to
achieve a satisfactory life service. Small components can be painted, aluminized,
electroplated, or clad with more corrosion resistant materials. For parts that also require wear
strength, they can be thermally sprayed or coated with thin-films. Finally, when dealing with
large components, the size, weight, and handling problems may limit the type of surface
treatment to be considered. The aim of the research work presented in this PhD thesis was to
study the interactions between the metal/ceramic and metal/metal coupling surfaces to
improve the wear resistance of the materials in sliding motion. Most of my research work is
included here as a collection of three papers submitted in the same format they were
published or in a preprint version. Each paper is an individual piece of work with separate
sections including: abstract, introduction, materials and experimental details, results and
discussion, conclusions, and references. A failure analysis study was carried out on some
specific mechanical components of diesel engines for industrial application. In order to
increase the wear resistance of rocker arms, pushrods and valves, the deposition of ceramic
coatings thermally sprayed was considered. Wear tests were performed on a plasma-sprayed
ceramic coating in sliding motion against steel in order to understand the effect of a normal
load applied, as well as the environmental conditions on the metal/ceramic coupling.
Moreover, the influence of relative humidity on the tribological behaviour of two types of
plasma-sprayed ceramic coatings and two types of HVOF-sprayed cermets in sliding motion
against alumina, was evaluated through pin-on-disk testing. Different techniques for the
microstructural examination were employed in this research study: Optical Microscopes (OM)
and Scanning Electron Microscopes (SEM) with Energy Dispersive X-ray Spectroscopy
(EDS) microprobe were used and also X-ray Diffraction (XRD) was carried out to describe
the morphology of worn surfaces and to identify the main wear mechanisms involved. In
addition, surface roughness, Vickers microhardness and fracture toughness measurements
were performed in order to characterise the materials subjected to wear testing.
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DeVries, Amanda Maria. "Silicon-based metal-semiconductor-metal photodetectors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ61017.pdf.
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Critchlow, Gary W. "Pretreatments for metal-to-metal bonding." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/7525.
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Hsiung, Le-Chun. "Thermodynamically stable metal-metal-composites (MeMeC)." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627020.
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Jesus, Ivo Sérgio Pinho de. "Resistência de ligações coladas metal-metal." Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/2507.
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Mestrado em Engenharia MecânicaAs juntas coladas são cada vez mais usadas em aplicações estruturais. Todavia, apesar dos muitos estudos já apresentados, continua a não haver critérios de rotura universalmente aceites que sirvam de base ao dimensionamento. O presente trabalho pretendeu dar um contributo para a definição de critérios de rotura de juntas coladas. O objecto de estudo foram as juntas de bissobreposição simples de chapas de aço inoxidável coladas com um adesivo epóxido largamente utilizado, a araldit standard. Realizaram-se ensaios ao corte via tracção das chapas de juntas com várias espessuras de aderente e vários comprimentos de sobreposição. Os resultados experimentais revelaram as tendências gerais esperadas, mas houve algumas anomalias que se julga estarem ligadas à degradação dos lotes de adesivo usados e a excessos de cola nos bordos. Além disso, houveram dispersões estatísticas elevadas nas resistências, que se deveram provavelmente à rotura adesiva observada e ao facto de cada provete envolver duas juntas de sobreposição simples. Posteriormente compararam-se os resultados experimentais com simulações numéricas por elementos finitos, que tiveram em conta o comportamento elasto-plástico dos aderentes e do adesivo. No caso deste último, porém, só foi possível considerar uma aproximação elasto-perfeitamente plástica obtida de ensaios de provetes maciços. Esta aproximação foi provavelmente a causa de algumas discrepâncias entre as curvas carga-deslocamento numéricas e experimentais. Com base nas simulações e nos resultados experimentais procurou-se relacionar a rotura das juntas com o atingir de deformações limite de tracção ou de corte no adesivo. Os resultados não foram claros a este respeito, se bem que alguns resultados dêem suporte aqueles critérios. ABSTRACT: Bonded joints are increasingly used in structural applications. However, widely accepted failure criteria remain unavailable for accurate design, in spite of the many studies reported. The present work aimed at contributing to the identification of such criteria. It involved single strap joints of stainless steel adherends bonded by the well-known araldit standard epoxy adhesive. Lap shear tests on conducted on joints with different adherend thicknesses and overlap lengths. In general, the results followed the expected trends, tough some anomalies were seen. The most likely causes were adhesive fillets and batch degradation. High scatter on joint strengths was observed, which was probably due to the adhesive failure mode and to the fact that the specimens tested involve two single-lap joints. Experimental results were compared to finite element analyses which considered elastic-plastic behaviour of adherends and adhesive. For the latter, however, it was only possible to adopt an elastic- perfectly plastic approximation obtained from bulk adhesive tests. This approximation was probably behind some discrepancies between experimental and numerical load-displacement curves. Finally, simulations and experimental results were combined in order to relate joint failure with the attainment of adhesive limit tensile and shear strains. No clear conclusions could be drawn, but some results did support such criteria.
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Sadjadi, Seyedabdolreza. "Ab initio relativistic-consistent calculations and charge density and experimental mass-spectroscopic analysis of mono and poly-nuclearclusters of group 11 and 12 transition metals and metal chlorides: ySeyedabdolreza Sadjadi." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B5060577X.
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The electron density function of molecular systems supplies a package of information. Quantum mechanical methods of producing and analyzing this function have been significantly improved during the past few years. The advent of accurate pseudopotentials and corresponding basis sets for Kohn-Sham density functional and for post-Hartree-Fock electron-correlated approaches have enabled the inclusion of scalar relativistic and spin-orbit coupling effects as well as electron correlation effects into the electron density function. The unpacking of the information embedded in such a function via the quantum theory of atoms in molecules (QTAIM) became possible by utilizing the very new subshell fitting method of reconstructing the density distribution of core electrons that had been replaced by the pseudopotentials.
These theoretical advances were applied in this thesis to characterize and explore the topological features of metal-metal bonding as one of the fundamental types of bonds formed between two elements. Group 11 and 12 transition metals which include gold and mercury as the most relativistic elements were the main focus of this work. Mono and poly-nuclear compounds (with up to 4 metal atoms) in both pure metal clusters and chloro-complexes were studied by ab initio MØller-Plesset perturbation calculations followed by QTAIM analysis on the relaxed density. Some of these chloro-complexes of copper, gold, zinc and cadmium metals were identified in the gas phase by mass spectrometric experiments. The general formulas of the set of molecules studied in group 11 were : M2, MCl, MCl+, MCl2, MCl2+, M2Cl+, M2Cl2^(s+), M2Cl3+, M3Cl2+, M3Cl3+, M3Cl5+, M4Cl5+ and M4Cl7+ and in group 12 were : M2, MCl, MCl+, MCl2, M2Cl3+, M3Cl5+, M4Cl7+ and M2^(s+). The topological features of metal-metal bonding were calculated along with atomic properties for each individual local minimum isomer found. The comparison of
the metal-metal bonding within the complexes and with the dimers revealed new
features of metal-metal bonding in 3d, 4d and 5d transition metal elements of
groups 11 and 12. With the aid of strong correlation between bond dissociation
energy and electron density at the location of the bond critical points found in the
case of dimers, the strength of the metal-metal bonding in the complexes was
estimated. The electron density’s basin properties calculated accurately for all the
clusters and their isomers in this thesis provided more insight also into the nature
of M-Cl bondings in the group 11 and 12 chloride clusters. Ultimately the bonding
information was used to predict the viability of these clusters in the gas phase.published_or_final_version
Chemistry
Doctoral
Doctor of Philosophy
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Fernandes, Paulo Jorge Luso. "Fatigue and fracture of metals in liquid-metal environments." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337963.
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Mullins, M. "Subcellular localization of metals in metal tolerant higher plants." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384378.
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Karakoc, Nihan. "Metal." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610393/index.pdf.
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This study aims synthesis of metal/polymer one dimensional nanostructures by micelle formation, reduction, and electrospinning route, and to analyze the morphological characteristics of composite nanofibers. The study was carried out in three main steps. First, the reverse micelle structures were established between the anionic surfactant and the metal ion. The surfactant acts as an agent to bind metal ions together so that the arrangements of metal ions can be controlled in the solution. As the surfactant concentration increases, reverse micelles grow and reverse wormlike micelle structures are observed. Wormlike micelles are elongated semi flexible aggregates which form a spherocylinder form repeating units. Metal ions are in the core and surrounded with the surfactant. The polymer attached to the wormlike structure acts as a shield and prevents phase separation in a hydrophilic medium. Different polymer and surfactant concentrations were tried to determine the optimum polymer and surfactant concentrations for reverse micelle formation. The size analyses of the reverse micelle structures were done by dynamic light scattering technique. In the second step, metal ions in the micelles were reduced by using hydrazine hydrate to obtain metal cores in the center of wormlike micelles. Finally, electrospinning was carried at room temperature and in air atmosphere. The characterization of nano composites was done by Scanning Electron Microscopy.
It was found that the size of the reverse micelle structures affects the distribution of metal nano partices in polymer nano fibers. In order to distribute the metal nano particles homogeneously, the optimum size of reverse wormlike micelles was found to be between 420 and 450 nm.
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Ebreo, Darren. "The role of metal ions in metal-on-metal total hip replacement." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59343/.
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Metal-on-metal (MoM) total hip replacement (THR) offered theoretical advantages of decreased wear and increased functional outcomes. MoM bearings have been associated with sterile inflammatory masses and significant soft tissue destruction with poorer outcomes following revision surgery. The natural history of adverse reactions to metal debris (ARMD) is unknown, but may represent contributions from bearing surface wear, taper junction wear, and corrosion. Immunological and genetic factors may influence susceptibility to development of ARMD. Between 1997 and 2004, 652 Ultima TPS THRs (DePuy) were implanted in 545 patients who went on to experience a high rate of early implant failure (13.8%). Management of these patients has evolved beyond regular clinical follow up with plain radiographs to include surveillance monitoring of trends in levels of blood metal ions and staging of disease using metal artefact reduction (MAR) MRI. This study investigated: • The natural history of ARMD in 28mm MoM THR using MAR MRI. • The possibility of diurnal variation of cobalt (Co) and chromium (Cr). • Differences in gene expression profiles of patients undergoing revision of a metal-on-polyethylene (MoP) THR for aseptic loosening and those with ARMD arising from MoM THR. In patients whose MARS MRI staging on initial scan is normal or where mild evidence of disease is demonstrated, further deterioration is unlikely. Where it does occur, the rate of deterioration is slow and there may be a latent period of many years. There is no diurnal variation in levels of cobalt (Co) in plasma or urine. There is diurnal variation in levels of plasma chromium, but this is not clinically significant. Patterns of gene expression in patients with aseptic loosening of a metal-onpolyethylene (MoP) THR, and patients with ARMD from a MoM THR investigated by a microarray experiment were found to be similar on a genome-wide level suggesting that they may share common factors in their aetiologies. These studies have helped to describe the natural history of ARMD on a cellular and radiological level, and have provided a contribution to the evidence base that will inform as to the optimum strategy for monitoring these patients before they develop catastrophic complications.
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Hussain, Mallik Mohd Raihan. "Effective Nonlinear Susceptibilities of Metal-Insulator and Metal-Insulator-Metal Nanolayered Structures." University of Dayton / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1591207594352716.
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Lord, James Kenneth. "Improving the metal-on-metal hip prosthesis." Thesis, University of Newcastle Upon Tyne, 2012. http://hdl.handle.net/10443/1674.
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Hip arthroplasty is an increasingly prevalent intervention, aimed at reducing pain and restoring function to patients suffering from common musculoskeletal diseases such as arthritis. Metal-on-metal (MoM) hip replacements were intended to be low-wear alternatives to conventional metal-on-polyethylene prostheses. Recent data has shown that revision rates for most MoM prostheses have not been as low as predicted and are not consistent across all models. Many failures result from complications arising from wear debris. Accurately quantifying wear has proved difficult. Using a co-ordinate measuring machine, a method for measuring the wear of ex-vivo MoM hip prostheses was developed and validated as accurate to within 0.5mm3. The method was applied to bearing surfaces and, where available, the internal tapers of femoral heads. Overall, 143 MoM hip explants were measured (95 resurfacings, 48 total hip replacements). Median total wear rates were 4.17mm3/year (mean=11.52, range=0.30-87.28mm3/year), notably higher than most simulator estimates of 1-2mm3/million cycles. Large differences were noted between different models of MoM hip. Time in vivo correlated with wear volume (SRCC=0.387, p<0.001) but not wear rate (SRCC=-0.086, p=0.169) suggesting that the prostheses wore at an unchanging rate through their lifetime. Acetabular cup inclination and anteversion correlated with wear volume (SRCC=0.414 and 0.233) and wear rate (SRCC=0.353 and 0.231, all p<0.001). Wear scars were consistently seen at the rim of the acetabular cup. The distance between these scars and the rim inversely correlated with volume (SRCC=-0.387, p<0.001) and rate (SRCC=-0.357, p<0.001). Patient blood metal ion levels were elevated (median 10.20μg/ml Cr, 9.73μg/ml Co) and correlated with wear volume (p<0.001). Surface roughness measurements were taken on the bearing surfaces and theoretical lubrication regimes (λ-ratio) calculated. There was an inverse correlation between worn λ-ratio and wear volume (p=0.038). Through these findings, recommendations are made for optimising future designs of hip prosthesis to minimise wear.
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Knottenbelt, Sushilla. "A DFT study of metal-metal bonding." Thesis, University of York, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424531.
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Kim, Yong-Seog. "Metal transfer in gas metal arc welding." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/14199.
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Dodd, Linzi Emma. "Fabrication optimisation of metal-oxide-metal diodes." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/9474/.
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This thesis is based on the design, research and development of devices required to successfully recover waste heat and convert it into electrical power through the use of Microsystems Technology. This takes place using optical nano-antennas, in the same way a radio antenna picks up a radio station. The main aim of this project is the rectification of this signal into a useful DC voltage. Here we have used high frequency metal-oxide-metal (MOM) diodes, which involve the use of two dissimilar metals separated by a native oxide. In order to make successful MOM diodes, the following must be considered: maximise the work function difference between the metals for asymmetry in I-V characteristics, produce a uniform oxide layer that is sufficiently thin (a few nm) for electron tunnelling to occur and reduce the diode size to sub-micron dimensions to increase the cut-off frequency. Currently the diodes consist of titanium, titanium oxide and platinum, which provides a high enough work function difference that the I-V characteristics show significant asymmetry and figure of merit values are among the best published. It has been found, using ToFSIMS and TEM analysis of the oxide, that the thickness of the oxide can be controlled between 1 nm and 7 nm using RIE etching and subsequent oxygen plasma regrowth. Different oxides have been fabricated with different stoichiometries depending on the process used. Furnace oxidation grows a complex oxide in the range 6.9 to 7.6 nm thick. By contrast a more simple oxide can be produced using a controlled reactive ion etch and subsequent plasma oxidation, with thicknesses in the range 1 to 6 nm. The final significant issue involves the cross-sectional area of the diodes, which also determines their cut-off frequency. Extrapolation of existing diode results suggests that, if made sufficiently small, they would function at high enough frequencies for rectification of radiation in the terahertz regime. Furthermore, phase shift lithography has been used to demonstrate 200 to 400nm lines in diode features, with alternative possible high scale processes discussed for future fabrication.
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Al-Saffar, Ali. "Modelling of metal on metal hip prostheses." Thesis, Cardiff University, 2015. http://orca.cf.ac.uk/79514/.
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Metal-on-metal (MOM) total hip replacement is an artificial hip joint has been used to replace damaged or diseased natural joints. MOM studies have demonstrated severe complications due to metal wear debris in tissues adjacent to the implants. Reducing the wear rate and operating with full film lubrication could reduce these problems; a better understanding of the lubrication mechanisms is also relevant to other hard bearing materials such as ceramics or new metal alloys. Ball-in-socket MOM contacts were analysed using the Abaqus Finite Element package to simulate dry contact between the acetabular cup and the femoral head. Different cup thicknesses of 4, 6, 8, and 10 mm were considered using a polyurethane foam block support system. Elastohydrodynamic lubrication (EHL) analyses were developed for the contacts using three different approaches to specify the contact. These were (i) A simple model based on the radii of relative curvature, (ii) An equivalent contact model developed so that its dry contact area and maximum pressure replicated the values obtained from the FE analysis, and (iii) A modified version of (ii) that also ensured equivalence of the gap shape outside the contact area. Published in vivo information for the hip joint contact forces over the walking cycle was used to specify the operating conditions for the EHL analysis. III This was achieved by developing techniques to transform the in vivo information to provide load direction and kinematic information relative to the nominal contact point between the components. The analysis method was found to be effective for all points of the walking cycle for cases where the cup thickness exceeded 5 mm and modelling approach (ii) was identified as satisfactory. For a cup thickness of 4 mm, membrane action began to emerge in the FE analyses so that such contacts behaved in a different way.
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Kelly, Aoife. "Processing of bulk hierarchical metal-metal composites." Thesis, University of Oxford, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.559831.
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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.
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Copenhaver, Ann Savena. "Photoelectron spectroscopy of supported metal-metal interactions." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184742.
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The bonding in a series of ligand-bridged metal dimer complexes has been characterized by He(I) and He(II) photoelectron spectroscopy and approximate molecular orbital calculations. Bridging ligands such as carbonyl, nitrosyl, methylene and pyrazolyl in the complexes [CpFe(NO)]₂, [Cp*Fe(NO)]₂, [CpRu(NO)]₂, [Cp*Co(CO)]₂, [CpFe(CO)₂]₂, [Cp*Fe(CO)₂]₂, [CpFe(CO)]₂-μCO-μCH₂, [Cp*Fe(CO)]₂-μCO-μCH₂, [CpFe(NO)]₂- μCh₂, [CpRu(NO)]₂-μCH₂, [CpCo(CO)]₂-μCH₂, [CpRh(CO)]₂-μCH₂, [Ir(pyrazolyl)(CO)₂]₂, [Ir(3-methylpyrazolyl)(CO)₂]₂ and [Ir(3,5-dimethylpyrazolyl)(CO)₂]₂ are investigated and their effects upon metal-metal interactions are surveyed. Due to the presence of two d⁷ or d⁸ late metal atoms per molecule, these complexes display many overlapping ionization bands in a narrow valence ionization region. Attention has been given to modelling the photoelectron single ionization with asymmetric and symmetric Gaussians. The overlapping ionizations are successfully represented in terms of the model bandshapes. Thermodynamic relationships between bond dissociation and photoelectron ionization energies are also investigated. With relationships of this type, trends in bond energies may be correlated with ionization energies. Ligand inductive and bonding effects as well as small changes in molecular geometry cause shifts in the metal-based ionizations, which aid chemical understanding and interpretation of the molecular orbital picture. By comparing a series of related metal dimers, the assignment of related ionizations in the photoelectron spectra becomes apparent. Changes in ligand π accepting ability and changes in metal and formal oxidation states are also probed. Addition information is provided by vibrational fine structure in Cp₂Os, [CpFe(NO)]₂, and [Cp*Co(CO)]₂ and spin-orbit splitting in Cp₂Os. The metal-ligand backbonding combinations are found to be the most stable interactions and are responsible for the stability of the metal dimers. Metal-metal interactions are found to be relatively unimportant. Ligands with stronger π accepting abilities allow for more stabilized supported metal dimer complexes.
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Dan, Tereza Violeta. "Phytoremediation of metal contaminated soils, metal tolerance and metal accumulation in Pelargonium sp." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58302.pdf.
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Chan, Lai-fung, and 陳麗鳳. "Synthesis, structures and properties of metal-metal bonded transition metal with organothiolate ligands." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40687703.
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Acho, Jacqueline A. "Reductive coupling, and, transition metal calixarene complexes : metal-metal quadruple bonds and pockets." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/32149.
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Chan, Lai-fung. "Synthesis, structures and properties of metal-metal bonded transition metal with organothiolate ligands." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B40687703.
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Lynn, Matthew Allen. "Metal, ligand, and symmetry influences on metal-metal bonds: Photoelectron spectroscopy and theory." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284089.
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Three sets of metal-metal bonded systems of the form M₂(L ͡ L)₄ have been studied by gas-phase ultraviolet photoelectron spectroscopy and electronic structure calculations to understand the electronic structures of and bonding in these molecules. The ligand sets range from the relatively poor electron donor trifluoroacetate ligand, to hydroxymethylpyridinate (mhp), and finally to the relatively strong electron donor N,N'-diphenylformamidinate (form) ligand. Not only does this study elucidate the methods by which metal and ligand interact throughout a series of differing electron donor ligand sets, but it also presents a cohesive understanding of the electronic structures of these systems in terms of overall molecular symmetry. In particular, the relative stabilities and orbital characters of the metal-metal bonding and antibonding orbitals are probed to understand the ability of a particular ligand set to affect the ability of two metal atoms to bind together. First, compounds of the form M₂(form)₄ (M = Cr, Mo, W, Ru, Rh, Pd) are examined. The spectra of the metal-metal quadruple bond-containing systems (i.e., M₂(form)₄ where M = Cr, Mo, W) are used to identify several metal- and ligand-based ionization features, which can then be used to identify the additional metal-based features in the spectra of the remaining systems. Given the ease with which functional groups can be added to the formamidinate ligand, a series of substituted Mo₂(form)₄ systems have been prepared and their ionization data have been compared with solution-phase electrochemical results. Next, the electronic structures of M₂(O₂CCF₃)₄ (M = Mo, Rh) are studied. Variable energy photon experiments reveal a predominance of ligand character in the M-M σ and π orbitals, despite the relatively poor overall electron donor ability of the ligand. The means by which such a ligand can interact by symmetry with these metal orbitals are studied by computational methods. Finally, the bonding in M₂(mhp)₄ (M = Cr, Mo, W, Ru, Rh) systems is probed. The lower symmetry of these molecules and the intermediate donor properties of this ligand set allow for correlation with the electronic structures of M₂(form)₄ and M₂(O₂CCF₃)₄. Unlike for the higher symmetry systems, ligand involvement in the M-M δ bond is observed and can be understood in terms of molecular symmetry arguments.
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Mokhtari, Morgane. "FeCr composites : from metal/metal to metal/polymer via micro/nano metallic foam, exploitation of liquid metal dealloying process." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEI088/document.
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Les métaux micro ou nanoporeux sont très attrayants notamment pour leur grande surface spécifique. Le désalliage dans un bain de métal liquide permet une dissolution sélective d'une espèce chimique (l'élément soluble) à partir d'un alliage d'origine (le précurseur) composé de l'élément soluble et d'un élément cible (qui deviendra nano/micro poreux) non soluble dans le bain de métal liquide. Quand le précurseur est plongé dans le bain de métal liquide, à son contact, l'élément soluble va se dissoudre dans le bain tandis que l'élément cible va en parallèle se réorganiser spontanément afin de former une structure poreuse. Quand l'échantillon est retiré du bain, il est sous la forme d'une structure bi-continue composée de deux phases : l'une étant la structure poreuse composée de l'élément cible et l'autre est une phase dans laquelle est présente l'élément du bain avec l'élément sacrificiel en solution solide. Cette phase peut être dissoute par une attaque chimique afin d’obtenir le métal nano/micro poreux. Les objectifs principaux de cette thèse sont l'élaboration et la caractérisation microstructurale et mécanique de 3 différents types de matériaux par désalliage dans un bain de métal liquide : des composites métal-métal (FeCr-Mg), des métaux poreux (FeCr) et des composites métal-polymère (FeCr-matrice époxy). Le dernier objectif est l'évaluation des possibilités d'utiliser la technique de désalliage dans un bain de métal liquide dans un contexte industriel. L'étude de la microstructure est basée sur des observations 3D faites par tomographie aux rayons X et des analyses 2D réalisées en microscopie électronique (SEM, EDX, EBSD). Pour mieux comprendre le désalliage, le procédé a été suivi in situ en tomographie aux rayons X et diffraction. Enfin, les propriétés mécaniques ont été évaluées par nanoindentation et compressionNanoporous metals have attracted considerable attention for their excellent functional properties. The first developed technique used to prepare such nanoporous noble metals is dealloying in aqueous solution. Porous structures with less noble metals such as Ti or Fe are highly desired for various applications including energy-harvesting devices. The less noble metals, unstable in aqueous solution, are oxidized immediately when they contact water at a given potential so aqueous dealloying is only possible for noble metals. To overcome this limitation, a new dealloying method using a metallic melt instead of aqueous solution was developed. Liquid metal dealloying is a selective dissolution phenomenon of a mono-phase alloy solid precursor: one component (referred as soluble component) being soluble in the metallic melt while the other (referred as targeted component) is not. When the solid precursor contacts the metallic melt, only atoms of the soluble component dissolve into the melt inducing a spontaneously organized bi-continuous structure (targeted+sacrificial phases), at a microstructure level. This sacrificial phase can finally be removed by chemical etching to obtain the final nanoporous materials. Because this is a water-free process, it has enabled the preparation of nanoporous structures in less noble metals such as Ti, Si, Fe, Nb, Co and Cr. The objectives of this study are the fabrication and the microstructure and mechanical characterization of 3 different types of materials by dealloying process : (i) metal/metal composites (FeCr-Mg), (ii) porous metal (FeCr) (iii) metal/polymer composites (FeCr-epoxy resin). The last objective is the evaluation of the possibilities to apply liquid metal dealloying in an industrial context. The microstructure study was based on 3D observation by X-ray tomography and 2D analysis with electron microscopy (SEM, SEM-EDX, SEM-EBSD). To have a better understanding of the dealloying, the process was followed in situ by X-ray tomography and X-ray diffraction. Finally the mechanical properties were evaluated by nanoindentation and compression
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Jones, Simon C. "Metal-metal coupling in bi- and multimetallic systems : organometallic pentalene and group 14-bridged cyclopentadienyl complexes of transition metals." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.270635.
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Ngule, Chrispus M. Jr. "In Vitro Adsorption of Heavy Metals Using Metal-Organic Frameworks." Youngstown State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1597664070125999.
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Langton, David. "Metal debris release from metal-on-metal hip arthroplasty : mechanism, quantification and clinical effects." Thesis, University of Newcastle upon Tyne, 2013. http://hdl.handle.net/10443/3629.
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Metal on metal (MoM) hip replacements consist of a cobalt-chromium-molybdenum alloy femoral head which articulates against an acetabular cup manufactured from similar material. MoM hip replacements were introduced in the 1980s. It was thought that the overall reduction in volumetric wear as well as the avoidance of polyethylene would lead to greater longevity of these prostheses. There had been isolated reports of adverse tissue reactions with previous generations of MoM devices but it was thought that improved manufacturing technology would eliminate these problems. In the 1990s, the Birmingham Hip Resurfacing (BHR) was developed. The positive mid-term results of this device led to a rapid increase in the use of the BHR throughout the world. For obvious reasons, the enhanced stability large diameter bearings provided proved extremely attractive to surgeons and patients. Manufacturers therefore began to develop total hip replacement systems for patients unsuitable for the resurfacing procedure. These systems used bearings of size 36mm and greater, in Contrast to the existing 28mm Metasul device. From 2005 onwards there began to emerge increasing numbers of reports of local complications in the tissues adjacent to MoM prostheses. These reactions included sterile masses, tissue destruction and osteolysis. The incidence of these tissue reactions was unknown, as were the risk factors for their development. This piece of work sought to quantity the volumetric and linear wear rates of failed MoM hips and to investigate the relationship these wear rates and a number of clinical parameters. These parameters included blood, serum and hip fluid chromium and cobalt concentrations, and the macro and microscopic appearance of periprosthetic tissue at revision surgery. In this way it was hoped that component design, host and surgical factors leading to adverse tissue reactions could be identified and potentially eliminated.
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McGrellis, Siobhan Ann. "Structure and chemistry of some low valent transition metal oxides containing metal-metal bonds." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384902.
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Davies, Andrew Paul. "The morphological and mutagenic effects of metal-on-metal versus metal-on-polyethylene prostheses." Thesis, University of Bristol, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396685.
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Malas, James C. "Methodology for design and control of thermomechanical processes." Ohio : Ohio University, 1991. http://www.ohiolink.edu/etd/view.cgi?ohiou1173324636.
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Eskhult, Jonas. "Electrochemical Deposition of Nanostructured Metal/Metal-Oxide Coatings." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8186.
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Duncan, Luke. "Biomaterial aspects of metal-on-metal hip resurfacing." Thesis, University of Surrey, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.549466.
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Gu, Yanjuan, and 谷艳娟. "Nanostructure of transition metal and metal oxide forelectrocatalysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37774396.
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Ramanathan, S. "Electrochemical studies on metal-metal oxide pH sensors." Thesis, University of Salford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376871.
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Kwon, Young-Min. "Pseudotumours following metal-on-metal hip resurfacing arthroplasty." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:446beb4e-4e36-4666-b6b3-4f00bd4a3dc8.
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Metal-on-metal hip resurfacing arthroplasty (MoMHRA) has undergone a recent resurgence as an alternative treatment option for young and active patients with significant hip osteoarthritis. Despite the satisfactory short-term implant survivorship, abnormal periprosthetic soft-tissue masses relating to the hip joint (pseudotumours) are being increasingly reported. These were found to be locally destructive, requiring revision surgery in a high proportion (75%) of patients, the outcome of which is poor. However, there is currently no definitive evidence of potential mechanisms involved in the occurrence of such destructive soft tissue masses. The broad aims of this thesis were: 1) to determine the extent of this emerging clinical complication (pseudotumour) with a high revision burden; and 2) to determine whether pseudotumour results from a local biological reaction to an increased wear debris burden generated by excessive MoMHRA implant wear. A clinical study investigated the prevalence of, and association between, pseudotumours and serum metal ion levels in 158 MoMHRA patients (201 hips). The overall prevalence of pseudotumour was found to be 4%, considerably higher than previously reported. The study also established that pseudotumour only occurred with elevated metal ion levels, suggesting the underlying cause is increased wear. It was postulated that pseudotumours are likely to be a biological reaction to the large amount of metal debris generated in vivo due to excessive wear. Two potential biological reactions mediating the occurrence of pseudotumours were then investigated. An in vitro clinical study demonstrated that systemic hypersensitivity type IV reaction, mediated by lymphocyte reactivity to these metals, is not the dominant biological response involved in pseudotumours. A further in vitro experiment demonstrated that metal particle-induced cytotoxicity is likely to be an important factor leading to pseudotumours. Subsequent research focused, firstly, on assessing the magnitude of bearing surface wear that occurs in pseudotumour patients, and secondly on elucidating the potential wear mechanism responsible for the increased implant wear in these patients. A retrieval study demonstrated that MoMHRA implants revised due to pseudotumour were associated with significantly greater linear wear rates. This combined with the metal ion data confirmed that pseudotumour is associated with increased wear at the MoM articulation. An edge-loading wear pattern was always found in the pseudotumour group. An in vivo study was then developed to investigate whether the edge-loading occurs during functional activities. Edge-loading in the pseudotumour group was found to occur with up to 4-fold increase in duration and up to 7-fold increase in force. This in vivo finding supported the in vitro retrieval study finding of an edge-loading wear pattern in the pseudotumour group, suggesting that edge-loading during functional activities is an important in vivo mechanism responsible for localised high wear and subsequent elevation of metal ion levels in MoMHRA patients with pseudotumours. It is concluded that pseudotumour is likely to result from a local biological reaction to increased metal debris load, generated by excessive MoMHRA implant wear due to edge-loading. In susceptible patients, the dose-dependent cytotoxicity of wear debris leads to subsequent necrosis of periprosthetic soft tissues. Clinicians need to be aware of pseudotumours and surgeons should undertake MoMHRA with great care in the knowledge that even with satisfactory component positioning, the problem can occur. In evaluating MoMHRA patients with unexplained symptoms with normal plain radiographs, further investigation with soft-tissue imaging modalities such as ultrasound or MRI is recommended.
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Trenholme, W. J. F. "Metal-organic frameworks for platinum group metal extraction." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/32795/.
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This Thesis describes the synthesis and characterisation of a variety of functionalised metal-organic frameworks (MOFs). These MOFs have been used for the extraction of platinum group metal (PGM) compounds from aqueous and organic solvents and for the storage of gases such as CO2, CH4 and the C2 hydrocarbons. Chapter 1 contains an introduction to PGM properties and uses with specific focus on the chemical properties which allow for separation of PGMs from base metal compounds and for separation between different PGM compounds. The synthesis and structure prediction of MOFs is then introduced, leading into an overview of the use of functionalised MOFs, especially those used for the encapsulation and extraction of metal ions from solution. General experimental techniques and details are described, as is the theory behind inductively coupled plasma optical emission spectrometry (ICP-OES), the most widely used analytical technique reported in this work. Chapter 2 describes the synthesis of chemically stable amine-functionalised Zr(IV) MOFs; UiO-68-NH2 and UiO-66-NH2, for extraction of PGM anions from aqueous and acidic solutions. ICP-OES was used to show that both materials exhibit close to 100% uptake of PtCl62- when present in just 3.5 equivalents per anion, comparable to the best materials reported for PtCl62- extraction. Furthermore, UiO-66-NH2 exhibited consistently higher PtCl62- uptake from aqueous solutions than four industrially used materials supplied by Johnson Matthey. Back-extraction of PtCl62- was demonstrated simply by heating the doped MOF in 4 M HCl, removing 99% of the PGM while maintaining the phase and crystallinity of UiO-66-NH2. Separation of PdCl62- from PtCl62- from acidic HCl solutions was exhibited by UiO-66-NH2, showing an exceptional selectivity of 20:1 for Pd:Pt from 2 M HCl. Likewise, 100% selectivity for PtCl62- and PdCl62- over CuCl2 and CuSO4 from acidic solutions was demonstrated, even in cases in which Cu was in 100-fold excess. Solid state NMR was employed to confirm the interaction between the framework and the PGM anions, with XPS results suggesting that the encapsulated Pt species within UiO-66-NH2 may be PtCl3(NH2)3 or PtCl4(NH2)2. Chapter 3 describes the synthesis and characterisation of a series of functionalised Cu(II) MOFs, NOTT-151, -155, -125 and -150, for the removal of neutral PGM complexes, Pd(OAc)2, PtCl4 and Rh2(OAc)4, from THF. The design of the MOFs allowed for an investigation into the effect of different topologies (ssa and fof), cage sizes and functional groups (amine, oxamide and methyl) on the uptake of each PGM complex. ICP-OES analysis showed that the MOFs were capable of extracting each PGM complex. The oxamide-functionalised NOTT-125 exhibited the most consistent uptake of Pd(OAc)2 with a maximum capacity of 35 mg g-1 (7 NH(CO)2NH groups per PtCl4). The amine-functionalised NOTT-155 showed the highest uptake of PtCl4, with a maximum capacity of 73 mg g-1 (4 NH2 groups per PtCl4). Uptake of Rh2(OAc)4 was generally low, however NOTT-125 showed a maximum extraction of 87 mg g-1 (3 NH(CO)2NH groups per PGM). The larger pore fof MOFs, NOTT-155 and NOTT-125, were more effective for each extraction than the MOFs of ssa topology, NOTT-151 and NOTT-150. However, of the ssa MOFs, amine-functionalised NOTT-151 was shown to give higher uptake of each PGM than the isostructural methyl-functionalised NOTT-150. This demonstrated the importance of incorporating a functional group capable of coordinating to the metal complex. Chapter 4 introduces the use of a nitrogen-rich triazine core in the synthesis of a variety of organic linkers to prepare MOFs for gas storage applications. The preparation of a novel 3,24-connected Cu(II) MOF of rht topology, denoted NOTT-160, is described and the structure characterised using X-ray crystallography. The material is shown to exhibit good uptake of C2 hydrocarbons with uptake of 128 cc g-1, 115 cc g-1, 110 cc g-1 for C2H2, C2H4, C2H6 respectively at 298 K and 1 bar (this becomes 212 cc g-1, 175 cc g-1 and 201 cc g-1 at 273 K and 1 bar). The selectivities of 79:1 and 70:1 calculated using Henry’s law for the separations of C2H2:CH4 and C2H4:CH4 respectively at 298 K are the third and second highest reported values for a MOF under these conditions. Ideal adsorbed solution theory (IAST) was also employed to calculate and predict these selectivities and shows agreement with the results obtained using Henry’s law. In addition, NOTT-160 shows an exceptional volumetric working capacity for CH4 of 221 cm3 cm-3 at 80 bar and 298 K. This is the second highest working capacity reported for a MOF under these conditions, with the excellent performance attributed to the high porosity and comparatively high crystal density of the material. Chapter 5 contains a summary of the work presented in this thesis.
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Lima, Daniel Frota. "Análise de cobertura de metal-metal por XRF." Universidade do Estado do Rio de Janeiro, 2011. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=3805.
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A proposta do referente estudo foi medir a espessura do depósito de um metal em
outro metal base, ou seja, utilizar o processo eletroquímico de Galvanoplastia ou
eletrodeposição deste metal, por meio da técnica de fluorescência de raios X (XRF). O uso
desta técnica justificou-se pelo interesse em reduzir os custos excessivos durante o processo
eletroquímico, bem como, minimizar as possíveis margens de erros para obter resultados
satisfatórios nas medidas. Neste trabalho, incluíram-se as medidas da espessura do Níquel
(Ni) e análises da intensidade de radiação incidentes e a radiação atenuante, em função da
espessura dos elementos Cromo (Cr) e Zinco (Zn), considerando como metal base o elemento
Ferro (Fe). Em decorrência disso, em todos os casos foram simulados os processos de
deposição do metal onde foram incluídos os resultados de absorção de raios X, além de
desprezar a influência de outros fatores como a temperatura, o pH, o tratamento de superfície,
entre outros, os quais são necessários para considerar em cada caso.The proposal concerning the study was to measure the thickness of the deposit of a basemetal into another metal, ie, using the electrochemical processes of the electroplating orelectrodeposition of this metal, through the technique of X-ray fluorescence (XRF). The use of this technique was justified by the interest in reducing the excessive costs during the electrochemical process, as well as minimize the possible margins of error to obtain satisfactory results in the measures. In this paper, we include measures of the thickness of the nickel (Ni) and analysis of radiation mitigation and radiation incidents, according to the thickness of the elements Chromium (Cr) and zinc (Zn), taking as base metal element iron (Fe). As a result, in all cases were simulated processes of metal deposition which included the results of X-ray absorption, and neglect the influence of other factors such as temperature, pH, surface treatment, among others, which are necessary to consider in each case.
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Li, Li. "Study of Metal-Insulator-Metal Diodes for Photodetection." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1367319217.
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Tao, Chenggang. "Fluctuations on metal surfaces and molecule/metal interfaces." College Park, Md.: University of Maryland, 2007. http://hdl.handle.net/1903/7638.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2007.Thesis research directed by: Dept. of Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Karar, Ayman A. "Surface plasmons for enhanced metal-semiconductor-metal photodetectors." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2013. https://ro.ecu.edu.au/theses/593.
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Surface Plasmon Polaritons (SPPs) are quantized charge density oscillations that occur when a photon couples to the free electron gas of the metal at the interface between a metal and a dielectric. The extraordinary properties of SPP allow for sub-diffraction limit waveguiding and localized field enhancement. The emerging field of surface plasmonics has applied SPP coupling to a number of new and interesting applications, such as: Surface Enhanced Raman Spectroscopy (SERS), super lenses, nano-scale optical circuits, optical filters and SPP enhanced photodetectors. In the past decade, there have been several experimental and theoretical research and development activities which reported on the extraordinary optical transmission through subwavelength metallic apertures as well as through periodic metal grating structures. The use of SPP for light absorption enhancement using sub-wavelength metal gratings promises an increased enhancement in light collection efficiency of photovoltaic devices. A subwavelength plasmonic nanostructure grating interacts strongly with the incident light and potentially traps it inside the subsurface region of semiconductor substrates. Among all photodetectors, the Metal-Semiconductor-Metal photodetector (MSM-PD) is the simplest structure. Moreover, due to the lateral geometry of the MSM-PDs, the capacitance of an MSM-PD is much lower than capacitances of p-i-n PDs and Avalanche PDs, making its response time in the range of a few tens of picoseconds for nano-scale spacing between the electrode fingers. These features of simple fabrication and high speed make MSM-PDs attractive and essential devices for high-speed optical interconnects, highsensitivity optical samplers and ultra-wide bandwidth optoelectronic integrated circuits (OEIC) receivers for fibre optic communication systems. However, while MSM-PDs offer faster response than their p-i-n PD and avalanche PD counterparts, their most significant drawbacks are the high reflectivity of the metal fingers and the very-low light transmission through the spacing between the fingers, leading to very low photodetector sensitivity. This thesis proposes, designs and demonstrates the concept of a novel plasmonicbased MSM-PD employing metal nano-gratings and sub-wavelength slits. Various metal nano-gratings are designed on top of the gold fingers of an MSM-PD based on gallium arsenide (GaAs) for an operating wavelength of 830 nm to create SPP-enhanced MSM-PDs. Both the geometry and light absorption near the designed wavelength are theoretically and experimentally investigated.
Finite Difference Time Domain (FDTD) simulation is used to simulate and design plasmonic MSM-PDs devices for maximal field enhancement. The simulation results show more than 10 times enhancement for the plasmonic nano-grating MSM-PD compared with the device without the metal nano-gratings, for 100 nm slit difference, due to the improved optical signal propagation through the nano-gratings. A dual beam FIB/ SEM is employed for the fabrication of metal nano-gratings and the sub-wavelength slit of the MSM-PD. Experimentally, we demonstrate the principle of plasmonics-based MSM-PDs and attain a measured photodetector responsivity that is 4 times better than that of conventional single-slit MSM-PDs. We observe reduction in the responsivity as the bias voltage increases and the input light polarization varies. Our experimental results demonstrate the feasibility of developing high-responsivity, low bias-voltage high-speed MSM-PDs. A novel multi-finger plasmonics-based GaAs MSM-PD structure is optimized geometrically using the 2-D FDTD method and developed, leading to more than 7 times enhancement in photocurrent in comparison with the conventional MSM-PD of similar dimensions at a bias voltage as low as 0.3V. This enhancement is attributed to the coupling of SPPs with the incident light through the nano-structured metal fingers. Moreover, the plasmonic-based MSM-PD shows high sensitivity to the incident light polarization states. Combining the polarization sensitivity and the wavelength selective guiding nature of the nano-gratings, the plasmonic MSM-PD can be used to design high-sensitivity polarization diversity receivers, integrating polarization splitters and polarization CMOS imaging sensors. We also propose and demonstrate a plasmonic-based GaAs balanced metalsemiconductor- metal photodetector (B-MSM-PD) structure and we measure a common mode rejection ratio (CMRR) value less than 25 dB at 830nm wavelength. This efficient CMRR value makes our B-MSM-PD structure suitable for ultra-high-speed optical telecommunication systems. In addition, this work paves the way for the monolithic integration of B-MSM-PDs into large scale semiconductor circuits. This thesis demonstrates several new opportunities for resonant plasmonic nanostructures able to enhance the responsivity of the MSM-PD. The presented concepts and insights hold great promise for new applications in integrated optics, photovoltaics, solidstate lighting and imaging below the diffraction limit. In Chapter 10 we conclude this thesis by summarizing and discussing some possible applications and future research directions based on SPP field concentration.
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Bharde, A. "Microbial synthesis of metal oxide and metal nanoparticles." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2007. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2553.
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Harris, Bonnie L. "Scrap Metal." Digital Commons at Loyola Marymount University and Loyola Law School, 2018. https://digitalcommons.lmu.edu/etd/508.
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Sze-To, Lap, and 司徒立. "The structural chemistry of coordination compounds containing d-block or f-block metals." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45204470.
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Findon, Matthew M. "Semi-solid slurry formation via liquid metal mixing." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0721103-161140/.
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Palaniswamy, Hariharasudhan. "Determination of process parameters for stamping and sheet hydroforming of sheet metal parts using finite element method." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195621470.
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