Navegando por Autor "Loureiro, Francisco J.A."

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Designing experiments for the preparation of Ni- GDC cermets with controlled porosity as SOFC anode materials: effects on the electrical properties
(Elsevier, 2018-12-15) Paskocimas, Carlos Alberto; Araújo, Allan Jedson Menezes de; Grilo, João Paulo de Freitas; Loureiro, Francisco J.A.; Campos, Liszandra Fernanda Araújo; Nascimento, Rubens Maribondo do; Macedo, Daniel Araújo de
NiO-Ce0.9Gd0.1O1.95 (NiO-GDC) composites (30, 40 and 50 wt% NiO) were obtained by a “one-step” synthesis method. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses were applied to the calcined compositions, revealing powders in the nanometer range. NiO-GDC composites were sintered at 1450-1550 °C and the respective Ni-GDC cermets were produced in a 10%H2-N2 atmosphere at 800 °C. A factorial design tool allowed to establish a regression equation that correlates the effects of Ni content and sintering temperature on the porosity of Ni-GDC cermets. Impedance spectroscopy was used to analyse the electrical properties of the solid oxide composites in air (at 500-650 °C) and of the Ni-GDC cermets in 10%H2-N2 (at 650 °C). The impedance analysis in reducing conditions revealed an improved in the electrical properties for the Ni-GDC cermet derived from the composite with 50 wt% NiO and sintered at 1450 °C. The electrical resistivity values are among the best ones reported for Ni-based cermets produced by different conditions

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