What Are the Characteristics of Tungsten Dioxide?

Tungsten dioxide (WO₂), also known as brown tungsten oxide, is an inorganic compound composed of tungsten and oxygen. It mainly has the following characteristics:

I. Appearance and Color: Tungsten dioxide is brownish-yellow in powder form, with a monoclinic crystal structure. Its rutile structure exhibits distorted WO6 octahedral centers.

II. Density: It has a density of approximately 10.9~11g/cm³, indicating a high specific gravity.

III. Melting Point and Boiling Point: The melting point is around 1600°C, and the boiling point is around 1730°C.

IV. Conductivity: Tungsten dioxide exhibits good electrical conductivity, with an electronic conductivity of approximately 3.5×10² S/cm.

V. Solubility: Tungsten dioxide is insoluble in water, alkaline solutions, hydrochloric acid, and diluted sulfuric acid but is soluble in concentrated sulfuric acid, forming a red salt.

VI. Instability: Tungsten dioxide undergoes disproportionation reactions easily in inert gases, producing both metallic tungsten and higher-valent tungsten oxides such as tungsten trioxide, blue tungsten oxide, and purple tungsten oxide. In air, tungsten dioxide is rapidly oxidized to tungsten trioxide.

VII. Reactivity:

Reaction with oxidants: Reacts with concentrated nitric acid to form higher-valent tungsten oxides; reacts with nitrogen oxides at 500°C to produce blue tungsten oxide; reacts with iodine to produce volatile WO2I2.

Reaction with reductants: Easily reduced to metallic tungsten by carbon at 1020°C; also reduced to tungsten powder by hydrogen at temperatures between 700~900°C.

VIII. Application Fields:

Tungsten Powder Production: Tungsten dioxide is an important raw material for producing tungsten powder, which is crucial for the manufacture of tungsten carbide powder, high-density tungsten alloys, and tungsten materials.

Electronic Components: Due to its good electrical conductivity and stability at high temperatures, tungsten dioxide is a key raw material for the production of electronic tubes, resistors, capacitors, thermocouples, and semiconductors.

Energy Storage: Tungsten dioxide can be used as an additive in lithium-ion battery anode materials, effectively addressing the large volume changes of tungsten trioxide anode materials during cycling.

Chemical Catalysis: With good oxidation, reduction, acidity, and alkalinity properties, tungsten dioxide is an important component of catalysts, catalyzing various chemical reactions under different conditions.

Building Materials: Tungsten dioxide can be used as an additive in building materials to improve cement performance and enhance the strength and durability of concrete.

Additionally, tungsten dioxide has potential applications in the glass, ceramics, coatings, cosmetics, and other industries, demonstrating its versatility.

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