Niobium dioxide

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Niobium dioxide
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Names
IUPAC name
niobium(IV) oxide, niobium dioxide
Other names
niobium(IV) oxide, columbium dioxide
Identifiers
12034-59-2 YesY
EC Number 234-809-7
Jmol 3D model Interactive image
PubChem 82839
  • InChI=1S/Nb.2O
  • O=[Nb]=O
Properties
NbO2
Molar mass 124.91 g/mol
Appearance bluish black
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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Infobox references

Niobium dioxide, is the chemical compound with the formula NbO2. It is a bluish black non-stoichiometric solid with a composition range of NbO1.94-NbO2.09[1] It can be prepared by reacting Nb2O5 with H2 at 800–1350 °C.[1] An alternative method is reaction of Nb2O5 with Nb powder at 1100 °C.[2]

The room temperature form NbO2 has a tetragonal, rutile-like structure with short Nb-Nb distances indicating Nb-Nb bonding.[3] High temp 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[1], NbO2 is produced as an intermediate, by the hydrogen reduction of Nb2O5.[6] The NbO2 is subsequently reacted with magnesium vapour to produce niobium metal.[7]

References

  1. 1.0 1.1 1.2 1.3 C. K. Gupta, A. K. Suri, S Gupta, K Gupta (1994), Extractive Metallurgy of Niobium, CRC Press, ISBN 0-8493-6071-4
  2. Pradyot Patnaik (2002), Handbook of Inorganic Chemicals,McGraw-Hill Professional, ISBN 0-07-049439-8
  3. Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
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  6. Patent EP1524252, Sintered bodies based on niobium suboxide, Schnitter C, Wötting G
  7. Method for producing tantallum/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.)