Iron(II) selenide
{{Use dmy dates|date=July 2014}}
{{Chembox
| Name =
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| IUPACName = Iron(II) selenide
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| Section1 = {{Chembox Identifiers
| CASNo = 1310-32-3
| CASNo_Ref = {{cascite|correct|CAS}}
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 64EUH87C9Z
| PubChem = 14795
| RTECS =
| EINECS = 215-177-1
| ChemSpiderID = 14262536
| SMILES = [Fe]=[Se]
| InChI = 1S/Fe.Se
| InChIKey = WALCGGIJOOWJIN-UHFFFAOYSA-N
}}
| Section2 = {{Chembox Properties
| Formula = FeSe
| MolarMass = 134.807 g/mol
| Appearance = black crystals
| Density = 4.72 g/cm3
| MeltingPtC = 965
| BoilingPt =
| Solubility = 0.975 mg/100mL{{citation needed|date=June 2020}}
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| Section3 = {{Chembox Structure
| CrystalStruct = hexagonal / tetragonal}}
| Section4 = {{Chembox Hazards
| GHS_ref=[https://pubchem.ncbi.nlm.nih.gov/compound/14795#section=Safety-and-Hazards]
| GHSPictograms = {{GHS06}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|301|331|373|410}}
| PPhrases = {{P-phrases|260|261|264|270|271|273|301+316|304+340|316|319|321|330|391|403+233|405|501}}
| MainHazards = toxic
| FlashPt =
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| Section9 = {{Chembox Related
| OtherAnions = Iron(II) oxide
Iron(II) sulfide
Iron(II) telluride
| OtherCations = Manganese(II) selenide
Cobalt(II) selenide
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Iron(II) selenide refers to a number of inorganic compounds of ferrous iron and selenide (Se2−). The phase diagram of the system Fe–Se{{cite journal | author = Okamoto H | year = 1991 | title = The Fe–Se (Iron-Selenium) System | journal = Journal of Phase Equilibria | volume = 12 | issue = 3| pages = 383–389 | doi = 10.1007/BF02649932 | s2cid = 99966041 }} reveals the existence of several non-stoichiometric phases between ~49 at. % Se and ~53 at. % Fe, and temperatures up to ~450 °C. The low temperature stable phases are the tetragonal PbO-structure (P4/nmm) β-Fe1−xSe and α-Fe7Se8. The high temperature phase is the hexagonal, NiAs structure (P63/mmc) δ-Fe1−xSe. Iron(II) selenide occurs naturally as the NiAs-structure mineral achavalite.
More selenium rich iron selenide phases are the γ phases (γ and γˈ), assigned the Fe3Se4 stoichiometry, and FeSe2, which occurs as the marcasite-structure natural mineral ferroselite, or the rare pyrite-structure mineral dzharkenite.
It is used in electrical semiconductors.{{citation needed|date=July 2017}}
Superconductivity
β-FeSe is the simplest iron-based superconductor but with diverse properties.{{Cite journal|author1=Yu. V. Pustovit |author2=A. A. Kordyuk |year=2016 |title=Metamorphoses of electronic structure of FeSe-based superconductors (Review article) |journal=Low Temp. Phys. |volume=42 |issue=11 |page=995 |doi=10.1063/1.4969896 |arxiv=1608.07751|bibcode=2016LTP....42..995P |s2cid=119184569 }} It starts to superconduct at 8 K at normal pressure{{Cite journal|author=F.-C. Hsu |year=2008 |title=Superconductivity in the PbO-type structure α-FeSe |journal=Proc. Natl. Acad. Sci. USA |volume=105 |issue=38 |arxiv=0807.2369|display-authors=etal |doi=10.1073/pnas.0807325105 |pmid=18776050 |pmc=2531064 |pages=14262–14264|bibcode=2008PNAS..10514262H |doi-access=free }} but its critical temperature (Tc) is dramatically increased to 38 K under pressure,{{cite journal|doi=10.1038/nmat2491|pmid=19525948|title=Electronic and Magnetic Phase Diagram of β-Fe1.01Se with superconductivity at 36.7 K under pressure|year=2009|last1=Medvedev|first1=S.|last2=McQueen|first2=T. M.|last3=Troyan|first3=I. A.|last4=Palasyuk|first4=T.|last5=Eremets|first5=M. I.|last6=Cava|first6=R. J.|last7=Naghavi|first7=S.|last8=Casper|first8=F.|last9=Ksenofontov|first9=V.|last10=Wortmann|first10=G.|last11=Felser|first11=C.|journal=Nature Materials|volume=8|issue=8|pages=630–633|arxiv = 0903.2143 |bibcode = 2009NatMa...8..630M |s2cid=117714394 }} by means of intercalation, or after quenching at high pressures.{{cite journal |last1=Deng |first1=Liangzi |last2=Bontke |first2=Trevor |last3=Dahal |first3=Rabin |last4=Xie |first4=Yu |last5=Gao |first5=Bin |last6=Li |first6=Xue |last7=Yin |first7=Ketao |last8=Gooch |first8=Melissa |last9=Rolston |first9=Donald |last10=Chen |first10=Tong |last11=Wu |first11=Zheng |last12=Ma |first12=Yanming |last13=Dai |first13=Pengcheng |last14=Chu |first14=Ching-Wu |title=Pressure-induced high-temperature superconductivity retained without pressure in FeSe single crystals |journal=Proceedings of the National Academy of Sciences |date=13 July 2021 |volume=118 |issue=28 |pages=e2108938118 |doi=10.1073/pnas.2108938118 | arxiv=2104.05662 |pmid=34234019 |pmc=8285973 |bibcode=2021PNAS..11808938D |doi-access=free }} The combination of both intercalation and pressure results in re-emerging superconductivity at 48 K.
In 2013 it was reported that a single atomic layer of FeSe epitaxially grown on SrTiO3 is superconductive with a then-record transition temperature for iron-based superconductors of 70 K.{{Cite journal|author=R. Peng |year=2014 |title=Enhanced superconductivity and evidence for novel pairing in single-layer FeSe on SrTiO3 thin film under large tensile strain |journal=Physical Review Letters |volume=112 |issue=10 |page=107001 |arxiv=1310.3060|display-authors=etal |doi=10.1103/PhysRevLett.112.107001 |pmid=24679321 |bibcode=2014PhRvL.112j7001P|s2cid=118446521 }} This discovery has attracted significant attention and in 2014 a superconducting transition temperature of over 100K was reported for this system.{{cite journal |author=J.-F. Ge |year=2014 |title=Superconductivity in single-layer films of FeSe with a transition temperature above 100 K |journal=Nature Materials |volume=14 |issue=3 |pages=285–9 |doi=10.1038/nmat4153 |pmid=25419814 |arxiv=1406.3435 |display-authors=etal |bibcode=2015NatMa..14..285G|s2cid=119227626 }}
References
{{reflist}}
{{Iron compounds}}
{{Selenides}}
Category:Semiconductor materials