Niobium

Niobium
General Info
Atomic Symbol	Atomic symbol::Nb
Atomic Number	Atomic number::41
Atomic Weight	Atomic weight::92.9064 g/mol
Chemical series	Transition metal
Appearance
Group, Period, Block	5, 5, d
Electron configuration	[Kr] 5s1 4d4
Electrons per shell	2,8,18,12,1
CAS number	CAS number::7440-03-1
Physical properties
Phase
Density	Density::8.4 g/ml
Melting point	Melting point::2477 °C
Boiling point	Boiling point::4744 °C
Isotopes of Niobium
iso NA half-life DT DE (MeV) DP 81Nb syn 44ns p - 80Kr 81Nb syn 44ns β+ - 81Zr 81Nb syn 44ns β+p - 80Y 82Nb syn <51ms β+ - 82Zr 83Nb syn 4.1s β+ - 83Kr 84Nb syn 9.8s β+ - 84Zr 84Nb syn 9.8s β+p - 83Y 85Nb syn 20.9s β+ - 85Zr 86Nb syn 1.47m β+ - 86Zr 87Nb syn 3.75m β+ - 87Zr 88Nb syn 14.5m β+ - 88Zr 89Nb syn 2.031h β+ - 89Zr 90Nb syn 14.61h β+ - 90Zr 91Nb syn 6.8x102 y ε - 91Zr 91mNb syn 60.8 d e+ 0.104e 91Nb 92Nb syn 10.15 d ε - 92Zr 92Nb syn 10.15 d γ 0.934 - 92Nb syn 3.47x107 y ε - 92Zr 92Nb syn 3.47x107 y γ 0.561, 0.934 - 93Nb 100% 93Nb is stable with 52 neutrons. 93mNb syn 16.13 y IT 0.031e 93Nb 94Nb syn 2.03x104 y β- 0.471 94Mo 94Nb syn 2.03x104 y γ 0.702, 0.872 - 95Nb syn 34.991 d β- 0.159 95Mo 95Nb syn 34.991 d γ 0.765 - 95mNb syn 3.61 d IT 0.235 95Nb
All properties are for STP unless otherwise stated.

Niobium is a chemical element known by the chemical symbol Nb. It is perhaps best known for its usage in jewelry, possessing a wide range of colors due to anodizing. However, this metal is also a superconductor under certain conditions, making it a component of super magnets and particle accelerators. Niobium's other unique properties, including its extremely high melting point, make niobium useful in a wide variety of products. Niobium is a relatively soft metal with a density about one third of gold's. Niobium can be found in nature in minerals like columbite or pyrochlore and is mined extensively in Russia, Brazil, and Australia, among other countries. Niobium is named after Niobe, a prideful princess in Greek mythology, and was first discovered in 1701, but it was not isolated until forty three years later.

Properties

Niobium is a lustrous transition metal with a natural gray or white coloration. Niobium is soft because of its low density, and under cryogenic conditions, niobium conducts electricity as a superconductor. A natural film of oxide will form on the surface of pure niobium, making it resistant to corrosion. Niobium's resistance to heat and corrosion make it one of the five refractory metals; the other four are tungsten, molybdenum, tantalum, and rhenium. Niobium is particularly sensitive to reactions with alkali metals and oxidizers, but is inert to acidic elements. At temperatures above 400°C, niobium oxidizes and becomes very brittle. To prevent this, niobium is often coated in a protective layer when used in certain industrial products. Because it reacts with carbon, nitrogen, sulfur, the halogen family, and especially oxygen, niobium must be stored in a controlled atmosphere to maintain its pure form. Maintaining niobium's pure form is important because both its conductivity and resistance to corrosion depend on its purity in the compound it is in. These two properties are the most commonly exploited in industry.

Occurrences

Samarskite Ore is a Yttrium - Niobium mineral

There are approximately 17-20 million ppm (parts per million) of niobium in the earth's crust, making it neither rare nor common. Niobium occurs in nature mainly in compounds such as columbite and pyrochlore and is mined in large quantities in Brazil, Russia, and Australia. Almost all compounds containing niobium also contain tantalum, and the two are usually associated with each other because of their similar properties. Pure niobium does not occur naturally and is always found in compounds. In addition to its mineral form, niobium can also be found in small amounts in plants and lichen. Although many plants contain no niobium, some mosses and lichens contain up to 0.45 ppm, and some plants found near niobium deposits have been known to contain over 1.00 ppm. Niobium is also collected as a natural by-product of the tin extraction process.

Uses

A sheet of metal colorized by the anodization process

Because of niobium's ability to act as a superconductor under cryogenic conditions, researchers have recently begun to explore niobium's potential as a particle accelerator, to promising results. Superconductive niobium cavities, after being thoroughly polished, act as particle accelerators even more efficient than currently employed technology. This new breakthrough promises increased efficiency in a variety of fields, including medical, military, pharmaceutical, scientific, and in manufacturing. In the medical field, niobium is most dominantly used in MRI scanners because of its strong magnetic field and superconductivity. Niobium's superconductivity also makes it invaluable for use in superconducting magnets. In 1997, the scientists at the Lawrence Berkeley Laboratory in California synthesized a super magnet of tin and niobium; its strength was three times that of the previous strongest magnet in the world.

Niobium has also found a use in jewelry production. Niobium is malleable enough to form by hand and can be cut with little effort, yet it is hard enough to maintain its shape after crafting. Niobium is completely hypoallergenic; in the past 20 years, no cases of allergic reactions have been recorded in relation to niobium's use in body piercings. Another reason for niobium's use in jewelry is its ability to adopt a wide variety of colors in the process of anodization. This process is relatively simple as it only requires only a few instruments to accomplish, and many independent craftsman are able to anodize this metal in their own homes.

Because of niobium's extremely high melting point, it is also used as an alloy in nuclear reactors and in jet engines. When combined with other metals, niobium adds durability, strength and malleability to that alloy, giving it use in the manufacturing of pipes and many automobile parts. Although not as effective as tantalum, niobium is sometimes used in the production of capacitors for computer parts for its ability to hold electrical charges.

History

1829 portrait of Charles Hatchett, who is credited with the the original discovery of niobium.

The discovery of Niobium is attributed to Charles Hatchett. In 1801, Hatchett noticed a sample of columbite in The British Museum, sent from America seventy years prior. For these seventy years, no one had decided to examine the sample, but Hatchett took an interest in the black rock. He suspected that there was an undiscovered element within, and he was able to extract what he thought was a pure element from it and named it columbium, after the ore it originated from. However, many scientists doubted this new element because of its extreme similarities to tantalum and understandably so, for columbium is a compound composed of niobium and tantalum, both elements possessing very similar properties. In 1844, however, German chemist Heinrich Rose proved that columbium was composed of two similar but distinctly different elements. Rose then renamed the element niobium, after Greek mythology's Niobe, the daughter of Tantalus from which tantalum derived its name.

Video

An experienced jewelry maker demonstrates the anodization process, and a brief overview of niobium's implementation as a particle accelerator.