Utente:Grasso Luigi/sanbox1/Biossido di niobio
| Biossido di niobio | |
|---|---|
 | |
  | |
| Nome IUPAC | |
| Ossido di niobio(IV), biossido di niobio [1][2] | |
| Nomi alternativi | |
| Diossiniobio | |
| Caratteristiche generali | |
| Formula bruta o molecolare | NbO2 |
| Massa molecolare (u) | 124.91 [3] |
| Aspetto | bluish black |
| Numero CAS | Immagine_3D |
| Numero EINECS | 234-809-7 |
| PubChem | 82839 |
| SMILES | O=[Nb]=O |
| Proprietà chimico-fisiche | |
| Temperatura di fusione | 1915 °C [4] |
| Indicazioni di sicurezza | |
| Simboli di rischio chimico | |
| |
| attenzione | |
| Frasi H | 315 - 319 - 335 - 413 |
| Consigli P | 261 - 264 - 271 - 273 - 280 - 302+352 - 304+340 - 305+351+338 - 312 - 321 - 332+313 - 337+313 - 362 - 403+233 |
Il diossido di niobio, è un composto chimico con formula NbO2. È un solido nero bluastro non-stechiometrico con una gamma di composizione di NbO1.94-NbO2.09[4] Si prepara facendo reagire Nb2O5 con H2 a 800–1350 °C.[4] Un metodo alternativo è la reazione di Nb2O5 con polvere di Nb a 1100 °C.[5]
Struttura[modifica | modifica wikitesto]
CrystalStruct = Tetragonal, tI96SpaceGroup = I41/a, No. 88
The room temperature form NbO2 has a tetragonal, rutile-like structure with short Nb-Nb distances indicating Nb-Nb bonding.[6] High temp form also has a rutile-like structure with short Nb-Nb distances.[7]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.[8]
Reazioni chimiche[modifica | modifica wikitesto]
NbO2 is insoluble in water and is a powerful reducing agent, reducing carbon dioxide to carbon and sulfur dioxide to sulfur.[4] In an industrial process for the production of niobium metal [1], NbO2 is produced as an intermediate, by the hydrogen reduction of Nb2O5.[9] The NbO2 is subsequently reacted with magnesium vapour to produce niobium metal.[10]
Note[modifica | modifica wikitesto]
- ^ Nomenclature of Inorganic Chemistry : IUPAC Recommendations 2005 (Red Book), Cambridge, The Royal Society of Chemistry, 2005, ISBN 978-0-85404-438-2.
- ^ (EN) PubChem Compound, CID 82839 - Compound Summary, su pubchem.ncbi.nlm.nih.gov, National Center for Biotechnology Information. URL consultato il 17 Gennaio 2019.
- ^ (EN) IUPAC Commission on Isotopic Abundances and Atomic Weights., Atomic weights of the elements 2017, su Queen Mary University of London.
- ^ a b c d 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, A Powder Neutron Diffraction Study of Semiconducting and Metallic Niobium Dioxide, in Journal of Solid State Chemistry, vol. 113, 1994, p. 9, DOI:10.1006/jssc.1994.1334.
- ^ High-pressure structural phase transitions in semiconducting niobium dioxide, in Physical Review B, vol. 59, n. 21, 1999, p. 13650, 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.)
Altri progetti[modifica | modifica wikitesto]
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