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Influence of pH in Obtaining Indium Tin Oxide Nanoparticles by Microwave Assist...
Oliveira,Fernando Modesto Borges de; Varela,José Arana; Orlandi,Marcelo OrnaghiA systematic study about synthesis of In1-xSnxO2 (ITO) nanostructured crystals by microwave-assisted solvothermal method is reported. Different solutions using InCl3.4H2O and SnCl4.5H2O precursors in ethylene glycol solvent were prepared in distinct pHs (acid and basic ones). The syntheses were performed at 200 ºC using a heating rate of 50 ºC min-1 and soaking time of 30 minutes. All the synthesized powders we...
Energia de superfície para nanossuperfícies de TiO2 na direção (001)
Lazaro,Sergio de; Penteado,Renato Ferras; Tebcherani,Sergio Mazureck; Berger,Danielle; Varela,José Arana; Kubaski,Evaldo TonioloIn this work was made an investigation about bulk and surface models (at maximum 20 layers) of the TiO2 material in the (001) direction. TiO2 commercial sample was feature using XDR technique to determine phase and crystallites average size. Bulk and (001) surface models were simulated for TiO2 material using DFT/B3LYP and its results were used for calculating energy surface, electronic levels, superficial atom...
Microstructural and nonohmic properties of ZnO.Pr6O11 CoO polycrystalline system
Ramírez,Miguel Angel; Fernández,José Francisco; Frutos,José de; Bueno,Paulo Roberto; Longo,Elson; Varela,José AranaThe microstructure and electrical properties of varistors composed of (95-x) ZnO + x Pr6O11 + 5 CoO (ZPC), (x = 0.1, 0.5 and 1.0) and sintered at 1300 and 1350 °C, were investigated. According to X-ray diffraction, several phases (ZnO, Pr2O3 and Pr2CoO4) are present when x = 1.0. Using Scanning Electron Microscopy, all of these compositions contain precipitates. These phases are important regarding the developm...
Grain size effect on the electrical response of SnO2 thin and thick film gas se...
Savu,Raluca; Ponce,Miguel Adolfo; Joanni,Ednan; Bueno,Paulo Roberto; Castro,Miriam; Cilense,Mario; Varela,José Arana; Longo,ElsonPorous nano and micro crystalline tin oxide films were deposited by RF Magnetron Sputtering and doctor blade techniques, respectively. Electrical resistance and impedance spectroscopy measurements, as a function of temperature and atmosphere, were performed in order to determine the influence of the microstructure and working conditions over the electrical response of the sensors. The conductivity of all sample...
Obtenção de filmes finos de TiO2 nanoestruturado pelo método dos precursores po...
Stroppa,Daniel Grando; Giraldi,Tania Regina; Leite,Edson Roberto; Varela,José Arana; Longo,ElsonThis work focuses in optimizing setup for obtaining TiO2 thin films by polymeric precursor route due to its advantages on stoichiometric and morphological control. Precursor stoichiometry, synthesis pH, solids concentration and rotation speed at deposition were optimized evaluating thin films morphology and thickness. Thermogravimetry and RMN were applied for precursor's characterization and AFM, XRD and ellips...
Electronic ceramics based on polycrystalline SnO2, TiO2 and (Sn xTi1-x)O2 solid...
Bueno,Paulo Roberto; Varela,José AranaIn the present text we discuss on electronic properties arising from polycrystalline semiconductor ceramics of SnO2, TiO2 and (Sn xTi1-x)O2 solid solution rutile-type structure. This is intended to be a short overview of the most recent papers in this area. One of the most important content discussed in this text is based on sinterability of these polycrystalline ceramics, which depends on the target applicatio...
Evaluation of rare earth oxides doping SnO2.(Co1/4,Mn3/4)O-based varistor system
Dibb,Alessandro; Cilense,Mario; Bueno,Paulo Roberto; Maniette,Yves; Varela,José Arana; Longo,ElsonThe present paper aims to verify the inuence of rare earth oxide such as lanthanum (La2O3) and neodymium (Nd2O3) doping SnO2 + 0.25%CoO + 0.75%MnO2 + 0.05%Ta2O5 system. The analysis focus on microstructural inuence on electrical properties. Microstructural analysis were made by using Transmission Electron Microscopy (TEM) at different regions of the samples. From such analysis it was found that La2O3 and Nd2O3 ...
Effect of viscosity and temperature on the microstructure of BBT thin films
Costa,Gustavo Carneiro da; Simões,Alexandre Zirpoli; Gasparotto,Gisele; Zaghette,Maria Aparecida; Stojanovic,Biljana; Cilense,Mario; Varela,José AranaThin films of BBT were deposited on silicate and Pt/Ti /SiO2 (111) substrates by spin- coating from the polymeric precursor method (Pechini process). The obtained films were characterized by optical microscopy, X-ray diffraction and atomic force microscopy. The influence of viscosity on the morphology of BBT thin films as well as the influence of temperature on crystallization, morphology and properties of BBTa...
Estudo da corrosão de cadinhos de SnO2-ZnO, na fusão de vidros contendo metais ...
Nascimento,Erlandson Thiago Oliveira; Lima,Ana Paula Kawabe de; Varela,José Arana; Longo,Élson; Hernandez,Antonio CarlosNeste trabalho foi estudada resistência de cadinhos de SnO2 dopados com 1%mol de ZnO frente a corrosão na fusão de vidro contendo metais pesados. Os cadinhos foram obtidos através do processo de colagem de barbotina, e a sinterização foi realizada até a temperatura de 1400ºC por 4 horas. Os vidros foram fundidos uma única vez por 1 hora, sendo que o vidro de composição 50B2O3-50PbO à 700 ºC, o de composição 60B...