Tellurium is a chemical element with the symbol Te and atomic number 52. It is a brittle, mildly toxic, silver-white metalloid which looks similar to tin. Tellurium is chemically related to selenium and sulfur. It is primarily used in alloys, and only about 5% of tellurium production goes into making single element compounds (tellurides). The primary use for tellurium compounds is as semiconductors in infrared detectors, photocells and solar cells.
Applications in Electronics
Semiconductor applications make up the bulk of demand for tellurium. In fact, it was the first well known application for this element. German chemist Ferdinand Reich discovered tellurium while studying samples of an iron ore called stibnite that came from Joachimsthal in Bohemia (now part of the Czech Republic). He named it after the Latin word for earth, tellus. At that time, other chemists were trying to find a new metal similar to antimony or bismuth that could be used in strengthening lead or copper alloys.
Tellurium was identified as such an element and its ability to improve the properties of other metals was quickly exploited commercially. For example, adding just 0.1% tellurium to lead increases its malleability (the ability to be hammered into shape) by 10 times whilst also making it more resistant against corrosion by acids. This combination made “acid-proof” lead an important material for pipes carrying corrosive fluids such as sewage – particularly before modern plastics became available.
The most important application for telluride semiconductors today is probably in cadmium zinc sulfide (CZTS) solar cells where they are used as absorber layers because CZTS has similar optical absorption properties to silicon but can be made using solution processing techniques rather than expensive high-vacuum crystal growth methods. Other solution processed semiconductor materials such as copper indium gallium selenide (CIGS) also use small amounts of tellurides in their devices.