Periodic Table -> Niobium
Niobium DetailsNiobium Symbol:
NbNiobium Atomic Number:
41Niobium Atomic Weight:
92.906What is Niobium?
Niobium (atomic number 41, symbol 41) is a ductile, grey, soft transition metal, found in pyrochlore. Columbite is the main commercial source for this element.
Niobium has chemical and physical properties similar to tantalum, which is why the two elements are difficult to distinguish. Its cubic crystalline structure is body-centered and also resembles that of tantalum.
In 1801, Charles Hatchett, who discovered niobium, reported a new element that was similar to tantalum. In 1846, William Wollaston wrongly assumed that columbium and tantalum were identical. A series of studies were conducted between 1846 and 1865, and the findings confirmed that columbium and niobium were the same element. Both names were used interchangeably for a century, and the name niobium was officially adopted in 1949.
The element is a paramagnetic metal, and at cryogenic temperatures, it becomes a superconductor. Niobium is an elemental type II superconductor, along with technetium and vanadium. When in its pure form, it is relatively ductile and soft, but impurities make it harder. The element has only one stable isotope, Nb-93, but more than 32 radioisotopes have been produced, with atomic mass ranging from 81 to 113. The least stable isotope, Nb-113 has a half-life of about 30 milliseconds, and the most stable one, Nb-92 has a half-life of 34,000,000 years. Over 25 nuclear isomers have been identified, with atomic mass ranging from 84 to 104. Niobium-93 is the most stable isomer, with a half-life of 16.13 years.
The processing of niobium takes place in a protective atmosphere because it reacts with the halogens, carbon, oxygen, sulfur, and nitrogen. At room temperatures, it is inert to acids, but is attacked by concentrated, hot acids, especially oxidizing agents and alkalis. Its atomic radius is 146 pm, and its melting point is 2410 °C.
Niobium has many applications and is a microalloying component of steel. When added to steel, niobium nitride and niobium carbide form within the structure of the steel.
They improve the precipitation of hardening, the retardation of recrystallization, and the grain refining of steel. In turn, these effects increase the weldability, formability, strength, and toughness of the microalloyed steel. The niobium content of microalloyed stainless steels is under 0.1 percent. Niobium and its alloys are also used for the production of superalloys, superconducting magnets, jewelry, and electroceramics. The element is often used with gold or silver in commemorative coins.
Small amounts of the element give a greater strength to metals that are exposed to low temperatures. Niobium is also added to alloys for cutting tools, missiles, nuclear reactors, and welding rods. Niobium-titanium and niobium-tin alloys are used in superconducting magnets that produce strong magnetic fields. Alloys of niobium are used for surgical implants and particle accelerators.
The major mining sites are found in Canada, Nigeria, Russia, Zaire, and Brazil, which produces over 85 percent of the word’s niobium. While there are considerable deposits of pytochlore, the amount of unmined reserves is unknown. Plant species show traces of niobium, but some lichens and mosses contain 0.45 ppm. Niobium and its compounds cause skin and eye irritation and can be toxic, but human poisoning has not been reported. When inhaled, the element is retained in the bones and lungs and interferes with calcium. The inhalation of niobium pentoxide and nitride results in scarring of the lungs in laboratory animals.
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