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| Names | |
|---|---|
| Other names niobium(II) oxide | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
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| ECHA InfoCard | 100.031.631 |
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| Properties | |
| NbO | |
| Molar mass | 108.905 g/mol[1] |
| Appearance | grey solid[1] |
| Odor | odorless |
| Density | 7.30 g/cm3[1] |
| Melting point | 1,937 °C (3,519 °F; 2,210 K)[1] |
| Solubility | slightly soluble inHCl insoluble innitric acid |
| Structure[2] | |
| Cubic,cP6 | |
| Pm3m, No. 221 | |
a = 0.4211 nm | |
Formula units (Z) | 3 |
| Thermochemistry[3] | |
| 41.3 J/(mol·K) | |
Std molar entropy(S⦵298) | 48.1 J/(mol·K) |
Std enthalpy of formation(ΔfH⦵298) | −405.85 kJ/mol |
Gibbs free energy(ΔfG⦵) | −378.6 kJ/mol |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Niobium monoxide is theinorganic compound with theformulaNbO. It is a grey solid with metallic conductivity.[1]
NbO adopts an unusual cubic structure, similar to the rock salt structure but with some missing atoms compared to it, so that both niobium and oxygen atoms have square planar coordination geometries. The niobium centers are arranged in octahedra, and there is a structural similarity to the octahedral niobium clusters in lower halides of niobium. In NbO the Nb–Nb bond length is 298 pm which compares to 285 pm in the metal.[2] One study of the bonding concludes that strong and nearly covalent bonds exist between the metal centers.[4]
It is a superconductor with a transition temperature of 1.38 K.[5] It is used in capacitors where a layer ofNb2O5 is formed around NbO grains as the dielectric.[6][7][8]
NbO can be prepared by reduction ofNb2O5 by H2. More typically, it is prepared bycomproportionation:[9]
