Niobium dioxide

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Niobium dioxide
Names
IUPAC name
niobium(IV) oxide, niobium dioxide
Other names
niobium(IV) oxide, columbium dioxide
Identifiers
3D model (
JSmol
)
ECHA InfoCard
100.031.632 Edit this at Wikidata
EC Number
  • 234-809-7
  • InChI=1S/Nb.2O
  • O=[Nb]=O
Properties
NbO2
Molar mass 124.91 g/mol
Appearance bluish black solid
Melting point 1,915 °C (3,479 °F; 2,188 K)[1]
Structure
Tetragonal, tI96
I41/a, No. 88
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Niobium dioxide, is the

non-stoichiometric solid with a composition range of NbO1.94-NbO2.09.[1] It can be prepared by reducing Nb2O5 with H2 at 800–1350 °C.[1] An alternative method is reaction of Nb2O5 with Nb powder at 1100 °C.[2]

Properties

The room temperature form of NbO2 has a tetragonal, rutile-like structure with short Nb-Nb distances, indicating Nb-Nb bonding.[3] The high temperature form also has a rutile-like structure with short Nb-Nb distances.[4] Two high-pressure phases have been reported: one with a rutile-like structure (again, with short Nb-Nb distances); and a higher pressure with baddeleyite-related structure.[5]

NbO2 is insoluble in water and is a powerful reducing agent, reducing carbon dioxide to carbon and sulfur dioxide to sulfur.[1] In an industrial process for the production of niobium metal, NbO2 is produced as an intermediate, by the hydrogen reduction of Nb2O5.[6] The NbO2 is subsequently reacted with magnesium vapor to produce niobium metal.[7]

References

  1. ^
  2. .
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  4. ^ Patent EP1524252, Sintered bodies based on niobium suboxide, Schnitter C, Wötting G
  5. ^ Method for producing tantalum/niobium metal powders by the reduction of their oxides by gaseous magnesium, US patent 6171363 (2001), Shekhter L.N., Tripp T.B., Lanin L.L. (H. C. Starck, Inc.)