Names | |
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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 | |
3D model (
JSmol)
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ECHA InfoCard | 100.031.632 |
EC Number |
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PubChem
CID
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CompTox Dashboard (
EPA)
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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 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 reducing 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 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]