What is "samarium"

Samarium \Sa*ma"ri*um\, n. [NL., fr. E. samarskite.] (Chem.) A rare metallic element of doubtful identity.

Note: Samarium was discovered, by means of spectrum analysis, in certain minerals (samarskite, cerite, etc.), in which it is associated with other elements of the earthy group. It has been confounded with the doubtful elements decipium, philippium, etc., and is possibly a complex mixture of elements not as yet clearly identified. Symbol Sm. Provisional atomic weight 150.2.

n. A metallic chemical element (''symbol'' Sm) with an atomic number of 62.

n. a gray lustrous metallic element of the rare earth group; is used in special alloys; occurs in monazite and bastnasite [syn: Sm, atomic number 62]

Samarium is a chemical element with symbol Sm and atomic number 62. It is a moderately hard silvery metal that readily oxidizes in air. Being a typical member of the lanthanide series, samarium usually assumes the oxidation state +3. Compounds of samarium(II) are also known, most notably the monoxide SmO, monochalcogenides SmS, SmSe and SmTe, as well as samarium(II) iodide. The last compound is a common reducing agent in chemical synthesis. Samarium has no significant biological role and is only slightly toxic.

Samarium was discovered in 1879 by the French chemist Paul Émile Lecoq de Boisbaudran and named after the mineral samarskite from which it was isolated. The mineral itself was earlier named after a Russian mine official, Colonel Vasili Samarsky-Bykhovets, who thereby became the first person to have a chemical element named after him, albeit indirectly. Although classified as a rare earth element, samarium is the 40th most abundant element in the Earth's crust and is more common than such metals as tin. Samarium occurs with concentration up to 2.8% in several minerals including cerite, gadolinite, samarskite, monazite and bastnäsite, the last two being the most common commercial sources of the element. These minerals are mostly found in China, the United States, Brazil, India, Sri Lanka and Australia; China is by far the world leader in samarium mining and production.

The major commercial application of samarium is in samarium-cobalt magnets, which have permanent magnetization second only to neodymium magnets; however, samarium compounds can withstand significantly higher temperatures, above , without losing their magnetic properties, due to the alloy's higher Curie point. The radioactive isotope samarium-153 is the major component of the drug samarium (Sm) lexidronam (Quadramet), which kills cancer cells in the treatment of lung cancer, prostate cancer, breast cancer and osteosarcoma. Another isotope, samarium-149, is a strong neutron absorber and is therefore added to the control rods of nuclear reactors. It is also formed as a decay product during the reactor operation and is one of the important factors considered in the reactor design and operation. Other applications of samarium include catalysis of chemical reactions, radioactive dating and an X-ray laser.