ɪˈlʊəriəm/, /tɛl-) is a chemical elementthat has the symbol Te and atomic number52. A brittle silver-white metalloidwhich looks like tin, tellurium is chemically related to seleniumand sulfur. Tellurium is primarily used in alloys and as a semiconductor.
Tellurium is extremely rare, one of the nine rarest metallic elements on earth. It is in the same chemical family as
oxygen, sulfur, selenium, and polonium(the chalcogens).
crystalline, tellurium is silvery-white and when it is in its pure state it has a metallic luster. This is a brittle and easily pulverized metalloid. Amorphous tellurium is found by precipitating it from a solution of tellurous or telluric acid(Te(OH)6). However, there is some debate whether this form is really amorphous or made of minute crystals.
Tellurium is a p-type
semiconductorthat shows a greater conductivity in certain directions which depends on atomic alignment. Chemically related to seleniumand sulfur, the conductivity of this element increases slightly when exposed to light ( photoelectric effect).
It can be doped with
copper, gold, silver, tin, or other metals. When in its molten state, tellurium is corrosive to copper, iron, and stainless steel.
Tellurium gives a greenish-blue flame when burned in normal air and forms
tellurium dioxideas a result.
Metal alloys cite web | title = Mineral Yearbook 2007: Selenium and Tellurium | first = Micheal W. | last = George| publisher = United States geological Survey | date = 2007| url = http://minerals.usgs.gov/minerals/pubs/commodity/selenium/myb1-2007-selen.pdf]
*It is mostly used in
alloys with other metals. It is added to leadto improve its strength and durability, and to decrease the corrosive action of sulfuric acid.
*When added to
stainless steeland copperit makes these metals more workable. It is alloyed into cast ironfor chill control.
* Used in
* It is used in
* Tellurium is used in
* Organic tellurides have been employed as initiators for living radical polymerisation and electron-rich mono- and di-tellurides possess
metalorganicsof both seleniumand tellurium are used in the semiconductor industry, and are prepared by adduct purification. [doi|10.1016/0022-0248(88)90613-6 Journal of Crystal Growth Volume 93, Issues 1-4 , 1988, Pages 744-749] [US patent|5117021 Method for purification of tellurium and selenium alkyls]
Semiconductor and electronic industry uses:
*Tellurium is used in the media layer of several types of rewritable
optical discs, including ReWritable Compact Discs ( CD-RW), ReWritable Digital Video Discs ( DVD-RW) and ReWritable Blu-ray Discs ( [http://www.engadget.com/2006/10/19/panasonic-says-that-its-100gb-blu-ray-discs-will-last-a-century/ See here] ).
*Tellurium is used in the new
phase change memory[http://www.geek.com/phase-change-memory-from-intel-later-this-year/?rfp=dta chips] developed by Intel. Also [http://www.spectrum.ieee.org/print/1501 see here] .
Bismuth telluride(Bi2Te3) is used in thermoelectricdevices.
*Tellurium is used in
cadmium telluride(CdTe) solar panels. NRELlab tests using this material achieved some of the highest efficiencies for solar cell electric power generation. [http://www.firstsolar.com First Solar Inc.] started massive commercial production of CdTe solar panels in recent years, significantly increased tellurium demand. If some of the cadmium in CdTe is replaced by zincthen CdZnTe is formed which is used in solid-state x-raydetectors.
*Alloyed with both cadmium and mercury, to form mercury cadmium telluride, an
infraredsensitive semiconductormaterial is formed. Organotellurium compounds such as dimethyl telluride, diethyl telluride, diisopropyl telluride, diallyl tellurideand methyl allyl tellurideare used as precursors for MOVPEgrowth of II-VI compound semiconductors. Diisopropyl telluride (DIPTe) is employed as the preferred precursor for achieving the low temperature growth of CdHgTe by MOVPE.
Latin"tellus" meaning "earth") was discovered in 1782 by the Hungarian Franz-Joseph Müller von Reichenstein(Müller Ferenc) in Nagyszeben (now, Sibiu) Transylvania. In 1789, another Hungarian scientist, Pál Kitaibel, also discovered the element independently, but later he gave the credit to Müller. In 1798, it was named by Martin Heinrich Klaprothwho earlier isolated it.
Tellurium was used as a chemical bonder in the making of the outer shell of the first atom bomb. The 1960s brought growth in thermoelectric applications for tellurium, as well as its use in free-machining
steel, which became the dominant use.
With an abundance in the Earth's crust even lower than
platinum, tellurium is, apart from the precious metals, the rarest stable solid element in the earth's crust. Its abundance in the Earth's crust is 1 to 5 ppb, compared with 5 to 37 ppb for platinum. By comparison, even the rarest of the lanthanides have crustal abundances of 500 ppb.
The extreme rarity of tellurium in the Earth's crust is not a reflection of its cosmic abundance, which is in fact greater than that of
rubidium[http://www.orionsarm.com/science/Abundance_of_Elements.html] , even though rubidium is ten thousand times more abundant in the Earth's crust. Rather, the extraordinarily low abundance of tellurium on Earth results from the fact that, during the formation of the Earth, the stable form of elements in the absence of oxygenand waterwas controlled by the oxidation and reduction of hydrogen. Under this scenario elements such as tellurium which form "volatile hydrides" were severely depleted during the formation of the Earth's crust through evaporation. Tellurium and selenium are the heavy elements most depleted in the Earth's crust by this process.
Tellurium is sometimes found in its native (elemental) form, but is more often found as the tellurides of
gold( calaverite, krennerite, petzite, sylvanite, and others). Tellurium compounds are the only chemical compounds of gold found in nature, but tellurium itself (unlike gold) is also found combined with other elements (in metallic salts). The principal source of tellurium is from anodesludges produced during the electrolytic refining of blister copper. It is a component of dusts from blast furnacerefining of lead. Treatment of 500 tons of copper ore [http://www.stda.net/se-te.htm typically yields] one pound of tellurium. Tellurium is produced mainly in the US, Canada, Peru, and Japan. [http://www.mmta.co.uk/economicsFacts/Articles/MiningJournalReview/Tellurium.pdf See here] .
Commercial-grade tellurium is usually marketed as minus 200-mesh powder but is also available as slabs, ingots, sticks, or lumps. The year-end price for tellurium in 2000 was US$14 per pound. In recent years, tellurium price was [http://arizonageology.blogspot.com/2007/05/arizona-tellurium-rush.html driven up] by increased demand and limited supply, reaching as high as US$100 per pound in 2006. [http://www.resourceinvestor.com/pebble.asp?relid=31031 See also here] .
Telluride, Colorado, "
Tellurium is in the same series as
sulfurand seleniumand forms similar compounds. A compound with metal or hydrogen and similar ions is called a telluride. Goldand silvertellurides are considered good ores. Compounds with tellurate ions complexes TeO42- or TeO66- are known as tellurates. Also tellurites TeO32-. Also tellurols –TeH, named with prefix tellanyl- or suffix -tellurol.:"See also: "
There are 30 known
isotopes of tellurium with atomic masses that range from 108 to 137. Naturally found tellurium consists of eight isotopes (listed in the table to the right); three of them are observed to be radioactive. 128Te has the longest known half-life, 2.2×1024 years, among all radioactive isotopes.Fact|date=November 2007
Tellurium and tellurium compounds should be considered to be mildly
toxicand need to be handled with care.
Acute poisoning is rare.cite web
last = Harrison
first = W
coauthors = S Bradberry, J Vale
title = Tellurium
International Programme on Chemical Safety
url = http://www.intox.org/databank/documents/chemical/tellur/ukpid84.htm
accessdate = 2007-01-12 ] Tellurium is not reported to be carcinogenic.
Humans exposed to as little as 0.01 mg/m3 or less in air develop "tellurium breath", which has a
garlic-like odor. [cite web
title = Tellurium
Los Alamos National Laboratory
url = http://periodic.lanl.gov/elements/52.html
accessdate = 2007-01-12 ] The garlic odor that is associated with human intake of tellurium compounds is caused from the tellurium being metabolized by the body. When the body metabolizes tellurium in any oxidation state, the tellurium gets converted into
dimethyl telluride. Dimethyl telluride is volatile and produces the garlic-like smell. Even though the metabolic pathways of tellurium are not known, it is generally assumed that they resemble those of the more extensively studied selenium, because the final methylated metabolic products of the two elements are similar.
* [http://www.webelements.com/webelements/elements/text/Te/index.html WebElements.com – Tellurium]
* [http://minerals.er.usgs.gov/minerals/pubs/commodity/selenium USGS Mineral Information on Selenium and Tellurium]
* [http://www.stda.net/home.htm Selenium Tellurium Development Association]
* [http://www.mrteverett.com/Chemistry/pdictable/q_elements.asp?Symbol=Te Comprehensive Data on Tellurium]
Wikimedia Foundation. 2010.
Look at other dictionaries:
Tellurium — Tel*lu ri*um, n. [NL., from L. tellus, uris, the earth.] (Chem.) A rare nonmetallic element, analogous to sulphur and selenium, occasionally found native as a substance of a silver white metallic luster, but usually combined with metals, as with… … The Collaborative International Dictionary of English
Tellurĭum — (lat.), Maschine zur Versinnlichung der bei der täglichen Rotation und dem jährlichen Umlauf der Erde um die Sonne eintretenden Erscheinungen, besonders des durch den Parallelismus der Erdachse bedingten Wechsels der Jahreszeiten. Ein sehr… … Meyers Großes Konversations-Lexikon
Tellurium — (von/lat. tellus ‚(Mutter) Erde‘) steht für: den lateinischen Namen eines chemischen Elements, siehe Tellur eine Planetenmaschine, siehe Orrery Diese Seite ist eine Begriffsklärung zur Unters … Deutsch Wikipedia
Tellurium — Tellurium, so v.w. Tellur … Pierer's Universal-Lexikon
Tellurĭum — Tellurĭum, ein Apparat, durch welchen der Lauf der Erde um die Sonne, u. die Richtung der Erdachse während dieses Laufes, wovon die Jahreszeiten abhängen, so wie der Lauf des Mondes um die Erde dargestellt wird. Zugleich können durch den Apparat… … Pierer's Universal-Lexikon
Tellurium — Tellurĭum (lat.), mechan. Lehrmittel zur Veranschaulichung der Bewegung der Erde um die Sonne … Kleines Konversations-Lexikon
Tellurium — Tellurium, neulat., mechanische Vorrichtung, um die Bewegung der Erde um die Sonne u. die damit zusammenhängenden Erscheinungen zu erklären … Herders Conversations-Lexikon
tellurium — Symbol: Te Atomic number: 52 Atomic weight: 127.60 Silvery metalloid element of group 16. Eight natural isotopes, nine radioactive isotopes. Used in semiconductors and to a degree in some steels. Chemistry is similar to sulphur. Discovered in… … Elements of periodic system
tellurium — metallic element, named by German chemist and mineralogist Martin Heinrich Klaproth (1743 1817) from L. tellus (gen. telluris) earth (see TELLURIAN (Cf. tellurian)) … Etymology dictionary
tellurium — [te loor′ē əm, təlo͞or′ē əm] n. [ModL: coined (1798) by M. H. Klaproth (1743 1817), Ger chemist, for element discovered (1783) by F. J. M. von Reichenstein, Austrian mineralogist < L tellus, earth (see TELLURIAN) + IUM, in contrast to URANIUM] … English World dictionary