Niobium(IV) oxide
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IUPAC name
niobium(IV) oxide, niobium dioxide
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| Other names
niobium(IV) oxide, columbium dioxide
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| Identifiers | |
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3D model (JSmol)
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| ECHA InfoCard | 100.031.632 |
| EC Number | 234-809-7 |
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PubChem CID
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| Properties | |
| NbO2 | |
| Molar mass | 124.91 g/mol |
| Appearance | bluish black |
| Melting point | 1,915 °C (3,479 °F; 2,188 K) |
| Structure | |
| Tetragonal, tI96 | |
| I41/a, No. 88 | |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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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 It can be prepared by reacting Nb2O5 with H2 at 800–1350 °C. An alternative method is reaction of Nb2O5 with Nb powder at 1100 °C.
The room temperature form NbO2 has a tetragonal, rutile-like structure with short Nb-Nb distances indicating Nb-Nb bonding. High temp form also has a rutile-like structure with short Nb-Nb distances. 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.
NbO2 is insoluble in water and is a powerful reducing agent, reducing carbon dioxide to carbon and sulfur dioxide to sulfur. In an industrial process for the production of niobium metal [1], NbO2 is produced as an intermediate, by the hydrogen reduction of Nb2O5. The NbO2 is subsequently reacted with magnesium vapour to produce niobium metal.
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