Niobium monoxide

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Niobium monoxide
Other names
niobium(II) oxide, columbium monoxide
3D model (JSmol)
ECHA InfoCard 100.031.631
Molar mass 108.906 g/mol
Appearance grey solid
Odor odorless
Density 7.30 gcm3
Melting point 1,940 °C (3,520 °F; 2,210 K)
Solubility slightly soluble in HCl
insoluble in nitric acid
41.25 J/mol K
-405.85 kJ/mol
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 monoxide is the inorganic compound with the formula NbO. It is a grey solid with metallic conductivity.[1]

Structure and electronic properties[edit]

It adopts an unusual structure, being cubic as is rock salt structure, but where both niobium and oxygen atoms are four coordinate square planar.[1] The niobium centers are arranged in octahedra, and there is a structural similarity to the octahedral niobium clusters in lower halides of niobium.[1] In NbO the Nb-Nb bond length is 298 pm which compares to 285 pm in the metal.[1] One study of the bonding concludes that strong and nearly covalent bonds exist between the metal centers.[2]

It is a superconductor at 1.38 K.[3] It is used in capacitors where a layer of Nb2O5 is formed around NbO grains as the dielectric.[4][5][6]


NbO can be prepared by reduction of Nb2O5 by H2[1] More typically, it is prepared by comproportionation:[7]

Nb2O5 + 3 Nb → 5 NbO


  1. ^ a b c d e Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  2. ^ Electronic band structure and bonding in Nb3O3, Physical Review B (Condensed Matter), 48, 23, 1993, 16986-16991 doi:10.1103/PhysRevB.48.16986
  3. ^ Superconductivity In the TiO and NbO systems, Hulm, J. K.; Jones, C. K.; Hein, R. A.; Gibson, J. W., Journal of Low Temperature Physics, 7, 3-4, 291-307, doi:10.1007/BF00660068
  4. ^ C. Nico et al. Sintered NbO powders for electronic device applications The Journal of Physical Chemistry C 2011, Volume 115(11), Pages: 4879–4886 doi:10.1021/jp110672u
  5. ^ C. Nico et al. NbO/Nb2O5 core–shells by thermal oxidation Journal of the European Ceramic Society 2013, Volume 33(15-16), Pages: 3077–3083 doi:10.1016/j.jeurceramsoc.2013.06.020
  6. ^ Kazumi Naito, Isao Kabe,(Showa Denko K.K.) Production method of solid electrolytic capacitor US patent 6882522(2005)
  7. ^ T. B. Reed, E. R. Pollard "Niobium Monoxide" Inorg. Synth. 1995, vol. 30, pp. 108–110. doi:10.1002/9780470132616.ch22