Samarium

Samarium is a rare earth element with a hardness and density similar to zinc. With a boiling point of {{convert|1794|C|F}}, samarium is the third most volatile lanthanide after ytterbium and europium and comparable in this respect to lead and barium; this helps separation of samarium from its ores.{{cite book|editor=J.A. Dean|title=Lange's Handbook of Chemistry|edition=15th|publisher=McGraw-Hill|location=New York, NY|year=1999|at=Section 3; Table 3.2 Physical Constants of Inorganic Compounds|isbn= 978-0-07016384-3}} When freshly prepared, samarium has a silvery lustre, and takes on a duller appearance when oxidized in air. Samarium is calculated to have one of the largest atomic radii of the elements; with a radius of 238 pm, only potassium, praseodymium, barium, rubidium and caesium are larger.{{cite journal |last1=Clementi |first1=E. |last2=Raimond |first2=D. L. |last3=Reinhardt |first3=W. P. |year=1967 |title=Atomic Screening Constants from SCF Functions. II. Atoms with 37 to 86 Electrons |journal=Journal of Chemical Physics |volume=47 |issue=4 |pages=1300–1307 |bibcode=1967JChPh..47.1300C |doi=10.1063/1.1712084}}

In ambient conditions, samarium has a rhombohedral structure (α form). Upon heating to {{convert|731|C|F}}, its crystal symmetry changes to hexagonal close-packed (hcp),; it has actual transition temperature depending on metal purity. Further heating to {{convert|922|C|F}} transforms the metal into a body-centered cubic (bcc) phase. Heating to {{convert|300|C|F}} plus compression to 40 kbar results in a double-hexagonally close-packed structure (dhcp). Higher pressure of the order of hundreds or thousands of kilobars induces a series of phase transformations, in particular with a tetragonal phase appearing at about 900 kbar. In one study, the dhcp phase could be produced without compression, using a nonequilibrium annealing regime with a rapid temperature change between about {{convert|400|C|F}} and {{convert|700|C|F}}, confirming the transient character of this samarium phase. Thin films of samarium obtained by vapor deposition may contain the hcp or dhcp phases in ambient conditions.{{cite journal|doi=10.1016/0022-5088(85)90294-2|last1=Shi|first1=N.|date=1985|page=21|volume=113|journal=Journal of the Less Common Metals|last2=Fort|first2=D.|title=Preparation of samarium in the double hexagonal close packed form|issue=2}}

Samarium and its sesquioxide are paramagnetic at room temperature. Their corresponding effective magnetic moments, below 2 bohr magnetons, are the third-lowest among lanthanides (and their oxides) after lanthanum and lutetium. The metal transforms to an antiferromagnetic state upon cooling to 14.8 K.{{cite journal |last1=Lock |first1=J. M. |title=The Magnetic Susceptibilities of Lanthanum, Cerium, Praseodymium, Neodymium and Samarium, from 1.5 K to 300 K |journal=Proceedings of the Physical Society |series=Series B |volume=70 |page=566 |date=1957 |doi=10.1088/0370-1301/70/6/304 |issue=6 |bibcode=1957PPSB...70..566L}}{{cite journal |last1=Huray |first1=P. |last2=Nave |first2=S. |last3=Haire |first3=R. |title=Magnetism of the heavy 5f elements |journal=Journal of the Less Common Metals |volume=93 |page=293 |date=1983 |doi=10.1016/0022-5088(83)90175-3 |issue=2}} Individual samarium atoms can be isolated by encapsulating them into fullerene molecules.{{cite journal |doi=10.1016/S0921-4526(02)00991-2 |title=Electronic and geometric structures of metallofullerene peapods |date=2002 |last1=Okazaki |first1=T. |journal=Physica B |volume=323 |issue=1–4 |page=97 |bibcode=2002PhyB..323...97O |last2=Suenaga |first2=Kazutomo |last3=Hirahara |first3=Kaori |last4=Bandow |first4=Shunji |last5=Iijima |first5=Sumio |last6=Shinohara |first6=Hisanori |display-authors=3}} They can also be intercalated into the interstices of the bulk C₆₀ to form a solid solution of nominal composition Sm₃C₆₀, which is superconductive at a temperature of 8 K.{{cite journal |last1=Chen |first1=X. |last2=Roth |first2=G. |title=Superconductivity at 8 K in samarium-doped C60 |journal=Physical Review B |volume=52 |date=1995 |doi=10.1103/PhysRevB.52.15534 |pmid=9980911 |issue=21 |pages=15534–15536 |bibcode=1995PhRvB..5215534C}} Samarium doping of iron-based superconductors – a class of high-temperature superconductor – increases their transition to normal conductivity temperature up to 56 K, the highest value achieved so far in this series.{{cite journal |arxiv=0811.0761 |title=Superconductivity at 56 K in Samarium-doped SrFeAsF |last1=Wu |first1=G. |date=2008 |doi=10.1088/0953-8984/21/14/142203 |pmid=21825317 |journal=Journal of Physics: Condensed Matter |volume=21 |issue=14 |page=142203|bibcode=2009JPCM...21n2203W |last2=Xie |first2=Y. L. |last3=Chen |first3=H. |last4=Zhong |first4=M. |last5=Liu |first5=R. H. |last6=Shi |first6=B. C. |last7=Li |first7=Q. J. |last8=Wang |first8=X. F. |last9=Wu |first9=T. |s2cid=41728130 |display-authors=3}}

In air, samarium slowly oxidizes at room temperature and spontaneously ignites at {{convert|150|C|F}}. Even when stored under mineral oil, samarium gradually oxidizes and develops a grayish-yellow powder of the oxide-hydroxide mixture at the surface. The metallic appearance of a sample can be preserved by sealing it under an inert gas such as argon.

Samarium is quite electropositive and reacts slowly with cold water and rapidly with hot water to form samarium hydroxide:

: {{chem2|2Sm_{(s)} + 6H2O_{(l)} → 2Sm(OH)3_{(aq)} + 3H2_{(g)}|}}

Samarium dissolves readily in dilute sulfuric acid to form solutions containing the yellowGreenwood, p. 1243 to pale green Sm(III) ions, which exist as {{chem2|[Sm(OH2)9](3+)|}} complexes:{{cite web| url =https://www.webelements.com/samarium/chemistry.html| title =Chemical reactions of Samarium| publisher=Webelements| access-date=2009-06-06}}

: {{chem2|2Sm_{(s)} + 3H2SO4_{(aq)} → 2Sm(3+)_{(aq)} + 3SO4(2-)_{(aq)} + 3H2_{(g)}|}}

Samarium is one of the few lanthanides with a relatively accessible +2 oxidation state, alongside Eu and Yb.{{Cite book |title=The lanthanides and actinides: synthesis, reactivity, properties and applications |date=2022 |editor=Stephen T. Liddle |editor2=David P. Mills |editor3=Louise S. Natrajan |isbn=978-1-80061-015-6 |location=London |oclc=1251740566 |page=213}} {{chem2|Sm(2+)}} ions are blood-red in aqueous solution.Greenwood, p. 1248

{{Main article|Samarium compounds}}

The most stable oxide of samarium is the sesquioxide Sm₂O₃. Like many samarium compounds, it exists in several crystalline phases. The trigonal form is obtained by slow cooling from the melt. The melting point of Sm₂O₃ is high (2345 °C), so it is usually melted not by direct heating, but with induction heating, through a radio-frequency coil. Sm₂O₃ crystals of monoclinic symmetry can be grown by the flame fusion method (Verneuil process) from Sm₂O₃ powder, that yields cylindrical boules up to several centimeters long and about one centimeter in diameter. The boules are transparent when pure and defect-free and are orange otherwise. Heating the metastable trigonal Sm₂O₃ to {{convert|1900|C|F}} converts it to the more stable monoclinic phase. Cubic Sm₂O₃ has also been described.

Samarium is one of the few lanthanides that form a monoxide, SmO. This lustrous golden-yellow compound was obtained by reducing Sm₂O₃ with samarium metal at high temperature (1000 °C) and a pressure above 50 kbar; lowering the pressure resulted in incomplete reaction. SmO has cubic rock-salt lattice structure.Greenwood, p. 1239

{{see also|Samarium monochalcogenides}}

Samarium forms a trivalent sulfide, selenide and telluride. Divalent chalcogenides SmS, SmSe and SmTe with a cubic rock-salt crystal structure are known. These chalcogenides convert from a semiconducting to metallic state at room temperature upon application of pressure.{{Cite journal |last1=Bakar |first1=Abu |last2=Afaq |first2=A. |last3=Khan |first3=M. Faizan |last4=ul Aarifeen |first4=Najm |last5=Imran Jamil |first5=M. |last6=Asif |first6=Muhammad |date=2020-01-01 |title=Insight into the structural, vibrational and thermodynamic properties of SmX (X = S, Se, Te) chalcogenides: First-principles investigations |url=https://www.sciencedirect.com/science/article/pii/S0921452619306209 |journal=Physica B: Condensed Matter |language=en |volume=576 |pages=411715 |doi=10.1016/j.physb.2019.411715 |s2cid=204206623 |issn=0921-4526|url-access=subscription }} Whereas the transition is continuous and occurs at about 20–30 kbar in SmSe and SmTe, it is abrupt in SmS and requires only 6.5 kbar. This effect results in a spectacular color change in SmS from black to golden yellow when its crystals of films are scratched or polished. The transition does not change the lattice symmetry, but there is a sharp decrease (~15%) in the crystal volume.{{Cite book |title=Magnetism: a synchrotron radiation approach |date=2006 |publisher=Springer |first1=E. |last1=Beaurepaire |isbn=978-3-540-33242-8 |location=Berlin |oclc=262692720}} It exhibits hysteresis, i.e., when the pressure is released, SmS returns to the semiconducting state at a much lower pressure of about 0.4 kbar.{{cite journal|last1=Jayaraman|first1=A.|last2=Narayanamurti|first2=V.|last3=Bucher|first3=E.|last4=Maines|first4=R.|title=Continuous and Discontinuous Semiconductor-Metal Transition in Samarium Monochalcogenides Under Pressure|journal=Physical Review Letters|volume=25|page=1430|date=1970|doi=10.1103/PhysRevLett.25.1430|bibcode=1970PhRvL..25.1430J|issue=20}}

File:Samarium(III) chloride hexahydrate.jpg

Samarium metal reacts with all the halogens, forming trihalides:Greenwood, pp. 1236, 1241

:2 Sm (s) + 3 X₂ (g) → 2 SmX₃ (s) (X = F, Cl, Br or I)

Their further reduction with samarium, lithium or sodium metals at elevated temperatures (about 700–900 °C) yields the dihalides. The diiodide can also be prepared by heating SmI₃, or by reacting the metal with 1,2-diiodoethane in anhydrous tetrahydrofuran at room temperature:Greenwood, p. 1240

:Sm (s) + ICH₂-CH₂I → SmI₂ + CH₂=CH₂.

In addition to dihalides, the reduction also produces many non-stoichiometric samarium halides with a well-defined crystal structure, such as Sm₃F₇, Sm₁₄F₃₃, Sm₂₇F₆₄, Sm₁₁Br₂₄, Sm₅Br₁₁ and Sm₆Br₁₃.{{cite journal |last1=Baernighausen |first1=H. |last2=Haschke |first2=John M. |title=Compositions and crystal structures of the intermediate phases in the samarium-bromine system |journal=Inorganic Chemistry |volume=17 |page=18 |date=1978 |doi=10.1021/ic50179a005}}

Samarium halides change their crystal structures when one type of halide anion is substituted for another, which is an uncommon behavior for most elements (e.g. actinides). Many halides have two major crystal phases for one composition, one being significantly more stable and another being metastable. The latter is formed upon compression or heating, followed by quenching to ambient conditions. For example, compressing the usual monoclinic samarium diiodide and releasing the pressure results in a PbCl₂-type orthorhombic structure (density 5.90 g/cm³),{{cite journal|last1=Beck|first1=H. P.|title=Hochdruckmodifikationen der Diiodide von Sr., Sm und Eu. Eine neue PbCl2-Variante?|journal=Zeitschrift für anorganische und allgemeine Chemie|volume=459|page=81|date=1979|doi=10.1002/zaac.19794590108}} and similar treatment results in a new phase of samarium triiodide (density 5.97 g/cm³).{{cite journal|last1=Beck|first1=H. P.|last2=Gladrow|first2=E.|title=Zur Hochdruckpolymorphie der Seltenerd-Trihalogenide|journal=Zeitschrift für anorganische und allgemeine Chemie|volume=453|page=79|date=1979|doi=10.1002/zaac.19794530610}}

Sintering powders of samarium oxide and boron, in a vacuum, yields a powder containing several samarium boride phases; the ratio between these phases can be controlled through the mixing proportion. The powder can be converted into larger crystals of samarium borides using arc melting or zone melting techniques, relying on the different melting/crystallization temperature of SmB₆ (2580 °C), SmB₄ (about 2300 °C) and SmB₆₆ (2150 °C). All these materials are hard, brittle, dark-gray solids with the hardness increasing with the boron content. Samarium diboride is too volatile to be produced with these methods and requires high pressure (about 65 kbar) and low temperatures between 1140 and 1240 °C to stabilize its growth. Increasing the temperature results in the preferential formation of SmB₆.

{{Main|Samarium hexaboride}}

Samarium hexaboride is a typical intermediate-valence compound where samarium is present both as Sm²⁺ and Sm³⁺ ions in a 3:7 ratio.{{cite journal|last1=Nickerson|first1=J.|last2=White|first2=R.|last3=Lee|first3=K.|last4=Bachmann|first4=R.|last5=Geballe|first5=T.|last6=Hull|first6=G.|title=Physical Properties of SmB₆ |journal=Physical Review B|volume=3|page=2030|date=1971|doi=10.1103/PhysRevB.3.2030|issue=6|bibcode=1971PhRvB...3.2030N }} It belongs to a class of Kondo insulators; at temperatures above 50 K, its properties are typical of a Kondo metal, with metallic electrical conductivity characterized by strong electron scattering, whereas at lower temperatures, it behaves as a non-magnetic insulator with a narrow band gap of about 4–14 meV.{{cite journal |doi=10.1103/PhysRevB.52.R14308 |pmid=9980746 |last1=Nyhus |date=1995 |first1=P. |pages=14308–14311 |volume=52|last2=Cooper|journal=Physical Review B|first2=S.|last3=Fisk|first3=Z.|author4-link=John Sarrao |last4=Sarrao |first4=J. |title=Light scattering from gap excitations and bound states in SmB₆ |issue=20|bibcode=1995PhRvB..5214308N }} The cooling-induced metal-insulator transition in SmB₆ is accompanied by a sharp increase in the thermal conductivity, peaking at about 15 K. The reason for this increase is that electrons themselves do not contribute to the thermal conductivity at low temperatures, which is dominated by phonons, but the decrease in electron concentration reduces the rate of electron-phonon scattering.{{cite journal |last1=Sera |first1=M. |last2=Kobayashi |first2=S. |last3=Hiroi |first3=M.|last4=Kobayashi|first4=N.|last5=Kunii|first5=S.|title=Thermal conductivity of RB₆ (R=Ce, Pr, Nd, Sm, Gd) single crystals |journal=Physical Review B |volume=54 |date=1996 |doi=10.1103/PhysRevB.54.R5207 |pmid=9986570|issue=8 |pages=R5207–R5210|bibcode=1996PhRvB..54.5207S }}

File:Samarium-sulfate.jpg

Samarium carbides are prepared by melting a graphite-metal mixture in an inert atmosphere. After the synthesis, they are unstable in air and need to be studied under an inert atmosphere. Samarium monophosphide SmP is a semiconductor with a bandgap of 1.10 eV, the same as in silicon, and electrical conductivity of n-type. It can be prepared by annealing at {{convert|1100|C|F}} an evacuated quartz ampoule containing mixed powders of phosphorus and samarium. Phosphorus is highly volatile at high temperatures and may explode, thus the heating rate has to be kept well below 1 °C/min. A similar procedure is adopted for the monarsenide SmAs, but the synthesis temperature is higher at {{convert|1800|C|F}}.

Numerous crystalline binary compounds are known for samarium and one of the group 14, 15, or 16 elements X, where X is Si, Ge, Sn, Pb, Sb or Te, and metallic alloys of samarium form another large group. They are all prepared by annealing mixed powders of the corresponding elements. Many of the resulting compounds are non-stoichiometric and have nominal compositions Sm_aX_b, where the b/a ratio varies between 0.5 and 3.{{cite journal |last1=Gladyshevskii|first1=E. I.|last2=Kripyakevich|first2=P. I.|title=Monosilicides of rare earth metals and their crystal structures|journal=Journal of Structural Chemistry|volume=5|page=789|date=1965|doi=10.1007/BF00744231|issue=6|bibcode=1965JStCh...5..789G |s2cid=93941853}}{{cite journal|last1=Smith|first1=G. S.|last2=Tharp|first2=A. G.|last3=Johnson|first3=W.|title=Rare earth–germanium and –silicon compounds at 5:4 and 5:3 compositions|journal=Acta Crystallographica|volume=22|page=940|date=1967|doi=10.1107/S0365110X67001902|issue=6|doi-access=free|bibcode=1967AcCry..22..940S }}

Samarium forms a cyclopentadienide {{chem2|Sm(C5H5)3}} and its chloroderivatives {{chem2|Sm(C5H5)2Cl}} and {{chem2|Sm(C5H5)Cl2}}. They are prepared by reacting samarium trichloride with {{chem2|NaC5H5}} in tetrahydrofuran. Contrary to cyclopentadienides of most other lanthanides, in {{chem2|Sm(C5H5)3}} some {{chem2|C5H5}} rings bridge each other by forming ring vertexes η¹ or edges η² toward another neighboring samarium, thus creating polymeric chains. The chloroderivative {{chem2|Sm(C5H5)2Cl}} has a dimer structure, which is more accurately expressed as {{chem2|(η(5)\sC5H5)2Sm(\m\sCl)2(\h(5)\sC5H5)2}}. There, the chlorine bridges can be replaced, for instance, by iodine, hydrogen or nitrogen atoms or by CN groups.Greenwood, p. 1249

The ({{chem2|C5H5}})⁻ ion in samarium cyclopentadienides can be replaced by the indenide ({{chem2|C9H7}})⁻ or cyclooctatetraenide ({{chem2|C8H8}})²⁻ ring, resulting in {{chem2|Sm(C9H7)3}} or {{chem2|KSm(\h(8)\sC8H8)2}}. The latter compound has a structure similar to uranocene. There is also a cyclopentadienide of divalent samarium, {{chem2|Sm(C5H5)2}} a solid that sublimates at about {{convert|85|C|F}}. Contrary to ferrocene, the {{chem2|C5H5}} rings in {{chem2|Sm(C5H5)2}} are not parallel but are tilted by 40°.{{cite journal|last1=Evans|first1=William J.|last2=Hughes|first2=Laura A.|last3=Hanusa|first3=Timothy P.|title=Synthesis and x-ray crystal structure of bis(pentamethylcyclopentadienyl) complexes of samarium and europium: (C₅Me₅)₂Sm and (C₅Me₅)₂Eu|journal=Organometallics|volume=5|page=1285|date=1986|doi=10.1021/om00138a001|issue=7}}

A metathesis reaction in tetrahydrofuran or ether gives alkyls and aryls of samarium:

:{{chem2|SmCl3 + 3LiR → SmR3 + 3LiCl}}

:{{chem2|Sm(OR)3 + 3LiCH(SiMe3)2 → Sm{CH(SiMe3)2}3 + 3LiOR}}

Here R is a hydrocarbon group and Me = methyl.

{{main|Isotopes of samarium}}

Naturally occurring samarium is composed of five stable isotopes: ¹⁴⁴Sm, ¹⁴⁹Sm, ¹⁵⁰Sm, ¹⁵²Sm and ¹⁵⁴Sm, and two extremely long-lived radioisotopes, ¹⁴⁷Sm (half-life t_1/2 = 1.06{{e|11}} years) and ¹⁴⁸Sm (7{{e|15}} years), with ¹⁵²Sm being the most abundant (26.75%).{{NUBASE2020|ref}} ¹⁴⁹Sm is listed by various sources as being stable,{{NUBASE2020|ref}}{{Cite web |publisher=Brookhaven National Laboratory |title=Chart of the nuclides |url=http://www.nndc.bnl.gov/chart/reCenter.jsp?z=62&n=87 |access-date=2011-02-13 |archive-date=2017-07-29 |archive-url=https://web.archive.org/web/20170729181515/http://www.nndc.bnl.gov/chart/reCenter.jsp?z=62&n=87 |url-status=dead }} but some sources state that it is radioactive,Holden, Norman E. "Table of the isotopes" in {{RubberBible86th}} with a lower bound for its half-life given as {{val|2|e=15}} years.{{NUBASE2020|ref}} Some observationally stable samarium isotopes are predicted to decay to isotopes of neodymium.{{cite journal |last1=Belli |first1=P. |last2=Bernabei |first2=R. |last3=Danevich |first3=F. A. |last4=Incicchitti |first4=A. |last5=Tretyak |first5=V. I. |title=Experimental searches for rare alpha and beta decays |date=2019 |journal=European Physical Journal A |volume=55 |number=140 |pages=4–6 |doi=10.1140/epja/i2019-12823-2 |arxiv=1908.11458 |bibcode=2019EPJA...55..140B |s2cid=201664098 }} The long-lived isotopes ¹⁴⁶Sm, ¹⁴⁷Sm, and ¹⁴⁸Sm undergo alpha decay to neodymium isotopes. Lighter unstable isotopes of samarium mainly decay by electron capture to promethium, while heavier ones beta decay to europium.{{NUBASE2020|ref}} The known isotopes range from ¹²⁹Sm to ¹⁶⁸Sm.{{NUBASE2020|ref}}{{cite journal |last1=Kiss |first1=G. G. |last2=Vitéz-Sveiczer |first2=A. |last3=Saito |first3=Y. |display-authors=et al. |title=Measuring the β-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the nucleosynthesis yields in the rare-earth region |journal=The Astrophysical Journal |volume=936 |issue=107 |date=2022 |page=107 |doi=10.3847/1538-4357/ac80fc |bibcode=2022ApJ...936..107K |s2cid=252108123 |doi-access=free |hdl=2117/375253 |hdl-access=free }} The half-lives of ¹⁵¹Sm and ¹⁴⁵Sm are 90 years and 340 days, respectively. All remaining radioisotopes have half-lives that are less than 2 days, and most these have half-life less than 48 seconds. Samarium also has twelve known nuclear isomers, the most stable of which are ^141mSm (half-life 22.6 minutes), ^143m1Sm (t_1/2 = 66 seconds), and ^139mSm (t_1/2 = 10.7 seconds).{{NUBASE2020|ref}} Natural samarium has a radioactivity of 127 Bq/g, mostly due to ¹⁴⁷Sm,{{cite report |url=https://www-pub.iaea.org/MTCD/Publications/PDF/Pub1512_web.pdf |title=Radiation Protection and NORM Residue Management in the Production of Rare Earths from Thorium Containing Minerals |publisher=International Atomic Energy Agency |series=Safety Report Series |number=68 |date=2011 |page=174 |access-date=2022-07-25}} which alpha decays to ¹⁴³Nd with a half-life of 1.06{{e|11}} years and is used in samarium–neodymium dating.{{cite journal|last1=Depaolo|first1=D. J.|last2=Wasserburg|first2=G. J.|title=Nd isotopic variations and petrogenetic models |journal=Geophysical Research Letters|volume=3|pages=249|year=1976|doi=10.1029/GL003i005p00249|bibcode=1976GeoRL...3..249D|issue=5|url=https://authors.library.caltech.edu/41937/1/grl330.pdf}}{{cite journal|last1=McCulloch|first1=M. T.|last2=Wasserburg|first2=G. J. |title=Sm-Nd and Rb-Sr Chronology of Continental Crust Formation |journal=Science |volume=200 |pages=1003–11 |year=1978 |doi=10.1126/science.200.4345.1003 |issue=4345 |pmid=17740673 |bibcode=1978Sci...200.1003M |s2cid=40675318 |url=https://resolver.caltech.edu/CaltechAUTHORS:20131107-143832294 }} ¹⁴⁶Sm is an extinct radionuclide, with the half-life of 9.20{{e|7}} years. There have been searches of samarium-146 as a primordial nuclide, because its half-life is long enough such that minute quantities of the element should persist today.{{cite journal | last=Macfarlane | first=Ronald D. | title=Natural Occurrence of Samarium-146 | journal=Nature | volume=188 | issue=4757 | year=1960 | issn=0028-0836 | doi=10.1038/1881180a0 | pages=1180–1181| bibcode=1960Natur.188.1180M | s2cid=4217617 }} It can be used in radiometric dating.{{cite journal |title=Separation of samarium and neodymium: a prerequisite for getting signals from nuclear synthesis |author=Samir Maji |journal=Analyst |volume=131 |pages=1332–1334 |year=2006 |doi=10.1039/b608157f |pmid=17124541 |issue=12 |bibcode=2006Ana...131.1332M |display-authors=1 |last2=Lahiri |first2=Susanta |last3=Wierczinski |first3=Birgit |last4=Korschinek |first4=Gunther}}

Samarium-149 is an observationally stable isotope of samarium (predicted to decay, but no decays have ever been observed, giving it a half-life at least several orders of magnitude longer than the age of the universe), and a product of the decay chain from the fission product ¹⁴⁹Nd (yield 1.0888%). ¹⁴⁹Sm is a decay product and neutron-absorber in nuclear reactors, with a neutron poison effect that is second in importance for reactor design and operation only to ¹³⁵Xe.{{cite book|title=DOE Fundamentals Handbook: Nuclear Physics and Reactor Theory |date=January 1993 |publisher=U.S. Department of Energy |url=http://www.hss.energy.gov/nuclearsafety/ns/techstds/standard/hdbk1019/h1019v2.pdf |pages=34, 67 |archive-url=https://web.archive.org/web/20090322040810/http://www.hss.energy.gov/nuclearsafety/ns/techstds/standard/hdbk1019/h1019v2.pdf |archive-date=2009-03-22 }}{{Cite web |last=K. |first=Khattab |date=2005 |title=Comparison of xenon-135 and samarium-149 poisoning in the Miniature Neutron Source Reactor |url=https://inis.iaea.org/search/search.aspx?orig_q=RN:36069288 |language=Arabic}} Its neutron cross section is 41000 barns for thermal neutrons.{{Cite conference |first1=Carlos E. |last1=Espinosa |first2=Bardo E.J. |last2=Bodmann |title=Modeling and simulation of nuclear fuel in scenarios with long time scales |url=https://inis.iaea.org/search/search.aspx?orig_q=RN:46133777 |conference=19. ENFIR: meeting on nuclear reactor physics and thermal hydraulics |language=English}} Because samarium-149 is not radioactive and is not removed by decay, it presents problems somewhat different from those encountered with xenon-135. The equilibrium concentration (and thus the poisoning effect) builds to an equilibrium value during reactor operations in about 500 hours (about three weeks), and since samarium-149 is stable, its concentration remains essentially constant during reactor operation.DOE Handbook, pp. 43–47.

File:153Sm-lexidronam structure.svg|alt=Chemical structure of samarium (153Sm) lexidronam]]

Samarium-153 is a beta emitter with a half-life of 46.3 hours. It is used to kill cancer cells in lung cancer, prostate cancer, breast cancer, and osteosarcoma. For this purpose, samarium-153 is chelated with ethylene diamine tetramethylene phosphonate (EDTMP) and injected intravenously. The chelation prevents accumulation of radioactive samarium in the body that would result in excessive irradiation and generation of new cancer cells. The corresponding drug has several names including samarium (¹⁵³Sm) lexidronam; its trade name is Quadramet.{{cite web|access-date=2009-06-06|url=http://www.centerwatch.com/patient/drugs/dru267.html|title=Centerwatch About drug Quadramet|archive-date=2008-10-09|archive-url=https://web.archive.org/web/20081009094258/http://www.centerwatch.com/patient/drugs/dru267.html}}{{cite journal |last1=Pattison |first1=John E. |title=Finger doses received during 153Sm injections |journal=Health Physics |volume=77 |issue=5 |pages=530–5 |date=1999 |pmid=10524506 |doi=10.1097/00004032-199911000-00006|bibcode=1999HeaPh..77..530P }}{{cite journal |last1=Finlay |first1=I. G. |last2=Mason |first2=M. D. |last3=Shelley |first3=M. |title=Radioisotopes for the palliation of metastatic bone cancer: a systematic review |journal=The Lancet Oncology |volume=6 |issue=6 |pages=392–400 |date=2005 |pmid=15925817 |doi=10.1016/S1470-2045(05)70206-0}}

File:Lecoq de Boisbaudran.jpg, the discoverer of samarium | alt=Lecoq de Boisbaudran]]

Detection of samarium and related elements was announced by several scientists in the second half of the 19th century; however, most sources give priority to French chemist Paul-Émile Lecoq de Boisbaudran.Greenwood, p. 1229[http://www.britannica.com/EBchecked/topic/520309/samarium Samarium], Encyclopædia Britannica on-line Boisbaudran isolated samarium oxide and/or hydroxide in Paris in 1879 from the mineral samarskite {{chem2|((Y,Ce,U,Fe)3(Nb,Ta,Ti)5O16}}) and identified a new element in it via sharp optical absorption lines.{{cite book |first=C. R. |last=Hammond |chapter=The Elements |title=Handbook of Chemistry and Physics |edition=81st |publisher=CRC press |isbn=978-0-8493-0481-1 |chapter-url-access=registration |chapter-url=https://archive.org/details/crchandbookofche81lide |date=2004-06-29 |pages=4–27 |location=Boca Raton New York Washington }} Swiss chemist Marc Delafontaine announced a new element decipium (from {{langx|la|decipiens}} meaning "deceptive, misleading") in 1878,{{cite journal |title=Sur le décepium, métal nouveau de la samarskite |first=Marc |last=Delafontaine |journal=Journal de pharmacie et de chimie |volume=28 |page=540 |date=1878 |url=https://gallica.bnf.fr/ark:/12148/bpt6k78100m.image.r=Decipium.f548.langEN |language=fr}}{{cite journal |title=Sur le décepium, métal nouveau de la samarskite |first=Marc |last=Delafontaine |journal=Comptes rendus hebdomadaires des séances de l'Académie des Sciences |volume=87 |page=632 |date=1878 |url=https://gallica.bnf.fr/ark:/12148/bpt6k3044x.image.r=Decipium.f694.langEN |language=fr}} but later in 1880–1881 demonstrated that it was a mix of several elements, one being identical to Boisbaudran's samarium.{{CIAAW2003}}{{cite journal|title=Sur le décipium et le samarium |first=Marc |last=Delafontaine |journal=Comptes rendus hebdomadaires des séances de l'Académie des Sciences |volume=93 |page=63 |date=1881 |language=fr |url=https://gallica.bnf.fr/ark:/12148/bpt6k3049g.image.r=Decipium.f63.langEN}} Though samarskite was first found in the Ural Mountains in Russia, by the late 1870s it had been found in other places, making it available to many researchers. In particular, it was found that the samarium isolated by Boisbaudran was also impure and had a comparable amount of europium. The pure samarium(III) oxide was produced only in 1901 by Eugène-Anatole Demarçay,{{cite book |last1=Weeks |first1=Mary Elvira |title=The discovery of the elements |date=1956 |publisher=Journal of Chemical Education |location=Easton, PA |url=https://archive.org/details/discoveryoftheel002045mbp |edition=6th}}{{cite journal |title=The discovery of the elements. XIII. Some elements predicted by Mendeleeff |pages=1605–1619 |last=Weeks |first=Mary Elvira |author-link=Mary Elvira Weeks |doi=10.1021/ed009p1605 |journal=Journal of Chemical Education |volume=9 |issue=9 |date=1932 |bibcode=1932JChEd...9.1605W}} and in 1903 Wilhelm Muthmann isolated the element.

Boisbaudran named his element samarium after the mineral samarskite, which in turn honored Vassili Samarsky-Bykhovets (1803–1870). Samarsky-Bykhovets, as the Chief of Staff of the Russian Corps of Mining Engineers, had granted access for two German mineralogists, the brothers Gustav and Heinrich Rose, to study the mineral samples from the Urals.[https://bse.sci-lib.com/article099149.html Samarskite], Great Soviet Encyclopedia (in Russian){{cite journal|url= https://gallica.bnf.fr/ark:/12148/bpt6k3046j/f214.pagination|first= Lecoq de|last= Boisbaudran|title= Recherches sur le samarium, radical d'une terre nouvelle extraite de la samarskite|journal= Comptes rendus hebdomadaires des séances de l'Académie des sciences|volume= 89|date=1879|pages= 212–214}}Shipley, Joseph Twadell. [https://books.google.com/books?id=m1UKpE4YEkEC&pg=PA90 The Origins of English Words: A Discursive Dictionary of Indo-European Roots], JHU Press, 2001, p.90. {{ISBN|0-8018-6784-3}} Samarium was thus the first chemical element to be named after a person. The word samaria is sometimes used to mean samarium(III) oxide, by analogy with yttria, zirconia, alumina, ceria, holmia, etc. The symbol Sm was suggested for samarium, but an alternative Sa was often used instead until the 1920s.[https://elements.vanderkrogt.net/element.php?sym=Sm Samarium: History & Etymology]. Elements.vanderkrogt.net. Retrieved on 2013-03-21.{{cite journal|last1=Coplen|first1=T. B.|last2=Peiser|first2=H. S.|title=History of the recommended atomic-weight values from 1882 to 1997: A comparison of differences from current values to the estimated uncertainties of earlier values (Technical Report)|journal=Pure and Applied Chemistry |volume=70 |page=237 |date=1998|doi=10.1351/pac199870010237|s2cid=96729044|url=https://zenodo.org/record/1236255|doi-access=free}}

Before the advent of ion-exchange separation technology in the 1950s, pure samarium had no commercial uses. However, a by-product of fractional crystallization purification of neodymium was a mix of samarium and gadolinium that got the name "Lindsay Mix" after the company that made it, and was used for nuclear control rods in some early nuclear reactors.{{Cite journal |last1=Ghaemi |first1=Arezoo |last2=Tavakkoli |first2=Haman |last3=Rajabi |first3=Negar |date=2015-06-01 |title=Solvent influence upon complex formation between 4,13-didecyl-1,7,10,16-tetraoxa-4,13-diazacyclooctadecane with samarium(III) metal cation in binary mixed non-aqueous solvents |journal=Russian Journal of Applied Chemistry |language=en |volume=88 |issue=6 |pages=977–984 |doi=10.1134/S1070427215060130 |s2cid=97051960 |issn=1608-3296}} Nowadays, a similar commodity product has the name "samarium-europium-gadolinium" (SEG) concentrate.{{Cite web |title=Chemistry in Its Element - Samarium |url=http://www.rsc.org/chemistryworld/podcast/Interactive_Periodic_Table_Transcripts/Samarium.asp |archive-url=https://web.archive.org/web/20160304045647/http://www.rsc.org/chemistryworld/podcast/Interactive_Periodic_Table_Transcripts/Samarium.asp |archive-date=4 March 2016}} It is prepared by solvent extraction from the mixed lanthanides isolated from bastnäsite (or monazite). Since heavier lanthanides have more affinity for the solvent used, they are easily extracted from the bulk using relatively small proportions of solvent. Not all rare-earth producers who process bastnäsite do so on a large enough scale to continue by separating the components of SEG, which typically makes up only 1{{endash}}2% of the original ore. Such producers therefore make SEG with a view to marketing it to the specialized processors. In this manner, the valuable europium in the ore is rescued for use in making phosphor. Samarium purification follows the removal of the europium. {{As of | 2012}}, being in oversupply, samarium oxide is cheaper on a commercial scale than its relative abundance in the ore might suggest.

File:Samarskite-fresh.jpg

Samarium concentration in soils varies between 2 and 23 ppm, and oceans contain about 0.5–0.8 parts per trillion. The median value for its abundance in the Earth's crust used by the CRC Handbook is 7 parts per million (ppm)ABUNDANCE OF ELEMENTS IN THE EARTH’S CRUST AND IN THE SEA, CRC Handbook of Chemistry and Physics, 97th edition (2016–2017), p. 14-17 and is the 40th most abundant element.{{Cite book |last=Emsley |first=John |url=https://books.google.com/books?id=2EfYXzwPo3UC&dq=%2240th+most+abundant+element%22&pg=PA466 |title=Nature's Building Blocks: An A-Z Guide to the Elements |date=2011-08-25 |publisher=OUP Oxford |isbn=978-0-19-960563-7 |language=en}} Distribution of samarium in soils strongly depends on its chemical state and is very inhomogeneous: in sandy soils, samarium concentration is about 200 times higher at the surface of soil particles than in the water trapped between them, and this ratio can exceed 1,000 in clays.

Samarium is not found free in nature, but, like other rare earth elements, is contained in many minerals, including monazite, bastnäsite, cerite, gadolinite and samarskite; monazite (in which samarium occurs at concentrations of up to 2.8%) and bastnäsite are mostly used as commercial sources. World resources of samarium are estimated at two million tonnes; they are mostly located in China, US, Brazil, India, Sri Lanka and Australia, and the annual production is about 700 tonnes. Country production reports are usually given for all rare-earth metals combined. By far, China has the largest production with 120,000 tonnes mined per year; it is followed by the US (about 5,000 tonnes) and India (2,700 tonnes).{{cite web|url=http://minerals.usgs.gov/minerals/pubs/commodity/rare_earths/mcs-2010-raree.pdf|title=Rare Earths |publisher=United States Geological Survey|date=January 2010|access-date=2010-12-10}} Samarium is usually sold as oxide, which at the price of about US$30/kg is one of the cheapest lanthanide oxides.[https://web.archive.org/web/20121014122537/http://lynascorp.com/page.asp?category_id=1&page_id=25 What are their prices?], Lynas corp. Whereas mischmetal – a mixture of rare earth metals containing about 1% of samarium – has long been used, relatively pure samarium has been isolated only recently, through ion exchange processes, solvent extraction techniques, and electrochemical deposition. The metal is often prepared by electrolysis of a molten mixture of samarium(III) chloride with sodium chloride or calcium chloride. Samarium can also be obtained by reducing its oxide with lanthanum. The product is then distilled to separate samarium (boiling point 1794 °C) and lanthanum (b.p. 3464 °C).

Very few minerals have samarium being the most dominant element. Minerals with essential (dominant) samarium include monazite-(Sm) and florencite-(Sm). These minerals are very rare and are usually found containing other elements, usually cerium or neodymium.{{Cite journal |last1=Masau |first1=M. |last2=Cerny |first2=P. |last3=Cooper |first3=M. A. |last4=Chapman |first4=R. |last5=Grice |first5=J. D. |date=2002-12-01 |title=MONAZITE-(Sm), A NEW MEMBER OF THE MONAZITE GROUP FROM THE ANNIE CLAIM #3 GRANITIC PEGMATITE, SOUTHEASTERN MANITOBA |url=http://www.canmin.org/cgi/doi/10.2113/gscanmin.40.6.1649 |journal=The Canadian Mineralogist |language=en |volume=40 |issue=6 |pages=1649–1655 |doi=10.2113/gscanmin.40.6.1649 |bibcode=2002CaMin..40.1649M |issn=0008-4476}}{{Cite journal |last1=Repina |first1=S. A. |last2=Popova |first2=V. I. |last3=Churin |first3=E. I. |last4=Belogub |first4=E. V. |last5=Khiller |first5=V. V. |date=December 2011 |title=Florencite-(Sm)—(Sm,Nd)Al₃(PO₄)₂(OH)₆: a new mineral species of the alunite–jarosite group from the subpolar Urals |url=https://link.springer.com/10.1134/S1075701511070191 |journal=Geology of Ore Deposits |language=en |volume=53 |issue=7 |pages=564–574 |doi=10.1134/S1075701511070191 |bibcode=2011GeoOD..53..564R |s2cid=97229772 |issn=1075-7015|url-access=subscription }}{{cite web|url=http://www.mindat.org/min-11438.html |title=Monazite-(Sm): Monazite-(Sm) mineral information and data |website=Mindat.org |access-date=2016-03-04}}{{cite web|url=http://www.mindat.org/min-42495.html |title=Florencite-(Sm): Florencite-(Sm) mineral information and data |website=Mindat.org |access-date=2016-03-04}} It is also made by neutron capture by samarium-149, which is added to the control rods of nuclear reactors. Therefore, {{sup|151}}Sm is present in spent nuclear fuel and radioactive waste.

File:Samariumiodide.jpg using {{chem2|SmI2}}|alt=Barbier reaction using samarium diiodide]]

An important use of samarium is samarium–cobalt magnets, which are nominally {{chem2|SmCo5}} or {{chem2|Sm2Co17}}.{{cite web |url=https://www.stanfordmagnets.com/two-grades-of-samarium-cobalt-magnets-smco5-sm2co17.html |title=Two Grades of Samarium Cobalt Magnets: SmCo5 & Sm2Co17 |last=Marchio |first=Cathy |date=Apr 16, 2024 |website=Stanford Magnets |access-date=Aug 23, 2024}} They have high permanent magnetization, about 10,000 times that of iron and second only to neodymium magnets. However, samarium magnets resist demagnetization better; they are stable to temperatures above {{convert|700|C|F}} (cf. 300–400 °C for neodymium magnets). These magnets are found in small motors, headphones, and high-end magnetic pickups for guitars and related musical instruments. For example, they are used in the motors of a solar-powered electric aircraft, the Solar Challenger, and in the Samarium Cobalt Noiseless electric guitar and bass pickups.

Samarium and its compounds are important as catalysts and chemical reagents. Samarium catalysts help the decomposition of plastics, dechlorination of pollutants such as polychlorinated biphenyls (PCB), as well as dehydration and dehydrogenation of ethanol. Samarium(III) triflate {{chem2|Sm(OTf)3}}, that is {{chem2|Sm(CF3SO3)3}}, is one of the most efficient Lewis acid catalysts for a halogen-promoted Friedel–Crafts reaction with alkenes.{{cite journal|last1=Hajra |first1=S.|last2=Maji |first2=B.|last3=Bar |first3=S. |title=Samarium Triflate-Catalyzed Halogen-Promoted Friedel-Crafts Alkylation with Alkenes|date=2007|journal= Org. Lett.|volume= 9|issue= 15|pages= 2783–2786|doi= 10.1021/ol070813t|pmid=17585769}} Samarium(II) iodide is a very common reducing and coupling agent in organic synthesis, for example in desulfonylation reactions; annulation; Danishefsky, Kuwajima, Mukaiyama and Holton Taxol total syntheses; strychnine total synthesis; Barbier reaction and other reductions with samarium(II) iodide.{{cite book| page=1128| url=https://books.google.com/books?id=U3MWRONWAmMC&pg=PA1128|title =Advanced inorganic chemistry |edition=6th |last1= Cotton|first1=F. Albert |last2=Wilkinson |first2=Geoffrey |last3=Murillo |first3=Carlos A. |last4=Bochmann |first4=Manfred |publisher= Wiley|location=New Delhi, India|date=2007|isbn =978-81-265-1338-3}}

In its usual oxidized form, samarium is added to ceramics and glasses where it increases absorption of infrared light. As a (minor) part of mischmetal, samarium is found in the "flint" ignition devices of many lighters and torches.

Samarium-149 has a high cross section for neutron capture (41,000 barns) and so is used in control rods of nuclear reactors. Its advantage compared to competing materials, such as boron and cadmium, is stability of absorption – most of the fusion products of {{sup|149}}Sm are other isotopes of samarium that are also good neutron absorbers. For example, the cross section of samarium-151 is 15,000 barns, it is on the order of hundreds of barns for {{sup|150}}Sm, {{sup|152}}Sm, and {{sup|153}}Sm, and 6,800 barns for natural (mixed-isotope) samarium.[https://web.archive.org/web/20110706160607/http://www-nds.ipen.br/sgnucdat/b3.pdf Thermal neutron capture cross sections and resonance integrals – Fission product nuclear data]. ipen.br

Samarium-doped calcium fluoride crystals were used as an active medium in one of the first solid-state lasers designed and built by Peter Sorokin (co-inventor of the dye laser) and Mirek Stevenson at IBM research labs in early 1961. This samarium laser gave pulses of red light at 708.5 nm. It had to be cooled by liquid helium and so did not find practical applications.Bud, Robert and Gummett, Philip [https://books.google.com/books?id=HMx_6FtHBcUC&pg=PA268 Cold War, Hot Science: Applied Research in Britain's Defence Laboratories, 1945–1990], NMSI Trading Ltd, 2002 {{ISBN|1-900747-47-2}} p. 268{{cite journal|last1=Sorokin|first1=P. P.|title=Contributions of IBM to Laser Science—1960 to the Present|journal=IBM Journal of Research and Development|volume=23|page=476|date=1979|doi=10.1147/rd.235.0476|issue=5|bibcode=1979IBMJ...23..476S}} Another samarium-based laser became the first saturated X-ray laser operating at wavelengths shorter than 10 nanometers. It gave 50-picosecond pulses at 7.3 and 6.8 nm suitable for uses in holography, high-resolution microscopy of biological specimens, deflectometry, interferometry, and radiography of dense plasmas related to confinement fusion and astrophysics. Saturated operation meant that the maximum possible power was extracted from the lasing medium, resulting in the high peak energy of 0.3 mJ. The active medium was samarium plasma produced by irradiating samarium-coated glass with a pulsed infrared Nd-glass laser (wavelength ~1.05 μm).{{cite journal |last=Zhang |first=J. |title=A Saturated X-ray Laser Beam at 7 Nanometers |journal=Science |volume=276 |page=1097 |date=1997 |doi=10.1126/science.276.5315.1097 |issue=5315}}

In 2007 it was shown that nanocrystalline BaFCl:Sm{{sup|3+}} as prepared by co-precipitation can serve as a very efficient X-ray storage phosphor.{{cite journal|last1=Riesen|first1=Hans |last2=Kaczmarek|first2=Wieslaw |title=Efficient X-ray Generation of Sm{{sup|2+}} in Nanocrystalline BaFCl/Sm{{sup|3+}}: a Photoluminescent X-ray Storage Phosphor|journal=Inorganic Chemistry|date=2007-08-02|volume=46|issue=18|pages=7235–7 |doi=10.1021/ic062455g|pmid=17672448}} The co-precipitation leads to nanocrystallites of the order of 100–200 nm in size and their sensitivity as X-ray storage phosphors is increased a remarkable ~500,000 times because of the specific arrangements and density of defect centers in comparison with microcrystalline samples prepared by sintering at high temperature.{{cite journal|last1=Liu|first1=Zhiqiang |last2=Stevens-Kalceff|first2=Marion |last3=Riesen|first3=Hans |title=Photoluminescence and Cathodoluminescence Properties of Nanocrystalline BaFCl:Sm3+ X-ray Storage Phosphor|journal=Journal of Physical Chemistry C|date=2012-03-16|volume=116|issue=14 |pages=8322–8331|doi=10.1021/jp301338b}} The mechanism is based on reduction of Sm{{sup|3+}} to Sm{{sup|2+}} by trapping electrons that are created upon exposure to ionizing radiation in the BaFCl host. The {{sup|5}}D{{sub|J}}–{{sup|7}}F{{sub|J}} f–f luminescence lines can be very efficiently excited via the parity allowed 4f{{sup|6}}→4f{{sup|5}}5d transition at ~417 nm. The latter wavelength is ideal for efficient excitation by blue-violet laser diodes as the transition is electric dipole allowed and thus relatively intense (400 L/(mol⋅cm)).{{cite journal|last1=Wang|first1=Xianglei |last2=Liu|first2=Zhiqiang |last3=Stevens-Kalceff|first3=Marion |last4=Riesen|first4=Hans |title=Mechanochemical Preparation of Nanocrystalline BaFCl Doped with Samarium in the 2+ Oxidation State|journal=Inorganic Chemistry|date=August 12, 2014 |volume=53|issue=17|pages=8839–8841 |doi=10.1021/ic500712b|pmid=25113662}}

The phosphor has potential applications in personal dosimetry, dosimetry and imaging in radiotherapy, and medical imaging.{{cite web|title=Dosimetry&Imaging Pty Ltd|url=http://www.oelimaging.com |access-date=2018-11-28|archive-url= https://web.archive.org/web/20170926094926/http://oelimaging.com/ |archive-date=2017-09-26}}

• The change in electrical resistivity in samarium monochalcogenides can be used in a pressure sensor or in a memory device triggered between a low-resistance and high-resistance state by external pressure,{{Cite patent|number=20100073997|title=Piezo-Driven Non-Volatile Memory Cell with Hysteretic Resistance|gdate=2010-03-25|invent1=Elmegreen|invent2=Krusin-elbaum|invent3=Liu|invent4=Martyna|inventor1-first=Bruce G.|inventor2-first=Lia|inventor3-first=Xiao Hu|inventor4-first=Glenn J.|url=https://www.freepatentsonline.com/y2010/0073997.html}} and such devices are being developed commercially.{{Cite web |title=About us |url=https://tenzo-sms.ru/en/about |access-date=2022-12-31 |website=tenzo-sms.ru}} Samarium monosulfide also generates electric voltage upon moderate heating to about {{convert|150|C|F}} that can be applied in thermoelectric power converters.{{cite journal|last1=Kaminskii|first1=V. V. |last2=Solov'ev |first2=S. M. |last3=Golubkov|first3=A. V.|title=Electromotive Force Generation in Homogeneously Heated Semiconducting Samarium Monosulfide |doi=10.1134/1.1467284 |date=2002 |page=229 |volume=28 |journal=Technical Physics Letters |url=http://www.tenzo-sms.ru/en/articles/5 |issue=3 |bibcode=2002TePhL..28..229K |s2cid=122463906 |archive-url=https://web.archive.org/web/20120315180549/http://www.tenzo-sms.ru/en/articles/5 |archive-date=2012-03-15|url-access=subscription }}
• Analysis of relative concentrations of samarium and neodymium isotopes {{sup|147}}Sm, {{sup|144}}Nd, and {{sup|143}}Nd allows determination of the age and origin of rocks and meteorites in samarium–neodymium dating. Both elements are lanthanides and are very similar physically and chemically. Thus, Sm–Nd dating is either insensitive to partitioning of the marker elements during various geologic processes, or such partitioning can well be understood and modeled from the ionic radii of said elements.Bowen, Robert and Attendorn, H -G [https://books.google.com/books?id=k90iAnFereYC&pg=PA270 Isotopes in the Earth Sciences], Springer, 1988, {{ISBN|0-412-53710-9}}, pp. 270 ff
• The Sm{{sup|3+}} ion is a potential activator for use in warm-white light emitting diodes. It offers high luminous efficacy due to narrow emission bands; but the generally low quantum efficiency and too little absorption in the UV-A to blue spectral region hinders commercial application.{{cite journal|last1=Baur|first1=F.|last2=Katelnikovas|first2=A. |last3=Sazirnakovas|first3=S. |last4=Jüstel|first4=T. |title=Synthesis and Optical Properties of Li{{sub|3}}Ba{{sub|2}}La{{sub|3}}(MoO{{sub|4}}){{sub|8}}:Sm{{sup|3+}} |journal=Zeitschrift für Naturforschung B |volume=69|pages=183–192 |date=2014|doi=10.5560/ZNB.2014-3279|issue=2|s2cid=197099937}}
• Samarium is used for ionosphere testing. A rocket spreads samarium monoxide as a red vapor at high altitude, and researchers test how the atmosphere disperses it and how it impacts radio transmissions.{{cite journal |last1=Caton |first1=Ronald G. |last2=Pedersen |first2=Todd R. |last3=Groves |first3=Keith M. |last4=Hines |first4=Jack |last5=Cannon |first5=Paul S. |last6=Jackson-Booth |first6=Natasha |last7=Parris |first7=Richard T. |last8=Holmes |first8=Jeffrey M. |last9=Su |first9=Yi-Jiun |last10=Mishin |first10=Evgeny V. |last11=Roddy |first11=Patrick A. |last12=Viggiano |first12=Albert A. |last13=Shuman |first13=Nicholas S. |last14=Ard |first14=Shaun G. |last15=Bernhardt |first15=Paul A. |last16=Siefring |first16=Carl L. |last17=Retterer |first17=John |last18=Kudeki |first18=Erhan |last19=Reyes |first19=Pablo M. |title=Artificial ionospheric modification: The Metal Oxide Space Cloud experiment |journal=Radio Science |date=May 2017 |volume=52 |issue=5 |pages=539–558 |doi=10.1002/2016rs005988|url=https://pure-oai.bham.ac.uk/ws/files/40897676/Caton_et_al_2017_Radio_Science.pdf |bibcode=2017RaSc...52..539C |s2cid=55195732 }}{{cite web |last1=Zell |first1=Holly |title=First of Four Sounding Rockets Launched from the Marshall Islands |url=https://www.nasa.gov/mission_pages/sounding-rockets/news/mosc.html |website=NASA |language=en |date=2013-06-07 |access-date=2019-08-15 |archive-date=2021-10-11 |archive-url=https://web.archive.org/web/20211011040155/https://www.nasa.gov/mission_pages/sounding-rockets/news/mosc.html |url-status=dead }}
• Samarium hexaboride, {{chem2|SmB6}}, has recently been shown to be a topological insulator with potential uses in quantum computing.{{Cite journal |last1=Li |first1=G. |last2=Xiang |first2=Z. |last3=Yu |first3=F. |last4=Asaba |first4=T. |last5=Lawson |first5=B. |last6=Cai |first6=P. |last7=Tinsman |first7=C. |last8=Berkley |first8=A. |last9=Wolgast |first9=S. |last10=Eo |first10=Y. S. |last11=Kim |first11=Dae-Jeong |last12=Kurdak |first12=C. |last13=Allen |first13=J. W. |last14=Sun |first14=K. |last15=Chen |first15=X. H. |date=2014-12-05 |title=Two-dimensional Fermi surfaces in Kondo insulator SmB 6 |url=https://www.science.org/doi/10.1126/science.1250366 |journal=Science |language=en |volume=346 |issue=6214 |pages=1208–1212 |doi=10.1126/science.1250366 |pmid=25477456 |arxiv=1306.5221 |bibcode=2014Sci...346.1208L |s2cid=119191689 |issn=0036-8075}}{{Cite journal|last1=Botimer|arxiv=1211.6769 |first1=J. |last2=Kim |first2=D. J. |last3=Thomas |first3=S. |last4=Grant |first4=T. |last5=Fisk |first5=Z. |author6=Jing Xia |title=Robust Surface Hall Effect and Nonlocal Transport in SmB₆: Indication for an Ideal Topological Insulator |journal=Scientific Reports |volume=3 |issue=3150 |pages=3150 |year=2013|doi=10.1038/srep03150 |bibcode=2013NatSR...3.3150K |pmid=24193196 |pmc=3818682}}{{cite journal |last1=Zhang |first1=Xiaohang |last2=Butch |first2=N. P. |last3=Syers |first3=P. |last4=Ziemak |first4=S. |last5=Greene |first5=Richard L. |last6=Paglione |first6=Johnpierre |title=Hybridization, Correlation, and In-Gap States in the Kondo Insulator SmB₆ |year=2013 |doi=10.1103/PhysRevX.3.011011 |journal=Physical Review X |volume=3 |issue=1|pages=011011 |arxiv=1211.5532|bibcode=2013PhRvX...3a1011Z |s2cid=53638956 }}{{Cite journal |arxiv=1211.5104 |first1=Steven |last1=Wolgast |first2=Cagliyan |last2=Kurdak |first3=Kai |last3=Sun |first4=J. W. |last4=Allen |first5=Dae-Jeong |last5=Kim |first6=Zachary |last6=Fisk |title=Low-temperature surface conduction in the Kondo insulator SmB₆|journal=Physical Review B |volume=88 |issue=18 |pages=180405 |date=2012 |display-authors=3|doi=10.1103/PhysRevB.88.180405 |bibcode=2013PhRvB..88r0405W |s2cid=119242604 }}

{{Chembox

| container_only = yes

|Section7={{Chembox Hazards

| Hazards_ref = {{Sigma-Aldrich|id=263184|name=Samarium 263184|access-date=2023-04-11}}

| ExternalSDS =

| GHSPictograms = {{GHS02}}

| GHSSignalWord = Warning

| HPhrases = {{H-phrases|261}}

| PPhrases = {{P-phrases|P231 + P232|P280|P370 + P378|P501}}

| NFPA-H = 2

| NFPA-F = 3

| NFPA-R = 2

| NFPA-S = W

| NFPA_ref = {{cite web|url=https://www.fishersci.com/store/msds?partNumber=AA40297DH&productDescription=SAMR+RD+6.35MMDIA+99.9+25MM&vendorId=VN00024248&countryCode=US&language=en |title=Safety Data Sheet |access-date=2023-04-11 |date=2020-02-14 |publisher=Thermo Fisher Scientific }}

}}

}}

Samarium salts stimulate metabolism, but it is unclear whether this is from samarium or other lanthanides present with it. The total amount of samarium in adults is about 50 μg, mostly in liver and kidneys and with ~8 μg/L being dissolved in blood. Samarium is not absorbed by plants to a measurable concentration and so is normally not part of human diet. However, a few plants and vegetables may contain up to 1 part per million of samarium. Insoluble salts of samarium are non-toxic and the soluble ones are only slightly toxic.{{cite book|title= Nature's Building Blocks: An A–Z Guide to the Elements|last= Emsley|first= John|publisher= Oxford University Press|date=2001|location= Oxford, England, UK|isbn= 0-19-850340-7|chapter= Samarium|pages= [https://archive.org/details/naturesbuildingb0000emsl/page/371 371–374]|chapter-url= https://books.google.com/books?id=j-Xu07p3cKwC&pg=PA371|url= https://archive.org/details/naturesbuildingb0000emsl/page/371}}{{cite journal |last1=Bayouth |first1=J. E. |last2=Macey |first2=D. J. |last3=Kasi |first3=L. P. |last4=Fossella |first4=F. V. |title=Dosimetry and toxicity of samarium-153-EDTMP administered for bone pain due to skeletal metastases |journal=Journal of Nuclear Medicine |year=1994 |volume=35 |issue=1 |pages=63–69 |url=https://jnm.snmjournals.org/content/35/1/63.long |pmid=7505819}} When ingested, only 0.05% of samarium salts are absorbed into the bloodstream and the remainder are excreted. From the blood, 45% goes to the liver and 45% is deposited on the surface of the bones where it remains for 10 years; the remaining 10% is excreted.[http://www.ead.anl.gov/pub/doc/samarium.pdf Human Health Fact Sheet on Samarium] {{webarchive|url=https://web.archive.org/web/20120407032958/http://www.ead.anl.gov/pub/doc/samarium.pdf |date=2012-04-07 }}, Los Alamos National Laboratory

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{{reflist}}

• {{cite book|ref=Greenwood|last1=Greenwood |first1=Norman N.|last2=Earnshaw |first2=Alan |date=1997|title= Chemistry of the Elements |edition=2nd|publisher= Butterworth–Heinemann|isbn= 9780080379418}}

{{sister project links|d=Q1819|v=The_periodic_table/Samarium|voy=no|q=no|wikt=samarium|s=no|b=no|n=no|c=Samarium|m=no|mw=no|species=no}}

• [https://education.jlab.org/itselemental/ele062.html It's Elemental – Samarium]
• [https://www.organic-chemistry.org/chemicals/reductions/samariumlowvalent.shtm Reducing Agents > Samarium low valent]

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Category:Chemical elements

Category:Chemical elements with rhombohedral structure

Category:Lanthanides

Category:Reducing agents