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About Tellurium

Tellurium Bohr

Tellurium was discovered in Franz Joseph Muller in 1782 when he isolated it as a trace component from a sample of gold ore. He initially believed his find to be antimony, but eventually realized its properties did not match any known element and reported his findings to other chemists. In 1798, Martin Heinrich Klaproth completed further tests to confirm that a new element had in fact been discovered, and named it “tellurium”, meaning “earth.”

Tellurium is a brittle, silver-white, semiconducting metalloid that also exhibits mild photoconductivity. One of the largest uses for tellurium are in semiconducting compound materials that exploit its unique electrical properties. Cadmium telluride is particularly well known as the basis for a type of thin film solar cell that can be manufactured with relatively little impact on the environment and used in some installations at a comparable cost to traditional silicon cells. Cadmium zinc telluride is likewise used in solar cells, as well as in radiation detectors, terahertz wave generation and detection devices, electro-optic modulators, solid-state x-ray detectors, and photoreactive gratings. When tellurium is added as a dopant to zinc selenide, the resultant material is a scintillator material used in x-ray and gamma ray detectors. Bismuth telluride and lead telluride are both thermoelectric materials used in thermoelectric refrigeration and in portable thermal generators. Additionally, tellurium’s photoconductivity once lent it to use along with the similar element selenium in photocopiers, however modern photocopiers use organic photoconductors in place of these elements.

Tellurium also plays a significant role in technology in the form of chalcogenide glasses. These glasses, made using sulfur, selenium, or tellurium compounds, exhibit high refractive indices and non-linear optical effects, and are frequently used in optical fibers for telecommunications, lasers, photonic integrated circuits, and other optical applications. Additionally, some chalcogenide glasses including GeSbTe and AgInSbTe undergo predictable changes in crystal structure driven by thermal energy, and this property is exploited in rewritable optical disks and phase-change computer memory.

Another major use of tellurium is as an additive to metal alloys. It is used primarily to improve the machinability of steel or copper, and to improve strength and durability of lead. It is also found in some forms of cast iron. Additionally, telluride compounds may be used as pigments to color ceramics, as components of blasting caps, or as catalysts for some industrial chemical processes.

Tellurium is a relatively rare element, and is produced commercially mostly from byproducts of electrolytic copper refining. Tellurium is also occasionally recovered from old devices which contained it, most often outdated photocopiers.

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Tellurium is a p-type semiconductor, and shows greater conductivity in certain directions, depending on alignment of the atoms. Many tellurium compounds exhibit photoconductivity--their conductivity increases slightly with exposure to light--which makes many tellurides candidates for solar energy applications. Tellurium improves the machinability of copper and stainless steel, and its addition to lead improves its strength and hardness. High Purity (99.999%) Tellurium Oxide (TeO2) PowderTellurium is used as a basic ingredient in blasting caps, and is added to cast iron for chill control. Tellurium is used in ceramics. Bismuth telluride has been used in thermoelectric devices. High Purity (99.99999%) Tellurium (Te) Sputtering TargetTellurium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Tellurium oxides are available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Tellurium fluoride is another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Tellurium is also available in soluble forms including chlorides and nitrates. These compounds can be manufactured as solutions at specified stoichiometries.

Tellurium Properties

Tellurium (Te) atomic and molecular weight, atomic number and elemental symbolTellurium is a Block P, Group 16, Period 5 element. The number of electrons in each of Tellurium's shells is 2, 8, 18, 18, 6 and its electron configuration isTellurium Bohr Model[Kr] 4d10 5s2 5p4. In its elemental form tellurium's CAS number is 13494-80-9. The tellurium atom has a radius of and its Van der Waals radius is Tellurium is most commonly sourced from the anode sludges produced as a byproduct of copper refining. Elemental Tellurium Tellurium was first discovered by Franz Muller von Reichenstein in 1782. The name Tellurium originates from the Greek word 'Tellus' meaning Earth.

Symbol: Te
Atomic Number: 52
Atomic Weight: 127.6
Element Category: metalloid
Group, Period, Block: 16 (chalcogens), 5, p
Color: silvery lustrous gray/ silvery
Other Names: Tellur, Telúrio
Melting Point: 449.51°C, 841.118°F, 722.66 K
Boiling Point: 988°C, 1810.4°F, 1261.15 K
Density: 6247 kg·m3
Liquid Density @ Melting Point: 5.70 g·cm3
Density @ 20°C: 6.24 g/cm3
Density of Solid: 6240 kg·m3
Specific Heat: 0.0481 Cal/g/K @ 25°C
Superconductivity Temperature: N/A
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 13.5
Heat of Vaporization (kJ·mol-1): 104.6
Heat of Atomization (kJ·mol-1): 197
Thermal Conductivity: (1.97–3.38) W·m-1·K-1
Thermal Expansion: N/A
Electrical Resistivity: 4.36x10(5) nΩ-cm @ 25°C
Tensile Strength: N/A
Molar Heat Capacity: 25.73 J·mol-1·K-1
Young's Modulus: 43 GPa
Shear Modulus: 16 GPa
Bulk Modulus: 65 GPa
Poisson Ratio: N/A
Mohs Hardness: 2.25
Vickers Hardness: N/A
Brinell Hardness: 180 MPa
Speed of Sound: (20 °C) 2610 m·s-1
Pauling Electronegativity: 2.1
Sanderson Electronegativity: 2.62
Allred Rochow Electronegativity: 2.01
Mulliken-Jaffe Electronegativity: 2.41 (16.7% s orbital)
Allen Electronegativity: 2.158
Pauling Electropositivity: 1.9
Reflectivity (%): 50
Refractive Index: 1.000991
Electrons: 52
Protons: 52
Neutrons: 76
Electron Configuration: [Kr] 4d10 5s2 5p4
Atomic Radius: 140 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 138±4 pm
Covalent Radius (Å): 1.37
Van der Waals Radius: 206 pm
Oxidation States: 6, 4, -2
Phase: Solid
Crystal Structure: hexagonal
Magnetic Ordering: diamagnetic
Electron Affinity (kJ·mol-1) 190.173
1st Ionization Energy: 869.3 kJ·mol-1
2nd Ionization Energy: 1794.64 kJ·mol-1
3rd Ionization Energy: 2697.75 kJ·mol-1
CAS Number: 13494-80-9
EC Number: 236-813-4
MDL Number: MFCD00134062
Beilstein Number: N/A
SMILES Identifier: [Te]
InChI Identifier: InChI=1S/Te
PubChem CID: 6327182
ChemSpider ID: 4885717
Earth - Total: 1490 ppb 
Mercury - Total: 122 ppb
Venus - Total: 830 ppb
Earth - Seawater (Oceans), ppb by weight: N/A
Earth - Seawater (Oceans), ppb by atoms: N/A
Earth -  Crust (Crustal Rocks), ppb by weight: 1
Earth -  Crust (Crustal Rocks), ppb by atoms: 0.2
Sun - Total, ppb by weight: N/A
Sun - Total, ppb by atoms: N/A
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 2100
Meterorite (Carbonaceous), ppb by atoms: 300
Typical Human Body, ppb by weight: N/A
Typical Human Body, ppb by atom: N/A
Universe, ppb by weight: 9
Universe, ppb by atom: 0.09
Discovered By: Franz-Joseph Müller von Reichenstein
Discovery Date: 1782
First Isolation: Martin Heinrich Klaproth

Health, Safety & Transportation Information for Tellurium

Safety data for Tellurium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental Tellurium.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Danger
Hazard Statements H301
Hazard Codes T
Risk Codes 25
Safety Precautions 45
RTECS Number WY2625000
Transport Information UN 3288 6.1/PG 3
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Skull and Crossbones-Acute Toxicity

Tellurium Isotopes

Tellurium has six stable isotopes: 120Te, 122Te, 123Te, 124Te, 125Te and 126Te.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
105Te 104.94364(54)# 1# µs Unknown 5/2+# N/A 845.82 -
106Te 105.93750(14) 70(20) µs [70(+20-10) µs] a to 102Sn 0+ N/A 863.21 -
107Te 106.93501(32)# 3.1(1) ms a to 103Sn; ß+ to 107Sb 5/2+# N/A 871.29 -
108Te 107.92944(11) 2.1(1) s ß+ to 108Sb; a to 104Sn; ß+ + p to 107Sb; ß+ + a to 104Ln 0+ N/A 888.68 -
109Te 108.92742(7) 4.6(3) s ß+ to 109Sb; ß+ + p to 108Sb; a to 105Sn ; ß+ + a to 105Ln (5/2+) N/A 896.76 -
110Te 109.92241(6) 18.6(8) s ß+ to 110Sb; ß+ + p to 110Sb 0+ N/A 904.84 -
111Te 110.92111(8) 19.3(4) s ß+ to 111Sb (5/2)+# N/A 912.92 -
112Te 111.91701(18) 2.0(2) min ß+ to 112Sb 0+ N/A 930.31 -
113Te 112.91589(3) 1.7(2) min ß+ to 113Sb (7/2+) N/A 938.39 -
114Te 113.91209(3) 15.2(7) min ß+ to 114Sb 0+ N/A 946.47 -
115Te 114.91190(3) 5.8(2) min ß+ to 115Sb 7/2+ N/A 954.55 -
116Te 115.90846(3) 2.49(4) h EC to 116Sb 0+ N/A 971.95 -
117Te 116.908645(14) 62(2) min EC to 117Sb 1/2+ N/A 980.02 -
118Te 117.905828(16) 6.00(2) d EC to 118Sb 0+ N/A 988.1 -
119Te 118.906404(9) 16.05(5) h EC to 119Sb 1/2+ 0.25 996.18 -
120Te 119.90402(1) Observationally Stable - 0+ N/A 1004.26 0.09
121Te 120.904936(28) 19.16(5) d EC to 121Sb 1/2+ N/A 1012.34 -
122Te 121.9030439(16) STABLE - 0+ N/A 1020.42 2.55
123Te 122.9042700(16) >600E+12 y - 1/2+ -0.73679 1028.5 0.89
124Te 123.9028179(16) STABLE - 0+ N/A 1036.58 4.74
125Te 124.9044307(16) Observationally Stable - 1/2+ -0.88828 1044.65 7.07
126Te 125.9033117(16) STABLE - 0+ N/A 1052.73 18.84
127Te 126.9052263(16) 9.35(7) h ß- to 127I 3/2+ 0.64 1060.81 -
128Te 127.9044631(19) 2.2(3)E+24 y - to 128Xe 0+ N/A 1068.89 31.74
129Te 128.9065982(19) 69.6(3) min ß- to 129I 3/2+ 0.7 1076.97 -
130Te 129.9062244(21) 790(100)E+18 y - to 130Xe 0+ N/A 1085.05 -
131Te 130.9085239(21) 25.0(1) min ß- to 131I 3/2+ N/A 1093.13 -
132Te 131.908553(7) 3.204(13) d ß- to 132I 0+ N/A 1101.21 -
133Te 132.910955(26) 12.5(3) min ß- to 133I (3/2+) N/A 1099.97 -
134Te 133.911369(11) 41.8(8) min ß- to 134I 0+ N/A 1108.05 -
135Te 134.91645(10) 19.0(2) s ß- to 135I (7/2-) N/A 1116.12 -
136Te 135.92010(5) 17.63(8) s ß- to 136I; ß- + n to 135I 0+ N/A 1114.89 -
137Te 136.92532(13) 2.49(5) s ß- to 137I; ß- + n to 136I 3/2-# N/A 1122.97 -
138Te 137.92922(22)# 1.4(4) s ß- to 138I; ß- + n to 137I 0+ N/A 1131.04 -
139Te 138.93473(43)# 500# ms [>300 ns] ß- to 139I; ß- + n to 138I 5/2-# N/A 1129.81 -
140Te 139.93885(32)# 300# ms [>300 ns] ß- to 140I; ß- + n to 139I 0+ N/A 1137.89 -
141Te 140.94465(43)# 100# ms [>300 ns] ß- to 141I; ß- + n to 140I 5/2-# N/A 1136.65 -
142Te 141.94908(64)# 50# ms [>300 ns] ß- to 142I 0+ N/A 1144.73 -