Influence of Tungsten Oxide Film Thick

Tungsten oxide films are of critical importance forelectrochromic device technology ,such as for smart windows capable of varying the throughput of visible light and solar energy.

Surface acoustic wave has been excited from a SAW device with 5.96 μm-thick ZnO and 1.15μm-thick UNCD films, which is successfully used for the streaming, pumping, and jetting of microdroplets of different sizes. The critical behaviors of different microfluidic phenomena were analyzed at different powers applied to the IDTs. The microfluidic efficiencies of the different ZnO-based SAW devices were investigated. Droplet pumping and jetting with different volumes were compared for the SAW devices with and without UNCD inter layers. Results show that the pumping velocities increase exponentially with the input power and those of the ZnO/UNCD devices are much larger than those of the ZnO/Si SAW devices at the same power. Based on the accurate analysis of the jetting dynamics, the maximum jetting angle is observed which depends on the droplet volume in the range 1.5–8μL during the jetting duration. The maximum jetting angle oscillates around 69° for droplets larger than 8μL.

Droplet streaming and nebulization on a 36oY-cut LiTaO3 SAW device have been realized using the SH-SAW. The streaming inside the droplet is sensitive to the position of the droplet, the coupling angle and droplet shape, which results in different  flow patterns. Droplet nebulization was enhanced with the increased aperture size of the driven IDTs and mainly occurred in horizontal direction along two lateral sides of the droplet, which is perpendicular to the designed SAW propagation direction. The atomization duration increases with the droplet size, while it decreases with the driven power at a given drop size.

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ZnO Films and Tungsten Oxide Film

Tungsten trioxide is used for many purposes in everyday life. It is frequently used in industry to manufacture tungstates for x-ray screen phosphors, for fireproofing fabrics and in gas sensors. Due to its rich yellow color, WO3 is also used as a pigment in ceramics and paints.In recent years, tungsten trioxide has been employed in the production of electrochromic windows, or smart windows. These windows are electrically switchable glass that change light transmission properties with an applied voltage.This allows the user to tint their windows, changing the amount of heat or light passing through.

The deposition process of ZnO/ultra-nanocrystal diamond (UNCD) film is simplified using the high target ultilisation sputtering technology and hot-filament chemical vapor deposition technique, which allow the growth of the high-quality multi-layer films with strong (0002) texture and fine grains. The ZnO/UNCD films have been successfully applied to fabricate SAW devices and the transmission signal obtained for the Rayleigh mode SAW is better than those using the conventional magnetron sputtering technique. The phase velocities show a significant thickness effect. The temperature coefficients of the frequency (TCF) for the SAW devices have been measured and a value of less than -30ppm/oC for the TCF could be obtained when the thickness of the UNCD layer ranges from 1.14 to 1.79 μm. For the SAW device with ZnO thickness of 7.68 μm and UNCD thickness of 1.06 mm, SAW achieves a coupling coefficient of 5.2%.The low TCF of -23.4 ppm/oC was obtained for the SAW devices with the 2.72μm-thick ZnO and 1.1 μm-thick UNCD film.

Love mode surface acoustic wave ultraviolet sensors have been fabricated using sputtered ZnO films on 36 Y-cut LiTaO3 substrate. Results from the UV sensing measurements show that the amplitude response of the Love mode SAW UV sensor operated at 41.5 MHz changed up to  6.4 dB and the fre-quency shift approached 150kHz under a 254 nm illumination at the power density of 350 μW/cm2. Whereas under a 365 nm illumination at a power density of 570 μW/cm2 the amplitude of thetransmission signal decreased only 2.5dB with no significant frequency shift. The frequency hopping effect during the downshift and recovery periods was identified due to the simultaneous interplays between the variations of the acoustic velocity andattenuation during the acoustic-electric interaction.

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Tungsten Oxide Nanocrystals Synthesized

Tungsten oxide, also known as tungsten trioxide or tungstic anhydride, WO3, is a chemical compound containing oxygen and the transition metal tungsten. It is obtained as an intermediate in the recovery of tungsten from its minerals.Tungsten ores are treated with alkalis to produce WO3. Further reaction with carbon or hydrogen gas reduces tungsten trioxide to the pure metal.

Tungsten oxide (hydrate) nanocrystals have been synthesized via hydrothermal route assisted by ammonium benzoate (AB), which showed the products with various morphologies, including the flower-shape, spherical and star-shape. Based on the analysis of the Fourier transform infrared spectra and observations of the time-dependent growth, a new self-assembly growth mechanism has been proposed for the formation of the different microstructures. The star-netted WO3 nanocrystals were applied as a sensitive layer for the relative humidity performed using a ZnO/LiTaO3.Love mode SAW device. The frequency shift has been observed with a sensitive response to the change of the relative humidity from 30% to 90%, and the frequency shift is linearly related to the relative humidity.

A new one-step method using the special holder has been developed to sputter-deposit the ZnO films. The typical columnar structure is inclined and the column inclination angle has been changed from 0o to 34o. X-ray diffraction analysis shows that the strains in the ZnO films decreased with substrate tilt angle. The optical characterization indicates tha the band-gap energies decreased from 3.19 eV to 3.07 eV, which has a linear relation to the strain in the ZnO films.

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EDM Parameters of Silver Tungsten Alloy(b)

After the selection process is regulated quasi-polar and other process parameters, most of the artifacts are generally divided into coarse, medium, fine in order to convert several gage, both to ensure the technical requirements of the workpiece, but also to ensure the highest possible overall production efficiency. Select electric gage order should be determined according to the principal contradiction. Such as processing cavity mold, electrode wear ratio must be less than 1 percent, according to the requirements of the electrode should be selected loss ratio and peak current pulse width for roughing, then the production efficiency, rough degree in secondary position considered.

Such as precision machining small module gear die, in addition to side rough-givers, the main consideration should be to select the appropriate discharge gap, to ensure that they meet the requirements of the die gap.

Select the pulse interval of time, when roughing take long pulse width of 1 / 5-1 / 10, finishing 2-5 times to take the pulse width, pulse between the large, low productivity, but the width is too small, the processing unstable, arcing.

Processing area hours should not choose too large peak current, otherwise within the electrode gap is too thick causing galvanic corrosion product discharge centralized, easy arcing. Therefore, in the beginning may be rough few actual processing area should be temporarily reduce or increase the peak current pulse interval, or deliberately timed to strengthen carrying knives, electric fire until after the discharge area increases, the current increases to normal value. With increasing depth of processing should also be strengthened accordingly carrying knives and punch, pumping chip functions.

tungsten-silver-alloy


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Tungsten oxide and Zinc Oxide Using

Tungsten oxide and Zinc oxide used as important functional materials have been widely applied into chromic devices, microsensors, surface acoustic wave (SAW)devices and microfluidic devices. Based on the nanotechnology and advanceddeposition techniques, highly functionalized films with good crystallinity could be grown under the optimized conditions, which have a vital significance on the improvement of the performance of the devices. The tungsten oxide nanocrystals withnovel microstructures have been controllably synthesized assisted by the dual-functional reagents. The sputtered ZnO films have been used to fabricate the SAW devices using the microelectromechanical systems technology, and the high-performance SAW devices have been successfully applied into the sensors and microfluidics.

Hexagonal tungsten oxide nanocrystals with microplate, urchin-like, and microspherical morphologies have been hydrothermally synthesized using ammoniumtartrate (AT). The spherical microstructure changed to a microplate one and the crystalphase was partially transferred from hexagonal WO3 to orthorhombic WO3 when the pH value was reduced from 1.08 to 0.6. Besides the adsorption action of the NH4+ and Na+ ions, the capping effect was reinforced by the hydrogen bonding from the tartrate groups with the increase in the concentration of AT. The optical analysis indicated that the bandgap increased with the decrease in the diameter of the hex-WO3 nanocrystals. The enhancement of the blue emission of the nanocrystals originates from the local intercalation of the Na+ ions and the oxygen defects.

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