Tellurium is critical to efficient, thin-film photovoltaic cells that produce electricity from sunlight. Several materials can replace tellurium in most of its uses, but with losses in efficiency and product characteristics. With the shift to green-energy living, tellurium use is only expected to grow, and quickly.
The primary concern surrounding tellurium is supply. In fact, the U.S. Department of Energy has estimated that the demand for tellurium will cause supply deficiency by 2025. Considering that most of the tellurium used by the United States is imported, and that all tellurium production in the U.S. is from a single refinery in Texas, it cannot be disputed that trade wars and geopolitical tensions could limit the ability of the U.S. to secure necessary tellurium resources in the future.
Beyond the basics above, what else should we know about tellurium? Check out the 20 interesting facts below!
- Tellurium was discovered in compound form with gold by Franz-Joseph Müller von Reichenstein in 1782 in Transylvania, Romania. Müller was an Austrian mineralogist and mining engineer. Müller was unable to identify the new material he had found. In 1798, he sent a sample to Martin Heinrich Klaproth, an esteemed German chemist and the discoverer of uranium (1789), zirconium (1789) and cerium (1803). Klaproth isolated a new element from the sample and named it tellurium after the Latin word “tellus,” for Earth.
- Hungarian scientist Pál Kitaibel discovered tellurium independently in 1789, but he later gave the credit to Müller.
- In 1832, in Stockholm, Sweden, Jons Jacob Berzelius made a detailed study of tellurium and its compounds. He decided that tellurium was a metal, but belonged in the same group as the nonmetals sulfur and selenium due to the similarities of their compounds.
- The 1960s brought growth in thermoelectric applications for tellurium, as well as its use in free-machining steel, which became the dominant use.
- From 2014 to 2017, U.S. import sources of tellurium were: Canada, 66%; China, 27%; Germany, 3%; and other, 4%.
- In May 2018, the U.S. Department of the Interior, in coordination with other executive branch agencies, published a list of 35 critical minerals (83 FR 23295), including tellurium. This list was developed to serve as an initial focus, pursuant to Executive Order 13817, ‘‘A Federal Strategy to Ensure Secure and Reliable Supplies of Critical Minerals” (82 FR 60835).
- Tellurium is one of the least common elements on Earth – most rocks contain an average of about 3 parts per billion tellurium, making it rarer than the rare earth elements and eight times less abundant than gold.
- China is by far the leading global producer of tellurium.
- Tellurium is presently recovered as a primary ore from only two districts in the world; these are the gold-tellurium epithermal vein deposits located adjacent to one another at Dashuigou and Majiagou (Sichuan Province) in southwestern China, and the epithermal-like mineralization at the Kankberg deposit in the Skellefteå VMS district of Västerbotten County, Sweden. Combined, these two groups of deposits account for about 15 percent of the annual global production of tellurium.
- Despite the presence of tellurium in gold vein deposits, most of the world’s tellurium is produced as a byproduct of the mining of porphyry copper deposits.
- The refining of 550 tons of copper is required to produce one pound of tellurium.
- Tellurium is a metalloid, meaning it possesses the properties of both metals and nonmetals.
- Native tellurium typically appears as a brittle, silver-white substance.
- Tellurium has an atomic number of 52 and an atomic weight of 127.6.
- Tellurium is the lightest element to exhibit alpha decay.
- Tellurium combines with elements that are incapable of reducing their volume upon losing valence electrons.
- Global consumption estimates of tellurium by end use are solar, 40%; thermoelectric production, 30%; metallurgy, 15%; rubber applications, 5%; and other, 10%.
- Tellurium is essential for production of cadmium telluride (CdTe) for CdTe thin-film solar cells, photoreceptor and thermoelectric devices, integrated circuits, laser diodes, and medical instrumentation.
- As an alloying additive in steel, copper, lead, and iron, tellurium is used to improve machining characteristics, specifically in thermoelectric cooling applications where it improves ductility and tensile strength, and helps prevent sulfuric acid corrosion. When alloyed with cadmium, tellurium forms a compound that exhibits enhanced electrical conductivity.
- Tellurium finds essential use in many industrial applications: vulcanizing agent and accelerator in the processing of rubber and other durable products, catalyst for synthetic fiber production, blasting caps, pigment in glass and ceramics.