Papers by Author: M. Cilense

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Authors: W. Lacerda Jr., W.C. Las, M. Cilense, José Arana Varela
Authors: V.M. Vukotić, Tatjana Srećković, Z. Marinković, G. Brankovic, M. Cilense, D. Arandjelović
Authors: Alessandro Dibb, Sérgio M. Tebcherani, Maria Rita de C. Santos, M. Cilense, José Arana Varela, Elson Longo
Authors: A.L. Campos, T. Mazon, José Arana Varela, M.A. Zaghete, M. Cilense
Authors: A.A. Cavalheiro, M.A. Zaghete, Carlos de Oliveira Paiva-Santos, M.T. Silva Giotto, M. Cilense, José Arana Varela, Y.P. Mascarenhas
Authors: Juliana C. Bruno, A.A. Cavalheiro, M.A. Zaghete, M. Cilense, José Arana Varela
Abstract: The complex perovskite compound 0.9PbMg1/3Nb2/3O3-0.1PbTiO3 is one of the most promising relaxor ceramic because the addition of lead titanate increases Tm by about 5°C/mol% from intrinsic Tm value for pure PMN (near –7 to -15°C). A Ti-modified columbite precursor was used to prepare PMN-PT powders containing single perovskite phase. This variation on columbite route includes Ti insertion in MgNb2O6 orthorhombic structure so that individual PT synthesis becomes unnecessary. Furthermore, effects of Li additive on columbite and PMN-PT structures were studied by XRD to verify the phase formation at each processing step. XRD data were also used for the structural refinement by Rietveld method. The additive acts increasing columbite powders crystallinity, and the amount of perovskite phase was insignificantly decreased by lithium addition. By SEM micrographs it was observed that Li presence in PMN-PT powders leads to the formation of rounded primary particles and for 1mol% of additive, the grain size is not changed, different from when this concentration is enhanced to 2mol%.
Authors: A.A. Cavalheiro, S.M. Barrionuevo, M. Cilense, M.A. Zaghete, José Arana Varela
Authors: Daniela Russo Leite, W.C. Las, G. Brankovic, M.A. Zaghete, M. Cilense, José Arana Varela
Abstract: This paper reports a study of influence of Cr concentration on the electrical properties and microstructure of SnO2-based powders doped with Mn and Nb, prepared by an organic route (Pechini method). All the samples were compacted into discs and sintered at 1300°C for 3h, resulting in ceramics with relative density varying between 78% and 98%. The powders were characterized by X-ray diffraction analysis. Impedance spectroscopy characterization indicated that the conductivity decreases as Cr concentration increases, probably due to Cr segregation at grain boundaries, which reduces grain size, increasing the number of resistive boundaries.
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