Editing Samarium (section)

==Physical properties==
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 [[Volatility (chemistry)|volatile]] lanthanide after [[ytterbium]] and [[europium]] and comparable in this respect to [[lead]] and [[barium]]; this helps separation of samarium from its ores.<ref name="Lange">{{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}}</ref><ref name="CRC" /> When freshly prepared, samarium has a silvery [[Lustre (mineralogy)|lustre]], and takes on a duller appearance when oxidized in air. Samarium is calculated to have one of the largest [[atomic radius|atomic radii]] of the elements; with a radius of 238&nbsp;pm, only [[potassium]], [[praseodymium]], [[barium]], [[rubidium]] and [[caesium]] are larger.<ref>{{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}}</ref>

In ambient conditions, samarium has a [[rhombohedral]] structure (α form). Upon heating to {{convert|731|C|F}}, its crystal symmetry changes to [[Hexagonal crystal system|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 [[Cubic crystal system|body-centered cubic]] (''bcc'') phase. Heating to {{convert|300|C|F}} plus compression to 40&nbsp;[[bar (unit)|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 crystal system|tetragonal]] phase appearing at about 900&nbsp;kbar.<ref name="sm" /> 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.<ref name="sm">{{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}}</ref>

Samarium and its [[sesquioxide]] are [[paramagnetism|paramagnetic]] at room temperature. Their corresponding effective magnetic moments, below 2 [[bohr magneton]]s, are the third-lowest among lanthanides (and their oxides) after lanthanum and lutetium. The metal transforms to an [[antiferromagnetism|antiferromagnetic]] state upon cooling to 14.8&nbsp;K.<ref>{{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}}</ref><ref>{{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}}</ref> Individual samarium atoms can be isolated by encapsulating them into [[fullerene]] molecules.<ref>{{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}}</ref> They can also be intercalated into the interstices of the bulk C<sub>60</sub> to form a solid solution of nominal composition Sm<sub>3</sub>C<sub>60</sub>, which is [[superconductivity|superconductive]] at a temperature of 8&nbsp;K.<ref>{{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}}</ref> Samarium doping of [[iron-based superconductor]]s – a class of [[high-temperature superconductor]] – increases their transition to normal conductivity temperature up to 56&nbsp;K, the highest value achieved so far in this series.<ref name="Wu2008">{{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}}</ref>