Niobium (Nb)

Niobium is a chemical element with atomic number 41 in the periodic table. It’s the most plentiful metal found in Earth’s crust. Being a member of the transition metals family of periodic table elements, this superconductor can have 2, 3, or 5 electrons in the outermost valence shell that play a part in the chemical bonds of niobium with the other elements.

Named after the Greek goddess of tears, niobium is classified as one of the five major refractory metals. Element 41 also displays paramagnetic properties and superconductivity in the presence of strong electric currents and magnetic fields. 

Chemical and Physical Properties of Niobium

Property	Value
The symbol in the periodic table of elements	Nb
Atomic number	41
Atomic weight (mass)	92.91 g.mol-1
Group number	(Transition metals)
Period	5 (d-block)
Color	Lustrous white; also commonly found in blue, green, and yellow
Physical state	Solid metal at room temperature
Half-life	From less than 44 nanoseconds to 20.300 years
Electronegativity according to Pauling	Unknown
Density	8.4 g.cm-3 at 20°C
Melting point	2477°C, 4491°F, 2750K
Boiling point	4741°C, 8566°F, 5014K
Van der Waals radius	0.143 nm
Ionic radius	0.070 nm (+5) ; 0.069 nm (+4)
Isotopes	36
Most characteristic isotope	Niobium-93
Electronic shell	[Kr]4d45s1
The energy of the first ionization	652 kJ.mol-1
The energy of the second ionization	N/A
Discovery date	In 1801 by Charles Hatchett

With the periodic table symbol Nb, atomic number 41, atomic mass of 92.91 g.mol-1, and electron configuration [Kr]4d45s1, niobium is soft and ductile paramagnetic metal. It reaches its boiling point at 4741°C, 8566°F, 5014K, while the melting point is achieved at 2477°C, 4491°F, 2750K. Despite the high melting point, niobium has a lower density than the other refractory metals. Niobium’s atomic radius according to van der Waals is 0.143 nm, while its electronegativity according to Pauling is unknown.

Element 41 has a cubic crystalline body-centered structure and 2, 3, or 5 valence electrons. At extremely low (cryogenic) temperatures, this transition metal adopts superconducting properties in the presence of strong electric currents and magnetic fields. Being corrosion-resistant, niobium metal starts to develop the protective oxide film at a temperature of 200oC. The thickness of its oxide layer determines the color of the metal niobium, which can vary from white to blue, yellow, and green.

How Was Niobium Discovered?

The English mineralogist and analytical chemist Charles Hatchett (1765 – 1847) had performed numerous analytical researches on many types of minerals and ores in his private laboratory. By examining the mineral samples exposed in the British Museum, Hatchett’s interest was caught by a particular sample for which he believed contains a new, undiscovered substance.  

More than a century before Hatchett’s revolutionary chemical trial, the mineral sample that was an object of scientific interest to the English chemist was taken from a type of American ore and sent to England by John Winthrop the Younger. At the time, Winthorp was the first governor of Connecticut, United States. Originating from North America, the mineral sample was labeled columbite, in honor of the American continent discoverer, Cristopher Columbus. 

That special day in 1801, Hatchet was analysing the aforementioned mineral sample obtained from the British Museum. This English chemist attempted an experiment in which he heated a mineral sample with potassium carbonate. After that, he dissolved the resulting product in water, added acid to it which led to a precipitation. 

The outcome of Hatchett’s experiment discovered a new chemical element which was classified under the atomic number 41. Charles Hatchett named the new element columbium, as assigned the symbol Cb to the substance he discovered.

In 1864, Swedish scientist Christian Blomstrand succeeded in isolating the metal niobium by reduction of chloride exposed to heat in a hydrogen atmosphere.

How Did Niobium Get Its Name?

Almost half a century after Charles Hatchett discovered columbium, the German chemist Heinrich Rose managed to independently prove that the columbium contains not one, but two new substances that were extremely hard to tell apart – tantalum and niobium. 

Rose’s name choice of the new substance came from the fact that it shares many chemical and physical properties with tantalum, the element classified right above the niobium in the periodic table. This was also the reason why it was so difficult for the scientists to distinguish these two elements. 

The mythical side of this story relates the name niobium to the Greek goddess of tears, Niobe. Namely, she was the daughter of Tantalus – the son of Zeus and the nymph Plouto in the Greek mythology, to whom all things were elusive and ‘tantalising’. 

In this way, Heinrich Rose wanted to symbolically mark the scientifically proven similarities between the two new elements – niobium and tantalum. 

The International Union of Pure and Applied Chemistry (IUPAC) officially approved the name niobium in 1950.

Where Can You Find Niobium?

Niobium is mainly mined from pyrochlore deposits, after which it’s transformed into the niobium pentoxide Nb2O5. For commercial purposes, this chemical element is typically obtained from the mineral columbite as the main source. 

The locations rich in niobium mineral ores can be found worldwide. However, the most active niobium ore mines are located in:

• Brazil, where two of the largest producers of niobium mineral concentrates are found;
• La Vallée-du-Richelieu RCM, Montérégie, Québec, Canada; 
• Mayen-Koblenz District, Rhineland-Palatinate, Germany;
• Ilímaussaq complex, Kujalleq, Greenland;
• Several mining locations in Nigeria;
• Karnasurt Mountain, Lovozersky District, Murmansk Oblast, Russia;
• Bayan Obo mining district, Baotou City (Baotou Prefecture), Inner Mongolia, China.

Niobium in Everyday Life

Niobium is most commonly used in alloys which are further applied in:

• The construction of pipelines due to the hardness and resistance of the niobium alloys;
• In stainless steel alloys and other nonferrous metals used in the welding, nuclear industries, electronics, optics, and numismatics, niobium increases the corrosion resistance of the metals;
• At low temperatures, niobium becomes superconductor and is used in infrared light detectors;
• Along with vanadium and technetium, niobium-germanium (Nb3Ge), niobium-tin (Nb3Sn) and niobium-titanium alloys are used as type II superconductor wire for superconducting magnets for particle accelerators;
• When alloyed with zirconium, niobium is used in claddings for nuclear reactor cores;
• In superalloys applied in the production of superconducting magnets of magnetic resonance scanners; for manufacturing of jet engine components, gas turbines, rocket subassemblies, etc.
• Niobium has a popular application as an alloying agent and for making of jewelry, pacemakers, prosthetics, and medical implants;
• About 90% of world’s niobium quantities are invested in ferroniobium production which is further used in the automotive industry;
• Large quantities of this metal are also used in the steel industry for making high-strength low-alloy steels.

How Dangerous Is Niobium?

While the elemental form of niobium is non-toxic, the niobium compounds are considered to be highly toxic. Upon inhalation, the niobium particles are mainly absorbed in the lungs and bones which may lead to adverse health effects.

Environmental Effects of Niobium

There are no known negative environmental effects caused by the chemical element niobium.

Isotopes of Niobium

There are a total of 34 forms of niobium isolated from various minerals. Among them, 26 are radioactive isotopes of element 41. The stable isotope niobium-93 makes up the naturally occurring elemental form of niobium. 

Having a half-life of 34.7 million years, niobium-92 is the most stable radioisotope of this element among its radioactive forms. Apart from the isotopes 95Nb (35 days), 96Nb (23.4 hours) and 90Nb (14.6 hours), all the other radioisotopes have a half-life of less than two hours. 

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4]	Decay mode [n 5]	Daughter isotope [n 6][n 7]	Spin and parity [n 8][n 4]	Natural abundance (mole fraction)
	Excitation energy[n 4]							Normal proportion	Range of variation
81Nb	41	40	80.94903(161)#	<44 ns	β+, p	80Y	3/2−#
					p	80Zr
					β+	81Zr
82Nb	41	41	81.94313(32)#	51(5) ms	β+	82Zr	0+
83Nb	41	42	82.93671(34)	4.1(3) s	β+	83Zr	(5/2+)
84Nb	41	43	83.93357(32)#	9.8(9) s	β+ (>99.9%)	84Zr	3+
					β+, p (<.1%)	83Y
85Nb	41	44	84.92791(24)	20.9(7) s	β+	85Zr	(9/2+)
86Nb	41	45	85.92504(9)	88(1) s	β+	86Zr	(6+)
87Nb	41	46	86.92036(7)	3.75(9) min	β+	87Zr	(1/2−)
88Nb	41	47	87.91833(11)	14.55(6) min	β+	88Zr	(8+)
89Nb	41	48	88.913418(29)	2.03(7) h	β+	89Zr	(9/2+)
90Nb	41	49	89.911265(5)	14.60(5) h	β+	90Zr	8+
91Nb	41	50	90.906996(4)	680(130) a	EC (99.98%)	91Zr	9/2+
					β+ (.013%)	91Zr
92Nb	41	51	91.907194(3)	3.47(24)×107 a	β+ (99.95%)	92Zr	(7)+
					β− (.05%)	92Mo
93Nb	41	52	92.9063781(26)	Stable			9/2+	1.0000
94Nb	41	53	93.9072839(26)	2.03(16)×104 a	β−	94Mo	(6)+
95Nb	41	54	94.9068358(21)	34.991(6) d	β−	95Mo	9/2+
96Nb	41	55	95.908101(4)	23.35(5) h	β−	96Mo	6+
97Nb	41	56	96.9080986(27)	72.1(7) min	β−	97Mo	9/2+
98Nb	41	57	97.910328(6)	2.86(6) s	β−	98Mo	1+
99Nb	41	58	98.911618(14)	15.0(2) s	β−	99Mo	9/2+
100Nb	41	59	99.914182(28)	1.5(2) s	β−	100Mo	1+
101Nb	41	60	100.915252(20)	7.1(3) s	β−	101Mo	(5/2#)+
102Nb	41	61	101.91804(4)	1.3(2) s	β−	102Mo	1+
103Nb	41	62	102.91914(7)	1.5(2) s	β−	103Mo	(5/2+)
104Nb	41	63	103.92246(11)	4.9(3) s	β− (99.94%)	104Mo	(1+)
					β−, n (.06%)	103Mo
105Nb	41	64	104.92394(11)	2.95(6) s	β− (98.3%)	105Mo	(5/2+)#
					β−, n (1.7%)	104Mo
106Nb	41	65	105.92797(21)#	920(40) ms	β− (95.5%)	106Mo	2+#
					β−, n (4.5%)	105Mo
107Nb	41	66	106.93031(43)#	300(9) ms	β− (94%)	107Mo	5/2+#
					β−, n (6%)	106Mo
108Nb	41	67	107.93484(32)#	0.193(17) s	β− (93.8%)	108Mo	(2+)
					β−, n (6.2%)	107Mo
109Nb	41	68	108.93763(54)#	190(30) ms	β− (69%)	109Mo	5/2+#
					β−, n (69%)	108Mo
110Nb	41	69	109.94244(54)#	170(20) ms	β− (60%)	110Mo	2+#
					β−, n (40%)	109Mo
111Nb	41	70	110.94565(54)#	80# ms [>300 ns]			5/2+#
112Nb	41	71	111.95083(75)#	60# ms [>300 ns]			2+#
113Nb	41	72	112.95470(86)#	30# ms [>300 ns]			5/2+#
114Nb[2]	41	73
115Nb[2]	41	74
117Nb[3]	41	76

Source: Wikipedia

List of Niobium Compounds

The assumed oxidation states of niobium in a compound are +3 and +5. This transition metal is highly reactive with carbon, oxygen, sulfur, nitrogen and halogens. For this reason, the planned chemical reactions that include this element must be performed in a strictly controlled environment. 

At high temperatures, niobium reacts with most non-metals. It reacts at room temperature with fluorine; at 150 °C with chlorine, at 200 °C with chlorine; and at 400 °C with chlorine. 

The list of the most common niobium compounds includes:

• Lead magnesium niobate
• Diniobium pentaoxide
• Niobium bromide
• Niobium carbide
• Niobium chloride
• Niobium dioxide
• Niobium diselenide
• Niobium disulfide
• Niobium fluoride
• Niobium oxide
• Niobium monoxide
• Niobium nitride
• Niobium oxychloride
• Niobium pentaiodide
• Niobium pentoxide
• Niobium triselenide
• Niobium–tin
• Niobium–titanium
• Niobium(III) chloride
• Niobocene dichloride
• Niobium(IV) chloride
• Niobium(IV) fluoride
• Niobium(V) bromide
• Niobium(V) chloride
• Niobium(V) ethoxide
• Niobium(V) fluoride

The most widespread minerals from which niobium can be obtained are contained in the following list:

• Achalaite
• Aeschynite-(Y)
• Alsakharovite-Zn
• Aspedamite
• Betafite
• Billwiseite
• Carbokentbrooksite
• Charleshatchettite
• Coltan
• Coltan mining and ethics
• Columbite
• Ekplexite
• Euxenite
• Feklichevite
• Fergusonite
• Ferrokentbrooksite
• Georgbarsanovite
• Golyshevite
• Kentbrooksite
• Nenadkevichite
• Nioboholtite
• Oneillite
• Oxyyttropyrochlore-(Y)
• Peterandresenite
• Polycrase
• Pyrochlore
• Rynersonite
• Samarskite-(Y)
• Schiavinatoite
• Simpsonite
• Tantalite
• Tapiolite
• Taseqite
• Zimbabweite
• Zircophyllite
• Zirkelite
• Zirsilite-(Ce)

5 Interesting Facts and Explanations

1. The chemical elements niobium and tantalum are difficult to be distinguished because they share very similar chemical properties. 
2. The pure, elemental form of metallic niobium is very soft and ductile. Any presence of impurities adds to its hardness.  
3. In 1797, Charles Hatchett became a Fellow of the Royal Society as a distinguished chemist and discoverer of niobium. 
4. Along with tungsten, molybdenum, tantalum and rhenium, niobium is one of the five major refractory metals, i.e. metals that display very high resistance to both heat and wear. 
5. Ferroniobium is used in the automotive industry in order to lower the weight of vehicles.