BW Professional Cutter Expert www.tool-tool.com

Tellurium ( /tɪˈlʊəriəm/ or /tɛˈl(j)ʊəriəm/ te-LOOR-ee-əm) is a chemical element that has the symbol Te and atomic number 52. A brittle, mildly toxic, silver-white metalloid which looks similar to tin, tellurium is chemically related to selenium and sulfur. Tellurium was discovered in 1782 by Franz-Joseph Müller von Reichenstein in a mineral containing gold and tellurium. Martin Heinrich Klaproth named the new element in 1798 after the Latin word for "earth", tellus.

Although several gold deposits contain tellurium minerals, the main commercial source for tellurium is as a by-product of copper and lead production. Tellurium is primarily used in alloys, foremost in steel and copper to improve machinability. Applications in solar panels and as a semiconductor material also consume a considerable fraction of tellurium production.

Tellurium has no biological function, although fungi can incorporate it in place of sulfur and selenium into amino acids such as telluro-cysteine and telluro-methionine.[3] In humans, tellurium is partly metabolized into dimethyl telluride, (CH3)2Te, a gas with a garlic-like odor which is exhaled in the breath of victims of tellurium toxicity or exposure.

Contents

[hide]

• 1 Characteristics
  • 1.1 Physical properties
  • 1.2 Chemical properties
  • 1.3 Isotopes
  • 1.4 Occurrence
• 2 Production
• 3 Compounds
• 4 History
• 5 Applications
  • 5.1 Metallurgy
  • 5.2 Semiconductor and electronic industry uses
  • 5.3 Other uses
• 6 Biological role
• 7 Precautions
• 8 References
• 9 External links

[edit] Characteristics

[edit] Physical properties

When crystalline, tellurium is silvery-white and when it is in pure state it has a metallic luster. It 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).[4] Tellurium is a p-type semiconductor that shows a greater electrical conductivity in certain directions which depends on atomic alignment; the conductivity increases slightly when exposed to light (photoconductivity).[5] When in its molten state, tellurium is corrosive to copper, iron and stainless steel.

[edit] Chemical properties

Tellurium adopts a polymeric structure, consisting of zig-zag chains of Te atoms. This gray material resists oxidation by air and is nonvolatile.

[edit] Isotopes

Main article: Isotopes of tellurium

Naturally occurring tellurium has eight isotopes. Four of those isotopes, 122Te, 124Te, 125Te and 126Te, are stable. The other four, 120Te, 123Te, 128Te and 130Te, have been observed to be radioactive.[6][7] The stable isotopes make up only 33.2 % of the naturally occurring tellurium; this is possible due to the long half-lives of the unstable isotopes. They are in the range from 1013 to 2.2 1024 years. This makes 128Te the isotope with the longest half life among all radioisotopes.[8]

There are 38 known nuclear isomers of tellurium with atomic masses that range from 105 to 142. Tellurium is the lightest element known to undergo alpha decay, with isotopes 106Te to 110Te being able to undergo this mode of decay.[6] The atomic mass of tellurium (127.60 g·mol−1) exceeds that of the following element iodine (126.90 g·mol−1).[9]

[edit] Occurrence

See also Category: Telluride minerals

Tellurium on quartz (Moctezuma, Sonora, Mexico)

With an abundance in the Earth's crust comparable to that of platinum, tellurium is one of the rarest stable solid elements in the Earth's crust. Its abundance is about 1 µg/kg.[10] In comparison, even the rarest of the lanthanides have crustal abundances of 500 µg/kg (see Abundance of the chemical elements).[11]

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, even though rubidium is ten thousand times more abundant in the Earth's crust. The extraordinarily low abundance of tellurium on Earth is rather thought to be due to conditions in the Earth's formation, when the stable form of certain elements, in the absence of oxygen and water, was controlled by the reductive power of free hydrogen. Under this scenario, certain elements such as tellurium which form volatile hydrides were severely depleted during the formation of the Earth's crust, through evaporation of these hydrides. Tellurium and selenium are the heavy elements most depleted in the Earth's crust by this process.[citation needed]

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 most common chemical compounds of gold found in nature (rare non-tellurides such as gold aurostibite and bismuthide are known). Tellurium is also found combined with elements other than gold, in salts of other metals. In contrast to selenium, tellurium is not able to replace sulfur in its minerals. This is due to the large difference in ion radius of sulfur and tellurium. In consequence, many sulfide minerals contain considerable amounts of selenium, but only traces of tellurium.[12]

In the gold rush of 1893, diggers in Kalgoorlie discarded a pyritic material which got in their way as they searched for pure gold. The Kalgoorlie waste was thus used to fill in potholes or as part of sidewalks. Three years passed before it was realized that this waste was calaverite, a telluride of gold that had not been recognized. This led to a second gold rush in 1896 which included mining the streets.[13]

[edit] Production

The principal source of tellurium is from anode sludges produced during the electrolytic refining of blister copper. It is a component of dusts from blast furnace refining of lead. Treatment of 500 tons of copper ore typically yields one pound (0.45 kg) of tellurium. Tellurium is produced mainly in the United States, Peru, Japan, and Canada.[14] For the year 2006 the British Geological Survey gives the following numbers: United States 50 t, Peru 37 t, Japan 24 t and Canada 11 t.[15]

Tellurium production 2006

The anode sludges contain the selenides and tellurides of the noble metals in compounds with the formula M2Se or M2Te (M = Cu, Ag, Au). At temperatures of 500 °C the anode sludges are roasted with sodium carbonate under air. The metal ions are reduced to the metals, while the telluride is converted to sodium tellurite.[16]

M2Te + O2 + Na2CO3 → Na2TeO3 + 2 M + CO2

Tellurites can be leached from the mixture with water and are normally present as hydrotellurites HTeO3- in solution. Selenites are also formed during this process, but they can be separated by adding sulfuric acid. The hydrotellurites are converted into the insoluble tellurium dioxide while the selenites stay in solution.[16]

HTeO3- + OH- + H2SO4 → TeO2 + 2 SO42− + 2 H2O

The reduction to the metal is done either by electrolysis or by reacting the tellurium dioxide with sulfur dioxide in sulfuric acid.[16]

TeO2 + 2 SO2 + 2H2O → Te + SO42− + 4 H+

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, the tellurium price was driven up by increased demand and limited supply, reaching as high as US$100 per pound in 2006.[17][18]

[edit] Compounds

See also Category: Tellurium compounds

Tellurium belongs to the same chemical family as oxygen, sulfur, selenium and polonium: the chalcogen family. Tellurium and selenium compounds are similar. It exhibits the oxidation states −2, +2, +4 and +6, with the +4 state being most common.[4]

Tellurides

Reduction of Te metal produces the Tellurides and polytellurides, Ten2-. The −2 oxidation state is exhibited in binary compounds with many metals, such as zinc telluride, ZnTe, formed by heating tellurium with zinc.[19] Decomposition of ZnTe with hydrochloric acid yields hydrogen telluride (H2Te), a highly unstable analogue of the other chalcogen hydrides, H2O, H2S and H2Se:

ZnTe + 2 HCl → ZnCl2 + H2Te

H2Te is unstable, whereas salts of its conjugate base [TeH]- are stable.

Halides

The +2 oxidation state is exhibited by the dihalides, TeCl2, TeBr2 and TeI2. The dihalides have not been obtained in pure form,[20]:274 although they are known decomposition products of the tetrahalides in organic solvents, and their derived tetrahalotellurates are well-characterized:

Te + X2 + 2 X− → TeX2−

4

where X is Cl, Br, or I. These anions are square planar in geometry.[20]:281 Polynuclear anionic species also exist, such as the dark brown Te2I2−

6,[20]:283 and the black Te4I2−

14.[20]:285

Fluorine forms two halides with tellurium: the mixed-valence Te2F4 and TeF6. In the +6 oxidation state, the –OTeF5 structural group occurs in a number of compounds such as HOTeF5, B(OTeF5)3, Xe(OTeF5)2, Te(OTeF5)4 and Te(OTeF5)6.[21] The square antiprismatic anion TeF2−

8 is also attested.[16] The other halogens do not form halides with tellurium in the +6 oxidation state, but only tetrahalides (TeCl4, TeBr4 and TeI4) in the +4 state, and other lower halides (Te3Cl2, Te2Cl2, Te2Br2, Te2I and two forms of TeI). In the +4 oxidation state, halotellurate anions are known, such as TeCl2−

6 and Te2Cl2−

10. Halotellurium cations are also attested, including TeI+

3, found in TeI3AsF6.[22]

Oxocompounds

A sample of tellurium dioxide powder

Tellurium monoxide was first reported in 1883 as a black amorphous solid formed by the heat decomposition of TeSO3 in vacuum, disproportionating into tellurium dioxide, TeO2 and elemental tellurium upon heating.[23][24] Since then, however, some doubt has been cast on its existence in the solid phase, although it is known as a vapor phase fragment; the black solid may be merely an equimolar mixture of elemental tellurium and tellurium dioxide.[25]

Tellurium dioxide is formed by heating tellurium in air, causing it to burn with a blue flame.[19] Tellurium trioxide, β-TeO3, is obtained by thermal decomposition of Te(OH)6. The other two forms of trioxide reported in the literature, the α- and γ- forms, were found not to be true oxides of tellurium in the +6 oxidation state, but a mixture of Te4+, OH− and O−

2.[26] Tellurium also exhibits mixed-valence oxides, Te2O5 and Te4O9.[26]

The tellurium oxides and hydrated oxides form a series of acids, including tellurous acid (H2TeO3), orthotelluric acid (Te(OH)6) and metatelluric acid ((H2TeO4)n).[25] The two forms of telluric acid form tellurate salts containing the TeO2–

4 and TeO6−

6 anions, respectively. Tellurous acid forms tellurite salts containing the anion TeO2−

3. Other tellurium cations include TeF2+

8, which consists of two fused tellurium rings and the polymeric TeF2+

7.

Zintl cations

When tellurium is treated with concentrated sulfuric acid, it forms red solutions containing the Zintl ion, Te2+

4.[27] The oxidation of tellurium by AsF5 in liquid SO2 also produces this square planar cation, as well as with the trigonal prismatic, yellow-orange Te4+

6:[16]

4 Te + 3 AsF5 → Te2+

4(AsF−

6)2 + AsF3

6 Te + 6 AsF5 → Te4+

6(AsF−

6)4 + 2 AsF3

Other tellurium Zintl cations include the polymeric Te2+

7 and the blue-black Te2+

8, which consists of two fused 5-membered tellurium rings. The latter cation is formed by the reaction of tellurium with tungsten hexachloride:[16]

8 Te + 2 WCl6 → Te2+

8(WCl−

6)2

Interchalcogen cations also exist, such as Te2Se2+

6 (distorted cubic geometry) and Te2Se2+

8. These are formed by oxidizing mixtures of tellurium and selenium with AsF5 or SbF5.[16]

Organotellurium compounds

Main article: Organotellurium chemistry

Tellurium does not readily form analogues of alcohols and thiols, with the functional group –TeH and are called tellurols. The –TeH functional group is also attributed to using the prefix tellanyl-.[28] Like H2Te, these species are unstable with respect to loss of H2. Telluraethers (R-Te-R) are more stable as are telluroxides.

[edit] History

Klaproth named the new element and credited von Reichenstein with its discovery

Tellurium (Latin tellus meaning "earth") was discovered in the 18th century in a gold ore from the mines in Zlatna, near what is now Sibiu, Transylvania. This ore was known as "Faczebajer weißes blättriges Golderz" (white leafy gold ore from Faczebaja) or antimonalischer Goldkies (antimonic gold pyrite), and, according to Anton von Rupprecht, was Spießglaskönig (argent molybdique), containing native antimony.[29][30] In 1782 Franz-Joseph Müller von Reichenstein, who was then serving as the Austrian chief inspector of mines in Transylvania, concluded that the ore did not contain antimony, but that it was bismuth sulfide.[31] The following year, he reported that this was erroneous and that the ore contained mostly gold and an unknown metal very similar to antimony. After a thorough investigation which lasted for three years and consisted of more than fifty tests, Müller determined the specific gravity of the mineral and noted the radish-like odor of the white smoke which passed off when the new metal was heated, the red color which the metal imparts to sulfuric acid, and the black precipitate which this solution gives when diluted with water. Nevertheless, he was not able to identify this metal and gave it the names aurum paradoxium and metallum problematicum, as it did not show the properties predicted for the expected antimony.[32][33][34]

In 1789, another Hungarian scientist, Pál Kitaibel, also discovered the element independently in an ore from Deutsch-Pilsen which had been regarded as argentiferous molybdenite, but later he gave the credit to Müller. In 1798, it was named by Martin Heinrich Klaproth who earlier isolated it from the mineral calaverite.[33][34][35]

Tellurium was used as a chemical bonder in the making of the outer shell of the first atomic bomb. The 1960s brought growth in thermoelectric applications for tellurium, as well as its use in free-machining steel, which became the dominant use.[citation needed]

[edit] Applications

[edit] Metallurgy

The largest consumer of tellurium is metallurgy, where it is used in iron, copper and lead alloys. When added to stainless steel and copper it makes these metals more machinable. It is alloyed into cast iron for promoting chill for spectroscopic purposes, as the presence of electrically conductive free graphite tends to deleteriously affect spark emission testing results. In lead it improves strength and durability and decreases the corrosive action of sulfuric acid.[36]

[edit] Semiconductor and electronic industry uses

A CdTe photovoltaic array

Tellurium is used in cadmium telluride (CdTe) solar panels. National Renewable Energy Laboratory lab tests using this material achieved some of the highest efficiencies for solar cell electric power generation. Massive commercial production of CdTe solar panels by First Solar in recent years has significantly increased tellurium demand.[37][38][39] If some of the cadmium in CdTe is replaced by zinc then (Cd,Zn)Te is formed which is used in solid-state x-ray detectors.[40]

Alloyed with both cadmium and mercury, to form mercury cadmium telluride, an infrared sensitive semiconductor material is formed.[41] Organotellurium compounds such as dimethyl telluride, diethyl telluride, diisopropyl telluride, diallyl telluride and methyl allyl telluride are used as precursors for Metalorganic vapor phase epitaxy growth of II-VI compound semiconductors.[42] Diisopropyl telluride (DIPTe) is employed as the preferred precursor for achieving the low-temperature growth of CdHgTe by MOVPE.[43] For these processes highest purity metalorganics of both selenium and tellurium are used. The compounds for semiconductor industry and are prepared by adduct purification.[44][45]

Tellurium as a tellurium suboxide 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.[46][47]

Tellurium is used in the new phase change memory chips.[48] developed by Intel.[49] Bismuth telluride (Bi2Te3) and lead telluride are working elements of thermoelectric devices. Lead telluride is used in far-infrared detectors.

[edit] Other uses

• Used to color ceramics.[50]
• The strong increase in optical refraction upon the addition of selenides and tellurides into glass is used in the production of glass fibers for telecommunications. These chalcogenide glasses are widely used.[51][52]
• Mixtures of Selenium and tellurium are used with barium peroxide as oxidizer in the delay powder of electric blasting caps.[53]
• Organic tellurides have been employed as initiators for living radical polymerization and electron-rich mono- and di-tellurides possess antioxidant activity.
• Rubber can be vulcanized with tellurium instead of sulfur or selenium. The rubber produced in this way shows improved heat resistance.[54]
• Tellurite agar is used to identify member of the corynebacterium genus, most typically Corynebacterium diphtheriae, the pathogen responsible for diphtheria.[55]

[edit] Biological role

Tellurium has no known biological function, although fungi can incorporate it in place of sulfur and selenium into amino acids such as telluro-cysteine and telluro-methionine.[citation needed] Organisms have shown a highly variable tolerance to tellurium compounds. Most organisms metabolize tellurium partly to form dimethyl telluride although dimethyl ditelluride is also formed by some species. Dimethyl telluride has been observed in hot springs at very low concentrations.[56][57][58]

[edit] Precautions

Tellurium and tellurium compounds are considered to be mildly toxic and need to be handled with care, although acute poisoning is rare.[59] Tellurium is not reported to be carcinogenic.[59]

Humans exposed to as little as 0.01 mg/m3 or less in air develop "tellurium breath", which has a garlic-like odor.[50] 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, (CH3)2Te, which is volatile and is the cause of 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.[60][61][62]

引用出處： 

 http://en.wikipedia.org/wiki/Tellurium

歡迎來到Bewise Inc.的世界，首先恭喜您來到這接受新的資訊讓產業更有競爭力，我們是提供專業刀具製造商，應對客戶高品質的刀具需求，我們可以協助客戶滿足您對產業的不同要求，我們有能力達到非常卓越的客戶需求品質，這是現有相關技術無法比擬的，我們成功的滿足了各行各業的要求，包括：精密HSS DIN切削刀具、協助客戶設計刀具流程、DIN or JIS 鎢鋼切削刀具設計、NAS986 NAS965 NAS897 NAS937orNAS907 航太切削刀具,NAS航太刀具設計、超高硬度的切削刀具、醫療配件刀具設計、複合式再研磨機、PCD地板專用企口鑽石組合刀具、粉末造粒成型機、主機版專用頂級電桿、PCBN刀具、PCD刀具、單晶刀具、PCD V-Cut刀、捨棄式圓鋸片組、粉末成型機、航空機械鉸刀、主機版專用頂級電感、’汽車業刀具設計、電子產業鑽石刀具、木工產業鑽石刀具、銑刀與切斷複合再研磨機、銑刀與鑽頭複合再研磨機、銑刀與螺絲攻複合再研磨機等等。我們的產品涵蓋了從民生刀具到工業級的刀具設計；從微細刀具到大型刀具；從小型生產到大型量產；全自動整合；我們的技術可提供您連續生產的效能，我們整體的服務及卓越的技術，恭迎您親自體驗！！  

BW Bewise Inc. Willy Chen willy@tool-tool.com  bw@tool-tool.com  www.tool-tool.com skype:willy_chen_bw mobile:0937-618-190 Head &Administration Office No.13,Shiang Shang 2nd St., West Chiu Taichung,Taiwan 40356 http://www.tool-tool.com/ / FAX:+886 4 2471 4839 N.Branch 5F,No.460,Fu Shin North Rd.,Taipei,Taiwan S.Branch No.24,Sec.1,Chia Pu East Rd.,Taipao City,Chiayi Hsien,Taiwan

Welcome to BW tool world! We are an experienced tool maker specialized in cutting tools. We focus on what you need and endeavor to research the best cutter to satisfy users’ demand. Our customers involve wide range of industries, like mold & die, aerospace, electronic, machinery, etc. We are professional expert in cutting field. We would like to solve every problem from you. Please feel free to contact us, its our pleasure to serve for you. BW product including: cutting tool、aerospace tool .HSS  DIN Cutting tool、Carbide end mills、Carbide cutting tool、NAS Cutting tool、NAS986 NAS965 NAS897 NAS937orNAS907 Cutting Tools,Carbide end mill、disc milling cutter,Aerospace cutting tool、hss drill’Фрезеры’Carbide drill、High speed steel、Compound Sharpener’Milling cutter、INDUCTORS FOR PCD’CVDD(Chemical Vapor Deposition Diamond )’PCBN (Polycrystalline Cubic Boron Nitride) ’Core drill、Tapered end mills、CVD Diamond Tools Inserts’PCD Edge-Beveling Cutter(Golden Finger’PCD V-Cutter’PCD Wood tools’PCD Cutting tools’PCD Circular Saw Blade’PVDD End Mills’diamond tool. INDUCTORS FOR PCD . POWDER FORMING MACHINE ‘Single Crystal Diamond ‘Metric end mills、Miniature end mills、Специальные режущие инструменты ‘Пустотелое сверло ‘Pilot reamer、Fraises’Fresas con mango’ PCD (Polycrystalline diamond) ‘Frese’POWDER FORMING MACHINE’Electronics cutter、Step drill、Metal cutting saw、Double margin drill、Gun barrel、Angle milling cutter、Carbide burrs、Carbide tipped cutter、Chamfering tool、IC card engraving cutter、Side cutter、Staple Cutter’PCD diamond cutter specialized in grooving floors’V-Cut PCD Circular Diamond Tipped Saw Blade with Indexable Insert’ PCD Diamond Tool’ Saw Blade with Indexable Insert’NAS tool、DIN or JIS tool、Special tool、Metal slitting saws、Shell end mills、Side and face milling cutters、Side chip clearance saws、Long end mills’end mill grinder’drill grinder’sharpener、Stub roughing end mills、Dovetail milling cutters、Carbide slot drills、Carbide torus cutters、Angel carbide end mills、Carbide torus cutters、Carbide ball-nosed slot drills、Mould cutter、Tool manufacturer.

Bewise Inc.  www.tool-tool.com

ようこそＢｅｗｉｓｅ　Ｉｎｃ.の世界へお越し下さいませ、先ず御目出度たいのは新たな

情報を受け取って頂き、もっと各産業に競争力プラス展開。

弊社は専門なエンド・ミルの製造メーカーで、客先に色んな分野のニーズ、

豊富なパリエーションを満足させ、特にハイテク品質要求にサポート致します。

弊社は各領域に供給できる内容は：

（１）精密ＨＳＳエンド・ミルのＲ＆Ｄ

（２）Carbide Cutting tools設計

（３）鎢鋼エンド・ミル設計

（４）航空エンド・ミル設計

（５）超高硬度エンド・ミル

（６）ダイヤモンド・エンド・ミル

（７）医療用品エンド・ミル設計

（８）自動車部品＆材料加工向けエンド・ミル設計

弊社の製品の供給調達機能は：

（１）生活産業～ハイテク工業までのエンド・ミル設計

（２）ミクロ・エンド・ミル～大型エンド・ミル供給

（３）小Ｌｏｔ生産～大量発注対応供給

（４）オートメーション整備調達

（５）スポット対応～流れ生産対応

弊社の全般供給体制及び技術自慢の総合専門製造メーカーに貴方のご体験を御待ちしております。   

Bewise Inc. talaşlı imalat sanayinde en fazla kullanılan ve üç eksende (x,y,z) talaş kaldırabilen freze takımlarından olan Parmak Freze imalatçısıdır. Çok geniş ürün yelpazesine sahip olan firmanın başlıca ürünlerini Karbür Parmak Frezeler, Kalıpçı Frezeleri, Kaba Talaş Frezeleri, Konik Alın Frezeler, Köşe Radyüs Frezeler, İki Ağızlı Kısa ve Uzun Küresel Frezeler, İç Bükey Frezeler vb. şeklinde sıralayabiliriz.

BW специализируется в научных исследованиях и разработках, и снабжаем самым высокотехнологичным карбидовым материалом для поставки режущих / фрезеровочных инструментов для почвы, воздушного пространства и электронной индустрии. В нашу основную продукцию входит твердый карбид / быстрорежущая сталь, а также двигатели, микроэлектрические дрели, IC картонорезальные машины, фрезы для гравирования, режущие пилы, фрезеры-расширители, фрезеры-расширители с резцом, дрели, резаки форм для шлицевого вала / звездочки роликовой цепи, и специальные нано инструменты. Пожалуйста, посетите сайт  www.tool-tool.com  для получения большей информации.

BW is specialized in R&D and sourcing the most advanced carbide material with high-tech coating to supply cutting / milling tool for mould & die, aero space and electronic industry. Our main products include solid carbide / HSS end mills, micro electronic drill, IC card cutter, engraving cutter, shell end mills, cutting saw, reamer, thread reamer, leading drill, involute gear cutter for spur wheel, rack and worm milling cutter, thread milling cutter, form cutters for spline shaft/roller chain sprocket, and special tool, with nano grade. Please visit our web  www.tool-tool.com  for more info.