Samarium Chemische Eigenschaften,Einsatz,Produktion Methoden
R-S?tze Betriebsanweisung:
R11:Leichtentzündlich.
R15:Reagiert mit Wasser unter Bildung hochentzündlicher Gase.
R33:Gefahr kumulativer Wirkungen.
S-S?tze Betriebsanweisung:
S16:Von Zündquellen fernhalten - Nicht rauchen.
S30:Niemals Wasser hinzugie?en.
S33:Ma?nahmen gegen elektrostatische Aufladungen treffen.
Chemische Eigenschaften
silvery grey powder
Physikalische Eigenschaften
Samarium is a hard, brittle, silver-white metal. When freshly cut, it does not tarnish significantlyunder normal room temperature conditions. Four of its isotopes are radioactive andemit alpha particles (helium nuclei). They are Sm-146, Sm-147, Sm-148, and Sm-149.
Its melting point is 1,074°C, its boiling point is 1,794°C, and its density is 7.52g.cm
3.
Isotopes
There are 41 known isotopes of samarium. Seven of these are consideredstable. Sm-144 makes up just 3.07% of the natural occurring samarium, Sm-150 makesup 7.38% of natural samarium found on Earth, Sm-152 constitutes 26.75%, and Sm-154 accounts for 22.75%. All the remaining isotopes are radioactive and have very longhalf-lives; therefore, they are considered “stable.” All three contribute to the natural occurrenceof samarium: Sm-147 = 14.99%, Sm-148 = 11.24%, and Sm-149 = 13.82%.
Samarium is one of the few elements with several stable isotopes that occur naturallyon Earth.
Origin of Name
It is named after the mineral samarskite.
Occurrence
Samarium is the 39th most abundant element in the Earth’s crust and the fifth in abundance(6.5 ppm) of all the rare-earths. In 1879 samarium was first identified in the mineralsamarskite [(Y, Ce U, Fe)
3 (Nb, Ta, Ti
5)O
16]. Today, it is mostly produced by the ion-exchangeprocess from monazite sand. Monazite sand contains almost all the rare-earths, 2.8% of whichis samarium. It is also found in the minerals gadolinite, cerite, and samarskite in South Africa,South America, Australia, and the southeastern United States. It can be recovered as a byproductof the fission process in nuclear reactors.
Charakteristisch
Samarium is somewhat resistant to oxidation in air but will form a yellow oxide over time. Itignites at the rather low temperature of 150°C. It is an excellent reducing agent, releases hydrogenwhen immersed in water, and has the capacity to absorb neutrons in nuclear reactors.
Verwenden
Samarium is easy to magnetize, but very difficult to demagnetize. This makes it ideal forthe manufacture of permanent magnets (SmCo
5) that are part of the hard disks for computers.Samarium is also used as a neutron absorber in nuclear reactors, as well as for lasers andmetallurgical research. It makes up about 1% of the metals in misch metal, an alloy in cigarettelighter flints. It is also one of several rare-earths used in floodlights and carbon-arc lights usedby the motion picture industry. Samarium is used as a catalyst in several industries, includingthe dehydrogenation of ethanol alcohol.
Definition
A silvery element
of the lanthanoid series of metals. It
occurs in association with other lanthanoids.
Samarium is used in the metallurgical,
glass, and nuclear industries.
Symbol: Sm; m.p. 1077°C; b.p.
1791°C; r.d. 7.52 (20°C); p.n. 62; r.a.m.
150.36.
Hazard
The salts of samarium are toxic if ingested. These salts react with water, liberating hydrogen,which may explode.
Samarium Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
