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Samarium


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Atomic Number:62Atomic Symbol:Sm
Atomic Weight:150.4Electron Configuration:2-8-24-8-2
Shells:2,8,18,24,8,2Filling Orbital:4f6
Melting Point:1072oCBoiling Point:1900oC
Description:Silver colored rare earth metal.

History

(Samarskite, a mineral) Discovered spectroscopically by its sharp absorption lines in 1879 by Lecoq de Boisbaudran in the mineral samarskite, named in honor of a Russian mine official, Col Samarski.

Occurence

  • Samarium is found along with other members of the rare-earth elements in many minerals, including monazite and bastnasite, which are commercial sources.
  • It occurs in monazite to the extent of 2.8%.

Isolation

  • While misch metal containing about 1% of samarium metal, has long been used, samarium has not been isolated in relatively pure form until recent years.
  • Ion-exchange and solvent extraction techniques have recently simplified separation of the rare earths from one another; more rectnly, electrochemical deposition, using an electrolytic solution of lithium citrate and a mercury electrode, is said to be a simple, fast, and highly specific way to separate the rare earths.

Properties

  • Samarium metal can be produced by reducing the oxide with lanthanum.
  • Samarium has a bright silver luster and is reasonably stable in air.
  • Three crystal modifications of the metal exist, with transformations at 734 and 922C. The metal ignites in air at about 150C.
  • Twenty one isotopes of samarium exist.
  • Natural samarium is a mixture of several isotopes, three of which are unstable with long half-lives.

Uses

  • Samarium, along with other rare earths, is used for carbon-arc lighting for the motion picture industry.
  • The sulfide has excellent high-temperature stability and good thermoelectric efficiencies up to 1100C.
  • SmCo5 has been used in making a new permanent magnet material with the highest resistance to demagnetization of any known material.
  • It is said to have an intrinsic coercive force as high as 2200 kA/m.
  • Samarium oxide has been used in optical glass to absorb the infrared.
  • Samarium is used to dope calcium fluoride crystal for use in optical masers or lasers.
  • Compounds of the metal act as sensitizers for phosphors excited in the infrared; the oxide exhibits catalytic properties in the dehydration and dehydrogenation of ethyl alcohol.
  • It is used in infrared absorbing glass and as a neutron absorber in nuclear reactors.

Costs

The metal is priced at about $5/g.

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