Samarium (Sm)
lanthanideSolid
標準原子量
150.36 u電子配置
[Xe] 6s2 4f6融点
1073.85 °C沸点
1793.85 °C密度
7520 kg/m³酸化数
0, +1, +2, +3電気陰性度（Pauling）
1.17第1イオン化エネルギー
5.643722 eV発見年
1878原子半径
185 pm詳細
Samarium is a lanthanide metal with atomic number 62. It is a typical rare-earth element in its trivalent chemistry, but it is also notable for accessible divalent compounds and for the strong neutron-absorbing isotope ¹⁴⁹Sm. The element occurs with other light rare earths in minerals such as monazite and bastnäsite. Its technological importance is concentrated in permanent magnets, neutron control, phosphors, and specialized chemical reducing agents.
Samarium has a bright silver luster and is reasonably stable in air. Three crystal modifications of the metal exist, with transformations at 734 and 922°C. The metal ignites in air at about 150°C. The sulfide has excellent high-temperature stability and good thermoelectric efficiencies up to 1100°C.
The name derives from the mineral samarskite, in which it was found and that had been named for Colonel Samarski, a Russian mine official. Samarium was originally discovered in 1878 by the Swiss chemist Marc Delafontaine, who called it decipium. It was also discovered by the French chemist Paul-Emile Lecoq de Boisbaudran in 1879. In 1881, Delafontaine determined that his decipium could be resolved into two elements, one of which was identical to Boisbaudran's samarium. In 1901, the French chemist Eugène-Anatole Demarçay showed that this samarium earth also contained europium.
Samarium was observed spectroscopically by Jean Charles Galissard de Marignac, a Swiss chemist, in a material known as dydimia in 1853. Paul-Émile Lecoq de Boisbaudran, a French chemist, was the first to isolate samarium from the mineral samarskite ((Y, Ce, U, Fe)3(Nb, Ta, Ti)5O16) in 1879. Today, samarium is primarily obtained through an ion exchange process from monazite sand ((Ce, La, Th, Nd, Y)PO4), a material rich in rare earth elements that can contain as much as 2.8% samarium.
Discovered spectroscopically by its sharp absorption lines in 1879 by Lecoq de Boisbaudran in the mineral samarskite, named in honor of a Russian mine official, Col. Samarski.
Pure samarium is a silvery, moderately hard metal that tarnishes in air as oxide forms on the surface. It has the close-packed metallic character typical of lanthanides and is normally handled as ingots, pieces, powder, or alloy feedstock under conditions that limit oxidation.
The largest distinctive use of samarium is in samarium-cobalt permanent magnets, mainly SmCo₅ and Sm₂Co₁₇, which retain magnetization at higher temperatures and resist corrosion better than many neodymium magnets. ¹⁴⁹Sm is an effective neutron absorber and samarium compounds are used in control materials and reactor physics applications. Samarium-doped materials serve in some phosphors, lasers, and infrared-absorbing glasses. Samarium(II) iodide, SmI₂, is an important one-electron reducing reagent in organic synthesis.
Samarium is one of the rare earth elements used to make carbon arc lights which are used in the motion picture industry for studio lighting and projector lights. Samarium also makes up about 1% of Misch metal, a material that is used to make flints for lighters.
Samarium forms a compound with cobalt (SmCo5) which is a powerful permanent magnet with the highest resistance to demagnetization of any material known. Samarium oxide (Sm2O3) is added to glass to absorb infrared radiation and acts as a catalyst for the dehydration and dehydrogenation of ethanol (C2H6O).
Samarium, along with other rare earths, is used for carbon-arc lighting for the motion picture industry. SmCo5 has been used in making a new permanent magnet material with the highest resistance to demagnetization of any known material. It is said to have an intrinsic coercive force as high as 2200 kA/m. Samarium oxide has been used in optical glass to absorb the infrared. Samarium is used to dope calcium fluoride crystal for use in optical lasers or lasers. Compounds of the metal act as sensitizers for phosphors excited in the infrared; the oxide exhibits catalytic properties in the dehydration and dehydrogenation of ethyl alcohol. It is used in infrared absorbing glass and as a neutron absorber in nuclear reactors.
Isotopes in Earth/Planetary Science
One possible origin for the Moon is from debris ejected by an indirect giant impact of Earth by an astronomical body the size of Mars when the Earth was forming [436] R. M. Canup, E. Asphaug. Nature412, 708 (2001).. The kinetic energy liberated is thought to have melted a large part of the Moon forming a lunar magma ocean. Samarium isotope measurement results [437] A. Brandon. Nature450, 1169 (2007)., along with measurements of isotopes of hafnium, tungsten, and neodymium [438] K. Righter, C. K. Shearer. Geochim. Cosmochim. Acta67, 2497 (2003)., suggest that lunar magma formed about 70×106 years after the Solar System formed and had crystallized by about 215×106 years after formation. 147Sm (with a half-life of 1.06×1011 years) is used to study the formation of potassium, rare earth elements, and phosphorus-rich rocks [439] J. Edmunson, L. E. Borg. “The formation age of KREEP based on the 147Sm-143Nd geochemistry of KREEP-rich rocks: duration of lunar magma ocean crystallization and similarity to early mars”, in Workshop on Early Planetary Differentiation..
Isotopes in Geochronology
147Sm is used for determining formation ages of igneous and metamorphic rocks via analysis of the minerals which compose them, such as those shown in Fig. IUPAC.62.1 [440] T. Iizuka, O. Nebel, M. McCulloch. Early Crustal Evolution Deduced from a Combined U-Pb and Sm-Nd Isotopic Study of Mt. Narryer and Jack Hills Monazites, The Australian National University (2014), Feb. 28; http://rses.anu.edu.au/highlights/view.php?article=191., [441] K. Rankenburg, A. D. Brandon, C. R. Neal. Science312 1369 (2006)., [442] F. F. Hu, H. R. Fan, S. Liu, K. F. Yang, F. Chen. Resour. Geol.59, 407 (2009)..
Isotopes in Medicine
The radioisotope 153Sm (with a half-life of 1.9 days) is used in medicine to treat the severe pain associated with cancer that has spread to bones (Fig. IUPAC.62.2) [443] International Atomic Energy Agency. Optimization of Production and Quality Control of Therapeutic Radionuclides and Radiopharmaceuticals, IAEA-TECDOC-1114, IAEA VIENNA (1999)., [444] C. L. Maini, S. Bergomi, L. Romano, R. Sciuto. Eur. J. Nucl. Med. Mol. Imaging31, S171 (2004)., [445] N. Pandit-Taskar, M. Batraki, C. R. Divgi. J. Nucl. Med.45, 1358 (2004)..
Isotopes Used as a Source of Radioactive Isotope(s)
147Sm bombarded with 40Ca produces the radioisotope 182Pb [446] K. S. Toth, D. M. Moltz, J. M. Nitschke, P. A. Wilmarth, J. D. Robertson. AIP Conference Proc.283, 347 (1991)..
Samarium most commonly forms Sm³⁺ salts and oxides. Samarium(III) oxide, Sm₂O₃, is a stable sesquioxide used as a starting material for many other compounds. Halides such as samarium(III) chloride, SmCl₃, and samarium(III) fluoride, SmF₃, are typical ionic rare-earth salts. The Sm²⁺ state is less common but chemically important; samarium(II) iodide, SmI₂, is a mild, selective reductant, and samarium(II) sulfide, SmS, shows pressure-sensitive electronic behavior. Mixed-valence chemistry is known in some solids.
See more information at the Samarium compound page.
Compact samarium metal has low acute toxicity, but finely divided metal can burn and should be kept from ignition sources. Dusts and soluble samarium salts may irritate tissues and should not be inhaled or ingested. Natural samarium is weakly radioactive because of long-lived isotopes, especially ¹⁴⁷Sm and ¹⁴⁸Sm, but its specific activity is low. Reactor-produced or isotope-enriched materials can present additional radiation hazards depending on isotopic composition.
Little is known of the toxicity of samarium; therefore, it should be handled carefully.
Samarium is dispersed in the crust as a minor component of rare-earth minerals rather than as native metal. In soils and waters it is generally present as Sm³⁺ associated with phosphates, carbonates, oxides, and organic ligands. It is not known to have an essential biological role. Mining and processing can mobilize samarium together with other rare earths and, in monazite deposits, with thorium and uranium by-products.
Samarium is produced as part of rare-earth separation rather than from samarium-specific ores. Concentrates from monazite and bastnäsite are chemically processed, and individual rare earths are separated by solvent extraction or ion-exchange methods before conversion to oxides, metals, or alloys. Demand is much smaller than for cerium, lanthanum, or neodymium, but it is strategically important where high-temperature Sm-Co magnets are required. Recycling is limited compared with primary production, partly because samarium is often present in durable, specialized magnet assemblies.
Samarium is found along with other members of the rare-earth elements in many minerals, including monazite and bastnasite, which are commercial sources. It occurs in monazite to the extent of 2.8%. While misch metal containing about 1% of samarium metal, has long been used, samarium has not been isolated in relatively pure form until recently. Ion-exchange and solvent extraction techniques have recently simplified separation of the rare earths from one another; more recently, electrochemical deposition, using an electrolytic solution of lithium citrate and a mercury electrode, is said to be a simple, fast, and highly specific way to separate the rare earths. Samarium metal can be produced by reducing the oxide with lanthanum.
Samarium is a heavy element made mainly by neutron-capture processes in earlier generations of stars. Its stable and long-lived isotopes reflect contributions from both slow and rapid neutron-capture nucleosynthesis. In planetary materials it is lithophile and follows other rare earths into refractory minerals, making samarium-neodymium isotope systematics useful in geochemistry and cosmochemistry.
- Samarium was named from the mineral samarskite, which was itself named after Vasili Samarsky-Bykhovets.
- ¹⁴⁷Sm decays very slowly to ¹⁴³Nd and is used in Sm-Nd radiometric dating.
- ¹⁴⁹Sm has one of the largest thermal-neutron capture cross sections among naturally occurring nuclides.
- Samarium-cobalt magnets preceded modern neodymium-iron-boron magnets in many high-performance applications.
- SmS can change from a black semiconducting phase toward a golden metallic state under pressure.
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性質
物理的性質
- 原子半径（経験値）
- 185 pm 全元素の原子半径（経験値）を比較 →
- 共有結合半径
- 198 pm 全元素の共有結合半径を比較 →
- ファンデルワールス半径
- 229 pm 全元素のファンデルワールス半径を比較 →
- 密度
- 7520 kg/m³ 全元素の密度を比較 →
- モル体積
- 0.0199 L/mol
- 標準温度・圧力（STP）での相
- 固体 全元素の標準温度・圧力（STP）での相を比較 →
- 融点
- 1073.85 °C 全元素の融点を比較 →
- 沸点
- 1793.85 °C 全元素の沸点を比較 →
- 比熱容量
- 0.197 J/(g·K) 全元素の比熱容量を比較 →
- モル熱容量
- 29.54 J/(mol·K) 全元素のモル熱容量を比較 →
- 結晶構造
- 菱面体構造 全元素の結晶構造を比較 →
化学的性質
- 電気陰性度（Pauling）
- 1.17 全元素の電気陰性度（Pauling）を比較 →
- 電子親和力
- 0.156 eV
- 第1イオン化エネルギー
- 5.643722 eV 全元素の第1イオン化エネルギーを比較 →
- 第2イオン化エネルギー
- 11.078038 eV 全元素の第2イオン化エネルギーを比較 →
- 第3イオン化エネルギー
- 23.550081 eV 全元素の第3イオン化エネルギーを比較 →
- 第4イオン化エネルギー
- 41.640143 eV 全元素の第4イオン化エネルギーを比較 →
- 第5イオン化エネルギー
- 62.700216 eV 全元素の第5イオン化エネルギーを比較 →
- 酸化数
- 0, +1, +2, +3 全元素の酸化数を比較 →
- 価電子
- 3 全元素の価電子を比較 →
- 電子配置
- [Xe] 6s2 4f6
熱力学的性質
- 融解熱
- 0.08934031 eV 全元素の融解熱を比較 →
- 蒸発熱
- 1.71011 eV 全元素の蒸発熱を比較 →
- 昇華熱
- 2.145411 eV
- 原子化熱
- 2.145411 eV
- 原子化エンタルピー
- 2.142302 eV
原子核
- 陽子数
- 62 全元素の陽子数を比較 →
- 中性子数
- 90 全元素の中性子数を比較 →
- 既知の同位体
- 41 全元素の既知の同位体を比較 →
- 安定同位体
- 3 全元素の安定同位体を比較 →
- 最も安定な同位体
- Sm-152
- 発見年
- 1878
存在度
- 存在度（地殻）
- 7.05 mg/kg 全元素の存在度（地殻）を比較 →
- 存在度（海洋）
- 4.5 × 10−7 mg/L 全元素の存在度（海洋）を比較 →
結晶構造
- 格子定数a
- 900 pm
電子構造
- 各電子殻の電子数
- 2, 8, 18, 24, 8, 2 全元素の各電子殻の電子数を比較 →
識別子
- CAS登録番号
- 7440-19-9 全元素のCAS登録番号を比較 →
- 項記号
- 7F0
- InChI
- InChI=1S/Sm
- InChI Key
- KZUNJOHGWZRPMI-UHFFFAOYSA-N
電子配置 測定値
Sm: 4f⁶ 6s²[Xe] 4f⁶ 6s²1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁶ 4f⁶ 6s²原子モデル
同位体によって中性子数、質量、安定性は変わりますが、中性原子の電子配置は変わりません。
模式的な原子モデルです。実際の縮尺とは異なります。
原子の指紋
発光／吸収スペクトル
同位体分布
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 |
|---|---|---|---|
| 144 安定 | 143.9120065 ± 0.0000021 | 3.0700% | 安定 |
| 150 安定 | 149.9172829 ± 0.0000018 | 7.3800% | 安定 |
| 152 安定 | 151.9197397 ± 0.0000018 | 26.7500% | 安定 |
相／状態
理由: 融点（1073.85 °C）より1048.8 °C低い
模式図、実際の縮尺とは異なります
相転移点
相転移エネルギー
融点で1 molを融解させるのに必要なエネルギー
沸点で1 molを蒸発させるのに必要なエネルギー
昇華点で1 molを昇華させるのに必要なエネルギー
密度
標準条件下
標準条件下
原子スペクトル
全62件中10件を表示しています。 イオンの電荷の昇順で並べています。
準位データの収録状況 ?
| イオン | 電荷 | 準位 |
|---|---|---|
| Sm I | 0 | 501 |
| Sm II | +1 | 377 |
| Sm III | +2 | 58 |
| Sm IV | +3 | 24 |
| Sm V | +4 | 2 |
| Sm VI | +5 | 2 |
| Sm VII | +6 | 2 |
| Sm VIII | +7 | 2 |
| Sm IX | +8 | 2 |
| Sm X | +9 | 2 |
結晶構造のデータはありません
結晶構造: rhombohedral
イオン半径
| 電荷 | 配位 | スピン | 半径 |
|---|---|---|---|
| +2 | 7 | データなし | 122 pm |
| +2 | 8 | データなし | 127 pm |
| +2 | 9 | データなし | 132 pm |
| +3 | 6 | データなし | 95.8 pm |
| +3 | 7 | データなし | 102 pm |
| +3 | 8 | データなし | 107.89999999999999 pm |
| +3 | 9 | データなし | 113.19999999999999 pm |
| +3 | 12 | データなし | 124 pm |
化合物
同位体 (3)
Twenty one isotopes of samarium exist. Natural samarium is a mixture of several isotopes, three of which are unstable with long half-lives.
| 質量数 | 原子質量（u） | 天然存在比 | 半減期 | 崩壊形式 | |
|---|---|---|---|---|---|
| 144 安定 | 143.9120065 ± 0.0000021 | 3.0700% ± 0.0700% | 安定 | stable | |
| 150 安定 | 149.9172829 ± 0.0000018 | 7.3800% ± 0.0100% | 安定 | stable | |
| 152 安定 | 151.9197397 ± 0.0000018 | 26.7500% ± 0.1600% | 安定 | stable |
詳細な性質
共有結合半径（詳細）
- 共有結合半径（Pyykkö）
- 172 pm
- 共有結合半径（Pyykkö、二重結合）
- 134 pm
ファンデルワールス半径
- Alvarez
- 290 pm
- UFF
- 352 pm
- MM3
- 271 pm
原子半径と金属半径
- 原子半径（Rahm）
- 280 pm
番号付けの尺度
- Mendeleev
- 23
- Pettifor
- 28
- Glawe
- 27
電気陰性度の尺度
- Ghosh
- 0
- Miedema
- 3
- Gunnarsson–Lundqvist
- 6
- Robles–Bartolotti
- 5
分極率と分散
- 双極子分極率
- 192 a.u.
- 双極子分極率（不確かさ）
- 20 a.u.
- C₆ (Gould–Bučko)
- 3130 Ha·Bohr6
ミーデマパラメータ
- ミーデマモル体積
- 20.01 cm3/mol
- ミーデマ電子密度
- 2
供給リスクと経済性
- 生産集中度
- 97
- 相対供給リスク
- 10
- 埋蔵量の分布
- 50
- 政治的安定性（最大生産国）
- 24
- 政治的安定性（最大埋蔵国）
- 24
相転移と同素体
| 融点 | 1345.15 K |
| 沸点 | 2067.15 K |
酸化数の分類
専門参考データ
遮蔽定数 (13)
| n | 軌道 | σ |
|---|---|---|
| 1 | s | 1.2217 |
| 2 | p | 4.269 |
| 2 | s | 16.2652 |
| 3 | d | 13.7711 |
| 3 | p | 19.5815 |
| 3 | s | 19.9736 |
| 4 | d | 33.7604 |
| 4 | f | 38.4684 |
| 4 | p | 30.912 |
| 4 | s | 29.7076 |
結晶半径の詳細 (8)
| 電荷 | CN | スピン | rcrystal (pm) | 由来 |
|---|---|---|---|---|
| 2 | VII | 136 | ||
| 2 | VIII | 141 | ||
| 2 | IX | 146 | ||
| 3 | VI | 109.8 | from r^3 vs V plots, | |
| 3 | VII | 116 | estimated, | |
| 3 | VIII | 121.9 | from r^3 vs V plots, | |
| 3 | IX | 127.2 | from r^3 vs V plots, | |
| 3 | XII | 138 | calculated, |
同位体の崩壊形式 (52)
| 同位体 | モード | 強度 |
|---|---|---|
| 128 | B+ | — |
| 128 | B+p | — |
| 129 | B+ | 100% |
| 129 | B+p | — |
| 130 | B+ | — |
| 131 | B+ | 100% |
| 131 | B+p | — |
| 132 | B+ | 100% |
| 132 | B+p | — |
| 133 | B+ | 100% |
X線散乱因子 (508)
| エネルギー (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 0.18764 |
| 10.1617 | — | 0.19534 |
| 10.3261 | — | 0.20334 |
| 10.4931 | — | 0.21168 |
| 10.6628 | — | 0.22036 |
| 10.8353 | — | 0.22939 |
| 11.0106 | — | 0.2388 |
| 11.1886 | — | 0.24859 |
| 11.3696 | — | 0.25878 |
| 11.5535 | — | 0.26939 |
追加データ
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
7.05 milligrams per kilogram
参考文献 (1)
- [5] Samarium https://education.jlab.org/itselemental/ele062.html
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
4.5×10-7 milligrams per liter
参考文献 (1)
- [5] Samarium https://education.jlab.org/itselemental/ele062.html
Sources
Sources of this element.
Samarium is found along with other members of the rare-earth elements in many minerals, including monazite and bastnasite, which are commercial sources. It occurs in monazite to the extent of 2.8%. While misch metal containing about 1% of samarium metal, has long been used, samarium has not been isolated in relatively pure form until recently. Ion-exchange and solvent extraction techniques have recently simplified separation of the rare earths from one another; more recently, electrochemical deposition, using an electrolytic solution of lithium citrate and a mercury electrode, is said to be a simple, fast, and highly specific way to separate the rare earths. Samarium metal can be produced by reducing the oxide with lanthanum.
参考文献 (1)
- [6] Samarium https://periodic.lanl.gov/62.shtml
参考文献
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Samarium.
The element property data was retrieved from publications.