Blue tungsten oxide (BTO), also known as tungsten blue oxide (TBO) or β-tungsten oxide, is a compound of tungsten and oxygen.
The measured density of BTO is 7.15g/cm3, the density measured by X-ray is 7.16g/cm3, and the range of homogeneous phase is WO2.8975~2.9014 (1000°C). Its formula is WO3-x.
BTO’s composition is very complex, which may also exist WO2, WO3 and ammonium salts. Its most common form is WO2.9.
BTO is manufactured by calcination of APT under more or less reducing conditions. It consists of various different constituents, like trioxide, tungsten bronzes and different lower tungsten oxides. The relative amount of these compounds in TBO depends on the calcination parameters.
How to prepare BTO?
1. Moist tungsten oxide is exposed to ultraviolet light.
2. White gelatinous tungsten acid is exposed to indirect sunlight.
3. The suspensoid of tungsten oxide in hydrochloric acid by zinc reduction.
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