Samarium (Sm) is a chemical element, a rare-earth metal in the lanthanide series of the periodic table. This silvery-white metal is relatively stable in the air, and it slowly oxidizes to Sm₂O₃. French chemist Paul-\u00c9mile Lecoq de Boisbaudran identified samarium as a new element in 1879. It is mostly obtained from bastnasite but also occurs in many other rare-earth minerals and is present in nuclear fission products. Samarium is as abundant as tin in the Earth's crust. Samarium is used with cobalt in high-strength permanent magnets and in nuclear reactor control rods because it absorbs thermal neutrons. It is also used in display phosphors, TV screens, luminescent and infrared-absorbing glasses, and in the electronics and ceramics industries.

Where is samarium found on the periodic table?

Samarium (Sm) is a chemical element and a rare-earth metal belonging to the lanthanide series of the periodic table. It has an atomic number of 62. Samarium is a moderately soft metal with a silvery-white color.

What are the physical properties of samarium?

Samarium (Sm) is a rare-earth metal in the lanthanide series. It is a moderately soft, silvery-white metal that is relatively stable in air, oxidizing slowly to Sm₂O₃. Samarium dissolves rapidly in diluted acids, except hydrofluoric acid (HF), due to the formation of a protective SmF₃ layer. Samarium's physical properties include: Atomic Number : 62 Atomic Weight : 150.36 Melting Point : 1,074 °C (1,965 °F) Boiling Point : 1,794 °C (3,261 °F) Density : 7.520 g/cm3 (at 24 °C, or 75 °F) Oxidation States : +2, +3 Electron Configuration : [Xe]4f⁶6s² It is a moderately strong paramagnet above 109 K (-164 °C, or -263 °F). Below this temperature, antiferromagnetic order develops.

How is samarium used in everyday life?

Samarium (Sm) is a chemical element and a rare-earth metal used in various applications. Samarium is commonly used with cobalt in SmCo5- and Sm2Co17-based permanent magnets, which are suitable for high-temperature applications. Samarium is also added to optical glasses that are used as lenses. Samarium oxide (Sm2O3) is used for coloring glass yellow. Due to its high absorption cross-section for thermal neutrons, samarium is used in nuclear reactor control rods and for neutron shielding. It can also be found in display phosphors and TV screens that use cathode-ray tubes.

How is samarium extracted and processed?

Samarium (Sm) is extracted and processed through several methods, depending on the source ore and desired purity. Extraction: * Ores Samarium is mainly sourced from bastnasite but also found in monazite and products of nuclear fission. * Upgrading Rare-earth ores containing less than 10% REO are upgraded to about 60% through grinding and separation techniques like magnetic, electrostatic separation, and flotation. * Commercial Separation Liquid-liquid and ion-exchange techniques are used for commercial separation and purification of samarium. Processing: * Metallothermic Reduction Samarium metal is prepared through metallothermic reduction of its oxide ((Sm_2O_3)) with lanthanum metal, followed by distillation. * Calciothermic Process For high-purity samarium, the calciothermic process is used. Samarium oxide is converted to fluoride by heating with anhydrous hydrogen fluoride gas to form (RF_3). The fluoride powder is mixed with calcium metal and heated, forming calcium fluoride ((CaF_2)) and R. The (CaF_2) floats, allowing separation. The metal is further purified by sublimation or distillation.

What are samarium magnets and why are they important?

Samarium (Sm) is a silvery-white metal and a rare-earth element of the lanthanide series. Samarium is commonly used with cobalt in high-strength permanent magnets for high-temperature applications, such as in motors, generators, and sensors. Samarium magnets have lower Curie points and are suitable for applications above approximately 300 °C (570 °F). Samarium is also used in nuclear reactor control rods, neutron shielding, phosphors for displays and TV screens, and in the electronics and ceramics industries.

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Key People:: Paul-Émile Lecoq de Boisbaudran

Related Topics:: chemical element; rare-earth element; samarium-147; samarium-149; samarium-148

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samarium

chemical element

Also known as: Sm

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What is samarium?
Samarium (Sm) is a chemical element, a rare-earth metal in the lanthanide series of the periodic table. This silvery-white metal is relatively stable in the air, and it slowly oxidizes to Sm₂O₃.

French chemist Paul-\u00c9mile Lecoq de Boisbaudran identified samarium as a new element in 1879. It is mostly obtained from bastnasite but also occurs in many other rare-earth minerals and is present in nuclear fission products. Samarium is as abundant as tin in the Earth's crust.

Samarium is used with cobalt in high-strength permanent magnets and in nuclear reactor control rods because it absorbs thermal neutrons. It is also used in display phosphors, TV screens, luminescent and infrared-absorbing glasses, and in the electronics and ceramics industries.
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Where is samarium found on the periodic table?
Samarium (Sm) is a chemical element and a rare-earth metal belonging to the lanthanide series of the periodic table. It has an atomic number of 62. Samarium is a moderately soft metal with a silvery-white color.
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What are the physical properties of samarium?
Samarium (Sm) is a rare-earth metal in the lanthanide series. It is a moderately soft, silvery-white metal that is relatively stable in air, oxidizing slowly to Sm₂O₃. Samarium dissolves rapidly in diluted acids, except hydrofluoric acid (HF), due to the formation of a protective SmF₃ layer.

Samarium's physical properties include:
- Atomic Number: 62
- Atomic Weight: 150.36
- Melting Point: 1,074 °C (1,965 °F)
- Boiling Point: 1,794 °C (3,261 °F)
- Density: 7.520 g/cm3 (at 24 °C, or 75 °F)
- Oxidation States: +2, +3
- Electron Configuration: [Xe]4f⁶6s²
It is a moderately strong paramagnet above 109 K (-164 °C, or -263 °F). Below this temperature, antiferromagnetic order develops.
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How is samarium used in everyday life?
Samarium (Sm) is a chemical element and a rare-earth metal used in various applications. Samarium is commonly used with cobalt in SmCo5- and Sm2Co17-based permanent magnets, which are suitable for high-temperature applications. Samarium is also added to optical glasses that are used as lenses. Samarium oxide (Sm2O3) is used for coloring glass yellow. Due to its high absorption cross-section for thermal neutrons, samarium is used in nuclear reactor control rods and for neutron shielding. It can also be found in display phosphors and TV screens that use cathode-ray tubes.
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How is samarium extracted and processed?
Samarium (Sm) is extracted and processed through several methods, depending on the source ore and desired purity.

Extraction:
* Ores Samarium is mainly sourced from bastnasite but also found in monazite and products of nuclear fission.
* Upgrading Rare-earth ores containing less than 10% REO are upgraded to about 60% through grinding and separation techniques like magnetic, electrostatic separation, and flotation.
* Commercial Separation Liquid-liquid and ion-exchange techniques are used for commercial separation and purification of samarium.

Processing:
* Metallothermic Reduction Samarium metal is prepared through metallothermic reduction of its oxide ((Sm_2O_3)) with lanthanum metal, followed by distillation.
* Calciothermic Process For high-purity samarium, the calciothermic process is used. Samarium oxide is converted to fluoride by heating with anhydrous hydrogen fluoride gas to form (RF_3). The fluoride powder is mixed with calcium metal and heated, forming calcium fluoride ((CaF_2)) and R. The (CaF_2) floats, allowing separation. The metal is further purified by sublimation or distillation.
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What are samarium magnets and why are they important?
Samarium (Sm) is a silvery-white metal and a rare-earth element of the lanthanide series. Samarium is commonly used with cobalt in high-strength permanent magnets for high-temperature applications, such as in motors, generators, and sensors. Samarium magnets have lower Curie points and are suitable for applications above approximately 300 °C (570 °F). Samarium is also used in nuclear reactor control rods, neutron shielding, phosphors for displays and TV screens, and in the electronics and ceramics industries.
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samarium (Sm), chemical element, a rare-earth metal of the lanthanide series of the periodic table.

Samarium is a moderately soft metal, silvery white in colour. It is relatively stable in air, slowly oxidizing to Sm₂O₃. It rapidly dissolves in diluted acids—except hydrofluoric acid (HF), in which it is stable because of formation of a protective trifluoride (SmF₃) layer. Samarium is a moderately strong paramagnet above 109 K (−164 °C, or −263 °F). Below 109 K, antiferromagnetic order develops for the cubic sites in the samarium lattice, and the hexagonal site atoms finally order antiferromagnetically below 14 K (−259 °C, or −434 °F).

Samarium was isolated as an impure oxide and spectroscopically identified as a new element in 1879 by French chemist Paul-Émile Lecoq de Boisbaudran. Samarium occurs in many other rare-earth minerals but is almost exclusively obtained from bastnasite; it is also found in products of nuclear fission. In Earth’s crust, samarium is as abundant as tin.

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The seven naturally occurring isotopes of samarium are samarium-144 (3.1 percent), samarium-147 (15.0 percent), samarium-148 (11.2 percent), samarium-149 (13.8 percent), samarium-150 (7.4 percent), samarium-152 (26.8 percent), and samarium-154 (22.0 percent). Samarium-144, samarium-150, samarium-152, and samarium-154 are stable, but the other three naturally occurring isotopes are alpha emitters. A total of 34 (excluding nuclear isomers) radioactive isotopes of samarium have been characterized. Their mass ranges from 128 to 165, and their half-life can be as short as 0.55 second for samarium-129 or as long as 7 × 10¹⁵ years for samarium-148.

Liquid-liquid and ion-exchange techniques are used for the commercial separation and purification of samarium. The metal is conveniently prepared by metallothermic reduction of its oxide, Sm₂O₃, with lanthanum metal, followed by distillation of the samarium metal, which is one of the most volatile rare-earth elements. Samarium exists in three allotropic (structural) forms. The α-phase (or Sm-type structure) is a rhombohedral arrangement that is unique among the elements, with a = 3.6290 Å and c = 26.207 Å at room temperature. (The unit cell dimensions are given for the non-primitive hexagonal unit cell of the primitive rhombohedral lattice.) The β-phase is hexagonal close-packed with a = 3.6630 Å and c = 5.8448 Å at 450 °C (842 °F). The γ-phase is body-centred cubic with a = 4.10 Å (estimated) at 922 °C (1,692 °F).

The most common use of samarium is with cobalt (Co) in high-strength SmCo₅- and Sm₂Co₁₇-based permanent magnets suitable for high-temperature applications. The energy product of samarium-based permanent magnets is second to those based on neodymium, iron, and boron (Nd₂Fe₁₄B), but the latter have much lower Curie points than the samarium magnets and therefore are unsuitable for applications above approximately 300 °C (570 °F). Because of its high absorption cross section for thermal neutrons (samarium-149), samarium is used as an addition in nuclear reactor control rods and for neutron shielding. Other uses are in phosphors for displays and TV screens that use cathode-ray tubes, in special luminescent and infrared-absorbing glasses, in inorganic and organic catalysis, and in the electronics and ceramics industries.

In addition to its more stable +3 oxidation state, samarium, unlike most of the rare earths, has a +2 oxidation state. The Sm²⁺ ion is a powerful reducing agent that rapidly reacts with oxygen, water, or hydrogen ions. It can be stabilized by precipitation as the extremely insoluble sulfate SmSO₄. Other salts of samarium in the +2 state are SmCO₃, SmCl₂, SmBr₂, and Sm(OH)₂; they are reddish brown in colour. In its +3 oxidation state, samarium behaves as a typical rare-earth element; it forms a series of yellow salts in solutions.

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Element Properties
atomic number	62
atomic weight	150.36
melting point	1,074 °C (1,965 °F)
boiling point	1,794 °C (3,261 °F)
density	7.520 g/cm³ (24 °C, or 75 °F)
oxidation states	+2, +3
electron configuration	[Xe]4f ⁶6s²

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Rick Livingston.

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