Bismuth (pronEng|ˈbɪzməθ) is a
chemical elementthat has the symbol Bi and atomic number83. This heavy, brittle, white crystalline trivalent poor metalhas a pink tinge and chemically resembles arsenicand antimony. Of all the metals, it is the most naturally diamagnetic, and only mercury has a lower thermal conductivity. It is generally considered to be the last naturally occurring stable, non-radioactive element on the periodic table, although it is actually slightly radioactive, with an extremely long half-life.
Bismuth compounds are used in
cosmetics, medicines, and in medical procedures. As the toxicity of leadhas become more apparent in recent years, alloy uses for bismuth metal as a replacement for lead have become an increasing part of bismuth's commercial importance.
Bismuth is a brittle
metalwith a white, silver- pink hue, often occurring in its native form with an iridescentoxide tarnish showing many refractive colors from yellow to blue. When combusted with oxygen, bismuth burns with a blue flameand its oxide forms yellow fumes. Its toxicityis much lower than that of its neighbors in the periodic tablesuch as lead, tin, tellurium, antimony, and polonium.
ununpentiumis theoretically more diamagnetic, no other metalis verified to be more naturally diamagnetic than bismuth. ( Superdiamagnetismis a different physical phenomenon.) Of any metal, it has the second lowest thermal conductivity(after mercury) and the highest Hall coefficient. It has a high electrical resistance. When deposited in sufficiently thin layers on a substrate, bismuth is a semiconductor, rather than a poor metal. [ Semimetal-to-semiconductor transition in bismuth thin films, C. A. Hoffman, J. R. Meyer, and F. J. Bartoli, A. Di Venere, X. J. Yi, C. L. Hou, H. C. Wang, J. B. Ketterson, and G. K. Wong, Phys. Rev. B 48, 11431 (1993) doi|10.1103/PhysRevB.48.11431]
Elemental bismuth is one of very few substances of which the
liquidphase is denser than its solidphase ( waterbeing the best-known example). Because bismuth expands on freezing, it was long an important component of low-melting typesetting alloys, which needed to expand to fill printing molds.
While bismuth was traditionally regarded as the element with the heaviest stable
isotope, bismuth-209, it had long been suspected to be unstable on theoretical grounds. This was finally demonstrated in 2003 when researchers at the Institut d'Astrophysique Spatiale in Orsay, France, measured the alpha emission half-lifeof 209Bi to be 1.9 x 1019 years, [cite journal | last = Marcillac | first = Pierre de | coauthors = Noël Coron, Gérard Dambier, Jacques Leblanc, and Jean-Pierre Moalic | year = 2003 | month = April | title = Experimental detection of α-particles from the radioactive decay of natural bismuth | journal = Nature | volume = 422 | pages = 876–878 | doi = 10.1038/nature01541 ] over a billion times longer than the current estimated age of the universe. Owing to its extraordinarily long half-life, for nearly all applications bismuth can be treated as if it is stable and non-radioactive. The radioactivity is of academic interest, however, because bismuth is one of few elements whose radioactivity was suspected, and indeed theoretically predicted, before being detected in the laboratory.
New Latin"bisemutum" from German "Wismuth", perhaps from "weiße Masse", "white mass") was confused in early times with tinand leadbecause of its resemblance to those elements. The element was discovered by the Muslim alchemist, Jabir ibn Hayyan (also known as "Geber"), in the 8th century. Robert Briffault(1938). "The Making of Humanity", p. 195.] Basilius Valentinusdescribed some of its uses in 1450, and Claude François Geoffroydemonstrated in 1753 that this metal is distinct from lead.
"Artificial bismuth" was commonly used in place of the actual metal. It was made by hammering tin into thin plates, and cementing them by a mixture of white tartar, saltpeter, and
arsenic, stratified in a crucibleover an open fire. [1728 [http://digicoll.library.wisc.edu/cgi-bin/HistSciTech/HistSciTech-idx?type=turn&entity=HistSciTech000900240255&isize=L] ]
Bismuth was also known to the
Incasand used (along with the usual copper and tin) in a special bronze alloyfor knives. [ [http://adsabs.harvard.edu/abs/1984Sci...223..585G Bismuth Bronze from Machu Picchu, Peru ] ]
Occurrence and production
In the Earth's crust, bismuth is about twice as abundant as
gold. It is not usually economical to mine it as a primary product. Rather, it is usually produced as a byproduct of the processing of other metal ores, especially lead, copper, tin, silver, and gold, but also tungstenor other metal alloys.
The most important
ores of bismuth are bismuthiniteand bismite. In 2005, China was the top producer of bismuth with at least 40% of the world share followed by Mexico and Peru, reports the British Geological Survey. Native bismuth is known from Australia, Bolivia, and China.
According to the
USGS, world 2006 bismuth mine production was 5,700 tonnes, of which China produced 3,000 tonnes, Mexico 1,180 tonnes, Peru 950 tonnes, and the balance Canada, Kazakhstan and other nations. World 2006 bismuth refinery production was 12,000 tonnes, of which China produced 8,500 tonnes, Mexico 1,180 tonnes, Belgium 800 tonnes, Peru 600 tonnes, Japan 510 tonnes, and the balance Canada and other nations.
The difference between world bismuth mine production and refinery production reflects bismuth's status as a byproduct metal. Bismuth travels in crude
leadbullion (which can contain up to 10% bismuth) through several stages of refining, until it is removed by the Kroll-Betterton processor the Betts process. The Kroll-Betterton process uses a pyrometallurgical separation from molten lead of calcium-magnesium-bismuth drosses containing associated metals (silver, gold, zinc, some lead, copper, tellurium, and arsenic), which are removed by various fluxes and treatments to give high-purity bismuth metal (over 99% Bi). The Betts process takes cast anodes of lead bullion and electrolyzes them in a lead fluosilicate-hydrofluosilicic acid electrolyte to yield a pure lead cathode and an anode slime containing bismuth. Bismuth will behave similarly with another of its major metals, copper. Thus world bismuth production from refineries is a more complete and reliable statistic.
According to the Bismuth Advocate News, the price for bismuth metal from year-end 2000 to September 2005 was stuck in a range from $2.60 to $4.15 per lb., but after this period the price started rising rapidly as global bismuth demand as a lead replacement and other uses grew rapidly. New mines in Canada and Vietnam may relieve the shortages, but prices are likely to remain above their previous level for the foreseeable future.
Though virtually unseen in nature, high-purity bismuth can form distinctive
hopper crystals. These colorful laboratory creations are typically sold to collectors. Bismuth is relatively nontoxic and has a low melting point just above 271 °C, so crystals may be grown using a household stove, although the resulting crystals will tend to be lower quality than lab-grown crystals.
Bismuth oxychloride is sometimes used in
cosmetics. Bismuth subnitrate and bismuth subcarbonateare used in medicine. Bismuth subsalicylate(the active ingredientin Pepto-Bismoland (modern) Kaopectate) is used as an antidiarrheal and to treat some other gastro-intestinal diseases. Also, the product Bibrocatholis an organic molecule containing Bismuth and is used to treat eye infections. Bismuth subgallate(the active ingredientin Devrom) is used as an internal deodorant to treat malodor from flatulence(or gas) and faeces.
Some other current uses:
alloys have low melting points and are widely used for fire detection and suppression system safety devices.
*Bismuth is used as an alloying agent in production of malleable irons.
*A carrier for U-235 or U-233 fuel in
*Bismuth has also been used in
solders. The fact that bismuth and many of its alloys expand slightly when they solidify make them ideal for this purpose.
*Bismuth subnitrate is a component of glazes that produces an
Bismuth tellurideis an excellent thermoelectric material; it is widely used.
*A replacement propellant for
xenonin Hall effect thrusters
*In 1997 an antibody conjugate with Bi-213, which has a 45 minute half-life, and decays with the emission of an alpha-particle, was used to treat patients with leukemia.
*In 2001, Professor Barry Allen and Dr. Graeme Melville at St. George Hospital in Sydney successfully produced Bi-213 in linac experiments which involved bombarding radium with bremsstrahlung photons. This cancer research team used Bi-213 in its Targeted Alpha Therapy (TAT) program.
*The delta form of bismuth oxide when it exists at room temperature is a solid electrolyte for oxygen. This form normally only exists above and breaks down below a high temperature threshold, but can be electrodeposited well below this temperature in a highly alkaline solution.
In the early 1990s, research began to evaluate bismuth as a nontoxic replacement for lead in various applications:
*As noted above, bismuth has been used in solders; its low toxicity will be especially important for solders to be used in food processing equipment and copper water pipes.
*A pigment in artists' oil paint
*Ingredient in free-machining
brasses for plumbingapplications
*Ingredient in free-cutting steels for precision machining properties
*A catalyst for making acrylic fibres
*In low-melting alloys used in fire detection and extinguishing systems
*Ingredient in lubricating greases
*Dense material for
*In crackling microstars (
dragon's eggs) in pyrotechnics, as the oxide, subcarbonate, or subnitrate
*Replacement for lead in shot and
bullets. The UK, U.S., and many other countries now prohibit the use of lead shot for the hunting of wetland birds, as many birds are prone to lead poisoningdue to mistaken ingestion of lead (instead of small stones and grit) to aid digestion. Bismuth-tin alloy shot is one alternative that provides similar ballistic performance to lead. (Another less expensive but also more poorly performing alternative is "steel" shot, which is actually soft iron.)
*Bismuth core bullets are also starting to appear for use in indoor shooting ranges, where fine particles of lead from bullets impacting the backstop can be a chronic toxic inhalant problem. Owing to bismuth's crystalline nature, the bismuth bullets shatter into a non-toxic powder on impact, making recovery and recycling easy.Fact|powder is easy to clean up? --How about a vacuum cleaner?|date=June 2007 The lack of
malleabilitydoes, however, make bismuth unsuitable for use in expanding hunting bullets.
Fabrique Nationale de Herstaluses bismuth in the projectiles for its FN 303 less-lethal riot gun.
According to the
USGS, U.S. bismuth consumption in 2006 totaled 2,050 tonnes, of which chemicals (including pharmaceuticals, pigments, and cosmetics) were 510 tonnes, bismuth alloys 591 tonnes, metallurgical additives 923 tonnes, and the balance other uses.
Bismuth is not known to be toxic, compared to its periodic table neighbours (lead,
antimony, and polonium), although some compounds (including bismuth chloridedue to its corrosive acidity) are toxic and should be handled with care. As with lead, overexposure to bismuth can result in the formation of a black deposit on the gingiva, known as a bismuth linecite web|url=http://medical-dictionary.thefreedictionary.com/bismuth+line|title=bismuth line|publisher=Farlex, Inc.|accessdaymonth=8 February|accessyear=2008] .
Fine bismuth powder can be
pyrophoric. [cite book | last=Patnaik | first=Patnaik | title=Handbook of Inorganic Chemical Compounds | publisher= McGraw-Hill Professional| year=2002 | isbn=0070494398]
*Taylor, Harold A. Jr., "Bismuth", Financial Times Executive Commodity Reports (London: Mining Journal Books Ltd.) 2000 ISBN 1-84083 326 2
* [http://www.webelements.com/webelements/elements/text/Bi/index.html WebElements.com - Bismuth]
* [http://minerals.usgs.gov/minerals/pubs/commodity/bismuth/myb1-2006-bismu.pdf USGS 2006 Minerals Yearbook: Bismuth]
* [http://www.basicsmines.com/bismuth/index.html Bismuth Advocate News (BAN)]
* [http://minerals.usgs.gov/minerals/pubs/commodity/bismuth/ Bismuth Statistics and Information] - United States Geological Survey minerals information for bismuth
] by Jan Kihle Crystal Pulling Laboratories, Norway
* [http://physicsweb.org/article/news/7/4/16 Bismuth breaks half-life record for alpha decay]
* [http://periodic.lanl.gov/elements/83.html Los Alamos National Laboratory - Bismuth]
* [http://www.amazingrust.com/Experiments/how_to/Bismuth_Crystals.html Bismuth Crystals – Instructions & Pictures]
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