Papers by Author: José Arana Varela

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Authors: L. Perazolli, José Arana Varela, E.R. Leite, Elson Longo
Authors: W. Lacerda Jr., W.C. Las, M. Cilense, José Arana Varela
Authors: A.H.M. González, A.Z. Simões, José Arana Varela, M.A. Zaghete, Elson Longo
Authors: A.Z. Simões, M.A. Ramírez, B.D. Stojanović, Z. Marinković, Elson Longo, José Arana Varela
Abstract: The ferroelectric properties and leakage current mechanisms of preferred oriented Bi3.25La0.75Ti3O12 (BLT) thin films deposited on La0.5Sr0.5CoO3 (LSCO) by the polymeric precursor method were investigated. Atomic force microscopy indicates that the deposited films exhibit a dense microstructure with a rather smooth surface morphology. The improved ferroelectric and leakage current characteristics can be ascribed to the plate-like grains of the BLT films.
Authors: A.Z. Simões, A.M.H. Gonzalez, A.C. Cavalheiro, G. Gasparotto, M.A. Zaghete, B.D. Stojanović, José Arana Varela
Authors: A.Z. Simões, V. Bouquet, F. Moura, A. Ries, M.A. Zaghete, José Arana Varela
Abstract: A polymeric precursor solution was used to deposit pure and Mg doped LiNbO3 thin films on sapphire substrates by spin-coating. The effects of magnesium addition on crystallinity, morphology and optical properties of the annealed films were investigated. X-ray diffraction patterns indicate the oriented growth of the films. Phi-scan diffraction evidenced the epitaxial growth with two in-plane variants. AFM studies show that the films are very homogeneous, dense and present smooth surfaces. The refractive index and optical losses obtained by the prism coupling method were influenced by the magnesium addition.
Authors: V. Bouquet, E.R. Leite, Elson Longo, José Arana Varela
Authors: Vania Caldas de Sousa, E.R. Leite, José Arana Varela, Elson Longo
Authors: Z.Ž. Lazarević, B.D. Stojanović, José Arana Varela
Abstract: Our efforts were directed to the preparation of bismuth titanate – Bi4Ti3O12 (BIT) by mechanically assisted synthesis. The mechanical activation was applied to prepare bismuth titanate, Bi4Ti3O12, from bismuth oxide, Bi2O3, and titanium oxide, TiO2 (in an anatase crystal form). Mechanochemical synthesis was performed in a planetary ball mill in air atmosphere. Bismuth titanate ceramics was obtained by sintering at 1000 oC. The formation of Bi4Ti3O12 in the sintered samples was confirmed by X-ray diffraction analysis. Scanning electron microscopy, SEM, was used to study the particle size and powder morphology. The obtained results indicate that Bi4Ti3O12 from the powder synthesized by high-energy ball milling exhibits good sinterability, showing advantage of the mechanochemical process over conventional solid-state reaction.
Authors: Sonia M. Zanetti, P.R. Bueno, V.C.M. Sotilo, E.R. Leite, Elson Longo, José Arana Varela
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