Iron(II) selenide

Iron(II) selenide
Names
	IUPAC name Iron(II) selenide
Identifiers
CAS Number	1310-32-3 ;
3D model (JSmol)	Interactive image;
ChemSpider	14262536;
ECHA InfoCard	100.013.798
EC Number	215-177-1;
PubChem CID	14795;
UNII	64EUH87C9Z ;
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
Structure
Crystal structure	hexagonal / tetragonal
Hazards
	Occupational safety and health (OHS/OSH):
Main hazards	toxic
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H331, H373, H410
Precautionary statements	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). 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 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.