Nano violet tungsten oxide is a new type of near infrared shielding material with excellent infrared shielding rate, ultraviolet blocking rate and high visible light transmittance. With excellent thermal insulation properties, violet tungsten oxide nanopowder is gradually known to the public. While what the public may not know is --- how violet tungsten oxide is prepared?
The same batch of ammonium paratungstate (APT) was calcined in air to obtain yellow tungsten oxide. Pre-reduction was carried out in different temperatures and hydrogen atmosphere to obtain blue tungsten oxide and violet tungsten oxide of ATB, respectively. The prepared violet tungsten oxide, yellow tungsten oxide and blue tungsten oxide have the following characteristics:
1. Violet tungsten oxide has the smallest BET specific surface area.
2. The polymer of W18O49 is composed of a large number of fine needle-like crystals arranged in disorder, each of which resembles a loose sponge. Fine needle-like crystals are characteristic features inherent in W18O49.
3. X-ray diffraction phase analysis shows that the obtained violet tungsten oxide is monoclinic W18O49; yellow tungsten oxide is triclinic WO3; blue tungsten oxide is hexagonal ATB.
4. The crack on the blue tungsten oxide crystal is more than that of the yellow tungsten oxide.
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