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  • Resumo IPEN-doc 30308
    Microstructure and electrical conductivity of sol-gel synthesized and spark plasma sintered doped-lanthanum gallate
    2023 - MUCCILLO, E.N.S.; REIS, S.L.; GONIN, C.F.N.; BERTON, M.A.C.; MUCCILLO, R.
    Perovskite ceramics consisting of lanthanum gallate with partial substitutions for strontium and magnesium are candidates as solid electrolyte for application in solid oxide fuel cells operating at intermediate temperatures (~550 to ~750ºC). The main concern related to the application of this perovskite solid electrolyte is impurity phases, usually detected even in chemically synthesized powders. The La0.9Sr0.1Ga0.8Mg0.2O3-d (LSGM) composition display relatively low contents of impurity phases. In this work, the LSGM composition was synthesized by the sol-gel method and consolidated by spark plasma sintering to optimize the microstructure and electrical properties of this solid electrolyte. Chemically synthesized powders were consolidated in the 1100 to 1250ºC for 5 min. Sintered specimens with relative densities higher than 98% were obtained. Rietveld analysis of X-ray diffraction data revealed no detectable impurity phases. The microstructure evolution exhibited submicron sized grains with mixed fracture mode. High values of the electrical conductivity were obtained for all specimens.
  • Artigo IPEN-doc 28173
    Thermal and spectroscopic characterization of sol-gel-synthesized doped lanthanum gallate
    2021 - REIS, S.L.; GROSSO, R.L.; MUCCILLO, E.N.S.
    In this study, a complex oxide solid solution consisting of lanthanum gallate with partial substitutions for strontium and magnesium (La0.9Sr0.1Ga0.8Mg0.2O2.85) was synthesized by the sol–gel route, aiming to obtain a sinter active powder and a final material that could be stoichiometrically controlled. The thermal behavior of the synthesized powder involves several steps of decomposition. The linear shrinkage of green compacts up to 1500 °C was 31%. The bulk conductivity of sintered specimens increases with sintering temperature up to 1400 °C. The stoichiometry was maintained for sintering temperatures up to 1450 °C. Elemental mapping obtained by energy-dispersive spectroscopy evidenced magnesium segregation at the grain boundaries. The overall results evidence the suitability of the synthesis method for preparing doped lanthanum gallate.