%A"Dias, Maria Cely Freitas" %D2013 %I; Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil) %2 %J[] %K36 MATERIALS SCIENCE, ADDITIVES, CERIUM OXIDES, ELECTRIC CONDUCTIVITY, GADOLINIUM OXIDES, MICROSTRUCTURE, RAMAN SPECTROSCOPY, SINTERING, SOLID ELECTROLYTES, STRONTIUM OXIDES, TITANIUM OXIDES, X-RAY DIFFRACTION %PMedium: ED; Size: 76 page(s) %TSintering, microstructure and electrical conductivity of gadolinia-doped ceria with SrO, TiO{sub 2} and SrTiO{sub 3}; Sinterizacao, microestrutura e condutividade eletrica da ceria-gadolinia com adicoes de SrO, TiO{sub 2} e SrTiO{sub 3} %XCeria containing trivalent rare-earths is a solid electrolyte with higher ionic conductivity than the standard yttria fully-stabilized zirconia ionic conductor. This property turns these ceria-based ionic conductors promising materials for application in solid oxide fuel cells operating at intermediate temperatures (500-700 deg C). One of the most utilized approaches to optimize the electrical conductivity and other properties of these materials is the introduction of a second additive. In this work, ceria-20 mol% gadolinia with additions of 1, 2.5 and 5 mol% of SrO, TiO{sub 2} and SrTiO{sub 3} as co-additives were prepared by solid state reaction. The main purpose was to investigate the effects of the co-additives on densification, microstructure and electrical conductivity of the solid electrolyte. Sintered pellets were characterized by apparent density, X-ray diffraction, Raman spectroscopy, scanning electron microscopy and electrical conductivity by impedance spectroscopy. The additives were found to exert different influences in all studied properties. The way they influence the solid electrolyte properties depends on the type and content of the additive. SrO addition to doped ceria improves the intergranular conductivity, but decreases the apparent density of the pellets. Increase of densification was obtained with TiO{sub 2} addition. This additive promotes increase of the blocking of charge carriers at the grain boundaries due to solute exsolution and formation of the pyrochlore Gd{sub 2}Ti{sub 2}O{sub 7} phase at grain boundaries for contents in excess of the solubility limit. No influence on densification was found for SrTiO{sub 3} additions. (author) %0Thesis/Dissertation %NINIS-BR-13397;TRN: BR1400021006722 %1 %CBrazil %Rhttps://doi.org/ TRN: BR1400021006722 BRN %GPortuguese