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REE- Lanthanides

Name

Samarium

Symbol

Sm

Atomic number

62

Group

LREE

Subgroup

cerium subgroup

Occurrence / Extraction

Found with other rare earths in monazite, bastnäsite and samarskite ((Y,Ce,U,Fe)3(Nb,Ta,Ti)5O16).

Extraction:  obtained by heating samarium oxide (Sm2O3) with barium or lanthanum metal.

Use

Samarium is primarily utilized in the production of Samarium-Cobalt (Sm2Co17) permanent magnets. SmCo magnets are widely used in motors, such as those used to power specialized kinds of airplanes. It is also used in laser applications and for its dielectric properties.

They are utilized in lightweight electronic equipment where size or space is a limiting factor and where functionality at high temperature is a concern. Applications include electronic watches, aerospace equipment, microwave technology and servomotors.

Because of its weak spectral absorption band samarium is used in the filter glass on Nd:YAG solid state lasers to surround the laser rod to improve efficiency by absorbing stray emissions.

Samarium forms stable titanate compounds with useful dielectric properties suitable for coatings and in capacitors at microwave frequencies.  

Samarium is used as a catalyst in certain organic reactions: the samarium iodide (SmI2) is used by organic research chemists to make synthetic versions of natural products.

Properties

Samarium is a silvery-white metal. It is relatively stable at room temperature in dry air, but it ignites when heated above 150 C and forms an oxide coating in moist air. Like europium samarium has a relatively stable oxidation state (II). Samarium is the hardest and most brittle of the rare earth elements

Atomic mass:  150.35 g.mol -1
Electronegativity according to Pauling:  1.2
Density:  7.5 g.cm-3 at 20°C
Melting point: 1072 °C
Boiling point:  1778 °C
 
Named after the mineral samarskite.

Relative abundance

Samarium is regarded as a relatively abundant lanthanide. It occurs to the extent of about 4.5 to 7 parts per million in the Earth's crust. That makes it about as common as boron and two other lanthanides, thulium and gadolinium.

atomic mass (g.mol -1)

150.35

density (g/cm3)

7.5

Oxydation number

+2 +3

Melting point (°C)

1072

Boiling point (°C)

1778

Magnetic moment

 

Abundance in the Earth's crust ( ppm)

4.5

discovery

Paul-Émile Lecoq de Boisbaudran  in 1879