Editing Samarium (section)

===Chalcogenides===
{{see also|Samarium monochalcogenides}}
Samarium forms a trivalent [[samarium(III) sulfide|sulfide]], [[selenide]] and [[telluride (chemistry)|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.<ref>{{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}}</ref> Whereas the transition is continuous and occurs at about 20–30&nbsp;kbar in SmSe and SmTe, it is abrupt in SmS and requires only 6.5&nbsp;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.<ref name="b1">{{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}}</ref> 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.<ref name="emsley" /><ref>{{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}}</ref>