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A study of cation replacement in perovskite-related systems including high temperature superconductorsCurrie, David Blake January 1990 (has links)
No description available.
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Electrical and electrochemical studies of some solid electrolytesSivapalan, Nagalingam January 1987 (has links)
In Chapter 1 solid electrolytes are reviewed. The historical development, mechanism of ionic conduction in solids and the properties and applications of important solid electrolytes are given. Chapter 2 discusses impedance methods as applied to electrochemistry and the equivalent circuit representation of the solid electrolyte/electrode interface. The application of a computer program that gives theoretical impedance and/or admittance plots is also described. The application of four-electrode conductivity measurements to solid electrolytes is described in Chapter 3. Since this is the first time these four-electrode measurements have been employed with solid electrolytes, a detailed review of the theoretical calculations and the errors involved are presented. The results from the experiments on the solid electrolyte PyAg<SUB>5</SUB>I<SUB>6</SUB>(Py=C<SUB>5</SUB>H<SUB>6</SUB>N) are also given. In Chapter 4, the cathodic deposition of silver from PyAg<SUB>5</SUB>I<SUB>6</SUB> and its subsequent recovery by anodic polarisation are examined. The behaviour of solid silver and silver painted electrodes in this perspective is compared. The solid electrolyte galvanic cell AgmidPyAg<SUB>5</SUB>I<SUB>6mid</SUB>Me<SUB>4</SUB>NI<SUB>5</SUB>, C is investigated in Chapter 5. Various cell parameters are measured and the charge/discharge characteristics examined. Finally in Chapter 6 the behaviour of zeolites as solid ionic conductors is reviewed and the results of some preliminary studies on zeolite-Y are presented.
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Ionic transport in lithium salts and compositesRageb, Shakir Mahmud January 1991 (has links)
No description available.
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Determination of the structure of disordered materials by neutron scatteringKeen, David Anthony January 1990 (has links)
No description available.
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Ab initio studies of polarisabilities of ions in crystalsTole, Philip January 1989 (has links)
No description available.
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Theoretical and experimental studies of superionic mixed-metal fluoridesCox, Paul Andrew January 1989 (has links)
No description available.
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Colloidal interactions in ionic liquidsMamusa, Marianna 25 February 2014 (has links) (PDF)
Ionic liquids (ILs) are a novel class of ionic solvents, which are being used more and more often in chemical systems based on nanoparticles (NP) for several industrial and technological applications. However, at present we are unable to master the state of dispersion or aggregation of NP in these solvents, and the classic theories applied to colloidal stability, such as the DLVO, cannot be applied. In particular, the difficulty is found in the description of the electrostatic interactions in these ionic media. In this work, we try to better understand colloidal interactions in ILs through two systems that have been thoroughly characterized separately: magnetic maghemite nanoparticles, whose surface is well controlled in water, and the ionic liquid ethylammonium nitrate (EAN), known for its resemblance to water. These two systems are finally mixed together and studied at both the macroscopic and microscopic levels. We perform characterizations through several techniques: flame atomic absorption spectroscopy, optical microscopy under magnetic field, scattering methods (neutrons, X-rays and light), magneto-optic birefringence. We discover the importance of having a charged NP surface in order to obtain stable maghemite dispersions in EAN. In particular, the best colloidal stability is reached by adsorbing citrate molecules on the NP surface. We further investigate the effect of the NP's size and concentration, of the cationic counterion used to compensate the charge of citrate, of water content. Finally, we transfer our acquired knowledge to the realization of dispersions in biocompatible ILs.
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Synthèse et structuration de disulfure de germanium en présence de liquides ioniques et de tensioactifs / Synthesis and structuration of germanium disulfide in the presence of ionic liquids and surfactantsMathiaud, Romain 16 December 2014 (has links)
L'obtention de manière contrôlée de matériaux chalcogénures nanostructurés et possédant une surface spécifique importante ou fonctionnalisée est un défi très intéressant. En alliant une surface spécifique élevée à la polarisabilité des surfaces chalcogénures ou en élaborant des matériaux fonctionnalisés, on peut espérer une percée dans de nombreux domaines comme la catalyse, la séparation gazeuse, l'électrochimie, le photovoltaïque ou l'optique... L'objectif de cette thèse était de développer des voies de synthèse du disulfure de germanium (GeS2) par chimie douce à température et pression ambiantes. Pour cela, nous avons utilisé deux agents sulfurants, le sulfure de dihydrogène (H2S) et le thioacétamide que nous avons fait réagir avec du tétraéthoxyde de germanium en présence d'un solvant. Les synthèses ont été réalisées en l'absence ou en présence d'un structurant, le plus souvent un liquide ionique (LI). Les synthèses sans structurant ont permis l'obtention de nanoparticules de GeS2 amorphes ou nano-organisées de 20 à 35 nm de diamètre et de surface spécifique intéressante (320 m2.g-1 avec H2S, 270 m2.g-1 avec le thioacétamide). Les synthèses réalisées en présence de LI conduisent à des matériaux hybrides contenant GeS2 et le cation du LI utilisé, de formule générale 0.2GeS2-0.8 cation organique. Les particules obtenues de taille micrométrique et présentant de très faibles surfaces spécifiques ont une morphologie qui dépend de la nature du cation organique impliqué dans la synthèse (sphères ou roses des sables). Des mesures XPS montrent la présence de liaisons Ge-S- au sein de l'hybride. L'utilisation de lithium de bis(trifluorométhanesulfonyl)imide nous a conduit à synthétiser un matériau GeS2-Li dont la conductivité de ~10-10 S.cm-1 est celle d'un sel ionique. En l'absence de solvant et en faisant jouer au LI le rôle de solvant et de structurant, nous avons pu préparer le premier iono-chalcogel qui, après optimisation, pourrait conduire à un matériau poreux. Par ailleurs, l'utilisation d'un structurant non ionique, l'hexadecylamine (HDA), au-delà de sa concentration micellaire critique, a conduit à l'obtention d'un matériau hybride nanométrique (environ 15 nm) qui possède non seulement une surface spécifique intéressante (130 m2.g-1) mais surtout une porosité intra-granulaire. En résumé, ce premier travail exploratoire nous a permis d'obtenir, selon le procédé de chimie douce choisi, du disulfure de germanium sous forme soit de nanoparticules aux surfaces spécifiques intéressantes, soit de particules présentant une certaine porosité intragranulaire, soit de matériaux hybrides où un cation organique interagit avec GeS2. / The controlled elaboration of nanostructured chalcogenides with high specific area or functionalized surface is an interesting challenge. Breakthrough in various domains such as catalysis, gas separation, electrochemistry, photovoltaics or optics can be achieved by the production of chalcogenide materials with functionalized surface or high specific area coupled with high polarisability.The aim of the thesis was to develop new soft chemistry routes for the synthesis of germanium disulfide at room temperature and pressure. Two sulfur precursors, i.e. hydrogen sulfide (H2S) and thioacetamide, and a germanium precursor, the tetraethoxigermanium were used for the syntheses. The syntheses were carried out either in the presence or in the absence of a template, in most case an ionic liquid (IL).Syntheses without templating agent led to amorphous or nano-organized GeS2 nanoparticles of 20 to 35 nm in diameter and interesting specific areas (320 m2.g-1 with H2S, 270 m2.g-1 with thioacetamide). Hybrid materials comprising GeS2 and LI cation with a general formula 0.2GeS2-0.8 organic cation were obtained in the presence of IL. The obtained particles of nanometric sizes and with hardly any specific area have a morphology that depends on the nature of the organic cation present during the synthesis, i .e. spheres or gypsum rosette-like particles. XPS measurements indicate the presence of Ge-S- bonds in the hybrid material. The use of lithium de bis(trifluorométhanesulfonyl)imide led to the elaboration of a GeS2-Li material which conductivity of ~10-10 S.cm-1 is that of an ionic salt.A first iono-chalcogel which could lead after optimization to a porous chalcogenide has been elaborated when using the IL as both the solvent and the templating agent and in the absence of any other solvent. The use of hexadecilamine (HDA) above its critical micellar concentration, led to hybrid nanoparticles of 15 nm in size with interesting specific area (130 m2.g-1) but also intra-granular porosity.In conclusion, this exploratory work led to the elaboration of GeS2 either as naoparticles with high specific area or particles with intragranular porosity or finally hybrid materials with GeS2 interacting with an organic cation, the final product depending upon the chosen soft chemistry route.Keywords: chalcogenide, ionic liquid, organic-inorganic hybrid, morphology, soft chemistry
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HCaRG "Hypertension-related Calcium Regulated Gene", un gène candidat de la réparation rénale : caractérisation de son interaction avec le cytosquelette et son expression géniqueCroisetière, Christian January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.
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HCaRG "Hypertension-related Calcium Regulated Gene", un gène candidat de la réparation rénale : caractérisation de son interaction avec le cytosquelette et son expression géniqueCroisetière, Christian January 2007 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
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