Appearance and Characteristics
Harmful effects:
Tellurium is very toxic and teratogenic (can cause harm to developing embryos). Exposure to as little as 0.01 mg/m2 or less in air leads to “tellurium breath”, which has a garlic-like odor.
Characteristics:
Tellurium is a rare, silvery-white, brittle, lustrous metalloid. It burns in air with a greenish-blue flame and forms white tellurium dioxide (TeO2). When present in compounds, tellurium exists mostly in the oxidation state IV and VI. Tellurium is a semiconductor material and is slightly photosensitive. It forms many compounds corresponding to those of sulfur and selenium, the elements above it in the periodic table. For example, it forms tellurides with other metals and tellurite (TeO32-) and tellurate (TeO42-) compounds. Tellurium has radioactive isotopes and is the lightest element to exhibit alpha decay.
Uses of Tellurium
Tellurium is alloyed with copper and stainless steel to make these metals more workable. It is added at very low levels to lead to decreases the corrosive action of sulfuric acid in batteries and to improve the lead’s strength and hardness. Tellurium is used as a coloring agent in ceramics.
Tellurium is also used in the electronics industry, for example with cadmium and mercury to form photosensitive semiconductors. Cadmium telluride (CdTe) is used as a thin film in solar panels to convert sunlight into electricity. CdTe panels have an efficiency rating of between 11 and 13 percent compared to amorphous silicon solar panels which have an efficiency of between 7 to 9 percent.
It is used in vulcanizing rubber and in catalysts for petroleum cracking and in blasting caps for explosives.