BOILING POINT: 2,567°C
DENSITY: 8,551/kg m −3
MOST COMMON IONS: Dy 4+ , Dy 3+ , Dy 2+
Dysprosium, taking its name from the Greek word dysprositos, meaning "hard to obtain," is a metallic element, discovered, but not isolated, in 1886 in Paris by the French scientist Paul-Émile Lecoq de Boisbaudran. Its isolation was made possible by the development of ion-exchange separation in the 1950s. Dysprosium belongs to a series of elements called rare earths , lanthanides , or "4f elements." The occurrence of dysprosium is low: 4.5 ppm (parts per million), that is, 4.5 grams per metric ton in Earth's crust, and 2 × 10 −7 ppm in seawater. Two minerals that contain many of the rare earth elements (including dysprosium) are commercially important: monazite (found in Australia, Brazil, India, Malaysia, and South Africa) and bastnasite (found in China and the United States). As a metal , dysprosium is reactive and yields easily oxides or salts of its triply oxidized form (Dy 3+ ion).
Dysprosium or its compounds are used in small quantities in several high-technological applications owing to their thermal, magnetic, and optical properties. For instance, dysprosium is susceptible to large magnetization and is a part of special magnetic alloys (e.g., those used for data storage on CDs). A cermet (a combination of a heat resistant ceramic with a metal) of dysprosium oxide and nickel enables the control of nuclear reactors, as it easily absorbs neutrons. Dysprosium is put into mercury-vapor lamps and several materials used to generate lasers, to enhance their optical properties. Dysprosium-cadmium chalcogenides are a source of infrared radiation. Some special purpose eyeglasses (e.g., those worn by glassblowers) contain dysprosium.
Kaltsoyannis, Nikolas, and Scott, Peter (1999). The f Elements. New York: Oxford University Press.