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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 |
| Hazards | |
| GHS labelling:[4] | |
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| Warning | |
| H315,H319,H335 | |
| P261,P264,P264+P265,P271,P280,P302+P352,P304+P340,P305+P351+P338,P319,P321,P332+P317,P337+P317,P362+P364,P403+P233,P405,P501 | |
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 unusualcubic structure, similar to the rock salt structure but with some missing atoms compared to it, so that both niobium and oxygen atoms havesquare planar coordination geometries. The niobium centers are arranged inoctahedra, and there is a structural similarity to the octahedral niobium clusters in lower halides of niobium. In NbO the Nb–Nbbond length is 298 pm which compares to 285 pm in the metal.[2] One study of the bonding concludes that strong and nearlycovalent bonds exist between the metal centers.[5]
It is asuperconductor with a transition temperature of 1.38 K.[6] It is used incapacitors where a layer ofNb2O5 is formed around NbO grains as thedielectric.[7][8][9]
NbO can be prepared by reduction ofNb2O5 byhydrogen. More typically, it is prepared bycomproportionation:[10]
