Tellurium



52 iodine
Po
General
Number tellurium, Te, 52
metalloids
Block p
Appearance silvery lustrous gray
(3)  g·mol−1
Kr] 5s2 4d10 5p4
shell 2, 8, 18, 18, 6
Physical properties
Phase solid
r.t.) 6.24  g·cm−3
Liquid m.p. 5.70  g·cm−3
F)
F)
kJ·mol−1
kJ·mol−1
Heat capacity (25 °C) 25.73  J·mol−1·K−1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K)     (775) (888) 1042 1266
Atomic properties
Crystal structure hexagonal
acidic oxide)
Electronegativity 2.1 (Pauling scale)
more) 1st:  869.3  kJ·mol−1
2nd:  1790  kJ·mol−1
3rd:  2698  kJ·mol−1
Atomic radius 140  pm
Atomic radius (calc.) 123  pm
Covalent radius 135  pm
Van der Waals radius 206 pm
Miscellaneous
Magnetic ordering nonmagnetic
Thermal conductivity (300 K)
(1.97–3.38)  W·m−1·K−1
Speed of sound (thin rod) (20 °C) 2610 m/s
Young's modulus 43  GPa
Shear modulus 16  GPa
Bulk modulus 65  GPa
Mohs hardness 2.25
Brinell hardness 180  MPa
CAS registry number 13494-80-9
Selected isotopes
Main article: Isotopes of tellurium
iso NA half-life DM DE (MeV) DP
120Te 0.09% >2.2×1016y ε ε 1.701 120Sn
121Te syn 16.78 d ε 1.040 121Sb
122Te 2.55% Te is neutrons
123Te 0.89% >1.0×1013 y ε 0.051 123Sb
124Te 4.74% Te is neutrons
125Te 7.07% Te is neutrons
126Te 18.84% Te is neutrons
127Te syn 9.35 h β- 0.698 127I
128Te 31.74% 2.2×1024 y β−β− 0.867 128Xe
129Te syn 69.6 min β- 1.498 129I
130Te 34.08% 7.9×1020 y β−β− 2.528 130Xe
References

Tellurium (semiconductor.

Contents

Notable characteristics

Tellurium is extremely rare, one of the chalcogens).

When acid (Te(OH)6). However, there is some debate whether this form is really amorphous or made of minute crystals.

Applications

Tellurium is a p-type sulfur, the conductivity of this element increases slightly when exposed to light.

It can be doped with stainless steel.

Tellurium gives a greenish-blue flame when burned in normal air and forms tellurium dioxide as a result.

Metal alloys

Other uses:

  • Used in ceramics.
  • It is used in chalcogenide glasses.
  • Tellurium is also used in blasting caps
  • Organic tellurides have also been employed as initiators for living radical polymerisation and electron-rich mono- and di-tellurides possess antioxidant activity.

High purity selenium and tellurium are used in the semiconductor industry, and are prepared by adduct purification. [1][2]

Semiconductor and electronic industry uses:

  • Tellurium is used in the media layer of ReWritable Compact Discs (CD-RW).
  • Tellurium is used in the media layer of ReWritable Digital Video Discs (DVD-RW).
  • Tellurium is used in the new phase change memory chips developed by Intel. See phase change memory. Also see here.
  • Tellurium is used in the media layer of ReWritable Blu-Ray DVD. See here.
  • Tellurium has potential applications in cadmium telluride (CdTe) solar panels. Some of the highest efficiencies for solar cell electric power generation have been obtained by using this material. 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 x-ray detectors.
  • Alloyed with both cadmium and MOVPE.

History

Tellurium (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 Klaproth who 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.

Occurrence

With an abundance in the Earth's crust even lower than lanthanides have crustal abundances of 0.5 ppm.

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 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 lead. Treatment of 500 tons of copper ore typically yields one pound of tellurium. Tellurium is produced mainly in the US, Canada, Peru, and Japan. 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 driven up by increased demand and limited supply, reaching as high as US$100 per pound in 2006. See also here.

See also: Telluride, Colorado, category:Telluride minerals

 

Compounds

Tellurium is in the same series as tellurites TeO32-. Also tellurols –TeH, named with prefix tellanyl- or suffix -tellurol.

See also: Category:Tellurium compounds

Isotopes

Main article: isotopes of tellurium

There are 30 known 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.[citation needed]

Precautions

Tellurium and tellurium compounds should be considered to be mildly toxic and need to be handled with care.

Acute poisoning is rare.[3] Tellurium is not reported to be carcinogenic.[3]

Humans exposed to as little as 0.01 mg/m3 or less in air develop "tellurium breath", which has a garlic-like odor.[4] 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.

References

  1. ^ doi:10.1016/0022-0248(88)90613-6 Journal of Crystal Growth Volume 93, Issues 1-4 , 1988, Pages 744-749
  2. ^ U.S. Patent 5,117,021  Method for purification of tellurium and selenium alkyls
  3. ^ a b Harrison, W; S Bradberry, J Vale (1998-01-28). Tellurium (HTML). International Programme on Chemical Safety. Retrieved on 2007-01-12.
  4. ^ Tellurium (HTML). Los Alamos National Laboratory (2003-12-15). Retrieved on 2007-01-12.
 
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