SM

Samarium (Sm) is a chemical element with the symbol Sm and atomic number 62. It is a soft, silvery metal in the lanthanide series and is considered a rare earth element. In nature, samarium occurs in several minerals, especially monazite and bastnasite, and is typically separated from other rare earths during ore processing by solvent extraction and ion-exchange methods. The most important isotope for dating is samarium-147, which decays to neodymium-143 with a half-life on the order of 106 billion years, providing a basis for Sm–Nd radiometric dating used in geology and planetary science. The most common oxidation state is +3.

Pure samarium is relatively reactive and oxidizes in air. It forms compounds such as the oxide Sm2O3 and various organometallics. In industry, samarium is best known for its role in samarium-cobalt magnets (SmCo), among the earliest high-performance permanent magnets, notable for strong magnetic strength and resistance to demagnetization at high temperatures. Samarium-doped materials are used in red phosphors for displays and lighting. Radioisotopes such as samarium-153 are used in medicine for palliative treatment of bone pain in cancer patients and in research.

Samarium was identified in 1879 by Paul-Émile Lecoq de Boisbaudran in the mineral samarskite and named after the mineral, which honors Russian mining engineer Vasili Samarsky-Bykhovets.