Thesis (doctoral)--Bonn. / Includes bibliographical references (p. 45).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Washington State University, December 2006. / Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references (leaves 62-68). Also available in electronic version.

Thesis (Ph. D.)--Lehigh University, 2006. / Vita. Includes bibliographical references and vita.

Ce travail vise à étudier les matériaux d'électrodes pour batteries Li-ion et Na-ion lors qu’ils fonctionnent à l'intérieur des batteries. Afin de comprendre l'évolution structurelle des matériaux alors que les ions Li+ ou Na+ sont insérés/extraits de leur cadre, on utilise principalement la diffraction, exploitant neutrons, rayons X et le rayonnement synchrotron (SR). Nous avons adopté une approche combinée des mesures ex situ, in situ et operando. Au début, nous avons conçu une cellule électrochimique pour mesures in situ de diffraction de neutrons sur poudre (NPD), avec un alliage en (Ti,Zr) "transparent aux neutrons"; cette cellule s'est ajoutée à l’ensemble de nos outils pour effectuer des études de type operando. Nous avons démontré leur faisabilité en utilisant LiFePO4, montrant de bonnes performances électrochimiques et des données NPD de haute qualité pour affinements structurales Rietveld. Ensuite, nous avons réalisé des études des spinelles Li1+xMn2-xO4 (x=0,0.05,0.10) et LiNi0.4Mn1.6O4: pendant le cyclage, nous avons rapporté des évolutions structurelles, des diagrammes de phases et paramètres subtils tels que le comportement du Li, ou les facteurs de température. L’utilisation complémentaire du SR a clarifié la nature de la phase ordonnée Li0.5Mn2O4. Nos études combinées ont concernées d’autres matériaux d'électrodes prometteurs: LiVPO4O et Na3V2(PO4)2F3. Les 2 révèle des comportements complexes pendant la (de)intercalation du Li+/Na+. Les données de haute qualité ont permis des analyses quantitatives, dévoilant la structure d'un grand nombre des phases ordonnées et menant à la compréhension du comportement des cations dans ces matériaux / This work aims at studying electrode materials for Li-ion and Na-ion batteries as they function inside batteries. Diffraction is the mainly used technique, exploiting neutrons, X-Rays and synchrotron radiation (SR), to obtain insights on the structural evolution of such materials as Li+ or Na+ are inserted/extracted from their framework. We adopted a combined approach of ex situ, in situ and operando measurements to extract a maximum of information from our studies. At first, we designed an electrochemical cell for in situ neutron powder diffraction (NPD) measurements, featuring a “neutron-transparent” (Ti,Zr) alloy; this cell, joined to others previously developed in our group, gave us a complete set of tools to perform our studies. We demonstrated the feasibility of operando NPD using LiFePO4, showing good electrochemical performances and high-quality NPD patterns for Rietveld structural refinements. Then we carried out detailed studies of spinels Li1+xMn2-xO4 (x = 0, 0.05, 0.10) and LiNi0.4Mn1.6O4: we reported phase diagrams, structural evolutions and subtle parameters as lithium's behavior inside the spinel framework, or thermal displacement parameters, directly upon cycling. Complementary use of SR shed light on other features, as the nature of the ordered phase Li0.5Mn2O4. Our combined studies concerned other promising electrode materials: LiVPO4O and Na3V2(PO¬4)2F3. Both revealed complex behaviors upon Li+/Na+

In this project a number of synthetic procedures were investigated with a view to preparing a new type of charge transfer polymer system having a structure based on that of side chain liquid crystal polymers, in that the hoped for polymer was composed of charge transfer acceptors connected to a polymer backbone via a flexible alkyl spacer linkage. As part of this work new charge transfer complexes were prepared some of which have shown possible novel properties, such as, co-operative magnetic effects and film forming capabilities. Finally, in order to characterise materials prepared, a Faraday magnetic susceptibility balance and instrumentation for measuring electrical conductivity has been built.

No description available.

No description available.

The objective of this work was to investigate the distribution of donor-like centres produced by boron implantation into p-type, Bridgeman grown Hg[0.8]Cd[0.2]Te and fabricate photodiodes from implanted substrates. Low carrier concentration substrates, 4-5x10[16]cm[-3], were implanted at room temperature with dose rates (&phis;) of 4x10[-2] or 6x10[-3]muAcm[-2], to a total dose of 1 x 10[15]B[+] cm[-2] (50,100keV) or 1x10[14]B[+]cm[-2] (150keV), respectively. Encapsulated specimens were annealed at 200&deg;C or 235&deg;C to activate the dopant or redistribute electrically active radiation damage centres to produce p-n junctions. The effects of materials processing on Hg[l-x]Cd[x]Te was investigated by x-ray photoelectron spectroscopy. Concentration profiles of electrically active centres were obtained from differential measurements of the Hall effect and resistivity at 77K. Through a comparison of distributions in as-implanted and annealed samples, the nature of donor-like centres forming the distributions were established. The quality of photodiodes produced from identical samples was assessed through current-voltage, capacitance-voltage and optoelectronic measurements. The nature and distribution of donor-like centres are dependent upon the dose rate of boron ions. An immobile defect is contained within the implanted region. Mercury interstitials (Hg[int]) are complexed within the implanted region for &phis; > 4x10[-2] muAcm[-2]. Irradiation enhanced diffusion of Hg[int] occurs if &phis; < 6x10[-3] muAcm[-2]. Thermal annealing redistributes bound and unbound accompanied by recombination with mercury vacancies and the formation of electrically neutral complexes. Annealing at 235&deg;C for 10 mins completely removes the donor-like activity ascribed to Hg's [int] and reduces the concentration of electrically active immobile defects. P-N junctions are formed between the mercury vacancy distribution and unbound Hg's[int] or the immobile damage centres in annealed substrates. Junction formation is inhibited by the formation of the bound Hg[int] complex. Optimum R[o]A[j] products may be obtained from junctions formed from the immobile defect centre, although degradation of the implanted region occurs after annealing at 235&deg;C. Anodic oxides grow by the differential electromigration of ions, which can produce a passivating layer to further anodization. The native oxide on Hg[0.8] Cd[0.2] Te is an ill-defined chemical mixture of the primary elements (Cd, Hg, Te). Native oxides degrade the R[o]A product of p-n junctions.