Spinel Phase
Mostrando 25-36 de 40 artigos, teses e dissertações.
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25. Síntese e estudo da atividade eletrocatalítica de óxidos de metais de transição e de nanopartículas de prata e ouro para a reação de redução de oxigênio / Synthesis and study of the electrocatalytic activity of transition metal oxides, and silver and gold nanoparticles for the oxygen reduction reaction
The oxygen reduction reaction (ORR) was studied on electrocatalysts composed by pure and mixed transition metal oxides of Mn, Co, and Ni, including spinel-like structures, and by Ag, Au, and Ag3M/C (M= Au, Pt, Pd e Cu) bimetallic nanoparticles, in alkaline electrolyte. The transition metal oxides were synthesized by thermal decomposition of their nitrates, a
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 10/08/2011
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26. Structural and photocatalytic characterization of BaFe2O4 obtained at low temperatures
Barium monoferrite BaFe2O4 classified as permanent magnet stands out among other ceramic magnets due to its high chemical stability, corrosion resistance and low production cost. In addition, experiments conducted on photocatalytic degradation of methyl orange and UV transmittance by spectrophotometry have shown that this material has photocatalytic properti
Materials Research. Publicado em: 14/10/2011
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27. Low temperature synthesis of magnesium oxide and spinel powders by a sol-gel process
Magnesium oxide and magnesium aluminate (MgAl2O4) spinel (MAS) powders have been synthesized by a simple aqueous sol-gel process using citrate polymeric precursors derived from magnesium chloride, aluminium nitrate and citrate. The thermal decomposition of the precursors and subsequent formation of cubic MgO and MAS were investigated by X-ray diffraction (XR
Materials Research. Publicado em: 2010-09
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28. Luminescence dosimeter based on magnesium doped aluminum oxide: production and characterization. / Confecção e caracterização de dosímetro luminescente de óxido de alumínio dopado com magnésio.
The aim of the present work is to obtain and characterize luminescent dosimeters made of magnesium doped aluminium oxide, for ionizing radiation dosimetry purposes. The material is produced by Pechini Method (US Patent 3.330.697, 1967), starting from a polymer that generates powder ceramic, after firing at predetermined temperatures. Dosimetric measurements
Publicado em: 2008
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29. Síntese, sinterização e caracterização de ferritas à base de Ni-Zn
Were synthesized different ferrites NixZn1-xFe2O4 (0,4 ≤ x ≤ 0,6) compositions by using citrate precursor method. Initially, the precursors citrates of iron, nickel and zinc were mixed and homogenized. The stoichiometric compositions were calcined at 350C without atmosphere control and the calcined powders were pressed in pellets and toroids. The
Publicado em: 2008
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30. Síntese análise das propriedades magnéticas da ferrita de NiMg e características de absorção de radiação
Foram sintetizadas diferentes composições da ferrita Ni1-xMgxFe2O4 com (0,2 ≤ x ≤ 0,7) pelo uso do método dos citratos precursores. Para se obter a fase estequiométrica Ni1-xMgxFe2O4, inicialmente foram misturados e homogeneizados os citratos precursores de ferro, níquel e magnésio. As composições estequiométricas foram calcinadas entre
Publicado em: 2008
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31. Síntese e caracterização da ferrita de MnZn obtida pelo método dos citratos precursores
It was synthesized MnZn ferrite with general formulae Mn1-xZnxFe2O4 (mol%), 0,3 ≤ x ≤ 0,7 by using the citrate precursor method. The precursors decomposition was studied by thermogravimetric analysis (TGA), differential thermogravimetric analysis (DTG), differential thermal analysis (DTA) and Fourier transform infrared (FTIR) of powder calcined a
Publicado em: 2007
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32. Desenvolvimento de catalisadores de ródio e cobalto para a reforma a vapor do etanol.
The development of technologies based on the use of biofuels has taken the attention of the scientific community, due to the current dependence on fossil fuels, which results in an increase of air pollution. This pollution increase is related to public health problems and climate changes. In this context, the use of fuel cells moved by hydrogen is a mean of
Publicado em: 2007
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33. High temperature oxidation behavior of AISI 304 and AISI 430 stainless steels
The oxidation behavior of AISI 304 and AISI 430 stainless steels was investigated from 1100 °C up to 1200 °C. Mössbauer spectroscopy and x ray diffraction were used to access the phase composition of the formed scales. The main crystalline phases found in the oxidized materials at temperatures above 1100 °C were hematite and magnetite for AISI 430 steel,
Materials Research. Publicado em: 2006-12
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34. Geology and metallogenetic potential of the anorthositic-leucogabbroic Lagoa da Vaca Complex, Curaça, Bahia State, Brazil / Geologia e potencial metalogenetico do complexo anortositico-leucogabroico de Lagoa da Vaca, municipio de Curaça, Bahia
The complex is one of the three litho-structural domains mapped (central domain), and has an outcrop width of 3 kilometers. It is made up mostly of north-south-trending layers of anorthositic, meta-leucogabbroic, meta-gabbroic and ultramafic compositions. Ultramafic rocks of unknown stratigraphic relations, vz. peridotite and amphibole meta-peridotite, were
Publicado em: 2006
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35. Pechini synthesis and microstructure of nickel-doped copper chromites
Spinel-type solid solutions were synthesized by the Pechini method and calcined between 500 and 900 °C for 4 hours and at 900 °C for 8 hours to produce ceramic pigments. The resulting powders were characterized by thermogravimetric analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), particl
Materials Research. Publicado em: 2005-06
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36. The characterization of Co xZn7-xSb2O12 spinel obtained by the pechini method
Oxides with spinel structures have been studied for many decades as they have been used in a variety of applications like pigments and refractories. They have also been used as a model structure to evaluate the relative stability of ions in octahedral and tetrahedral sites. Zinc- antimony spinels (Zn7Sb2O12) were synthesized by the Pechini method and the cat
Materials Research. Publicado em: 2005-06