Overview

Dysprosium was identified in 1886 by the French chemist Paul-Emile Lecoq de Boisbaudran, after a long struggle to separate it from holmium. Its name comes from the Greek dysprositos, hard to get at, a wry acknowledgement of the difficulty he had faced in isolating it. Dysprosium is a soft, silvery rare-earth metal, important today for the high-temperature performance of neodymium magnets and for control rods in nuclear reactors. Its strong magnetism and appetite for neutrons make dysprosium valuable in magnets that must work hot, as in electric-vehicle and wind-turbine motors, and in reactor control rods, though its scarcity makes it one of the more critical rare earths.

Adding even a few per cent of dysprosium to a neodymium-iron-boron magnet substantially raises its coercivity, its resistance to losing magnetism as it heats up, which is why electric-vehicle traction motors, which run hot under sustained load, depend on dysprosium-doped magnets even though dysprosium itself is scarcer and pricier than the neodymium it reinforces. At extremely low temperatures dysprosium compounds also show some of the largest magnetocaloric effects known, a property explored for magnetic refrigeration, a potentially more efficient alternative to conventional gas-compression cooling.