Samarium (Sm)

Stable isotopes of samarium available from ISOFLEX

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Samarium was discovered in 1879 by Paul-Émile Lecoq de Boisbaudran. It is named for the mineral samarskite, from which Lecoq de Boisbaudran isolated the new element. The mineral in turn takes its name from Vasili Samarsky-Bykhovets, the one-time chief of staff of the Russian Corps of Mining Engineers.

Samarium is a hard, brittle, yellow metal, which quickly develops an oxide film in air. Its hardness is similar to that of iron. It exhibits two crystal forms: an alpha form, with a rhombohedral crystal structure at ordinary temperatures, changes to the body-centered cubic form at 917 ºC. The densities of the two forms are 7.52 g/cm³ and 7.40 g/cm³, respectively. Samarium is insoluble in water and soluble in acid. It is stable in dry air at ordinary temperatures; however, it oxidizes in moist air, forming an oxide coating. The metal ignites in air at about 150 ºC. It is an active reducing agent (it reduces several metal oxides to metals), and it liberates hydrogen from water. Among samarium's trivalent salts, the sesquioxide is commercially important, and the divalent compounds are primarily halides. The trivalent salts of these halogens are more stable than their divalent counterparts.

Samarium salts are used in optical glass, capacitors, thermoionic generating devices and sensitizers of phosphors. The metal is doped with calcium fluoride crystals for use in lasers. It is also used with other rare earths for carbon-arc lighting. Its alloys are used in permanent magnets.

Properties of Samarium

Research

• Isotope geochemistry and revised geochronology of the Purrido Ophiolite (Cabo Ortegal Complex, NW Iberian Massif): Devonian magmatism with mixed sources and involved Mesoproterozoic basement
• Chemical separation of Nd from geological samples for chronological studies using ¹⁴⁶Sm–¹⁴²Nd and ¹⁴⁷Sm–¹⁴³Nd systematics