Iron(II) selenide

Iron(II) selenide

Names
IUPAC name Iron(II) selenide
Identifiers
CAS Number	1310-32-3 Y
3D model (JSmol)	Interactive image
ECHA InfoCard	100.013.798
EC Number	215-177-1
PubChem CID	14795
UNII	64EUH87C9Z Y
CompTox Dashboard (EPA)	DTXSID1061653
InChI InChI=1S/Fe.Se Key: WALCGGIJOOWJIN-UHFFFAOYSA-N
SMILES [Fe]=[Se]
Properties
Chemical formula	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)
Solubility in water	0.975 mg/100mL[citation needed]
Structure
Crystal structure	hexagonal / tetragonal
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	toxic
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). Infobox references

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-Fe_1−xSe and α-Fe₇Se₈. The high temperature phase is the hexagonal, NiAs structure (P6₃/mmc) δ-Fe_1−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]}