General information

Samarium (after the mineral Samarskit, which in turn is named after the mining engineer WM Samarski) is a chemical element with the element symbol Sm and the atomic number 62. In the periodic table, the silvery shining element is in the group of lanthanides and thus also belongs to the metals of the rare earths.
For the discovery of the Samarium, there are several representations in the literature.
1. 1853 showed the Swiss Jean Charles Galissard de Marignac samarium spectroscopically by a sharp absorption line in the Didymoxid after. 1879 isolated the Frenchman Paul Emile Lecoq de Boisbaudran the element of the mineral Samarskit (Y, Ce, U, Fe) 3 (Nb, Ta, Ti) 5O16). Mineral and element designation is derived from the Russian mining inspector Colonel Samarsky, who discovered the mineral.
2. 1878 discovered the Swiss chemist Marc Delafontaine Samarium, which he calls Decipum, in Didymium oxide. 1879 independently discovers Paul Emile Lecoq de Boisbaudran Samarium. 1881 shows Delafontaine that his isolated element contains another element besides samarium.
3. Marignac's 1 spectroscopic discovery of 1853, mentioned under 1878, was made by XNUMX by Paul Emile Lecoq de Boisbaudran.
1903, the German chemist Wilhelm Muthmann produced metallic samarium by electrolysis.
Of course, elemental samarium does not occur. However, some minerals like monazite, bastnasite and samarskite contain the element. Monazite contains up to 1% samarium.

Recovery

Starting from monazite or bastnaesite, the separation of the rare earths via ion exchange, solvent extraction or electrochemical deposition takes place. In a final process step, the high-purity samarium oxide with metallic lanthanum is reduced to the metal and sublimated.

Features

Samarium is reasonably stable in air, it forms a passivating, yellowish oxide layer. Shiny metallic samarium ignites above 150 ° C. It reacts with oxygen to form sesquioxide Sm2O3. It reacts violently with water to form hydrogen and samarium hydroxide. As with all lanthanoids, the most stable oxidation state is +3. Samarium comes in three modifications. The transition points are 734 ° C and 922 ° C. Sm3 + cations turn aqueous solutions yellow.
There are four stable and 19 unstable radioactive isotopes. The most common natural isotopes are 152Sm (26,7%), 154Sm (22,7%), and 147Sm (15%).

Usage

Together with other rare earths for carbon arc lamps for film projection systems.
Doping of calcium fluoride single crystals for maser and laser.
Because of its large thermal and epithermal neutron cross section, samarium is used as a neutron absorber in nuclear applications.
Samarium Cobalt Magnets:
SmCo5 permanent magnets have high demagnetization resistance and coercive force of up to 2200 kA / m. The improved Sm2Co17 alloy is more expensive to produce, but has higher magnetic properties and improved corrosion resistance.
They are used in stepper motors for quartz watches, drive motors in miniature tape devices (walkman, dictaphones), headphones, sensors, couplings in agitators and hard disk drives. As weight-saving magnetic materials, they are also used in aerospace applications.
Samarium oxide is added to optical glass for absorption of infrared light.
Samarium compounds are used to sensitize (phosphor) phosphorus when irradiated with infrared light.
As a catalyst; Samarium oxide catalyzes the hydrogenation and dehydrogenation of ethanol (alcohol).
In medicine, the isotope 153Samarium is used in conjunction with a bisphosphonate (Lexidronam) for the treatment of bone pain in cancers (radionuclide therapy for bone metastases).
Compounds with samarium in less favorable oxidation state + 2 (especially samarium (II) iodide and samarium (II) bromide) find application in organic synthesis (reducing agent and one-electron transfer reagent, eg, samarium-mediated pinacol couplings) ,
In conjunction with the radiopharmaceutical ethylenediaminetetra (methylenephosphonic acid) in nuclear medicine for the palliative treatment of bone and skeletal metastases.

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