General
Samarium (after the mineral Samarskit, which in turn is named after the mining engineer WM Samarski) is a chemical element with the elementary symbol Sm and the atomic number 62. In the periodic table, the silvery shining element in the group of lanthanides is one of the rare metals Earth.
For the discovery of the Samarium, there are several representations in the literature.
1. In 1853, the Swiss Jean Charles Galissard de Marignac verified samarium spectroscopically using a sharp absorption line in didymia. In 1879, the Frenchman Paul Emile Lecoq de Boisbaudran isolated the element from the mineral samarskite ((Y, Ce, U, Fe) 3 (Nb, Ta, Ti) 5016). Mineral and element designation is derived from the Russian mining inspector Colonel Samarsky, who discovered the mineral.
2. In 1878, the Swiss chemist Marc Delafontaine discovers samarium, which he calls Decipum, in didymium oxide. In 1879 Paul Emile Lecoq de Boisbaudran discovered samarium independently of him. In 1881, Delafontaine shows that his isolated element contains another element besides samarium.
3. Marignac’s 1853 spectroscopic discovery, mentioned under 1, was made in 1878 by Paul Emile Lecoq de Boisbaudran.
In 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.
particularities
Samarium is reasonably stable in the air, it forms a passivating, yellowish oxide layer. Metallic shiny samarium ignites above 150 ° C. With oxygen it reacts to the sesquoxide Sm2O3. It reacts violently with water to form hydrogen and samarium hydroxide. The most consistent oxidation state, as with all lanthanides, is +3. Samarium occurs in three modifications. The conversion points are 734 ° C and 922 ° C. Sm3 + cations color 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%).
use
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:
Permanent magnets made of SmCo5 have a high resistance against demagnetization as well as a coercive field strength 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 in bone metastases).
Compounds with samarium in the less favorable oxidation state +2 (in particular samarium (II) iodide and samarium (II) bromide) are used 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.
