Tellur
Last updated
Last updated
It was discovered in 1782 by the Austrian chemist and mineralogist Franz Joseph Müller von Reichenstein, who initially considered it to be "sulfured bismuth." It wasn't until 1797 that the Berlin chemist Martin Heinrich Klaproth could verify the discovery. Klaproth was a luminary, a man who also discovered uranium, zirconium, and cerium, and he named the resource discovered by Müller von Reichenstein "tellurium." The name Tellurium is derived from the Latin word for "earth."
The electrical conductivity, like in all semiconductors, can be increased by raising the temperature or by exposure to light. However, in tellurium, this leads to only a slight increase. The electrical conductivity and thermal conductivity of tellurium are anisotropic, meaning they depend on direction. Crystalline tellurium is a soft (Mohs hardness 2.25) and brittle material, which can be easily processed into powder. Increasing the pressure transforms tellurium into other crystalline modifications. Above 450 °C, tellurium transitions into a red melt.
Tellurium is a versatile element. As an additive, it makes metal alloys more resistant to corrosion. Cadmium telluride is used in photovoltaics (thin-film solar cells). Tellurium is also found in coatings for submarine cables, in optical storage discs, and in specialty glasses for optical fibers. Additionally, tellurium is used in the vulcanization of rubber.
Tellurium is a technically less significant element because its production is expensive and it can often be replaced by other elements or compounds. Elementary tellurium is used in the metal industry as an additive for steel, cast iron, copper and lead alloys, as well as in stainless steels.
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| Properties | Value |
|---|---|
Melting Point
449,5 °C
Boiling Point
989,8°C
Specific Weight
6,25g/cm³
Mass fraction/Earth's crust
0,001 ppm
Color
silver white
Annual Production
ca. 180 t
Main Producers
Kanada, Japan, Peru
Usage
Alloys, solar cells, photodiodes, semiconductors, CDs/DVDs, vulcanization of rubber
