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Structure-property relationships in oxides containing select platinum group metalsGatimu, Alvin J. 10 July 2012 (has links)
Oxide materials exhibit a wide variety of structures and properties. In particular, transition metal oxides tend to be highly stable while exhibiting a wide range of properties that can be used for numerous applications. This work focuses on investigating how the structures��� of 4d and 5d transition metal oxides influences their properties. Specifically oxides of Ru, Rh and Ir were investigated.
A complete solid solution was found between isostructural Pb���Mn���O������ and Pb���Rh���O������. Pb���Rh���O������ shows a Verwey-type transition at 185 K. This transition remains with a 3 % substitution of Mn for Rh but disappears with a 4 % substitution of Mn for Rh. The structure was found to expand in the direction perpendicular to the layers of the structure, which is the c-axis, despite a contracting unit cell. Bi for Pb substitution in Pb���Mn���O������ was found to be limited as compared to in Pb���Rh���O������.
Alkali metal substitution on the A-site of the orthorhombic perovskite SrRuO��� showed only low substitution levels were possible. Nonetheless, the substituted phases showed decreased ferromagnetic Curie temperatures, increased electrical resisitivity and relatively unchanged Seebeck coefficients. Thermoelectric studies of Sr[subscript 2-x]La[subscript x]CoRuO��� perovskite phases showed Sr���.���La���.���CoRuO��� with the best thermoelectric performance. This system showed possible correlations between cation ordering on the B-site and the charge carrier transport. A similar thermoelectric study of (RhV)[subscript 1+x]Ti[subscript 1-2x]O��� phases crystallizing in a disordered trirutile structure was done. Electron carriers were found to be dominant and dependent on Ti content. The electron carriers appear to become diminished at higher temperatures.
Sr���IrO��� crystallizes in a K���NiF���-type structure. Effects of Ti, Fe and Co substitution for Ir were investigated. A complete Sr���Ir[subscript 1-x]Ti[subscript x]O��� solid solution was synthesized and characterized while limited solubility was found for Fe and Co substitutions. All substitutions showed a decrease in the c-cell parameter coupled with a decrease in octahedral tilting. All substitutions also showed a decrease in magnetic susceptibility and an increase in the paramagnetic effective moment was observed for Co and Fe doped samples. An incomplete solid solution was formed for Sr���Ti[subscript 1-x]Rh[subscript x]O��� phases; however effects of increased octahedral tilting with higher Rh content were observed. / Graduation date: 2013
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Synthesis and characterization methods of palladium-doped ceria-zirconia compoundsGraves-Brook, Melissa Kaye, January 2005 (has links)
Thesis (M.S.) -- Mississippi State University. Dave C. Swalm School of Chemical Engineering. / Title from title screen. Includes bibliographical references.
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Preparacao de eletrolitos solidos ceramicos de zirconia estabilizada com calciaCAPRONI, ERICA 09 October 2014 (has links)
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Desenvolvimento de condutores protonicos ceramicos para operacao de celulas a combustivel de oxido solido com combustiveis metano e hidrogenio / Development of ceramic protonic conductors for solid oxide fuel cells operation under methane and hydrogen fuelsOLIVEIRA, OLAVO R. de 09 October 2014 (has links)
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Avaliacao da influencia de elementos de terras raras pesadas na microestrutura e nas propriedades mecanicas e eletricas de ceramicas de zirconia - itriaLAZAR, DOLORES R.R. 09 October 2014 (has links)
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Estudo de rotas de síntese e processamento cerâmico do compósito NiO-YSZ para aplicação como anodo em células a combustível do tipo óxido sólido (SOFC) / Study of synthesis routes and processing of NiO-YSZ ceramic composite for use as anode in solid oxide fuel cell (SOFC)YOSHITO, WALTER K. 09 October 2014 (has links)
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Obtencao de ceramicas de ceria - samaria - gadolinia para aplicacao como eletrolito em celulas a combustivel de oxido solido (SOFC) / Obtaining of ceria - samaria - gadolinia ceramics for application as solid oxide fuel cell (SOFC) electrolyteARAKAKI, ALEXANDER R. 09 October 2014 (has links)
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Preparação e caracterização de catalisadores de metais de transição suportados em zircônia. Uso na reforma a vapor do etanol para obtenção de hidrogênioBERGAMASCHI, VANDERLEI S. 09 October 2014 (has links)
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Desenvolvimento de queimadores para iluminação a gás à base de silicato de terras raras / Development of rare earth silicate burners for gas lightingSANTOS, SILAS C. dos 10 November 2014 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2014-11-10T12:28:16Z
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Preparacao de eletrolitos solidos ceramicos de zirconia estabilizada com calciaCAPRONI, ERICA 09 October 2014 (has links)
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