Hydrogen Impurities
Mostrando 1-12 de 12 artigos, teses e dissertações.
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1. Purification of raw palygorskite: a comparative study involving different processes and dispersing agents
Abstract Palygorskite (Pal) is a natural clay mineral with fibrous morphology and high surface area. Depending on the geological origin, it presents impurities, such as quartz and carbonates, which can harm some of its properties. Therefore, this work seeks to define a viable methodology for the purification of a Brazilian Pal. Two types of mixing processes
Cerâmica. Publicado em: 2021-06
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2. ADSORÇÃO DE CONTAMINANTES DO BIODIESEL POR FIBRAS DE BAGAÇO MODIFICADAS NA SUPERFÍCIE
Sugarcane bagasse fibers chemically modified on its surface were used to adsorb contaminants from biodiesel. Two biodiesel samples were used as adsorbates: crude and washed biodiesel. The contaminants were mainly glycerol and water, but also ions, and methanol. The biodiesel is usually washed, in order to remove most of the contaminants, but the procedure in
Quím. Nova. Publicado em: 2018-02
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3. Propriedades físicas do SnO2: defeitos, impurezas, ligas e superredes. / Physical properties of SnO2: defects, impurities, alloys and superlattices.
O dioxido de estanho na estrutura rutila (SnO2) é um semicondutor de gap largo e faz parte da classe dos óxidos condutores transparentes (TCO). Possui gap direto de 3,6 eV e condutividade do tipo n, mesmo quando não dopado intencionalmente. Estudos teóricos e experimentais atribuem este comportamento à presença de defeitos intrínsecos. Por outro lado,
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 19/08/2011
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4. Síntese e caracterização de catalisadores de LaNiO3 não suportados e suportados em Al2O3 e ZrO2 para a reforma a vapor do metano
Ionic oxides with ABO3 structure, where A represents a rare earth element or an alkaline metal and B is a transition metal from group VIII of the periodic table are potential catalysts for oxidation and good candidates for steam reforming reaction. Different methods have been considered for the synthesis of the oxide materials with perovskite structure to pr
Publicado em: 2007
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5. Theory of hydrogen complexes in Mn xGa1-xAs dilute magnetic semiconductors
Atomic hydrogen diffuses in semiconductor lattices and binds to impurities by forming complexes that can lead to a full neutralization of the impurity effects. In the present paper, the structural, vibrational, electronic and magnetic properties of complexes formed by H in the Mn xGa1-xAs (x=0.03) dilute magnetic semiconductor have been investigated by using
Brazilian Journal of Physics. Publicado em: 2006-06
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6. Contribuição para a sintese de diamante com dopagens de boro, nitrogenio ou enxofre / Study of diamond doping with boron, sulphur and nitrogen
We studied the diamond doping processes with introduction of doping impurities during the diamond growth in the chemical vapor deposition (CVD) technique, using a hot-filament reactor. Our research focused the use of boron, nitrogen or sulphur atoms in order to obtain diamond films with semiconductor properties of electronic (n-type) or hole (p-type) current
Publicado em: 2004
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7. Estudos de plasmas a altas temperaturas por espectroscopia visivel e ultravioleta no vacuo
In this thesis we present results on a wide variety of experiments related to magnetically confined plasma spectroscopy. We discuss the applicability of atomic models to our spectroscopy measurements, spectrometers absolute calibration, as well as the determination of many parameters of the plasma confined in the tokamak NOVA-UNICAMP. For these measurements,
Publicado em: 2003
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8. Poli(oxido de etileno-co-epicloridrina) : degradação foto-oxidativa e termica, e blenda com polipropileno
Polymers derived from ethylene oxide and epichlorohydrin, like poly(epichlorohydrin-co-ethylene oxide) elastomer, are studied as polymer electrolyte for application in photo-electrochemical devices. These materiaIs present the ability to form complexes with alkali salts, presenting high ionic conductivity. In these devices the conversion of the solar energy
Publicado em: 2003
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9. Magnetic properties of gadolinium-doped amorphous silicon films
Electron spin resonance (ESR) and dc-magnetization experiments have been performed in Gd-doped amorphous (a-)silicon films. The films were deposited by the cosputtering technique following different conditions rendering samples with varying Gd and hydrogen concentrations. In addition to films with different contents of impurities and, in order to probe the i
Brazilian Journal of Physics. Publicado em: 2002-06
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10. Simulation and optimization of an industrial PSA unit
The Pressure Swing Adsorption (PSA) units have been used as a low cost alternative to the usual gas separation processes. Its largest commercial application is for hydrogen purification systems. Several studies have been made about the simulation of pressure swing adsorption units, but there are only few reports on the optimization of such processes. The obj
Brazilian Journal of Chemical Engineering. Publicado em: 2000-12
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11. Resonant tunneling through donor impurities in double-barrier structures. / Tunelamento ressonante através de impurezas doadoras em estruturas de dupla barreira.
We have investigated resonant tunneling in GaAs/(AlGa)As double barrier structures which have been fabricated into square mesoscopic and macroscopic size mesas (∼ 10μm × 10μm) A δ layer with different concentrations of Silicon donors was incorporated at the centre of the quantum well. The I(V) characteristics show some features below the
Publicado em: 1994
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12. Ressonancia paramagnetica eletronica do ion Gd3+, em hidretos metalicos do tipo fase de laves AB2Hx
The ternary intermetallic hydrides LaRu2Hx, CeRu2Hx, YRh2Hx and YNi2Hx, doped with Gd3+ ions, were investigated in function of both the hydrogen concentration, x, and temperature. A single EPR line was observed for Gd in the uncharged LaRu2 compound (x = O) in the normal state. The EPR parameters were found in good agreement with the previously published dat
Publicado em: 1988