Niobium dioxide

Niobium dioxide

Black powder

Fixed

• 5.98 g · cm -3 ( α-Mod. )
• 5.84 g · cm -3 ( β-Mod. )

1915 ° C

Insoluble in water (at 20 ° C)

2.2-2.4 at 500 nm

Attention

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Niobium ( IV) oxide is a chemical compound selected from the group of oxides of niobium.

Production and representation

Niobium ( IV) oxide can be obtained at 800-1350 ° C. by reaction of niobium ( V) oxide with hydrogen. An alternative method of preparation is the reaction of niobium ( V) oxide with niobium powder at 1100 ° C.

Properties

Niobium ( IV) oxide is a black powder. The imaging methods mentioned above provide the α - niobium ( IV) oxide. Except for a reversible transformation into a high-temperature form is known a very close structural analogues β - modification. The latter is provided with transport means ( such as iodine, niobium (V ) chloride, mercury ( II) chloride ) of niobium (II ) oxide, niobium (IV ) oxide mixtures available. Both crystal structures are derived from the rutile type, but differ in niobium -niobium pairs. The α - modification has the space group I41 / a and the lattice parameters a = 13.681, c = 5.976. The β - modification has the space group I41 with the lattice parameters a = 9.686, c = 5.985 Å. The transmission range of the compound is 350-7000 nm, and the evaporation temperature at 1800-1900 ° C.