Thesis (doctoral)--Technische Universiteit Delft, 1997. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 152-158).

Thesis (M.S.)--University of Wisconsin--Madison, 1969. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Nevada, Reno, 2008. / "December, 2008." Includes bibliographical references (leaves 95-96). Online version available on the World Wide Web.

Submitted by Mery Piedad Zamudio Igami (mery@ipen.br) on 2017-03-10T15:20:01Z No. of bitstreams: 1 22060.pdf: 3959215 bytes, checksum: 0a58b276270c30e02d2f6935bafba229 (MD5) / Made available in DSpace on 2017-03-10T15:20:01Z (GMT). No. of bitstreams: 1 22060.pdf: 3959215 bytes, checksum: 0a58b276270c30e02d2f6935bafba229 (MD5) / Neste trabalho avaliou-se a ação positiva da substituição de lantânio por praseodímio e de lantânio por magnésio na performance eletroquímica de eletrodos de ligas de armazenamento de hidrogênio em estado bruto de fusão e com tratamento térmico. O La foi substituído por Mg nas ligas La0,7-xMgxPr0,3Al0,3Mn0,4Co0,5Ni3,8 (x=0,0-0,7) e por Pr nas ligas La0,7-yPryMg0,3Al0,3Mn0,4Co0,5Ni3,8 (y=0,0-0,7). Os parâmetros eletroquímicos analisados foram ativação, capacidade de descarga, retenção da capacidade de descarga, autodescarga e alta taxa de descarga. As ligas apresentaram comportamento passivo em relação à corrosão. As análises por MEV/EDS e por DRX com refinamento por Rietveld revelaram a presença majoritária de fases similares às fases LaNi5, PrNi5, LaMg2Ni9 e PrMg2Ni9 em função das composições das ligas estudadas. Os parâmetros de rede e os volumes da célula unitária das fases diminuíram com a substituição crescente de La por Mg e de La por Pr. As capacidades de descarga máxima decresceram com a substituição crescente de La por Mg e de La por Pr, acompanhando o decréscimo da abundância da fase similar à fase LaNi5 e o aumento da abundância da fase similar à fase LaMg2Ni9. Comparativamente, menores taxas de autodescarga e maior estabilidade cíclica foram observadas para o eletrodo da liga na condição x=0,1, ao passo que o eletrodo da liga na condição y=0,0 apresentou maiores valores de alta taxa de descarga, indicando melhor performance cinética. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

>Magister Scientiae - MSc / Hydrogen has been regarded as an ideal energy carrier for future, it can be stored as a liquid in cryogenic tanks, a gas in high pressure cylinders and as solid in metal hydrides. Hydrogen storage in metal hydrides is of research interest because hydrides often have high energy density than gas or liquid hydrogen and are relatively safe. Ti and Ti alloys are promising hydrogen storage material because they have high affinity for hydrogen, light in weight and react reversibly with hydrogen. This work aims to investigate the hydrogen storage capacity of CP- Ti and Ti6Al4V alloy and Pd/Ti6Al4V alloy, where Pd was deposited on Ti6Al4V alloy. Samples were hydrogenated from room temperature to 650 °C at atmospheric pressure in the vacuum furnace under the 15%H/Ar atmosphere. Hydrogenation was carried out for a period of 3 hours for all samples. Sample composition and layer thickness were determined using Rutherford backscattering spectrometry. The microstructure and phase transformation were investigated using optical microscopy and X-ray diffraction technique. Hydrogen storage capacity was determined using elastic recoil detection analysis and gravimetric method. It was found that hydrogenation temperature has an effect on hydrogen absorption, microstructure and phase transformation. Maximum hydrogen concentration was obtained at hydrogenation temperatures of 550 °C for all materials with 45.57 at.% in CP-Ti, 34.77 at.% in Ti6Al4V alloy and 39 at.% H in Pd/Ti6Al4V coated system. In CP-Ti it was found that hydrogen absorption begins at 550 °C and decreases at hydrogenation temperature of 650 °C and that hydrogenation at both temperatures leads to formation of titanium hydrides and needlelike microstructure. At temperatures below 550 °C no hydrides were formed. For Ti6Al4V alloy ERDA results showed that no significant hydrogen absorption occurred at temperatures below 550 °C and at hydrogenation temperature of 650 °C, hydrogen absorption decreased drastically. The δ- titanium hydride was detected in the sample hydrogenated at 550 °C. Fine needle like microstructure was observed in the sample hydrogenated at 550 °C, and at higher temperature (650 °C ) coarse needles were formed. Pd coatings on Ti6Al4V alloy was found to increase the absorption of hydrogen, and allowing hydrogen to be absorbed at low temperatures. / National Research Foundation (NRF)

No description available.

Although hydrides of metal carbonyls are widely known, the number of hydrides in the related family of metal nitrosyls is extremely small. The preparation of a series of nitrosyl hydrides from the treatment of [CpW(NO)I₂]₂ (Cp=ƞ⁵-C₅H₅) with Na[H₂Al(OCH₂CH₂OCH₃)₂] is described. The addition of one or two equivalents of the aluminum reagent results in the formation of [CpW(NO)IH]₂ or [CpW(NO)H₂]₂ respectively. The reaction of [CpW(NO)IH]₂ with a Lewis base (L=P(OPh)₃, P(OMe)₃, PPh₃ or PMe₃) gives the monometallic CpW(NO)IHL, while [CpW(NO)H₂]₂ reacts with P(OPh)₃ or P(OMe)₃ to yield [CpW(NO)HL]₂ which undergoes further reaction to give CpW(NO)H₂L. Proton NMR spectroscopy shows that all bimetallic species contain bridging hydride ligands and are therefore best, formulated as [CpW(NO)1]₂(µ-H)₂, [CpW(NO)H]₂(µ-H)₂ and [CpW(NO)L]₂(µ-H)₂. The ¹H NMR spectrum of [CpW(NO)H]₂(µ-H)₂ shows that there is no hydride ligand exchange on the NMR time scale and that ¹jH(terminal)W ≃ ¹jH(bridging)w > ²jHW. From this finding, it is possible to develop new criteria for assessing the static or fluxional nature of hydride ligands for several families of organotungsten hydrides (Cp₂W, CpW(CO)₃, W(CO)₃ and CpW(NO)x (x=l or 2)). Within each family, the magnitude of ¹JHW strongly reflects the type of metal hydride bonding, i.e. [Formula Omitted] and suggests that bridge bonding involves all the atoms in the bridge and therefore the "fused" notation is introduced. Treatment of CpW(NO)(CH₂SiMe₃)₂ with low pressures of H₂ (60-80 psig) in the presence of Lewis bases (L=P(0Ph)₃, PMePh₂) gives the unusually stable alkyl hydride compounds CpW(NO)(H)(CH₂SiMe₃)L. This chemistry is then extended to the Cp* (Cp*=ƞ⁵ -C₅Me₅) analogues, including the preparation of the appropriate starting materials. Upon thermolysis of Cp*W(NO)(H)(CH₂SiMe₃)(PMe₃) in C₆H₆, the intermolecular C-H activation product Cp*W(N0)(H)(C₆H₅)(PMe₃) is cleanly formed. However, intermolecular activation of CH₄, C₆H₁₂ or n-C₆H₁₄ does not occur under similar experimental conditions. Hydrogenolysis of Cp*W(NO)(CH₂SiMe₃)₂ at high pressures (≃920 psig) with no Lewis base present results in the formation of isolable [Cp*W(NO)H]₂(µ-H)₂ and [Cp*W(N0)H](µ-H)₂[Cp*W(N0)(CH₂SiMe₃)]. The latter is a new example of the rare class of dinuclear alkyl hydride complexes. Proton NMR spin tickling experiments on this compound allow the complete assignment of all couplings in the spectrum and show that ¹jH(terminal)W' ¹JH(bridging)W and ²jHW have the same sign. / Science, Faculty of / Chemistry, Department of / Graduate

<p> The relative acidities of some aryl germanes have been measured in liquid ammonia.</p> <p> The NMR spectra of phenyl silane and phenyl germane have been completely analysed and the chemical shifts shown to arise from the presence of an electric dipole in the molecule. The NMR spectrum of phenyl germyl anion was unambiguously assigned and partially analysed. The results are consistent with little delocalization of the negative charge from the Ge onto the ring.</p> <p> The vibrational spectra of the germyl anion have been observed and the geometry of the molecule estimated from a normal coordinate analysis of the data.</p> <p> The Raman spectrum of liquid ammonia-D3 has been measured and two bands in the Raman spectrum of liquid ammonia have been reassigned.</p> / Thesis / Doctor of Philosophy (PhD)

Copper hydrides such as [Ph₃PCuH]₆ (Stryker’s Reagent) are textbook reagents in organic chemistry for the selective hydrogenation of α,β-unsaturated carbonyl compounds. Despite their widespread use both stoichiometrically and catalytically, there are many important questions about polynuclear copper hydrides that have not been answered. I have investigated the electron transfer chemistry of [Ph₃PCuH]₆ and related copper hydrides. Copper hydrides (E₁/₂ = –1.0 to –1.2 V vs FcH/FcH⁺) are good one-electron reducing agents. Stopped-flow techniques have allowed the detection of electron transfer intermediates in copper hydride reactions. The fate of the copper containing products after electron transfer or hydride transfer reactions has been investigated. An unusual cationic copper hydride, [(Ph₃P)₇Cu₇H₆]⁺ was found to be the major product of these reactions. Methods of converting this species back to [Ph₃PCuH]₆ have been investigated. The chemistry of this cationic species plays an important role in catalytic use of copper hydrides.