Obtenção de filmes finos de TiO2 nanoestruturado pelo método dos precursores poliméricos

This 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 ellipsometry for thin films evaluation. Results showed successful attainment of homogeneous nanocrystalline anatase TiO2 thin films with outstanding control over morphological characteristics, mean grain size of 17 nm, packing densities between 57 and 75%, estimated surface areas of 90 m²/g and monolayers thickness within 20 and 128 nm

Synthesis, Characterization and Photophysical Properties of Eu 3+ Doped in BaMoO 4

and 4 Eu 3+ transitions at 523, 533, 554, 578, 589, 614, 652 and 699 nm, respectively. The emission spectra of the powders heat-treated at 800 and 900°C showed a marked increase in its intensities compared to the materials heattreated from 400 to 700°C. The decay times for the sample were evaluated and all of them presented the average value of 0.61 ms. Eu 3+ luminescence decay time follows one exponential curve indicating the presence of only one type of Eu 3+ symmetry site

Photolumiscent properties of nanorods and nanoplates Y2O3:Eu3+

Nanorods and nanoplates of Y2O3:Eu3+ powders were synthesized through the thermal decomposition of the Y(OH)3 precursors using a microwave-hydrothermal method in a very short reaction time. These powders were analyzed by X-ray diffraction, field emission scanning electron microscopy, Fourrier transform Raman, as well as photoluminescence measurements. Based on these results, these materials presented nanoplates and nanorods morphologies. The broad emission band between 300 and 440 nm ascribed to the photoluminescence of Y2O3 matrix shifts as the procedure used in the microwave-hydrothermal assisted method changes in the Y2O3:Eu3+ samples. The presence of Eu3+ and the hydrothermal treatment time are responsible for the band shifts in Y2O3:Eu3+ powders, since in the pure Y2O3 matrix this behavior was not observed. Y2O3:Eu3+ powders also show the characteristic Eu3+ emission lines at 580, 591, 610, 651 and 695 nm, when excited at 393 nm. The most intense band at 610 nm is responsible for the Eu3+ red emission in these materials, and the Eu3+ lifetime for this transition presented a slight increase as the time used in the microwave-hydrothermal assisted method increases

A Reescrita do riso: uma abordagem crítica de duas traduções portuguesas da obra The Importance of Being Earnest

Orientadora: Mestre Maria Helena GuimarãesO objectivo deste nosso trabalho é identificar, através de uma abordagem crítica de duas das traduções portuguesas da obra de Oscar Wilde The Importance of Being Earnest, quais os processos de fabricação do cómico, para utilizar aqui uma terminologia bergsoniana, bem como tentar sistematizar alguns dos problemas que a sua tradução coloca e apontar para estratégias que ajudem a solucionar as múltiplas dificuldades tradutivas presentes em textos marcados pela ironia e pelo humor. Cremos poder afirmar que as questões inerentes à tradução do Riso, do que de humorístico há num texto, escrito ou oral, raramente são abordadas pelos teóricos dos Estudos de Tradução, embora seja indiscutível o ser humor um fenómeno transversal a todas as culturas e os textos de cariz jocoso serem, em geral, bastante apreciados. Partimos deste pressuposto para estabelecer quer o nosso corpus de análise, quer a organização do nosso trabalho. A nossa investigação recairá, como já dissemos, sobre duas das traduções portuguesas existentes da obra de Oscar Wilde The Importance of Being Earnest, uma obra exemplar em termos da complexidade de interpretação e de tradução do humor, a saber: A Importância de Ser Earnest de Januário Leite1 Quanto Importa Ser Leal de António Pedro2 No Capítulo 2, socorrer-nos-emos das obras Le Rire, de Henri Bergson, e The Joke and its Relation to the Unconscious, de Sigmund Freud, para tentar chegar a uma definição do conceito de humor. No Capítulo 3, traçamos o quadro metodológico transdisciplinar que norteou este nosso trabalho de investigação. No Capítulo 4, tentaremos, com base na análise crítica comparada de duas traduções da peça de Oscar Wilde, The Importance of Being Earnest, apontar, pela via transdisciplinar, aqueles que consideramos ser os maiores obstáculos a uma correcta tradução do risível

Structural conditions that leads to photoluminescence emission in SrTi'O IND.3': an experimental and theoretical approach

Complex cluster [ TiO5·VOz] and [ SrO11·VOz] (where VOz =VOX ,VO•, VO•• vacancies were identified in disordered SrTiO3 powders prepared by the polymeric precursor method, based on experimental measurements by x-ray absorption near edge structure spectroscopy. The paramagnetic complex states of [ TiO5·VO•] and [ SrO11·VO•] with unpaired electrons were confirmed by electron paramagnetic resonance spectroscopy. The disordered powders showed strong photoluminescence at room temperature. Structural defects of disordered powders, in terms of band diagram, density of states, and electronic charges, were interpreted using high-level quantum mechanical calculations in the density functional framework. The four periodic models used here were consistent with the experimental data and explained the presence of photoluminescence.FAPESP/CEPIDCNPq/PRONEXCAPE

Electronic ceramics based on polycrystalline SnO2, TiO2 and (Sn xTi1-x)O2 solid solution

In 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 application used to project porous or highly dense microstructure. The majority of discussion is focused in two main applications: varistor and sensor. In both applications there are similarities involved in the control of the sensor and varistor properties, which can mainly ascribed to the grain boundary structure and composition. The similarities found are consistently explained by the fact that all of these n-type semicondutor ceramics have the tendency to establish a grain boundary region with a p-type semiconductor nature (due to metal transition atoms segregated at the grain boundary region and then favors negative charged species to adsorb and enrich this region). This configuration enables electrons to become localized on the surfaces, giving rise to a negative surface and, as a result, electron depletion layers are formed, acting as potential barriers which control the properties of the mentioned devices.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP