Análise de cobertura de metal-metal por XRF

A proposta do referente estudo foi medir a espessura do depósito de um metal em outro metal base, ou seja, utilizar o processo eletroquímico de Galvanoplastia ou eletrodeposição deste metal, por meio da técnica de fluorescência de raios X (XRF). O uso desta técnica justificou-se pelo interesse em reduzir os custos excessivos durante o processo eletroquímico, bem como, minimizar as possíveis margens de erros para obter resultados satisfatórios nas medidas. Neste trabalho, incluíram-se as medidas da espessura do Níquel (Ni) e análises da intensidade de radiação incidentes e a radiação atenuante, em função da espessura dos elementos Cromo (Cr) e Zinco (Zn), considerando como metal base o elemento Ferro (Fe). Em decorrência disso, em todos os casos foram simulados os processos de deposição do metal onde foram incluídos os resultados de absorção de raios X, além de desprezar a influência de outros fatores como a temperatura, o pH, o tratamento de superfície, entre outros, os quais são necessários para considerar em cada caso.

A large-area photolithography technique based on surface plasmons leakage modes

An atomic force microscope (AFM) assisted surface plasmons leakage radiation photolithography technique has been numerically demonstrated by using two-dimensional finite-difference time-domain (2D-FDTD) method. With the aid of a metallic AFM tip, particular characteristic of the Kretstchmann configuration to excite surface plasmons (SPs) is utilized to achieve large-area patterns with high spatial resolution and contrast, the photoresist could be exposed with low power laser due to the remarkable local field enhancement at the metal/dielectric interface and the resonant localized SPs modes near the tip. Good tolerance on the film thickness and incident angle has been obtained, which provides a good practicability for experiments. This photolithography technique proposed here can realize large-area, high-resolution, high-contrast, nondestructive, arbitrary-structure fabrication of nanoscale devices. (c) 2007 Elsevier B.V. All rights reserved.

Influence of synthetic method on the properties of La0.5Ba0.5FeO3 SOFC cathode

Power Point presentado en The Energy and Materials Research Conference - EMR2015 celebrado en Madrid (España) entre el 25-27 de febrero de 2015

A compact diode-pumped injection seeded Nd : YAG laser with resonance-detection technique

A diode pumped injection seeded single-longitudinal-mode (SLM) Nd:YAG laser is achieved by using the resonance-detection technique in Q-switching operation. The pulsed oscillator laser uses a folded cavity to achieve compact construction. This system operates at 100 Hz and provides over 20 mJ/pulse of single-frequency 1064 nm output. The M-2 values of horizontal and vertical axes are 1.58 and 1.41, respectively. The probability of putting out single-longitudinal-mode pulses is 100%. The 355 nm laser output produced by frequency tripling has a linewidth less than 200 MHz. The laser can run over eight hours continually without mode hopping.

Generation of 1.5-12 ns width-tunable 532 nm pulses by adopting laser-induced plasma shutter technique

The pulse-shaping technique has found widespread applications in nonlinear optics and material processing. Experimental research on laser-induced plasma shutter to control the 532 nm pulse width is conducted. The impacts of the total pulse output energy on pulse compression are investigated, and a useful conclusion can be drawn that there exists an optimal value of pulse energy at which the shortest output pulse of 3.23 ns can be obtained without a device for delay-time. Once the device for delay-time is employed to change the optical differences between two laser paths, the pulse width can be further shortened to 1.51 ns. In short, the 1.5-12 ns width-tunable 532 nm laser pulses have been obtained by adopting the laser-induced plasma shutter technique. (C) 2007 Elsevier GmbH. All rights reserved.

Effects of annealing on the color, absorption spectra, and light yield of Ce : YAlO3 single crystal grown by the temperature gradient technique

YAlO3 single crystal doped with Ce3+ at concentration 1% was grown by the temperature gradient technique. The as-grown crystal was pink. After H-2 annealing or air annealing at 1400degreesC for 20 h, the crystal was turned into colorless. We concluded there were two kinds of color centers in the as-grown crystal. One is F+ center attributed to absorption band peaking at about 530 nm, the other is O- center attributed to absorption band peaking at about 390 nm. This color centers model can be applied in explaining the experiment phenomena including the color changes, the absorption spectra changes, and the light yield changes of Ce:YAP crystals before and after annealing. (C) 2004 American Institute of Physics.

Growth, characterization and optical quality of CaF2 single crystals grown by the temperature gradient technique

The CaF2 single crystals with diameters up to 200 mm were successfully grown by modified temperature gradient technique (TGT), which are suitable for application as optical elements in the ultraviolet range. The optimizations of various growth parameters were systematically studied. Properties of as-grown CaF2 crystals were characterized by the nature of inclusions, dislocations, crystallinity, and impurities contents. The results showed that the dislocations and multinucleation were mostly constrained in the conical part of the crystals with the cylindrical parts having the best crystalline quality and lowest impurity contents. The high optical quality of TGT-grown CaF2 single crystals was also confirmed to have excellent optical transmission in 190-2500 nm and refractive index homogeneity. (c) 2005 Elsevier Ltd. All rights reserved.

Efficient laser oscillation of Yb : Y3Al5O12 single crystal grown by temperature gradient technique

Low-threshold and highly efficient continuous-wave laser performance of Yb:Y3Al5O12 (Yb:YAG) single crystal grown by a temperature gradient technique (TGT) was achieved at room temperature. The laser can be operated at 1030 and 1049 nm by varying the transmission of the output coupler. Slope efficiencies of 57% and 68% at 1049 and 1030 nm, respectively, were achieved for 10 at. % Yb:YAG sample in continuous-wave laser-diode pumping. The effect of pump power on the laser emission spectrum of both wavelengths is addressed. The near-diffraction-limited beam quality for different laser cavities was achieved. The excellent laser performance indicates that TGT-grown Yb:YAG crystals have very good optical quality and can be potentially used in high-power solid-state lasers.

Electrochemical fabrication and electronic behavior of polypyrrole nano-fiber array devices

Electrochemically active Polypyrrole (PPy) nano-fiber array device was fabricated via electrochemical deposition method using aluminum anodic oxide (AAO) membrane as template. After alkaline treatment electrochemically active PPy nano-fiber lost electrochemical activity, and became electrochemically inactive PPy. The electronic properties of PPy nano-fiber array devices were measured by means of a simple method. It was found that for an indium-tin oxide/electrochemically inactive PPy nano-fiber device, the conductivity of nano-fiber increased with the increase of voltage applied on the two terminals of nano-fiber. The electrochemical inactive PPy nano-fiber might be used as a nano-fiber switching diode. Both Au/electrochemically active PPy and Au/electrochemically inactive PPy nano-fiber devices demonstrate rectifying behavior, and might have been used for further application as nano-rectifiers. (c) 2005 Elsevier B.V. All tights reserved.

Defects in U3+: CaF2 single crystals grown under different conditions by the temperature gradient technique

Defects in as-grown U3+ : CaF2 crystals grown with or without PbF2 as an oxygen scavenger were studied using Raman spectra, thermoluminescence glow curves, and additional absorption (AA) spectra induced by heating and gamma-irradiation. The effects of heating and irradiation on as-grown U3+: CaF2 crystals are similar, accompanied by the elimination of H-type centers and production of F-type centers. U3+ is demonstrated to act as an electron donor in the CaF2 lattice, which is oxidized to the tetravalent form by thermal activation or gamma-irradiation. In the absence of PbF(2)as an oxygen scavenger, the as-grown U3+:CaF2 crystals contain many more lattice defects in terms of both quantity and type, due to the presence of O2- impurities. Some of these defects can recombine with each other in the process of heating and gamma-irradiation. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characteristics of large-sized ruby crystal grown by temperature gradient technique

Large ruby with the size of circle divide75 x 45 mm was grown by temperature gradient technique for the first time. Absorption spectrum was carried out in the range of 190-800 nm by spectrophotometer, and the concentration spatial distribution of Cr3+ in ruby was calculated from the absorption coefficient that based on the Beer-Lambert's Law. Cr3+ ions gradually increase alone both the growth axis and the radial direction. The shape and ingredient of the inclusions were measured by means of Leitz ride field microscopy and scanning electron microscopy. Lane photos and X-ray omega scan show the good quality of as grown ruby. The optimized growth conditions were pointed out based on the observation. (C) 2004 Elsevier B.V. All rights reserved.