Tungsten Oxide

Nano tungsten trioxide is a typical N-type semiconductor gas sensing material, it has a large surface area, stable chemical properties, a wide band gap, a variety of toxic gases have good sensitivity, can effectively improve gas sensor sensitivity and response speed, is a good gas-sensitive film material. The preparation and synthesis of nano tungsten trioxide thin film by gas phase method is mainly to convert the synthesized tungsten trioxide crystal into the state of gas phase of tungsten trioxide through steps of sublimation, evaporation and decomposition. By setting the experimental conditions, the tungsten trioxide is transformed into tungsten trioxide saturated vapor. Finally, as the temperature decreases, saturated steam will crystallize in cold to grow as nanostructured tungsten trioxide crystals. The preparation of nano tungsten trioxide gas-sensitive film gas method includes two kinds of chemical and physical methods. Chemical vapor deposition (CVD) principle is the use of g...

Sol gel method is widely used abroad, a kind of nano material preparation method, its principle is the prepared precursor (such as inorganic salt or metal alkoxide) dissolved in small molecule solvent in solution by mixing made uniform, solute and solvent hydrolysis reaction, hydrolysis condensation the reaction of nano particles and the formation of integrated sol. On the basis of the prepared sol, different processes can be used to prepare nano thin films and ultrafine powders with different properties. There are several ways to prepare tungsten trioxide thin films by sol-gel method: 1. Tungstic acid hydrochloric acid method; 2. Tungsten powder peroxide polytungstic acid method; 3. Tungstic acid colloid solution is prepared by ion exchange; 4. Polymer method. The traditional sol-gel method mostly controls the particle size of powders by controlling pH value, temperature and adding surfactants. Recently, some scholars have successfully controlled the particle size of WO 3  powder...

Nano tungsten trioxide is an excellent N-type semiconductor gas sensor, compared with the traditional materials, nano-tungsten trioxide gas sensor, high sensitivity, faster response speed and faster recovery is the most studied in recent years gas sensitive raw materials. There are methods for the synthesis of nano tungsten oxide films or gas phase method and solid phase method, liquid phase method. Electrodeposition is a gas phase method for preparing nano tungsten trioxide thin film, it is in a certain electrolyte and operating conditions, the metal or alloy from the compound solution, non aqueous solution or molten salt electrochemical deposition. The basic process of electrodeposition in preparing WO 3  thin films is: first, dissolve the W powder in a certain proportion with H 2 O 2 , then remove the excess H 2 O 2 , get the electrolyte solution and deposit it naturally, then use Pt as the working electrode and the other as the counter electrode. The WO 3  thin film can be...

Synthetic nano tungsten trioxide or thin film methods are usually gas phase method, solid phase method, liquid phase method. Sputtering method is a preparation of nano tungsten trioxide film gas phase preparation method. The most widely used sputtering method is magnetron sputtering. Some foreign scholars use metal W as a target, and use a mixed gas of Ar and O 2  to prepare a WO 3  thin film which is more gas-sensitive to NO x  by magnetron sputtering. In addition, there are scholars using DC magnetron sputtering device, the target is 99.95% W, in a vacuum degree of 2 × 10-6mbar reaction chamber, Ar (50%) - O 2  (50%) the mixed gas is subjected to direct current radio frequency excitation and discharge to deposit the WO 3  thinly on the substrate to obtain a WO 3  thin film. The electrochromic properties are also studied. Compared with other coating methods, the sputtering coating method has the following advantages: (1) Any substance can be spattered, esp...

Ball mill is a fine equipment used in industry and can also be used for mixing. The ball mill is composed of a cylinder and sphere, its working principle is when the cylinder rotates, installed in the cylinder body and the grinding body in grinding by centrifugal force and friction force with the cylinder to rotate to a height, and then automatically fall, the material in the cylinder impact and the grinding and grinding material. The main factors affecting the efficiency of the ball mill are the speed of the ball mill, the quantity of the ball, the amount of water and electrolyte, the time and the loading. The normal milling time is about 24-72 hours, and the length of the ball milling time directly affects the quality of the ball milling product. Generally speaking, coarse grained material is easier to grind to coffee, and the time is shorter. However, the milling time of gal material to cut below is usually prolonged by several times or longer. However, with the prolongation of ball...

Tungsten trioxide (WO 3 ) is a kind of transition metal oxides, it is not only a kind of N type semiconductor material, is also a kind of "d0" oxide, this dual identity so it has many characteristics. The research shows that there is rod, plate and rod plate three kinds of nano tungsten oxide crystal, gas sensing properties of tungsten oxide with different crystal morphology is slightly different, some scholars use tungsten trioxide for four kinds of common harmful gases were tested and concluded. (1) The best working temperature of WO 3  sensor in ethanol, acetone, ammonia and formaldehyde is 350 ℃, 300 ℃, 325 ℃ and 250 ℃, respectively, and the sensitivity reaches the maximum at gas concentration of 1000 ppm. 21.29, 10.82, 24.32 and 9.68 respectively, and the lowest detection concentration of gas sensors for four gases are 100ppm, 50ppm, 25ppm and 100ppm, respectively. (2) The best working temperature of nano-plate WO 3  gas sensor is 350 ℃, 300 ℃, 325 ℃ and 250 ℃, respecti...

Tungsten trioxide (WO 3 ) is a product of tungstate or calcining ammonium paratungstate, is an important intermediate compound of high purity tungsten. The general appearance of yellow powder, insoluble in water, soluble in alkaline solution, slightly soluble in acid. The crystal structure of tungsten trioxide has four kinds, the crystal type: it mainly depends on the temperature at 24 °C into ammonium metatungstate, heated to 300 °C and 350 °C, transformed into amorphous material (ammonium tungsten bronze), heated to 400 °C, into six party crystal WO 3 , when the temperature reached 500 °C, it became triclinic WO 3 . When the temperature reached 750 °C, the crystal was recrystallized. Crystal is not the same, WO 3  surface area and average particle size is not the same. The basic principle of preparation of tungsten trioxide mainly has three kinds: one is composed of tungsten and soda to eutectic ammonium paratungstate, plus roasting and acid decomposition and tungsten trioxide; ...

 In addition to the production of tungsten trioxide (WO3) ultrafine particles, they can be used to produce tungsten powder, tungsten carbide powder, yellow ceramics, electrode materials for energy storage batteries, anti-corrosion paints and coatings, and can also be used to make multifunctional mulch films. Compared with ordinary agricultural film, the agricultural film containing tungsten oxide additives has higher comprehensive performance, which is mainly manifested in better heat insulation effect and better light transmission performance. In areas with strong sunlight, when the temperature is too high, it is easy to produce drought and cell dehydration, which affects the physiological and metabolic activities of plants, such as photosynthesis, water metabolism, endogenous hormones, and thermal stability of cell membranes, which in turn leads to the appearance and growth of plants abnormal. Therefore, it is of practical significance to produce agricultural film with good heat...

At present, the industrial production of pure tungsten trioxide or APT is mainly purify the crude sodium tungstate solution. Ammonia purification of a thermal dissociation method is the South China University of Zhang Qixiao et al in the early 21st century proposed purification of ammonium arsenate solution method, it can be achieved by the crude ammonium tungstate solution directly prepared high purity tungsten trioxide. The use of ammonia purification heat from the main base of high pure tungsten trioxide solution is directly preparing high purity tungstic acid (H 2 WO 4 ), the quality of H 2 WO 4  directly affects the quality of the final product and cycle times. The process of ammonia purification by thermal dissociation is: 1.The pulp industry H 2 WO 4  slowly adding ammonia, WO 4  will dissolve (NH 4 )  2 WO 4  solution, and silica, crude H 2 WO 4  of ferric hydroxide, manganese oxide and calcium tungstate are reserved for ammonia dissolution in slag....

Tungsten trioxide is a transition metal oxide, with a semiconductor character, has great potential for gas-sensitive materials, sensitive to a variety of gases, especially toxic gases. In recent years, with the emergence of nanotechnology, it was found that nano-tungsten trioxide has a higher sensitivity and response speed. There are three main methods for preparing nano tungsten trioxide, gas phase method, liquid phase method and solid phase method. In general, hydrothermal method has become the most widely used method for the preparation of nano WO 3  by virtue of its economical, low cost and easy operation. Commonly used to produce gas-sensing elements of tungsten trioxide mainly nanorods, nano-plate, nano-plate rod-like mixed structure and other forms, as will eventually become what form, are generally in the process of hydrothermal synthesis by adjusting the parameters formed by the results, therefore, even with the same hydrothermal method of nano-tungsten trioxide, often be...

The nitrogen oxides produced by coal combustion as a pollutant will affect human health. The most harmful is NO 2 , which mainly affects the respiratory system of human beings, and can cause bronchitis and emphysema. SCR selective catalytic reduction technology has become the most widely used and most effective flue gas denitrification technology in the world. It has the advantages of low reaction temperature, high purification rate, reliable operation and small two pollution. After its catalysis, the main non-toxic and non polluting N 2  and H 2 O are produced. In the SCR  soot denitrification technology  selective catalytic reduction system, it is generally composed of ammonia storage system, ammonia and air mixing system, ammonia injection system, reactor system and monitoring control system, the thermal power plant, SCR reactor is usually installed in the boiler economizer and air preheater, here for the high dust temperature arrangement, smoke temper...

Photocatalysis is a photochemical reaction in the presence of a catalyst, it is a new science and technology. Common photocatalysts include metal oxides (TiO 2 , ZnO, Fe 2 O 3 , Bi 2 O 3 , WO 3 ) and metal sulfides (CdS, MoS 2 , MoSe 2 ). Titanium dioxide TiO 2  is the most white thing in the world, 1 grams of titanium dioxide can paint more than 450 square centimeter area to white. So it's the best paint for making white oil paint. The most well-known is that semiconductor photocatalysis performance of TiO 2 . TiO 2  photocatalysis is widely used because of its high activity, photochemical stability, non-toxic and cheap. Tungsten trioxide TiO 2  is a kind of tungsten compounds that are widely used, It can be used not only for hard alloys, but also for dyes, the most commendable thing is that tungsten trioxide also with excellent photocatalytic performance. Like TiO 2 , WO 3  also has high activity, photochemical stability, non-toxic and so on. If you com...

Tungsten trioxide is one transition metal oxide among a lot of metal oxide, belonging to the n-type semiconductor with its very widespread application. As a semiconductor gas sensor, tungsten trioxide has been considered one of the most promising new oxide sensitive materials to detect NO  x , SO x , NH 3 , H 2 S, etc.. Since carbon nanotubes have been discovered in 1991, the more innovative electrical, magnetic, optical, thermal and other physical and chemical properties of one-dimensional nano-materials rendered have caused more and more attention, and showing its value and broad application prospects. While, compared to the traditional tungsten oxide material, tungsten trioxide nanowire because of its greater surface area has broad application prospects on the fields of gas sensors, electroluminescence, photoluminescence, conductivity electrode and photocatalysis. In addition, the tungsten oxide nanowires also have a higher surface activity and stronger adsorption capacity, th...

Recently, the Chinese Academy of Physical and Chemical Research Institute has successfully synthesized a highly efficient water electrolyzing catalyst to achieve high efficiency at a low voltage of activating water molecules, and offered the potential for solving the future energy crisis. Hydrogen is considered as the best source of energy, unlike the other new energy sources, like solar, nuclear, ocean, biomass and geothermal energy and so on, it belongs to the energy of energetic body which is available direct combustion. Among the hydrogen production technologies, the way of solar water photolysis or photo-assisted electrolysis of water is one of the most promising and efficient pathway, which is depending on the semiconductor electrode, and moreover, the water electrolyzing catalyst can greatly improve the efficiency of water electrolysis hydrogen. Zhang Rui, one of the researchers led his team carried out a in-depth study on the nanostructure of "Hydrotalcite (LDH)...

In June, a primary school of Huayuan County of Hunan Province, China, occurred a serious mercury poisoning (Minamata disease) of many students, which resulted in 147 students urine mercury exceeded; its cause is a fifth-grade student took 50 ml of the remaining mercury in the wok of a waste workshop in a mineral water bottle to school, and gave it to the other students for playing. According to the source, this workshop was illegal constructed and operated unauthorized without Environmental Impact Assessment (EIA) and related procedures. For this accident, I am showing my deep sadness, someone innocent was suffered a serious injury because some unscrupulous manufacturers do not manage their hazardous substances.   China as the largest country which uses and emissions most  in global mercury, and has faced with the tremendous pressure to reduce emissions of mercury reductions in the "global mercury instrument" negotiations. This year, on June 18th to 19th, "the sec...

Virtual Reality (VR) and Augmented Reality (AR) are now leading the forefront of technology, what the surprises will be by the further combination of AR and VR? Recently, source pointed out that Halo holographic helmet has opened the official website pre-sale, and will deliver to the customers after the International Consumer Electronics Show in January 2017. It is reported that this holographic helmet can switch in a key between AR and VR, using the most advanced processor, and based on a whole new generation customization system, can achieve low latency display in the sensor; at the same time, it supports gesture recognition, without any external testing equipment to achieve SLAM, and supports real-time 3D modeling space. In addition, the key to switch between AR and VR of this holographic helmet in a key lies in the eyepiece glass with a special chemical materials sandwich, after conductive of the special sandwich of film, a reversible color change of light will occur, such as the ...

Because of tungsten powder and tungsten carbide powder chemical purity and physical properties has high requirement so producing tungsten powder and tungsten carbide powder process is very complex and the cost is higher too. But tungsten powder composition when not strictly required in most cases where there are a lot of impurities so using industrial pure carbon reduction tungsten powder is an economical and easy way. In a vacuum furnace use carbon reducing tungsten trioxide making high purity tungsten powder and tungsten carbide powder provided by melting and casting.  According to current science and technology, using industrial pure carbon or tungsten carbide powder as a casting material is fully meet the requirements. Using carbon restore tungsten trioxide is similar with using hydrogen restore tungsten trioxide. At atmospheric pressure, at a temperature condition of 750 ℃ heating tungsten trioxide so it will mix with carbon black or graphite powder occurring reduction. Th...