Samarium

Samarium, chemical element, symbol Sm; for physical constants see Periodic Table. Samarium was discovered spectroscopically in 1879 by Paul Émile Lecoq de Boisbaudran in the mineral samarskite. It is found in the minerals monazite and bastnasite, which are commercial sources. It is present to the extent of 1% in misch metal. The metal is prepared by reducing the oxide with barium. Samarium is a silvery, reactive metal. Ion-exchange and solvent extraction techniques have led to much easier isolation of the so-called rare-earth elements. An alloy of samarium with cobalt is used to make a permanent magnet with the highest resistance to demagnetization of any known material. Samarium and its compounds are used in carbon-arc lighting applications, permanent magnets, special glasses, and organic catalysts and as a neutron absorber in nuclear reactors.