Blue Tungsten Oxide (BTO, commonly referring to WO3-x) is a non-stoichiometric tungsten oxide with the following characteristics:
I. Color and Appearance
It appears as blue or dark blue powdered crystals, with the shade of blue correlated with the concentration of oxygen vacancies.
II. Oxygen Vacancies
Its chemical formula is WO3-x, where 0 < x < 1, and the oxygen vacancies contribute to its non-stoichiometric properties.
III. Density
The measured density of blue tungsten oxide is approximately 7.15g/cm3.
IV. Particle Size
It typically exists at the nanoscale, resulting in a large specific surface area.
V. Melting Point/Thermal Stability
Blue tungsten oxide has a melting point of approximately 1473°C, indicating its stability in high-temperature environments.
VI. Solubility
Blue tungsten oxide is virtually insoluble in water and most acids but soluble in sodium hydroxide solutions.
VII. Redox Properties
In addition to sharing the oxidative and catalytic properties of tungsten trioxide (WO3), it also exhibits reductive properties not possessed by WO3.
VIII. Chemical Stability
Its chemical stability is relatively poor, prone to redox reactions in the presence of oxidants or reductants.
IX. Catalytic Performance
It exhibits good catalytic activity in redox reactions and is commonly used in electrocatalysis and photocatalysis.
X. Electrical Properties
Oxygen vacancies impart good electrical conductivity and semiconductor characteristics, with a higher conductivity than stoichiometric WO?.
XI. Optical Properties
It strongly absorbs visible and near-infrared light, making it suitable for optoelectronic applications.
XII. Electrochromism and Photochromism
Blue tungsten oxide can change its color in response to external electric fields or light conditions, making it ideal as a color-changing material for smart windows. Additionally, this color-changing effect enhances the anti-aging ability and thermal insulation of film products.
XIII. Application Fields
Industrial Raw Material: It is an important raw material for preparing tungsten oxide, tungsten metal powder, tungsten carbide powder, and tungstates, widely used in metallurgy, chemicals, electronics, and other fields.
Optoelectronic Material: With unique optical properties such as significant absorption and emission characteristics, it is an ideal choice for optoelectronic conversion materials, enhancing the efficiency and stability of photoelectric conversion in devices like solar cells.
Gas-Sensitive Material: It has gas sensitivity and can be used to detect toxic gases such as nitrogen dioxide and ammonia, leading to the development of tungsten oxide thin-film gas sensors and tungsten oxide nanoparticle sensors.
Smart Window Material: Due to its electrochromic and photochromic properties, it can be used as a color-changing material for smart windows.
These characteristics make blue tungsten oxide a versatile material with wide-ranging applications.
