Structure and electrical properties of Ni-doped ceria

Reference Presenter Authors
06-104 Thayse Ricardo Silva Silva, T.R.(Universidade Federal da Paraíba); dos santos, j.r.(Universidade Federal da Paraíba); Ferreira, L.d.(Universidade Federal da Paraíba); Grilo, J.P.(Universidade de Aveiro); Macedo, D.A.(Universidade Federal da Paraíba); The present work reports the characterization of powders and sintered samples of composition Ce1-xNixO2-x/2 (0 ? x ? 0.2) obtained by the polymeric precursor method. The thermal decomposition behavior of precursor powders was studied by thermogravimetry. X-ray diffractometry (XRD) and physical nitrogen adsorption (BET method) were used to characterize powders calcined at 500 °C for 1 h. The lattice parameter and crystallite size were determined by Rietveld refinement of the XRD data. Structural characterization results indicated the attainment of solid solutions (SS) with crystalline fluorite-type structure for up to 10 mol% Ni+2 and mixtures SS + NiO for compositions containing 15 and 20 mol% nickel. The crystallite size of the solid solutions varied between 9 and 18 nm. Impedance spectroscopy of samples sintered at 1500 °C revealed a larger resistive contribution of the grain boundaries than that from grains, which is most likely due to intergrain porosity, as confirmed by scanning electron microscopy. The total electrical conductivity for the composition Ce0.9Ni0.1O1.95, reaching 0.1 at 600 °C in air, is much lower than literature data for rare earth-doped ceria ceramics.
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