Niobium

Niobium, ₄₁Nb
Niobium
Pronunciation	/naɪˈoʊbiəm/ (ny-OH-bee-əm)
Appearance	Gray metallic, bluish when oxidized
Standard atomic weight Ar°(Nb)
	92.90637±0.00001; 92.906±0.001 (abridged);
Niobium in the periodic table
	zirconium ← niobium → molybdenum
Atomic number (Z)	41
Group	group 5
Period	period 5
Block	d-block
Electron configuration	[Kr] 4d4 5s1
Electrons per shell	2, 8, 18, 12, 1
Physical properties
Phase at STP	solid
Melting point	2750 K (2477 °C, 4491 °F)
Boiling point	5017 K (4744 °C, 8571 °F)
Density (at 20° C)	8.582 g/cm3
Heat of fusion	30 kJ/mol
Heat of vaporization	689.9 kJ/mol
Molar heat capacity	24.60 J/(mol·K)
Atomic properties
Oxidation states	common: +5; −3, −1, 0, +1, +2, +3, +4
Electronegativity	Pauling scale: 1.6
Ionization energies	1st: 652.1 kJ/mol ; 2nd: 1380 kJ/mol ; 3rd: 2416 kJ/mol ; ;
Atomic radius	empirical: 146 pm
Covalent radius	164±6 pm
	Spectral lines of niobium
Other properties
Natural occurrence	primordial
Crystal structure	body-centered cubic (bcc) (cI2)
Lattice constant	a = 330.05 pm (at 20 °C)
Thermal expansion	7.07×10−6/K (at 20 °C)
Thermal conductivity	53.7 W/(m⋅K)
Electrical resistivity	152 nΩ⋅m (at 0 °C)
Magnetic ordering	paramagnetic
Young's modulus	105 GPa
Shear modulus	38 GPa
Bulk modulus	170 GPa
Speed of sound thin rod	3480 m/s (at 20 °C)
Poisson ratio	0.40
Mohs hardness	6.0
Vickers hardness	870–1320 MPa
Brinell hardness	735–2450 MPa
CAS Number	7440-03-1
History
Naming	after Niobe in Greek mythology, daughter of Tantalus (tantalum)
Discovery	Charles Hatchett (1801)
First isolation	Christian Wilhelm Blomstrand (1864)
Recognized as a distinct element by	Heinrich Rose (1844)
Isotopes of niobium v; e;
β+	91Zr
	Category: Niobium; view; talk; edit; \| references

Niobium is a chemical element; it has symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium,^[8] and it has similar ductility to iron. Niobium oxidizes in Earth's atmosphere very slowly, hence its application in jewelry as a hypoallergenic alternative to nickel. Niobium is often found in the minerals pyrochlore and columbite. Its name comes from Greek mythology: Niobe, daughter of Tantalus, the namesake of tantalum. The name reflects the great similarity between the two elements in their physical and chemical properties, which makes them difficult to distinguish.^[9]

English chemist Charles Hatchett reported a new element similar to tantalum in 1801 and named it columbium. In 1809, English chemist William Hyde Wollaston wrongly concluded that tantalum and columbium were identical. German chemist Heinrich Rose determined in 1846 that tantalum ores contain a second element, which he named niobium. In 1864 and 1865, a series of scientific findings clarified that niobium and columbium were the same element (as distinguished from tantalum), and for a century both names were used interchangeably. Niobium was officially adopted as the name of the element in 1949, but the name columbium remains in current use in metallurgy in the United States.

It was not until the early 20th century that niobium was first used commercially. Niobium is an important addition to high-strength low-alloy steels. Brazil is the leading producer of niobium and ferroniobium, an alloy of 60–70% niobium with iron. Niobium is used mostly in alloys, the largest part in special steel such as that used in gas pipelines. Although these alloys contain a maximum of 0.1%, the small percentage of niobium enhances the strength of the steel by scavenging carbide and nitride. The temperature stability of niobium-containing superalloys is important for its use in jet and rocket engines.

Niobium is used in various superconducting materials. These alloys, also containing titanium and tin, are widely used in the superconducting magnets of MRI scanners. Other applications of niobium include welding, nuclear industries, electronics, optics, numismatics, and jewelry. In the last two applications, the low toxicity and iridescence produced by anodization are highly desired properties. Niobium is considered a technology-critical element.

^ "Standard Atomic Weights: Niobium". CIAAW. 2017.
^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
^ ^a ^b ^c Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
^ Nb(–3) occurs in Cs₃Nb(CO)_₅; see John E. Ellis (2003). "Metal Carbonyl Anions: from [Fe(CO)₄]₂^- to [Hf(CO)₆]₂^- and Beyond†". Organometallics. 22 (17): 3322–3338. doi:10.1021/om030105l.
^ ^a ^b ^c ^d Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
^ ^a ^b Nb(0) and Nb(I) has been observed in Nb(bpy)₃ and CpNb(CO)₄, respectively; see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (2008). Lehrbuch der Anorganischen Chemie (in German) (102 ed.). Walter de Gruyter. p. 1554. ISBN 9783110206845.
^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.
^ Samsonov, G. V. (1968). "Mechanical Properties of the Elements". In G.V. Samsonov (ed.). Handbook of the Physicochemical Properties of the Elements. New York, US: IFI-Plenum. pp. 387–446. doi:10.1007/978-1-4684-6066-7_7. ISBN 978-1-4684-6066-7. Archived from the original on 2 April 2015.
^ Knapp, Brian (2002). Francium to Polonium. Atlantic Europe Publishing Company, p. 40. ISBN 0717256774.

[1] "Standard Atomic Weights: Niobium". CIAAW. 2017.

[CIAAW2021-2] Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (4 May 2022). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.

[Arblaster_2018-3] Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.

[4] Nb(–3) occurs in Cs₃Nb(CO)_₅; see John E. Ellis (2003). "Metal Carbonyl Anions: from [Fe(CO)₄]₂^- to [Hf(CO)₆]₂^- and Beyond†". Organometallics. 22 (17): 3322–3338. doi:10.1021/om030105l.

[GE28-5] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.

[lehrbuch-6] Nb(0) and Nb(I) has been observed in Nb(bpy)₃ and CpNb(CO)₄, respectively; see Holleman, Arnold F.; Wiberg, Egon; Wiberg, Nils (2008). Lehrbuch der Anorganischen Chemie (in German) (102 ed.). Walter de Gruyter. p. 1554. ISBN 9783110206845.

[NUBASE2020-7] Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3): 030001. doi:10.1088/1674-1137/abddae.

[r1-8] Samsonov, G. V. (1968). "Mechanical Properties of the Elements". In G.V. Samsonov (ed.). Handbook of the Physicochemical Properties of the Elements. New York, US: IFI-Plenum. pp. 387–446. doi:10.1007/978-1-4684-6066-7_7. ISBN 978-1-4684-6066-7. Archived from the original on 2 April 2015.

[9] Knapp, Brian (2002). Francium to Polonium. Atlantic Europe Publishing Company, p. 40. ISBN 0717256774.

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