Metallic Clusters
Mostrando 1-12 de 16 artigos, teses e dissertações.
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1. Theoretical Calculations on the Mechanism of Hydrogenation of Diphenylacetylene over Pdn (n = 1-4) Clusters
Diphenylacetylene (DPA) is a precursor of stilbene and benzil, and reduction of DPA or its derivatives with metallic reagents is both an old and contemporary topic of research. By means of density function theory (DFT) calculations, a detailed investigation of the mechanism of the hydrogenation of DPA over Pd clusters was carried out at the molecular level.
J. Braz. Chem. Soc.. Publicado em: 2020-10
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2. Mechanical Spectroscopy of Ti-15Zr-based Alloys with Mo Addition
In this paper, the effect of substitutional Mo amounts in internal friction and interstitial diffusion mechanisms was analyzed in Ti-15Zr-based alloys. Mechanical spectroscopy was obtained from room temperature up to 730 K with frequencies between 1 Hz and 40 Hz. Internal friction spectra were composed by anelastic relaxation peaks in β-type alloys (metasta
Mat. Res.. Publicado em: 27/11/2017
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3. Glass Forming Ability and Mechanical Properties of Zr57.52Co21.24Al9.24Ag12 bulk metallic glass
The effect of the partial substitution of Al for Ag in the glass forming ability (GFA) of the Zr57.52Co21.24Al21.24-xAgx (x = 8, 10, 12, and 14 at. %) family alloy are reported and discussed. Cylindrical and conical ingots were obtained using the suction casting technique. It was found that the Zr57.52Co21.24Al9.24Ag12 alloy showed a glassy structure, with a
Mat. Res.. Publicado em: 10/10/2016
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4. Mechanical spectroscopy study of the Cu36Zr59Al5 and Cu54Zr40Al6 amorphous alloys
A mechanical spectroscopy study of Cu-Zr-Al bulk metallic glasses, was performed with two types of equipment: a Kê-type inverted torsion pendulum and an acoustic elastometer, working in the frequency ranges of Hz and kHz, respectively, with a heating rate of 1 K/min. The analysis of the anelastic relaxation shows similar spectra for both types of equipment
Mat. Res.. Publicado em: 23/10/2012
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5. Preparação de vidros e vitrocerâmicas de óxidos de metais pesados contendo prata: propriedades ópticas, estruturais e eletroquímicas
Silver containing heavy metal oxide glasses and glass ceramics of the system WO3-SbPO4-PbO-AgCl with different AgCl contents have been prepared and their thermal, structural and optical properties characterized. Glass ceramics containing metallic silver nanoparticles have been prepared by annealing glass samples at temperatures above the glass transition and
Química Nova. Publicado em: 2012
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6. Processamento e estudo de ortoniobatos de terras raras e ortotungstatos de metais alcalinos terrosos
Two classes of orthoceramic compounds of general formula ABO4 were investigated in this work. The first group includes the lanthanide orthoniobates (RENbO4, RE = La-Lu, except Pm), which were synthesized by conventional solid-state route at 1150C in different conditions of time aiming the production of crystalline, single phase materials. Alkaline- earth-met
Publicado em: 2010
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7. Estudo da adsorção do líquido iônico [BMIM]+[BF4]sobre γ-Al2O3 por cálculos ab initio
Ionic liquids are, by definition, salts formed by an organic cation and an inorganic anion, with a low melting point. An important application of ionic liquids is that they can replace conventional solvents. Recently, they were also used as cocatalysts (in the form of solvents) for metallic clusters, in the process of removal of aromatics from petroleum. The
Publicado em: 2010
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8. Development of a aggregation source for metallic nano-clusters / Desenvolvimento de uma fonte de nano-agregados metalicos
Nanosystems are one of the most important fields of research in the current days, mainly motivated by their technological potential. This size regime present new and unexpected properties that strongly differ from their macroscopic counter-part. This happen mainly due to effects arising from their high surface-to-bulk ratio and because their sizes are compar
Publicado em: 2009
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9. Vacancies in carbon nanotubes: electronic, structural and transport properties / Vacâncias em nanotubos de carbono: propriedades eletrônicas, estruturais e de transporte
The main purpose of this dissertation is the study of the electronic and structural properties in the presence of different types of vacancies, in one of the most promising materials for nanoelectronics, carbon nanotubes. The defects studied in this work are monovacancy and multivacancies in (5, 5) armchair carbon nanotubes. For that purpose perform quantum
Publicado em: 2008
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10. Processos metalogenéticos em ambientes de arco magmático tipo andino, caso de estudo: mineralizações da região dos Andes Patagônicos setentrionais do Chile / Metallogenic processes in andean volcanic arc setting, study case: mineralizations in the Chilean North-Patagonion Andes
In the Patagonian Andes region between 41 and 44° S extensive and continuous plutonic rocks of the North-Patagonian Batholith north segment are exposed. During their evolution most of the granitic rocks were emplaced in metamorphic rocks and other parts were emplaced in Late Jurassic-Berriasan volcanic rocks, Early Cretaceous sedimentary and volcanic rocks,
Publicado em: 2008
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11. Estudo de dinamica molecular de nanoestruturas organicas e nanofios metalicos / Molecular dynamics study of organic nanostructures and metallic nanowires
Neste trabalho utilizamos métodos de física computacional para descrever o comportamento estrutural de formação de cadeias atômicas lineares suspensas (LACs) (i ) e de uma estrutura orgânica sobre superfície metálica (ii ). Ambos os temas foram desenvolvidos sobre o ponto de vista de física computacional e comparados com resultados experimentais esp
Publicado em: 2007
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12. Preparação de redes modificadas de poli(dimetilsiloxano) com ion piridinio ou etilenodiamina : estudo da adsorção de ions metalicos em etanolico / Preparation of modified poly(dimethylsiloxane) network with pyridine ion or ethylenediamine : study of metalic ion adsoption from ethanol solution
In this work elastomeric polymeric networks based on poly(dimethilsiloxane) PDMS, modified with pyridine ion or ethylenediamine, were prepared. These materials were characterized by infrared spectrometry, thermogravimetric analysis, differential scanning calorimetry and nuclear magnetic resonance (NMR) of Si and C. The results showed that both materials pres
Publicado em: 2007