Niobium dioxide
| Niobium dioxide | ||
|---|---|---|
 | ||
| IUPAC name niobium(IV) oxide, niobium dioxide | ||
| Other names niobium(IV) oxide, columbium dioxide | ||
| Identifiers | ||
| CAS number | 12034-59-2  | |
| PubChem | 82839 | |
| EC number | 234-809-7 | |
| Jmol-3D images | {{#if:O=[Nb]=O|Image 1 | |
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| Properties | ||
| Molecular formula | NbO2 | |
| Molar mass | 124.91 g/mol | |
| Appearance | bluish black | |
| Melting point | 1915 °C [1] | |
| Structure | ||
| Crystal structure | Tetragonal, tI96 | |
| Space group | I41/a, No. 88 | |
(verify) (what is: / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa) | ||
| 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, 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
- ↑ 1.0 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
- ↑ Pradyot Patnaik (2002), Handbook of Inorganic Chemicals,McGraw-Hill Professional, ISBN 0-07-049439-8
- ↑ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
- ↑ Bolzan, A; Fong, Celesta; Kennedy, Brendan J.; Howard, Christopher J. (1994). "A Powder Neutron Diffraction Study of Semiconducting and Metallic Niobium Dioxide". Journal of Solid State Chemistry 113: 9. Bibcode:1994JSSCh.113....9B. doi:10.1006/jssc.1994.1334.
- ↑ Haines, J.; Léger, J. M.; Pereira, A. S. (1999). "High-pressure structural phase transitions in semiconducting niobium dioxide". Physical Review B 59 (21): 13650. Bibcode:1999PhRvB..5913650H. doi:10.1103/PhysRevB.59.13650.
- ↑ Patent EP1524252, Sintered bodies based on niobium suboxide, Schnitter C, Wötting G
- ↑ 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.)
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