|a silvery metallic element of the lanthanide series occurring chiefly in monazite and bastnaesite and used in carbon-arc lighting, as a doping agent in laser crystals, and as a neutron-absorber. Symbol: Sm; atomic no: 62; atomic wt: 150.36; valency: 2 or 3; relative density: 7.520; melting pt: 1074°C; boiling pt: 1794°C|
|[C19: New Latin, from |
|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|
|a stew of meat, vegetables, potatoes, etc.|
samarium sa·mar·i·um (sə-mâr'ē-əm, -mār'-)
A metallic rare-earth element used in ferromagnetic alloys, in infrared absorbing glass, and as a neutron absorber in certain nuclear reactors. Atomic number 62; atomic weight 150.36; melting point 1,072°C; boiling point 1,790°C; specific gravity 7.52; valence 2, 3.
|samarium (sə-mâr'ē-əm) Pronunciation Key
A silvery-white metallic element of the lanthanide series that exists in several forms and has seven naturally occurring isotopes. It is used to make glass that absorbs infrared light and to absorb neutrons in the fuel rods of nuclear reactors. Atomic number 62; atomic weight 150.36; melting point 1,072°C; boiling point 1,791°C; specific gravity approximately 7.50; valence 2, 3. See Periodic Table.
(Sm), chemical element, rare-earth metal of the lanthanoid series of the periodic table. Samarium is silvery white in colour and is relatively stable in air. It was isolated as an impure oxide and spectroscopically identified as a new element (1879) by P.-E. Lecoq de Boisbaudran. Samarium occurs in many other rare-earth minerals but is almost exclusively obtained from monazite; it is also found in the products of nuclear fission. Ion-exchange techniques are used for its commercial separation and purification. The metal is conveniently prepared by the thermoreduction of its oxide, Sm2O3, with lanthanum metal, followed by distillation of the samarium metal, which is one of the most volatile rare-earth elements. Several allotropes (structural forms) of samarium exist; at room temperature its structure is rhombohedral
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