What is tungsten oxide?

Tungsten oxide is a powder metallurgy raw material for producing hard alloy and tungsten products. According to the national standard (GB/T 3457-1998), it is divided into two kinds, respectively tungsten trioxide (referred to as tungsten xanthelatine), the molecular formula is WO3, and tungsten oxide blue (referred to as blue tungsten, is a mixed tungsten oxide), the molecular formula W20O58. Xanthine is light yellow crystalline powder, blue tungsten is dark blue or blue black crystalline powder.

Physical and chemical properties of tungsten oxide

Tungsten oxide is a light yellow triclinic powder crystal. When the temperature is higher than 740℃, it turns into orange tetragonal crystal, and then returns to its original state after cooling. Stable in the air, melting point is 1473℃, boiling point is higher than 1750℃, the relative density of 7.16.

Tungsten trioxide is one of the most stable oxides of tungsten, insoluble in water and inorganic acids except hydrofluoric acid, can dissolve in hot concentrated sodium hydroxide solution and ammonia water to produce soluble tungstate. When the temperature is higher than 650℃, it can be reduced by H2, and at 1000 ~ 1100℃ it can be reduced by C to tungsten powder.

Who discovered tungsten discovery

Tungsten has a long history dating back to its discovery during the 18th century. Peter was one of the first to acknowledge a new element in the natural mineral tungsten, originally known as tungsten, explaining the choice of its element symbol as "W". Swedish chemist Karl made the discovery of the mineral scheelite with his research, as well as contribution.

In 1841, a chemist named Robert made the first procedure for preparing tungsten trioxide and sodium tungstate. He was granted a patent for his work shortly after and is considered the founder of systematic tungsten chemistry.

Structure and properties of tungsten oxide

WO3 is a transition metal oxide and an important N-type semiconductor oxide. WO3 crystal is composed of WO6 regular octahedron, in which W atom is in the center of the octahedron and O atom is located in the six corners. According to the tilt Angle and rotation direction of WO6 regular octahedron, many different crystal structures are formed, such as: Cubic phase (ReO3 type), monoclinic phase Ⅰ type (epsilon - WO3), monoclinic phase Ⅱ type (gamma - WO3), three phase (delta - WO3), are in photograph (beta WO3) and four phase (alpha WO3). Among them, gamma-WO3 is the most stable state at room temperature. In addition, hexagonal tungsten oxide (h-WO3) is another stable phase of WO3. It also consists of a WO6 octahedron, but has six-membered and three-membered rings, which share equatorial oxygen in the ab plane. WO3 has a good application in photocatalysis, gas sensors, supercapacitors, electrochromic devices, and the research on lithium ion battery electrode materials is also improving day by day.

Stable crystalline phases of tungsten oxide at different temperatures

In addition, tungsten oxide actually exists in nature, oxygen deficiency phenomenon is common, the atomic ratio of tungsten oxide cannot be in accordance with strict stoichiometric ratio, some exist quintuvalent and quadruvalent, so the molecular formula of tungsten oxide is generally written as WO3-x(x=0 ~ 1). Reduction of WO3 is usually accompanied by structural changes. Non-stoichiometric tungsten oxides mainly include W20O58, W18O49 and W24O68.

Application of tungsten oxide

Tungsten [WO3] Main applied:

1. Part of yellow tungsten oxide is used in the production of chemical products, such as paints and coatings, catalysts for petroleum industry, etc.; But the oxide is a kind of intermediate product, part of which is used in the production of tungsten powder and tungsten carbide powder, and then used in the production of tungsten products, and a large number of applications and production of tungsten alloy products, such as tungsten copper, tungsten nickel, tungsten nickel iron, tungsten silver, tungsten rhenium, tungsten thorium, etc.

2. Yellow tungsten oxide is used for many uses in daily life. Such as industrial X-ray screen phosphors produced by fireproof fabrics and gas sensors, tungstate.

3. Because of its rich yellow color, tungsten oxide is also used as a pigment in ceramics and paints.

4. At present, nano yellow tungsten oxide (VK-WO3 50nm) is more used in lithium battery anode materials, and used in new energy vehicles.

Violet tungsten [WO2.72(or W18O49)] mainly applied:

Purple tungsten oxide (VTO) is also known as tungsten purple oxide (TVO). Purple tungsten oxide is produced in the process of calcining ammonia metatungstate and varies in the amount of purple tungsten oxide produced by different manufacturers. It is not a compound in the chemical sense, but is made up of different components such as arsenic trioxide, tungsten-copper, and low levels of tungsten trioxide. The relative content of these compounds in purple tungsten oxide depends on the calcination parameters.

Purple tungsten oxide is a fine purple powder crystal. It is produced during the production of ammonia paratungstate under precise temperature control. Xiamen Zhongwu Online Technology Co., Ltd. produces two kinds of purple tungsten oxide with standard oxygen content. Purple tungsten oxide is mainly used in the production of metallic tungsten powder and tungsten carbide. Purple tungsten oxide can also be used to make ultrafine tungsten powder and nano tungsten powder.

Blue tungsten [WO2.72, WO2.90, W20O58, and (NH4) x ·WO3, etc.] mainly applied:

1. Materials for gas sensors

2. Solar sensitive film

3. Advanced paints

4: Catalyst

5. X-ray shielding and fireproof fabric