Electronic Surface States
Mostrando 1-12 de 30 artigos, teses e dissertações.
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1. Dielectric Behavior of α-Ag2WO4 and its Huge Dielectric Loss Tangent
The microwave-assisted hydrothermal method was used to obtain α-Ag2WO4. Rietveld refinement confirmed that α-Ag2WO4 is stable in the orthorhombic phase, without secondary phase. However, field-effect scanning electron microscope analysis showed that α-Ag2WO4 nanorods surfaces contain silver nanoparticles, confirmed by the X-ray photoelectron spectroscopy
Mat. Res.. Publicado em: 02/09/2019
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2. Estudio ab initio de propiedades electrónicas y estructurales de nanopartículas de SnO2 bajo presión
ABSTRACT Tin oxide (SnO2) has important applications, including as an elective material in the development of gas sensors. These devices improve their sensitivity and decrease their work temperature when the nanoparticle size is in the nanoscale order. Therefore, the gas sensor raises its efficiency noticeably. For this reason, the research of behavior at th
Matéria (Rio J.). Publicado em: 19/07/2018
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3. First-principles study of carbon chemisorption on γ-Fe(111) surface
In order to study the interaction between γ-Fe and carbon, the geometry structures, surface relaxations, adsorption energies and electronic structures for carbon chemisorption at four different adsorption sites on γ-Fe(111) surface at a monolayer coverage of 1 were studied using density functional theory. The electronic structures were compared with the ch
Brazilian Journal of Physics. Publicado em: 2010-12
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4. Catalisadores de Pt suportados, obtidos pelo método solgel : efeito do cério na atividade e estabilidade nas reações de reforma do metano
The effect of Ce as a structural and electronic promoter on the activity and stability of Pt catalysts supported on Al2O3 for methane reforming reactions were investigated to elucidate the metal-support interaction. Pt/Al2O3 and Pt/CeO2-Al2O3 catalysts were prepared by conventional method of wet impregnation on commercial supports and on CeO2- Al2O3 mixed ox
Publicado em: 2009
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5. Re(I) complexes and TiO2 films in photoinduced molecular devices / Complexos de Re(I) e filmes de TiO2 em dispositivos moleculares fotoinduzidos
The thesis focus on two main topics: characterization of TiO2 films for Dye-sensitized solar cells, DSCs, and investigation on photochemical and photophysical properties of Re(I) polypyridyl complexes. Mesoporous TiO2 films were prepared by sol-gel method and by commercial oxide (P25, Degussa) and were characterized by XRD, SEM, B.E.T. and XPS. Both oxides w
Publicado em: 2009
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6. Propriedades eletrônicas de nanofios semicondutores / Electronic properties of semiconductor nanowires
We have performed an extensive study on the electronic and structural properties of silicon nanowires (NWs) using parameter free computational simulations (DFT). We show that in Si NWs, surfaces whose atoms are connected to inner ones perpendicularly to the wires axes become electronically inactive at the band edges. However, when these bonds are oriented al
Publicado em: 2008
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7. Propriedades estruturais, eletronicas e magneticas de filmes finos de materiais magneticos / Structural, electronic and magnetic thin film properties of magnetic materials
A Física de superfícies, interfaces e filmes finos vem se desenvolvendo muito rapidamente nas últimas décadas com o aparecimento de inúmeras técnicas experimentais para estudo das propriedades de superfície. Por outro lado, tem ocorrido um grande avanço dos equipamentos de informática e dos métodos computacionais, com o desenvolvimento de novos alg
Publicado em: 2008
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8. Caracterização óptica de dispersões aquosas de nanotubos de carbono
It has been demonstrated that the electronic and optical properties of single-wall carbon nanotubes (SWNT) are strongly affected by the environment. This strong environmental effect is very relevant in analyzing the composition of carbon nanotube samples using optical techniques, especially in the case of separation experiments, where the SWNT environments a
Publicado em: 2008
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9. Análise teórica da superfície Si(111)-(7x7)
In this work, wecarry out theoretical study of the silicon surface reconstruction (7x7) grown in the [111] direction, denoted by Si(111)(7x7), using the Density Functional Theory formalism, within the Local Density Approximation (LDA) for the exchange correlation term. The interaction with the valence electrons and the core ion (nucleus more core electrons)
Publicado em: 2007
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10. Contribution to the study of ultra-sharp silicon microtips fabrication process / Contribuição ao estudo do processo de fabricação de microponteiras de silicio ultra-finas
In this work, we present a contribution to the study of ultra-sharp silicon microtips fabrication process using oxidation sharpening technique. The silicon microtips were fabricated and submitted to repeated oxidation steps and oxide strip to achieve ultra-sharp tips. SEM (Scaning Electronic Microscopy) investigation were performed to observe the gradual tip
Publicado em: 2007
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11. Thin-film ZnO/CdS/CuIn1-xGa xSe2 solar cells: anomalous physical properties of the CuIn1-xGa xSe2 absorber
Thin-film ZnO/CdS/CuIn1-xGa xSe2 solar cells are manufactured with ~20% solar-cell conversion efficiency. The CuIn1-xGa xSe2 (CIGS) absorber exhibits rather different physical properties compared with conventional semiconductors (e.g. Si, GaAs and ZnSe). For instance, (i) the valence-band maximum in CIGS consists of cation-d-anion-p hybridized states. (ii) C
Brazilian Journal of Physics. Publicado em: 2006-09
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12. The oxidation mechanism of CdTe (110) surface
Using a first-principles pseudopotential technique within a generalized gradient approximation of the density functional theory, we have investigated the mechanism of adsorption of molecular oxygen on the CdTe(110) surface. The determination of the more favorables structures and their formation through the activation barrier analysis indicates that the forma
Brazilian Journal of Physics. Publicado em: 2006-06