|Paris—Paul-Émile Lecoq de Boisbaudran elements
After Per Teodor Cleve separated holmium and thulium from erbium oxide, Paul-Émile Lecoq de Boisbaudran separated dysprosium oxide from holmium oxide by dissolving the holmium oxide in acid and precipitating the solution with ammonia.
Atomic number 66
Dysprosium is never free in nature. Seven stable isotopes are mixed in many minerals. The “D” in the name of the magnetostrictive alloy Terfenol-D stands for dysprosium. Neodymium-iron-boron magnets can have a little dysprosium to raise their resistance to corrosion and demagnetization. High-intensity metal-halide lamps may contain dysprosium halides. Adiabatic demagnetization refrigerators use paramagnetic crystal salts of dysprosium.
Hard to obtain
Lecoq named the new element dysprosium, meaning “hard to obtain” in Greek, because it had repeated his chemical procedure more than thirty times before any dysprosium appeared.