samarium


Also found in: Dictionary, Thesaurus, Medical, Financial, Acronyms, Wikipedia.
Related to samarium: europium, samarium oxide

samarium

(səmâr`ēəm), metallic chemical element; symbol Sm; at. no. 62; at. wt. 150.36; m.p. 1,072°C;; b.p. 1,791°C;; sp. gr. 7.54 at 20°C;; valence +2 or +3. Samarium is a lustrous silver-white metal. It is one of the rare-earth metalsrare-earth metals,
in chemistry, group of metals including those of the lanthanide series and actinide series and usually yttrium, sometimes scandium and thorium, and rarely zirconium. Promethium, which is not found in nature, is not usually considered a rare-earth metal.
..... Click the link for more information.
 of the lanthanide serieslanthanide series,
a series of metallic elements, included in the rare-earth metals, in Group 3 of the periodic table. Members of the series are often called lanthanides, although lanthanum (atomic number 57) is not always considered a member of the series.
..... Click the link for more information.
 in Group 3 of the periodic tableperiodic table,
chart of the elements arranged according to the periodic law discovered by Dmitri I. Mendeleev and revised by Henry G. J. Moseley. In the periodic table the elements are arranged in columns and rows according to increasing atomic number (see the table entitled
..... Click the link for more information.
. It has two crystalline forms (see allotropyallotropy
[Gr.,=other form]. A chemical element is said to exhibit allotropy when it occurs in two or more forms in the same physical state; the forms are called allotropes.
..... Click the link for more information.
). The metal does not oxidize at room temperature but ignites when heated above 150°C;. Samarium is found widely distributed in nature; it is obtained commercially from the minerals monazitemonazite
, yellow to reddish-brown natural phosphate of the rare earths, mainly the cerium and lanthanum metals, usually with some thorium. Yttrium, calcium, iron, and silica are frequently present.
..... Click the link for more information.
 and bastnasite. Naturally occurring samarium is a mixture of seven isotopes, three of which are radioactive with extremely long half-lives. The metal was not isolated in relatively pure form until recently, although it has long been used in pyrophoric alloys used in cigarette lighter flints. Samarium is used as a catalyst in certain organic reactions. A samarium-cobalt compound, SmCo5, is used to make magnets for use in computer memories. The oxide, samaria, is used in special infrared absorbing glass and cores of carbon arc-lamp electrodes. Since one isotope of samarium is a good neutron absorber, the element has found use in nuclear reactor control rods. Samarium was discovered in 1879 by P. E. Lecoq de Boisbaudran by spectroscopic analysis of the mineral samarskite.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/

samarium

[sə′mar·ē·əm]
(chemistry)
A rare-earth metal, atomic number 62, symbol Sm; melts at 1350°C, tarnishes in air, ignites at 200-400°C.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

samarium

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
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
For calculation of intensity ratio, the narrow bands (5 nm) of host luminescence around 520 nm and the samarium line at 602 nm were used and integrated in time from their beginning.
Moreover, signs of Sm clusters were not noticed, which display that the samarium atoms successfully replaced the regular Zn sites.
No presence of samarium shows the doping of Sm into the lattice of CeO2 which can be seen in XRD results.
Inelastic scattering of hellions from even-even stable samarium isotopes at 40.9 MeV.
Neodymium and samarium are critical to the strength of the US's national defense industry, but the current supply of these metals is entirely external to the country.
(37) Equally important are plans to resume mining of fresh ore having an approximate 12 percent content of neodymium and samarium. (38) This development is encouraging, but makes it even more disturbing to remember that this mine, perhaps the largest non-Chinese rare earth deposit in the world, was nearly purchased by China's state-owned China National Offshore Oil Corporation (CNOOC) as part of their bid for the oil company Unocal in 2005.
Uses of Specific Rare Earth Elements Magnets Magnets for Batteries for Wind for Element Vehicles Turbines Vehicles Lighting Yttrium X Dysprosium X X Terbium X Europium X Samarium X X Nepdymium X X X Praesodymium X X X Cerium X X Lanthanum X X Source: U.S.
Within the assemblies, the magnets themselves come in four materials: hard ferrite SrFe (HF type), samarium and cobalt combination AlNiCo (SC type), neodymium, iron and boron version NdFeB (ND type), and aluminum, nickel and cobalt combination AlNiCo (AN type).
The two main radio-isotopes used are strontium and samarium. The main advantage of samarium over strontium is its shorter scatter which causes less marrow suppression.
Taking into account the difficulties in the technology of production of intermetallic compound based on samarium and cobalt, and also the high cost of alloys based on samarium and niobium, the advantages and importance of the development of the magnetic alloys based on iron become evident.
Because samarium, which is number 62 on the periodic table, was the material initially used to make these magnets, they were named "rare earth." Samarium cobalt could produce more than 4,100 surface gauss in a tube magnet circuit.