Navegando por Autor "Fernandes, Joana D. G."
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Artigo Evaluation of CoAl2O4 as ceramic pigments(Elsevier, 2003-09-02) Melo, Dulce Maria de Araújo; Cunha, Jardel Dantas da; Fernandes, Joana D. G.; Bernardi, Maria Inês Basso; Melo, Marcus Antônio de Freitas; Martinelli, Antonio EduardoCoAl2O4 powder was obtained from a mixture of Co and Al oxalates at a ratio of 1:8 (Co:Al). The material was calcinated at different temperatures, established from TG data, and characterized using FTIR spectroscopy, X-ray diffraction, BET surface area, and thermal analysis. The dyeing characteristics of CoAl2O4 were established by coating ceramic substrates with different concentrations of the powderArtigo Low-temperature synthesis of single-phase crystalline LaNiO3 perovskite via Pechini method(Elsevier, 2002-03) Fernandes, Joana D. G.; Melo, Dulce Maria de Araújo; Zinner, Léa Barbieri; Salustiano, Clayton de Matos; Silva, Z. R.; Martinelli, Antonio Eduardo; Nasar, Marinalva Cerqueira; Alves Júnior, Clodomiro; Silva, Elson Longo da; Bernardi, Maria Inês BassoLaNiO3 powders were prepared from polymeric precursors. The material was calcinated either under flowing oxygen or in air at temperatures ranging from 300 to 800 °C. The formation of new phases upon calcination was investigated using X-ray diffraction, thermal gravimetric analysis, Fourier-transform infrared spectroscopy and CHN analysis. The results revealed the formation of a single-phase powder having the perovskite structure at temperatures as low as 600 °C. The atmosphere did not significantly affect the final productArtigo Systems involving cobalt and cerium oxides: characterization and catalytic behavior in the C6–C7 n-alkanes combustion(Elsevier, 2003-05) Pedrosa, Anne Michelle Garrido; Sousa, Marcelo José Barros; Melo, Dulce Maria de Araújo; Araújo, Antônio S.; Zinner, Léa Barbieri; Fernandes, Joana D. G.; Martinelli, Antonio EduardoThe objective of this work is to report the characterization and catalytic behavior of Co3O4, CeO2, and Co3O4–CeO2 catalysts in the C6–C7 n-alkanes combustion. X-ray diffraction indicated that crystalline oxides of Co3O4 and CeO2 are obtained by heat treatment at temperatures higher than 600 °C. The FTIR spectra are characteristic of cobalt and/or cerium oxides. The reactions were processed in a fixed bed continuous flow reactor, at 450 °C varying F/W ratio and n-alkanes. The results obtained showed that the catalysts give good activity in the C6–C7 n-alkanes combustion with high selectivity to carbon dioxide