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Samarium 62Sm105.35
Discovered in 1879 by P.E. Lecoq de Boisbaudran at Paris, France.
[Named after the mineral samarskite]
French: samarium
German: Samarium
Italian: samario
Spanish: samario
Description: Samarium
is a silvery-white metal of the so-called rare earth group (more correctly
termed the lanthanides). It is relatively stable in dry air, but in moist air
and oxide coating forms. Samarium is used in permanent magnets, organic
reagents, special glass, catalysts, ceramics and electronics.
Materials properties
| Density: |
7520 kg/m-3 [293 K] |
| Melting point: |
1350 °K |
| Boiling point: |
2064 °K |
| Molar volume: |
20.00 cm3 |
| Thermal conductivity: |
13.3 [300 K] Wm-1K-1 |
| Coefficient of linear thermal expansion: |
10.4 x 10-6 K-1 |
| Electrical resistivity: |
94.0 x 10-8 [293 K] Wm |
| Mass magnetic susceptibility: |
+1.52 x 10-7(s) kg-1m3 |
| Young's modulus: |
49.7 GPa |
| Rigidity modulus: |
19.5 GPa |
| Bulk modulus: |
37.8 GPa |
| Poisson's ratio: |
0.274 GPa |
| Radii: |
Sm3+ 100; Sm2+ 111; atomic 180; covalent 166 |
| Electronegativity: |
1.17 (Pauling); 1.07 (Allred); ≤ 3.1 eV (absolute) |
| Effective nuclear charge: |
2.85 (Slater); 8.01 (Clementi); 11.06 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): |
24 |
| Issotope mass range: |
138 -> 158 |
Biological data
| Biological role: |
None, but acts to stimulate metabolism. |
| Toxicity |
|
| Toxic intake: |
n.a. |
| Lethal intake: |
LD 50 (nitrate, oral, rat) = 2900 mg kg -1 |
| Hazards: |
Samarium is mildly toxic by ingestion, and is a skin and eye irritant. |
| Level in humans |
|
| Blood: |
0.008 mg dm-3 |
| Organs: |
n.a. but very low |
| Daily dietary intake : |
n.a. |
| Total mass of element in average [70 kg] person: |
c. 0.05 mg |
Crystal data
| Crystal structure, (cell dimentions / pm), space group |
α-Sm rhombohedral (a = 899.6, α=23° 13' ), R3m β-Sm cubic (a=407), Im3m T(α->β)= 1190 K high pressure form: h.c.p. (a=361.8, c=1166), P63/mmc |
| X-ray diffraction: mass absorption coefficients (µ/ρ)/cm2g-1 : |
CuKα 397 MoKα 58.6 |
| Neutron scattering length, b/10-12cm: |
0.080 |
| Thermal neutron capture cross-section, σa/barns: |
5922 |
Geological data
| Mineral |
Formula |
Density |
Hardness |
Crystal apperance |
| Monazite* |
(Ce,La,Nd,Th,etc.)PO4 |
5.20 |
5 - 5.5 |
mon., waxy/vit. yellow-brown |
*Although not a major constituent, samarium is present in extractable amounts.
| Chief ore: |
monazite |
| World production: |
c. 700 tonnes/year |
| Main mining areas: |
USA, Brazil, India, Sri Lanka, Australia |
| Reserves: |
c. 2 x 106 tonnes |
| Specimen: |
available as chips or ingots. Safe. |
| Abundances |
|
| Sun: |
5.2 (relative to H = 1 x 1023) |
| Earth's crust: |
7.9 p.p.m. |
| Seawater: |
|
| Atlantic surface: |
4.0 x 10-7 p.p.m. |
| Atlantic deep: |
6.4 x 10-7 p.p.m. |
| Pacific surface: |
4.0 x 10-7 p.p.m. |
| Pacific deep: |
10 x 10-7 p.p.m. |
| Residence time: |
200 years |
| Classification: |
recycled |
| Oxidation state: |
III |
Other sizes and specifications on request
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