AskDefine | Define niobium

Dictionary Definition

niobium n : a soft gray ductile metallic element used in alloys; occurs in niobite; formerly called columbium [syn: Nb, atomic number 41]

User Contributed Dictionary

English

Noun

  1. a metallic chemical element (symbol Nb) with an atomic number of 41.

Synonyms

  • columbium (in metallurgy; not in scientific use)

Related terms

Translations

External links

For etymology and more information refer to: http://elements.vanderkrogt.net/elem/nb.html (A lot of the translations were taken from that site with permission from the author)

Finnish

Noun

  1. niobium

Extensive Definition

Niobium (), or columbium (/kəˈlʌmbiəm/) is a chemical element that has the symbol Nb and atomic number 41. A rare, soft, gray, ductile transition metal, niobium is found in pyrochlore and columbite. It was first discovered in the latter mineral and so was initially named columbium; now that mineral is also called "niobite". Niobium is used in special steel alloys as well as in welding, nuclear industries, electronics, optics and jewelry.

Notable characteristics

Niobium is a shiny gray, ductile metal that takes on a bluish tinge when exposed to air at room temperature for extended periods. Niobium's chemical properties are almost identical to the chemical properties of tantalum, which appears below niobium in the periodic table.
When it is processed at even moderate temperatures niobium must be placed in a protective atmosphere. The metal begins to oxidize in air at 200 ° C; its most common oxidation states are +3, and +5, although others are also known.

Applications

Niobium has a number of uses: it is a component of some stainless steels and an alloy of other nonferrous metals. It is also a very important alloy addition in HSLA steels, which are widely used as structural components in modern automobiles. These alloys are strong and are often used in pipeline construction. Other uses;
Niobium becomes a superconductor when lowered to cryogenic temperatures. At atmospheric pressure, it has the highest critical temperature of the elemental superconductors: 9.3 K. Niobium has the largest magnetic penetration depth of any element. In addition, it is one of the three elemental superconductors that are Type II (the others being vanadium and technetium). Niobium-tin and niobium-titanium alloys are used as wires for superconducting magnets capable of producing exceedingly strong magnetic fields. Niobium is also used in its pure form to make superconducting accelerating structures for particle accelerators.

History

Niobium (Greek mythology: Niobe, daughter of Tantalus) was discovered by Charles Hatchett in 1801. Hatchett found niobium in columbite ore that was sent to England in the 1750s by John Winthrop, the first governor of Connecticut. There was a considerable amount of confusion about the difference between the closely-related niobium and tantalum that wasn't resolved until 1846 by Heinrich Rose and Jean Charles Galissard de Marignac, who rediscovered the element. Since Rose was unaware of Hatchett's work, he gave the element a different name, niobium. In 1864 Christian Blomstrand was the first to prepare the pure metal, reducing niobium chloride by heating it in a hydrogen atmosphere.
Columbium (symbol Cb) was the name originally given to this element by Hatchett, but the International Union of Pure and Applied Chemistry (IUPAC) officially adopted "niobium" as the name for element 41 in 1950 after 100 years of controversy. This was a compromise of sorts; the IUPAC accepted tungsten instead of wolfram, in deference to North American usage; and niobium instead of columbium, in deference to European usage. Not everyone agreed, however, and while many leading chemical societies and government organizations refer to it by the official IUPAC name, many leading metallurgists, metal societies, and most leading American commercial producers still refer to the metal by the original "columbium."

Occurrence

The element is never found as a free element but does occur in the minerals columbite ((Fe,Mn)(Nb,Ta)2O6), columbite-tantalite or coltan ((Fe,Mn)(Ta,Nb)2O6), pyrochlore ((Na,Ca)2Nb2O6OH,F), and euxenite ((Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6). Minerals that contain niobium often also contain tantalum. Large deposits of niobium have been found associated with carbonatites (carbon-silicate igneous rocks) and as a constituent of pyrochlore. Brazil and Canada are the major producers of niobium mineral concentrates and extensive ore reserves are also in Nigeria, Democratic Republic of Congo, and in Russia. A large producer in Brazil is CBMM located in Araxá, Minas Gerais.

Isotopes

Naturally occurring niobium is composed of one stable isotope (Nb-93). The most stable radioisotopes are Nb-92 with a half-life of 34.7 million years, Nb-94 (half life: 20300 years), and Nb-91 with a half life of 680 years. Nb-93 has a meta state form (93mNb) with gamma line energy at 31 keV and half-life of 16.13 years. Twenty three other radioisotopes have been characterized. Most of these have half lives that are less than two hours except Nb-95 (35 days), Nb-96 (23.4 hours) and Nb-90 (14.6 hours). The primary decay mode before the stable Nb-93 is electron capture and the primary mode after is beta emission with some neutron emission occurring in the first mode of the two mode decay of Nb-104, 109 and 110.
Only Nb-95 (35 days) and Nb-97 (72 minutes) and heavier isotopes (halflives in seconds) are fission products in significant quantity, as the other isotopes are shadowed by stable or very long-lived (Zr-93) isotopes of the preceding element zirconium from production via beta decay of neutron-rich fission fragments. Nb-95 is the decay product of Zr-95 (64 days), so disappearance of Nb-95 in used nuclear fuel is slower than would be expected from its own 35 day halflife alone.. Tiny amounts of the other isotopes may be produced as direct fission products.

Precautions

Niobium-containing compounds are relatively rarely encountered by most people, but some are toxic and should be treated with care. Niobium has no known biological role. Metallic niobium dust is an eye and skin irritant and also can be a fire hazard. However niobium metal, without compounds, is physiologically inert (and thus hypoallergenic) and harmless. It is frequently used in jewelry.

Niobium in numismatics

Niobium is frequently used as a precious metal in commemorative coins, often together with Silver or Gold. One of the most recent samples is the 25 euro 150 Years Semmering Alpine Railway Coin. The "phil" of the coin is made of green Niobium (other coins may use other colors, like brown, purple or yellow).

References

External links

niobium in Afrikaans: Niobium
niobium in Arabic: نيوبيوم
niobium in Bengali: নাইওবিয়াম
niobium in Belarusian: Ніобій
niobium in Bosnian: Niobijum
niobium in Catalan: Niobi
niobium in Czech: Niob
niobium in Corsican: Niobiu
niobium in Danish: Niobium
niobium in German: Niob
niobium in Estonian: Nioobium
niobium in Modern Greek (1453-): Νιόβιο
niobium in Spanish: Niobio
niobium in Esperanto: Niobio
niobium in Basque: Niobio
niobium in Persian: نیوبیوم
niobium in French: Niobium
niobium in Friulian: Niobi
niobium in Manx: Neeobium
niobium in Galician: Niobio
niobium in Korean: 나이오븀
niobium in Armenian: Նիոբիում
niobium in Hindi: नायोबियम
niobium in Croatian: Niobij
niobium in Ido: Niobio
niobium in Indonesian: Niobium
niobium in Icelandic: Níóbín
niobium in Italian: Niobio
niobium in Hebrew: ניאוביום
niobium in Javanese: Niobium
niobium in Swahili (macrolanguage): Niobi
niobium in Haitian: Nyobyòm
niobium in Kurdish: Niyobyûm
niobium in Latin: Niobium
niobium in Latvian: Niobijs
niobium in Luxembourgish: Niob
niobium in Lithuanian: Niobis
niobium in Lojban: jinmrni,obi
niobium in Hungarian: Nióbium
niobium in Malayalam: നിയോബിയം
niobium in Dutch: Niobium
niobium in Japanese: ニオブ
niobium in Norwegian: Niob
niobium in Norwegian Nynorsk: Niob
niobium in Occitan (post 1500): Niòbi
niobium in Uzbek: Niobiy
niobium in Polish: Niob
niobium in Portuguese: Nióbio
niobium in Romanian: Niobiu
niobium in Russian: Ниобий
niobium in Sicilian: Niobiu
niobium in Simple English: Niobium
niobium in Slovak: Niób
niobium in Slovenian: Niobij
niobium in Serbian: Ниобијум
niobium in Serbo-Croatian: Niobijum
niobium in Finnish: Niobium
niobium in Swedish: Niob
niobium in Tamil: நையோபியம்
niobium in Thai: ไนโอเบียม
niobium in Vietnamese: Niobi
niobium in Turkish: Niobyum
niobium in Ukrainian: Ніобій
niobium in Chinese: 铌
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