niobium(IV) oxide, niobium dioxide
niobium(IV) oxide, columbium dioxide
|Jmol 3D model||Interactive image|
|Molar mass||124.91 g/mol|
|Melting point||1,915 °C (3,479 °F; 2,188 K)|
|I41/a, No. 88|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
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 , 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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