Advanced Materials Research Vol. 465

Abstract: It has been reported that the etch rate of exposed aluminum lines and pads on MEMS chips can be significantly reduced by dissolving an appropriate amount of silicon (or silicic acid, water glass) and ammonium persulfate (AP) in TMAH solution. However the etch rates of the PECVD silicon nitride films，which is usually underlying aluminum lines and pad, were rarely reported in previous literatures. In this paper, silicon nitride films of high compressive stress, low compressive stress, micro-stress, low tensile stress and high tensile stress are prepared by adjusting the flow ratio of SiH4 to NH3 and plasma power. Then the films are etched in four kinds of previously reported doped TMAH solutions. The experimental results show that silicon nitride films depositing at low flow ratio of SiH4 to NH3 and lager RF power were etched more slowly in doped TMAH solution than that of depositing at high flow ratio of SiH4 to NH3 and low RF power.

Abstract: A catalyst, 8%Fe-10%MnOx-CeO2/ZrO2, was prepared and applied for selective catalytic reduction of NO with NH3 at low temperature. The effects of SO2 and H2O on the catalyst were studied. The results showed that in the absence of SO2 and H2O, the catalyst 8%Fe-10%MnOx-CeO2/ZrO2 has good activity and stability. The presence of SO2 and H2O make the catalyst deactivate, and the activity can be recovered mostly by heating at 400°C. Properties of the catalyst on different reaction stages were characterized by FT-IR to study the inactivation mechanism of the catalyst. The results showed that the catalyst deactivation is due to the deposition of ammonium sulfate on the catalyst and the sulphation of the metal oxides of the catalyst.

Abstract: Microbridge resonators have been widely used as sensing elements to measure various parameters, such as pressure, acceleration, biochemical adsorption and reactions, mass-flow, infrared ray et al. But no model has been built to calculate quantitatively the shift of resonance frequency due to heat convection, incident infrared ray, excited thermal power drift and ambient air pressure. In this paper, a theoretical analysis is given to calculate the resonance frequency shift due to the thermal power (static heating power and dynamic heating power) fluctuation and the added mass of the ambient air. The model can be used to design resonant sensors based on microbridge resonator, such as resonant mass-flow sensors, resonant IR detectors, resonant biochemical sensors and resonant vacuum gauge, et al.

Abstract: Leno enhanced the leno's contents of scientific and cultural,displayed the infinite charm This paper briefly introduces the history of leno, focus on the cooperation of Yanshan University and Suzhou Sacred Dragon Silk researched Reducing state multifunctional leno. reducing state multifunctional leno has excellent performance and a wide range of uses. It analyzed the waving process, applications of Reducing state multifunctional leno, and prospected its long term development. reducing state multifunctional of Chinese textile.

Abstract: Very dense and vertically aligned carbon nanofibers were synthesized using a CVD at the temperature of 350°C. A high density of catalytic particles, which are necessary for the growth of vertically aligned nanofibers, were prepared by direct current sputtering method. In our experiment, the sphere-shaped copper nanoparticles were deposited on silicon substrate, and then these nanoparticles catalyzed the growth of carbon fibers using acetylene as carbon source in hydrogen atmosphere. The growth of vertically aligned nanofibers showed that each copper catalyst particle grow two linear carbon nanofibers, along the vertical direction respectively.

Abstract: The band structure and density of states (DOS) of Ti_1-xSn_xO₂ solid solutions with x=0, 1/8, 1/4, 1/2 and 1 were investigated by means of the first-principle calculations based on density functional theory. The result indicated that band gap and Fermi level of TiO₂-SnO₂ vary continuously from those of pure TiO₂ to those of Sn content increasing. In addition, the DOS moves towards low energy and the bang gap is broadened with growing value of x. The wide band gap and the low density of the states in the conduction band result in the enhancement of photoactivity in Ti_1-xSn_xO₂.

Abstract: Perovskite-type oxides LaFeO3 and YFeO3 were prepared by the citrate method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), infrared spectrometer (IR), ultraviolet visible spectrometer (UV). The results show that complex oxides LaFeO3 and YFeO3 have stable perovskite structure. The mean particle diameter of YFeO3 is about 30~40 nm, while LaFeO3 is about 50~60 nm. Photocatalytic degradation experiments of azo dye acid red 3B were done using perovskite-type oxides LaFeO3 and YFeO3 as photocatalysts. Dye Acid Red 3B solution with the LaFeO3 and YFeO3 undergone several degradation stages and the photodegradation rates were respectively 68.2% and 90.0% after irradiating 2 hours. The results show that the perovskite-type oxide YFeO3 has better photocatalytic activity, which mainly relates with the factors of position A such as the negative, the electronic structure, ion radius and so on.

Abstract: The highly dispersed TiO2 sols composed of anatase crystallites (ca.5 nm) were prepared by peptization of amorphous precipitates with trifluoroactic acid (TFA) during the synthesis. The size and crystallinity of the particles were tuned by the subsequent hydrothermal treatment. The prepared TiO2 nanocrystals were characterized by X-ray diffraction and transmission electron microscopy (TEM). The TEM results indicated that the growth of the crystallites could be inhibited by the increasing addition of TFA and the average sizes of TiO2 nanocrystals were all ultrafine. The degradation of phenol over the nanocrystals after calcination at 500 °C was investigated. The photocatalytic results showed that the sample with a high addition of TFA obtained a better photocatalytic property than that of the commercial TiO2

Abstract: Monodisperse polystyrene nanospheres with different diameters and functional groups were synthesized by soap-free emulsion polymerization. Capillary electrophoresis (CE) was applied to the separation and detection of the nanospheres. Baseline separation was achieved for carboxylic and sulfonic functionalized colloids due to their difference in diameter and surface charge. The electrophoretic mobility of the sulfonic functionalized colloids decreased with increasing of particle size, and three sulfonic functionalized nanosphere samples with diameters of 190, 250 and 330 nm were separated successfully by CE.