samarium

Samarium is a chemical element with the symbol Sm and atomic number 62. It is a soft, silvery metal of the lanthanide series and is typically found with other rare earth elements. In nature it occurs with minerals such as monazite and bastnasite and is obtained commercially as a byproduct of refining those elements. The element is relatively reactive in air and forms an oxide layer; its compounds can be colorless or lightly colored. The most common oxidation state is +3, though Sm2+ can occur under reducing conditions.

Samarium has several isotopes; naturally occurring samarium comprises a mix of stable isotopes and one long‑lived radioisotope, 147Sm, which decays to 143Nd with a long half life and is used in Sm–Nd dating.

Applications of samarium include high-performance magnets such as samarium–cobalt (SmCo) compounds, valued for high temperature resistance and magnetic stability. It also appears in catalysts, polishing powders, and phosphors. In nuclear technology, 149Sm is a strong neutron absorber and is used in control rods and as a burnable poison.

Historically, the element was identified in 1879 by Paul-Émile Lecoq de Boisbaudran in a mineral called samarskite; its name honors the Russian mineralogist Vasili Samarsky-Bykhovets.

Occurrence and production of samarium stem from its classification as a rare-earth element. It is produced primarily as a byproduct of mining other lanthanides, with major production centers in China and elsewhere. Refining involves complex separation from neighboring elements due to chemical similarity.