RESUMO
The effect of SnO2 addition (0, 1, 2, 4 wt.%) on thermoelectric properties of c-axis oriented Al-doped ZnO thin films (AZO) fabricated by pulsed laser deposition on silica and Al2O3 substrates was investigated. The best thermoelectric performance was obtained on the AZO + 2% SnO2 thin film grown on silica, with a power factor (PF) of 211.8 µW/m·K2 at 573 K and a room-temperature (300 K) thermal conductivity of 8.56 W/m·K. PF was of the same order of magnitude as the value reported for typical AZO bulk material at the same measurement conditions (340 µW/m·K2) while thermal conductivity κ was reduced about four times.
RESUMO
A capillary light guide optical amplifier using nanocolloids of Yb3+-Er3+ co-doped NaYF4 as a filler was successfully demonstrated. A 7-cm-long and 150-micron-inner-diameter capillary light guide was capable to amplify a pulsed optical signal at 1550 nm with a gain coefficient of 0.15 cm-1 at a pump power of 4 mW (980-nm wavelength). The nanocolloid gain medium was prepared by pulverizing the phosphor powder with a high-speed planetary ball mill. Ball milling of the powder in water produced nanoparticles with a size of approximately 130 nm that after drying were transferred to a liquid with high refractive index (1.551 at 1550 nm) required to maintain light confinement within the fused silica capillary light guide. The results show that RE-doped colloids of nanocrystals can be potentially used as liquid gain media fillers in capillary light guide lasers and amplifiers with high photostability and low toxicity.
RESUMO
A detailed careful analysis of the infrared resonance (IR) spectra of polystyrene (PSt), polymethyl methacrylate (PMMA), polyacrylonitrile (PAN) and their co-mixtures were performed. Through this study the absorption peak area to weight ratios as well as working curves were obtained to test for their reliability as well as their suitability. Satisfactory results were achieved and these working curves were then used to measure the polymerized components of binary and ternary co-polymers. By investigating the acquired data we conclude that the monomer preferential polymeric sequence is St > MMA > AN. A quantitative method to measure P (St/AN/MMA) concentrations by IR spectroscopy is proposed in this work.
