Niobium pentoxide

• Diniobpentoxid
• Niobium oxide ( ambiguous )

White, odorless powder

Fixed

4.55 g · cm -3

1491 ° C ( α - modification)

Practically insoluble in water

Attention

> 10,000 g · kg -1 ( LD50, rat, oral)

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Niobium ( V) oxide is a chemical compound selected from the group of oxides of the element niobium. It is in the form of a non-combustible, white and odorless powder.

Production and representation

Niobium ( V) oxide is formed in the oxidation of niobium in air. In pure form, it can be obtained by hydrolysis of niobium ( V) chloride.

Niobium ( V) oxide can also be obtained in a sol -gel process from niobium ethoxide Nb ( OC2H5 ) 5.

Properties

Niobium ( V) oxide having a monoclinic crystal structure and a refractive index of 2.3 at 500 nm and is in the range of 350-7000 nm transparent. Niobium ( V) oxide, however, can have various modifications, of which the present B form is the most stable below 750 ° C. It crystallizes in the monoclinic platelets and has a structure such as antimony ( V) oxide with a near hexagonal dense oxygen lattice. The linking of the coordination polyhedron corresponds to the rutile type with the space group B2 / b ( a = 1273 pm, b = 556 pm, c = 488 pm, γ = 105 ° 05 '). Above about 750 ° C, the H form is thermodynamically stable.

Use

Niobium ( V) oxide is used in the refractive index of optical glass, such as lenses for cameras and copiers, as well as ophthalmic lenses, to increase. In addition, it is used for the preparation of lithium niobate, calcium -barium- niobate.