| Names | |
|---|---|
| IUPAC name Iron(II) selenide | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| ECHA InfoCard | 100.013.798 |
| EC Number |
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PubChem CID | |
| UNII | |
CompTox Dashboard (EPA) | |
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| Properties | |
| FeSe | |
| Molar mass | 134.807 g/mol |
| Appearance | black crystals |
| Density | 4.72 g/cm3 |
| Melting point | 965 °C (1,769 °F; 1,238 K) |
| 0.975 mg/100mL[ citation needed ] | |
| Structure | |
| hexagonal / tetragonal | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards | toxic |
| GHS labelling: | |
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| Danger | |
| H301, H331, H373, H410 | |
| P260, P261, P264, P270, P271, P273, P301+P316, P304+P340, P316, P319, P321, P330, P391, P403+P233, P405, P501 | |
| Related compounds | |
Other anions | Iron(II) oxide Iron(II) sulfide Iron(II) telluride |
Other cations | Manganese(II) selenide Cobalt(II) selenide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Iron(II) selenide refers to a number of inorganic compounds of ferrous iron and selenide (Se2−). The phase diagram of the system Fe–Se [1] 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 ]
β-FeSe is the simplest iron-based superconductor but with diverse properties. [2] It starts to superconduct at 8 K at normal pressure [3] but its critical temperature (Tc) is dramatically increased to 38 K under pressure, [4] by means of intercalation, [2] or after quenching at high pressures. [5] The combination of both intercalation and pressure results in re-emerging superconductivity at 48 K. [2]
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. [6] This discovery has attracted significant attention and in 2014 a superconducting transition temperature of over 100K was reported for this system. [7]