Assessment of NiO-CGO composites as cermet precursors
NiO-Ce0.9Gd0.1O1.95 (NiO-CGO) composite powders produced by a one-step chemical route were assessed as precursors of fuel cell anode cermets. Porous NiO-CGO composites were prepared by uniaxial pressing followed by firing at 1400 °C for 4 h. Ni-CGO cermets were subsequently obtained by reduction in...
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| Principais autores: | , , , |
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| Formato: | article |
| Idioma: | English |
| Publicado em: |
Elsevier
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| Endereço do item: | https://repositorio.ufrn.br/handle/123456789/45510 |
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| Resumo: | NiO-Ce0.9Gd0.1O1.95 (NiO-CGO) composite powders produced by a one-step chemical route were assessed as precursors of fuel cell anode cermets. Porous NiO-CGO composites were prepared by uniaxial pressing followed by firing at 1400 °C for 4 h. Ni-CGO cermets were subsequently obtained by reduction in 10 vol% H2 + 90 vol% N2 at 750 °C. Similar materials obtained by conventional mechanical mixing of commercial powders were also prepared and tested. The structure and particle size of the calcined material were investigated by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The electrical properties of all materials were duly studied by impedance spectroscopy (NiO-CGO) (in air and several N2 + O2 gas mixtures) or dc conductivity (Ni-CGO). The total and relative magnitude of impedance arcs observed in the low temperature impedance spectra can be used to obtain significant insight on microstructural characteristics, due to a variable role of NiO when shifting from a well percolated electronic conducting pathway to a dispersed ion-blocking phase. The confirmed superior conductivity of one-step materials was interpreted as a consequence of the presence of a network of well-connected and homogeneously distributed NiO(/Ni) grains, as shown by SEM |
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