Boron oxide is an inorganic substance, chemical formula B2O3, also known as boron trioxide, is the most important oxide of boron. It is a white waxy solid that generally exists in an amorphous state and is difficult to form crystals, but can also crystallize after high strength annealing. It is one of the most difficult substances known to crystallize. When molten, many basic metal oxides can be dissolved to produce glassy borates and metaborate (glass) with characteristic colors, which are used to produce elemental boron and fine boron compounds. It can also be combined with a variety of oxides to make boron glass, optical glass, heat-resistant glass, instrument glass and glass fiber, light protection materials and so on. It can also be used as a refractory inhibitor additive and desiccant for paint.

Physical properties:
Properties: Colorless glassy crystal or powder.
Density (g/mL, 25/4℃) : 1.812 (amorphous), 2.46 (crystalline)
Melting point (oC) :,450℃ (crystallization)
Boiling point (oC, atmospheric pressure) : 1860
Solubility: dissolves in water and becomes boric acid. Soluble in acid and alkali solution.

Chemical properties:
Alkali metals as well as magnesium and aluminum can be reduced to boron. When heated to 600 ℃, it can become a very viscous liquid. It can absorb water strongly in the air and form boric acid. It can be combined with a number of metal oxides to form a characteristic color of boron glass, which can be completely miscible with alkali metals, copper, silver, aluminum, arsenic, antimony and bismuth oxides.
Boron trioxide obtained from crystalline boric acid is a white, porous, slightly fused substance. It is easily crushed, but the water vapor in the atmosphere must be removed during operation. The boron trioxide is highly reactive and emits heat and sizzle when in contact with water vapor.

Save:
Keep the storage device sealed, stored in a cool, dry place, ensure that the work room has good ventilation or exhaust device, away from fire, heat sources. Should be stored separately from acids, do not mix.