SHIRLEY LEITE DOS REIS
4 resultados
Resultados de Busca
Agora exibindo 1 - 4 de 4
Artigo IPEN-doc 24368 Preparation of dense La0.9Sr0.1Ga0.8Mg0.2O3-δ with high ionic conductivity by solid-state synthesis2018 - REIS, S.L.; MUCCILLO, E.N.S.The results of a systematic investigation on the effects of processing steps, via solid-state reactions, on structural phase characteristics and ionic conductivity of La0.9Sr0.1Ga0.8Mg0.2O3-δ solid electrolyte are reported. The main purpose of this work is to establish an optimized route for obtaining good densification and high ionic conductivity of this solid electrolyte. Processing routes with three successive calcinations at 1250 °C followed by attrition milling (R1), and with two sequences of calcination at 1350 °C with intermediary attrition milling (R2) give rise to near full density at 1450 °C sintering temperature. The rate of grain growth is fast when the relative density reaches 95%. Elemental mapping reveals uniform distribution of the constituents in the matrix along with La4Ga2O9, LaSrGa3O7 and sub-micrometer MgO grains at grain boundaries. The ionic conductivity of grains remains unchanged with the processing route and sintering profile. The blocking effect of charge carriers at grain boundaries decreases with increasing the dwell temperature.Artigo IPEN-doc 21671 Microstructure and electrical conductivity of fast fired Sr- and Mg-doped lanthanum gallate2016 - REIS, S.L.; MUCCILLO, E.N.S.La0.9Sr0.1Ga0.8Mg0.2O3−δ solid electrolytes were consolidated by fast firing aiming to investigate the effects of the sintering method on densification, microstructure and ionic conductivity. Powder mixtures were prepared by solid state reaction at 1250 and 1350 °C for 12 h, and fast fired at 1450 and 1500 °C temperatures for 5 and 10 min. The content of impurity phases was found to be quite low with this sintering method. Relatively high density (>90% of the theoretical value) and low porosity (<1.5%) were readily obtained for powder mixtures calcined at 1250 °C. The activation energy for conduction was approximately 1 eV. Specimens fast fired at 1450 °C for 10 min with a mean grain size of 2.26 µm reached the highest value of total ionic conductivity, 22 mS cm−1, at 600 °C.Artigo IPEN-doc 21303 Phase composition, densification and electrical conductivity of Lasub(0.9)Srsub(0.1)Gasub(0.8)Mgsub(0.2)Osub(3-'delta') consolidated by the two-stage sintering method2015 - REIS, S.L.; MUCCILLO, E.N.S.The influence of the method of sintering on densification, phase assemblage and electrical conductivity of Sr- and Mg-doped lanthanum gallate was investigated aiming to optimize the sintering process of this solid electrolyte. Powder mixtures were prepared by solid state reactions, and the sintering of green compacts was carried out by the two-stage method varying the temperature of the first stage (T1) and the isothermal temperature (T2) and time (t2) profile. The type and content of predominant impurity phases depend on specific parameters of the sintering process. In the first stage of sintering, the content of impurity phases, such as LaSrGaO4 and La4Ga2O9, decreases with increasing temperature. The relative density of sintered specimens reaches 99% whenever T1 is 1500 1C. The mean grain size varies from 1.45 to 4.9 mm. At 600 1C the electrical conductivity attains 12 mS cm 1 for T1 1400 1C and T2 1350 1C for 5 h, with activation energy of approximately 1 eV.Artigo IPEN-doc 17257 Solid solution formation, densification and ionic conductivity of Gd- and Sm-doped ceria2011 - REIS, S.L.; SOUZA, E.C.C.; MUCCILLO, E.N.S.