Tungsten Oxide

Violet tungsten oxide is kind of short rod fine crystal and between these short rod fine crystals there have many voids, particle size distribution is relatively loose. Which are conducive to discharge water and help hydrogen into the crystal particles, therefore, not only the restore process can take place inside also can restore on the surface, violet tungsten oxide advantageous for the producing ultrafine tungsten powder. Besides the reduction process conditions during the reaction should able to better control, such as low dew point of hydrogen, flow rate, amount of loading the boat. After studies showed with the development of reduction reaction, the oxygen atom reduce and  oxygen vacancies increase of violet tungsten oxide, tungsten dioxide particles becomes more dense than γ- tungsten oxide’s. This is bad for hydrogen gas get into interior particles and the water which producing by reaction particles are not easily discharged. During the restore process, the reaction

As we all know, annealing, or thermal, treatment is one of the most effective ways to influence the structure and the properties of tungsten oxide films. To investigate the effects of the annealing temperatures on the structure and optical property of tungsten oxide thin film that were deposited by magnetron sputtering of WO3 bulk in a vacuum, the deposited films were annealed at 200℃ and 300℃ for 60 min and at 400℃ for 60 min and 180 min in air, respectively.    We find that the annealing temperature of 400℃ can effectively influence the structure and optical property of the deposited films. The films annealed at 200℃ and 300℃ display violetred under the sunlight as well as the as-deposited ones. Nevertheless, the film annealed at 400℃ exhibits transparency and appeared to be blue colored. If you have any inquiry of tungsten oxide, please feel free to contact us: Email: sales@chinatungsten.com      sales@xiamentungsten.com Tel.: +86 592 5129696      +86 592 5129

Nano tungsten oxide has strong organizational ability to grow and in a stable reaction conditions the interactions between molecular are fairly obvious. Molecular can epitaxial growth which is accordance with lattice arrangement strictly and to form the formation ratio complete and single component structure. With the improvement of nano technology, now there have been some special form of tungsten oxide, including arborescent, clitheriform, nanorods, nanowires and other special forms.  Producing method of special form tungsten oxide which can be divided into three types: high-temperature synthesis, hydrothermal synthesis method, and solution low temperature synthesis method. Although high-temperature synthesis method is most common, but it has high requirements in equipment so this method is difficult wildly be used. The hydrothermal synthesis method is acidification W (CO)  6  and ammonium tungstate, the reaction is from 2 to 100 hours at 160-200 ℃ range in autoclave for pr

The chemical formula of pyrochlore type tungsten oxide is  H 2 W 2 O 7 . Pyrochlore type tungsten oxide has recently found its wide applications in many different areas such as photoelectron-chemistry, functional material and sensing. In addition, pyrochlore type tungsten oxide can be used as intermediate product for the industrial production of  WO 3 . There are many kinds of synthesis methods of the pyrochlore type tungsten oxide. And there are two main types: Aurivillius type compound as precursor, pyrochlore type tungsten oxide is obtained by acid treatment. The second method is hydrothermal synthesis method, namely sodium tungstate solution acidification to a certain pH range and it can be obtained by hydrothermal reaction for a certain time. The hydrothermal method that has overwhelming superiorities than others also has its own sets of flaws such as high cost, long reaction time and low quality product. Therefore, how to intensify the preparation process of H 2 W 2 O 7  to obt

The films annealed at 200C and 300 C display violet–red under the sunlight as well as the as-deposited ones. Nevertheless, the film annealed at 400C exhibits transparency and appeared to be blue colored. The film annealed at 200C is amorphous, i.e. does not exhibit diffraction peaks while those annealed at 400C exhibit several sharp diffraction peaks, indicating the crystallization of this film happened. The peaks shown in Figs. 1(b) and 1(c) can be attributed to a mixture of polycrystalline phases, which includes hexagonal h-WO3 phase (JCPDS PDF-33-1387) and triclinic t-WO3 phase (JCPDS PDF-30-1387). It is also seen that the films annealed at 400C were dominated by hexagonal h-WO3 phases. Acosta et al. had prepared the tungsten oxide thin films by sputtering WO3 bulk. Their results indicated that the films mainly contained hexagonal h-WO3 phase and monoclinic α-WO3 phase. Usually, the polycrystalline monoclinic and triclinic phases can be observed in the films deposited by reactive m

Tungsten trioxide has shown good sensing properties towards various gases. Recently thin nanostructured WO3 films have been tested. Due to their large surface area to volume ratio they exhibit good sensitivity depending on the grain size. However in conventional WO3 thin films the average grain size exceeds the thickness of the surface space charge layer, so the electrical conduction is mainly controlled by the carriers transport across the grain boundaries. An alternative way seems to be in a monocrystalline material with nanometric dimensions.  Our objective is to fabricate nanosized tungsten oxide rods and to test their sensing properties under gas adsorption. We focus on the growth, the structure and the electrical properties of tungsten nanorods. The tungsten oxide nanorods were grown by vapour transport from a WO3 layer onto a substrate (Mica). The nanorods growth was controlled by the temperature gradient between the WO3 layer and the substrate. If you have any

Synergistic effect between ceria and tungsten oxide can make them to form WO3–CeO2–TiO2 catalysts for NO (nitrogen monoxide) reduction by ammonia were prepared by a sol–gel method. The catalysts were characterized by BET, XRD, Raman, NH3/NO adsorption and H2-TPR to investigate the relationships among the catalyst composition, structure, redox property, acidity and deNOx activity. WO3–CeO2–TiO2 catalysts show a high activity in a broad temperature range of 200–480 1C.  The low-temperature activity of catalysts is sensitive to the catalyst composition especially under low-O2-content atmospheres. It may be related to the synergistic effect between CeOx and WOx in the catalysts. On one hand, the interaction betweenceria and tungsten oxide promotes the activation of gaseous oxygen to compensate the lattice oxygen consumed in NH3-SCR (selective catalytic reduction) reaction at low temperatures. Meanwhile, the Br nsted acid sites mainly arise from tungsten oxides, Lewis acid sites m

Over the last decade, nanostructured tungsten oxide materials have attracted much interest due to their potential for catalyst, gas sensors, crystalline film and electrochromic material applications. Several studies have been conducted by using various techniques, including the oxygen plasma processing, plasma sputtering, chemical solution, sol-gel techniques, electron beam evaporation deposition, electrochemical etching, and the chemical vapor deposition techniques. Most work concerned the synthesis of nanoparticles for catalytic applications based on chemical solution methods.The nanostructured tungsten oxide materials were synthesized using a simple hot filament CVD technique. The details of the process were described elsewhere in our previous publications.  The tungsten filament acted as a precursor for tungsten oxide, and no catalyst or other tungsten-containing compound precursor was used. Both AlN and A ceramic substrates were used. Prior to the experiments, the subs