AskDefine | Define columbium

Dictionary Definition

columbium n : a former name for niobium

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English

Noun

  1. The former name of niobium

Translations

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

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