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Materials with potential for high temperature inorganic pigment applications (e.g. ceramics) have been synthesised using solid state methods and characterised using powder X-ray and neutron diffraction, magic angle spinning NMR, Mossbauer spectroscopy, UVNis spectroscopy and colour measurement techniques. A number of compounds containing tin (H) and niobium (V) have been modified and doped with various constituents to tailor and widen the colour properties of the bright yellow parent phases. The dark yellow (L*(91.28), a*(13.74), b*(54.76)) tin niobium oxide pyrochlores have been re-characterised using neutron diffraction techniques. These materials exhibit both cation and anion disorder caused by a stereoactive lone pair on the tin (H) metal centres. Solid state NMR and Mossbauer studies have shown the presence of tin (IV) on a symmetric site within the primary phase of the pure oxide pyrochlore and methods have been investigated to minimise the tin (H) disproportion method from where the tin (IV) is derived.

lack of consensus among the world researchers on the significance of Po-210 build up in lead cooled reactors. The second objective is to evaluate the advantages and disadvantages of selected candidate metal coolants. In addressing both objectives, the computer code ORIGEN was used. To establish the background basis for these assessments, fundamental concepts of reactor physics are reviewed and discussed.

of the solder. In this thesis, a new fabrication process for incorporating NiTi particles (10 vol.% NiTi) into Sn-In solder (80Sn-20In) using liquid phase sintering has been developed. The microstructures of the solders were characterized. The behavior of the solder joints during thermomechanical cycling was also characterized and the results showed that the shear stress induced in the composite solder joint is significantly reduced relative to that in the monolithic solder joint due to the generation of a back-stress associated with the B19Å fÅ *B2 phase transformation of the NiTi particles during the heating part of the cycle. This causes an appreciable reduction of the total inelastic strain range during cycling.

This thesis deals with the influence of the structure andchemical composition of platinum surfaces on the adsorption ofsome molecules. Three main lines can be distinguished : 1) thecharacterisation of clean/modified surfaces, 2) the adsorptionof some simple atoms and molecules on these surfaces andfinally 3) the adsorption of 2-butenal, a bi-functionalmolecule containing a C=C group conjugated with a C=O group.The main tools used in this work are scanning tunnellingmicroscopy, photoelectron spectroscopy and high-resolutionelectron energy loss spectroscopy, in combination with quantumchemical calculations. The platinum (111)(1× 1) and (110)(1× 2) surfacesare chosen as substrates. Pt(111) is a non-reconstructedclose-packed surface, while the Pt(110) surface is open, due toits missing row (MR) reconstruction, which results in thealternation of ridges, {111} microfacets and valleys. Titaniumgrows on Pt(111) in a Volmer-Weber mode. Pronounced reactionsbetween Pt and Ti are detected already at room temperature asthe Ti2p and Pt4f7/2core-level shifts are characteristic of the Pt3Ti alloy. Carbon segregated on the (110) surfaceappears as extended graphitic regions, which smoothen thesubstrate. Sn deposition at room temperature on Pt(110) resultsin the appearance of small islands, randomly spread over thesurface. The presence of mobile Sn ad-atoms and Pt-Sn-Ptalloyed chains in the valley of the MR reconstruction is alsoevidenced. Annealing the surface results in the rearrangementof the tin in the surface layer, together with a globalshortening of the terraces in the [110]direction and anincreased density of (1× n) (n&gt;2) defects. The adsorption of atomic hydrogen and oxygen has beenperformed on the Pt(111)( √ 3x √3)R30º surfacealloy and on Pt(110)(1× 2) respectively. The adsorptionsite of these atoms is changed as compared to the onedetermined on the clean Pt(111) surface (i.e. fcc hollow site): H is adsorbed on-top site on the (√3× √3)surface alloy, and O sits on the ridge of the missing rowreconstruction in bridge site. Carbon monoxide adsorption wasperformed on Pt(111) and Pt(110)(1× 2) surfaces, modifiedor not by tin. On the unmodified (111) surface, CO adsorbsfirst in top site, thenin bridge. Changing the geometry of thesurface to the (110) results in the vanishing of the bridgesite population. Modifying these surfaces by Sn does not changethe CO adsorption site. Finally, 2-butenal (CH3-CH=CH-CH=O) has been adsorbed at 100 K on thePt(111) surface and the Sn/Pt(111) surface alloys. On theunmodified Pt surface, comparison with results obtained forpropene (CH2=CH-CH3) adsorption evidences the involvement of the C=Cgroup of the 2-butenal molecule in the bonding to the Ptsurface. The carbonyl group is also suggested to take part inthe bonding, through a σccη1(O) configuration. This carbonyl group bondingdisappears when Sn is alloyed to the surface, and the formationof a new physisorbed phase is detected. / <p>NR 20140805</p>

The subject of the thesis is growth of aluminium structures one-dimensional chains on Si(100) surface. Growth characteristics of Al on Si(100) at room temperature and at higher temperature and various coverages were measured using STM. The results are discussed with respect to previous experiments and a way to find the value of activation energy of surface migration is proposed. An important part of the thesis is preparation and tests of a new low-temperature UHV apparatus for STM experiments. Functions of the apparatus are described. A way to prepare clean Si(100) surface as well as the methods of achieving atomic-scale resolution in STM were found in conditions previously unknown. A test of evaporators for Al and Sn is described. Al deposition has not been successful in the new apparatus yet. Sn deposition has been successful and low-temperature structures of tin on Si(100) were observed. They differ from room-temperature structures and contain kinks which were previously observed only in Al structures.

Cette thèse visait à développer des techniques d'ablation au laser et de fragmentation dans des liquides pour la synthèse de nouveaux NPs ayant des fonctionnalités utiles. L’approche de la thèse est axée sur l’élaboration de la technique ablative au laser pour la synthèse de matériaux conventionnels avec des paramètres pour des applications biomédicales sélectionnées, ainsi que sur le développement de cette technique pour la synthèse de nouveaux nanomatériaux destinés à des applications biomédicales. En particulier, il comprend:1. Nous avons élaboré un régime de fragmentation laser fs à partir de colloïdes de Si pour la synthèse de NPs de Si ayant une taille, une cristallinité et un état d'oxydation contrôlables.Nous avons testé un certain nombre d’applications biomédiales particulières de Si Si préparés de cette manière.2. Nous avons développé une technique d'ablation et de fragmentation au laser fs pour fabriquer des noyaux Au NPs et des carottes en Au-Si nus pour SERSapplications. Une approche est basée sur l'ablation au laser de la cible Au dans une solution colloïdale de NP Si.3. Pour la première fois, nous avons synthétisé de nouveaux NP plasmoniques à base de nitrure de titane. Nous avons également montré qu’une étape supplémentaire de fragmentation du laser fs entraînait une diminution de la taille des NP à 5 nm. En outre, nous avons constaté que ces NP ont un très large pic d'extinction dans le proche IR.4. Pour la première fois, nous avons démontré la synthèse de NPs organiques fluorescentes d'un luminophore à émission induite par agrégation spécialement conçu (AIE LP). La luminosité de ces NP a été jugée comparable à celle des points quantiques. / This thesis as aimed at the development of techniques of fs laser ablation and fragmentation in liquids for the synthesis of novel NPs having useful functionalities. The approach of the thesis is focused on the elaboration of the laser ablative technique for the synthesis of conventional materials with parameters for selected biomedical applications, as well as the development of this technique for the synthesis of novel nanomaterials for biomedical applications. In particular it includes:1. We elaborated a regime of fs laser fragmentation from Si colloids for the synthesis of Si NPs having controllable size, crystallinity and oxidation state. We tested so-prepared Si NPs a number of particular biomedial applications.2. We elaborated a technique of fs laser ablation and fragmentation to fabricate bare Au NPs and Au-Si core-shells for SERSapplications. One approache is based on laser ablation of Au target in colloidal solution of Si NPs. 3. For the first time we synthesized novel plasmonic NPs based on titanium nitride. We also showed that an additional fs laser fragmentation step leads to the decrease of NPs size to 5 nm. Besides, we found that such NPs have a very broad extinction peak in the near IR.4. For the first time we demonstrated the synthesis of fluorescent organic NPs of specially designed aggregation-induced emission luminophore (AIE LP). The brightness of such NPs was determined to be comparable to that of quantum dots.

Neste trabalho foram investigados o efeito da adição de diferentes quantidades de IrO2 (entre 1 e 30% em mol) em eletrodos de SnO2 e suas atividades eletrocatalíticas para a reação de oxidação de etanol. A inovação deste trabalho está na composição do eletrodo onde a concentração de IrO2 varia de níveis da ordem de dopante até concentrações típicas de ADE. O método de preparação utilizado permitiu a obtenção de filmes homogêneos e com estequiometria controlada, comprovados pela técnica de Energia Dispersiva de Raios-X (EDX). A análise de Microscopia Eletrônica de Varredura (MEV) mostrou que os filmes possuem morfologia com trincas. Na análise por Difração de Raios-X (DRX) ficou evidente a formação de solução sólida. A caracterização por Voltametria Cíclica mostrou que a carga voltamétrica e a corrente relacionada a reação de desprendimento de oxigênio (RDO) aumentam com a concentração de IrO2 na composição do eletrodo. Adicionalmente, a ordem da estabilidade eletroquímica encontrada é a seguinte: 30 >> 1 @ 10 > 5% em mol de IrO2. Para avaliar a atividade eletrocatalítica destes eletrodos para a reação de oxidação de etanol foram utilizadas as técnicas de voltametria cíclica, eletrólise a corrente constante e Infravermelho com Transformada de Fourier (FTIR) in situ. Foram identificados como produtos acetaldeído, acido acético e CO2. Comprovouse que o ácido acético não é oxidado nas condições experimentais empregadas. Observou-se que os eletrodos contendo 5 e 10% em mol de IrO2 apresentaram as maiores velocidades de oxidação do etanol formando preferencialmente ácido acético. Os eletrodos contendo 1 e 30% em mol de IrO2 apresentaram maior seletividade para CO2 em relação as outras composições. A adição de 1% em mol de IrO2 no SnO2 foi suficiente para promover uma estabilidade satisfatória para a aplicação deste eletrodo. Outra observação importante foi que este eletrodo apresentou a menor seletividade para a formação de ácido acético permitindo uma maior formação de CO2. / In this work was investigated the effect of the IrO2 addition (1 30 mol% contents) on SnO2 electrodes and its electrocatalytic activities towards ethanol oxidation. The new approach of this work is related to the IrO2 contents on the electrodes compositions shifts between the dopant levels until Dimensionally Stable Anodes (DSA®) concentrations. The preparation method used allowed to obtain homogeneous films with controlled stoichiometry, that was confirmed by Energy Dispersive X-ray (EDX) analysis. The Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD) analysis showed a cracked morphology and the formation of solid solution, respectively. The voltammetric experiments showed an increase in the Oxygen Evolution Reaction (OER) currents and the voltammetric charges for the higher IrO2 contents. In addition, the stability order found is 30 >> 1 @ 10 > 5 mol% IrO2. In order to investigate the electrodes activities towards ethanol oxidation, the cyclic voltammetry, electrolysis and Fourier Transform Infrared (FTIR) in situ techniques were used. The presence of products as acetaldehyde, acetic acid and CO2 was detected. Acetic acid was not oxided in the experimental conditions employed. The 5 and 10 mol% IrO2 electrodes showed higher ethanol oxidation rates with the preferential acetic acid formation. The electrodes containing 1 and 30 mol% IrO2 are more selective to CO2 production than the others compositions. The addition of 1 mol% IrO2 was enough to enhance the electrode stability, that make it applicable. Another interesting observation is that the IrO2 1 mol% electrode presented the smaller selectivity for the acid acetic formation allowing the complete oxidation of ethanol possible.

O comportamento eletroquímico do estanho em solução de cloreto de sódio a 2% em massa, com e sem a presença de quantidades mínimas de ácido cítrico, foi investigado por meio de medidas potenciodinâmicas e potenciostáticas. O sistema simula, dentro das limitações experimentais, os processos eletroquímicos ocorridos em enlatados (folha de flandres) contendo salmoura. Os primeiros ensaios potenciodinâmicos mostraram a ocorrência de dois processos de oxidação, relacionados após as medidas com eletrodo de disco rotativo, aos estágios de passivação do metal. Os parâmetros eletroquímicos da corrosão na região pré-passiva de potenciais, foram determinados pela extrapolação da região de Tafel das curvas de polarização potenciodinâmica, realizadas com e sem a adição de ácido cítrico. Um mecanismo de reação foi proposto segundo os resultados destes parâmetros eletroquímicos, bem como, a eficiência de inibição do ácido orgânico sobre a corrosão pré-passiva do metal em meio de cloreto. A complementação deste estudo cinético foi verificada mediante a determinação da ordem de reação com relação aos íons cloreto, a qual aproxima-se da unidade, levando à conclusão de que a etapa determinante da velocidade da reação inclui a presença destas espécies. Em complementação foram realizadas medidas potenciostáticas e potenciodinâmicas, a fim de avaliar a corrosão por pites do estanho em cloreto de sódio, de modo que as alterações ocorridas na superfície do eletrodo foram acompanhadas microscopicamente. Novamente verificou-se o efeito da adição de quantidades mínimas de ácido cítrico, porém agora, sobre a corrosão por pites. Os resultados mostraram que a concentração necessária para inibir efetivamente a corrosão por pites é 10-2 M. / Abstract no available.

Wu Yuen Sze. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1999. / Includes bibliographical references (leaves 98-107). / Abstracts in English and Chinese. / Table of contents --- p.i / Acknowledgements --- p.iv / Abstract --- p.v / List of compounds --- p.vi / Abbreviations --- p.x / Chapter Chapter 1 --- Synthesis and Structures of Low-valent Group14 Organometallic Compounds --- p.1 / Chapter 1.1 --- General apects of low-valent group 14 compounds --- p.1 / Chapter 1.2 --- Structures of germylenes and stannylenes --- p.3 / Chapter 1.3 --- Tetravalent group 14 Metal amides --- p.7 / Chapter 1.4 --- Objectives --- p.11 / Chapter 1.5 --- Results and Discussion --- p.12 / Chapter 1.5.1 --- Synthesis of germanium(II) compound [Ge{C(C5H4N- 2)C(Ph)N(SiMe3)2}{N(SiMe3)C(Ph)C(SiMe3)(C5H4N- 2)}] (29) --- p.12 / Chapter 1.5.2 --- Synthesis of tin(II) amide [Sn{N(SiMe3)C(Ph)C- (SiMe3)(C5H4N-2)}2] (30) --- p.14 / Chapter 1.5.3 --- Synthesis of tin(IV)(amide)dichloride [Sn{N(SiMe3)C- (Ph)C(SiMe3)(C5H4N-2)}2Cl2] (31) --- p.15 / Chapter 1.5.4 --- Spectroscopic Properties of Compounds 29-31 --- p.16 / Chapter 1.5.5 --- Molecular Structure of [Ge{C(C5H4N-2)C(Ph)N(Si- Me3)2}{N(SiMe3)C(Ph)C(SiMe3)C(C5H4N-2)}] (29) --- p.21 / Chapter 1.5.6 --- Molecular structure of [Sn{N(SiMe3)C(Ph)C(SiMe3)- (C5H4N-2)}2] (30) --- p.25 / Chapter 1.5.7 --- Molecular structure of [Sn{N(SiMe3)C(Ph)C(SiMe3)- (C5H4N-2)}2C12] (31) --- p.28 / Chapter Chapter 2 --- Synthesis and Structure of Group 14 Metal- Chalcogenones --- p.32 / Chapter 2.1 --- Multiple bond between group 14 metals and chalcogens --- p.32 / Chapter 2.2 --- Results and Discussion --- p.39 / Chapter 2.2.1 --- "Synthesis of germane- and stannane-chalcogenones [(RI)(R1.)Ge=E], [E = S 59, Se 60], [(R1)2Sn=S] (61)， [(R1)(R1.)Sn=Se] (62)" --- p.39 / Chapter 2.2.2 --- Spectroscopic properties of compounds 59-62 --- p.41 / Chapter 2.2.3 --- Molecular structure of [{N(SiMe3)C(Ph)C(SiMe3)- (C5H4N-2)}2Sn=S] (61) --- p.46 / Chapter 2.2.4 --- "Molecular structure of [{N(SiMe3)2C(Ph)C(C5H4N-2)}- {N(SiMe3)C(Ph)C(SiMe3)(C5H4N-2)}M=E] [M = Ge, E =S 59，Se 60; M = Sn,E = Se 62]" --- p.52 / Chapter Chapter 3 --- Reactivity of Low-valent Group 14 Organometallics Compounds --- p.59 / Chapter 3.1 --- Introduction --- p.59 / Chapter 3.1.1 --- Lewis-base behavior --- p.60 / Chapter 3.1.2 --- Lewis-acid behavior --- p.63 / Chapter 3.1.3 --- Oxidative-addition (or insertion) reactions --- p.65 / Chapter 3.2 --- Results and Discussion --- p.69 / Chapter 3.2.1 --- Lewis acid base behavior of [Sn(R2)2] (27) --- p.69 / Chapter 3.2.1.1 --- "Reaction of [Sn(R2)2] (27) with group 11 metal derivatives (M = Ag, X = Cl 91,I 92,SCN 93，CN94; M = Cu, X = Cl 95，I 96)-Synthesis of [(R2)2Sn→(μ- MX)]2" --- p.69 / Chapter 3.2.2 --- Oxidative-addition (or insertion) reaction of tin(II) compounds --- p.73 / Chapter 3.2.2.1 --- Reaction of AgNCO with [Sn(R2)2] (27) 一 Synthesis of [(R2)2Sn(NCO)2](97) --- p.73 / Chapter 3 .2.3 --- Spectroscopic properties of compounds 91-97 --- p.74 / Chapter 3.2.4 --- Molecular structure of [{CH(SiMe3)C9H6N-8}2Sn→(μ- AgCl)]2 (91) --- p.80 / Chapter 3.2.5 --- Molecular structure of [{CH(SiMe3)C9H6N-8}2Sn- (NCO)2] (97) --- p.85 / Appendix I / Chapter A. --- Experimental procedures for chapter 1 --- p.87 / Chapter B. --- Experimental procedures for chapter 2 --- p.90 / Chapter C. --- Experimental procedures for chapter 3 --- p.93 / Appendix II / Chapter A. --- References for chapter 1 --- p.98 / Chapter B. --- References for chapter 2 --- p.102 / Chapter C. --- References for chapter 3 --- p.104 / Appendix III / Chapter A. --- General procedures --- p.106 / Chapter B. --- Physical and analytical measurements --- p.106 / Appendix IV / Table A.l. Selected crystallographic data for compounds 29，30，31 --- p.109 / Table A.l. Selected crystallographic data for compounds 59，60，61 --- p.110 / "Table A.l. Selected crystallographic data for compounds 62, 91，97" --- p.111