Chemistry:Niobium dioxide
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| 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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PubChem CID
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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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| 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 reducing Nb2O5 with H2 at 800–1350 °C.[1] An alternative method is reaction of Nb2O5 with Nb powder at 1100 °C.[2]
Properties
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]
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 (1): 9–14. doi:10.1006/jssc.1994.1334. Bibcode: 1994JSSCh.113....9B.
- ↑ Haines, J.; Léger, J. M.; Pereira, A. S. (1999). "High-pressure structural phase transitions in semiconducting niobium dioxide". Physical Review B 59 (21): 13650. doi:10.1103/PhysRevB.59.13650. Bibcode: 1999PhRvB..5913650H.
- ↑ Patent EP1524252, Sintered bodies based on niobium suboxide, Schnitter C, Wötting G
- ↑ Method for producing tantalum/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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