Iron(II) chromite

Iron(II) chromite
Names
	IUPAC name Iron(2+) chromite
	Other names Ferrous chromite;
Identifiers
CAS Number	1308-31-2;
3D model (JSmol)	Interactive image;
ChemSpider	65793926;
ECHA InfoCard	100.013.782
EC Number	215-159-3;
PubChem CID	129627662;
RTECS number	GB4000000;
UNII	W86U2Q2334;
CompTox Dashboard (EPA)	DTXSID10892418 ;
	InChI InChI=1S/2Cr.Fe.4O/q;;+2;;;2*-1 Key: VUIWSEWFMMYPHW-UHFFFAOYSA-N;
	SMILES O=[Cr][O-].O=[Cr][O-].[Fe+2];
Properties
Chemical formula	FeCr2O4
Molar mass	223.833 g·mol−1
Appearance	Brown-black solid
Density	5.0 g/cm3
Melting point	2,190 to 2,270 °C (3,970 to 4,120 °F; 2,460 to 2,540 K)
Solubility in water	insoluble
Refractive index (nD)	2.16
Structure
Crystal structure	cubic
Space group	Fd-3m (No. 227)
Lattice constant	a = 8.378 Å α = 90°, β = 90°, γ = 90°
Hazards
	GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302+H332, H317
Precautionary statements	P261, P280, P301+P312, P304+P340, P312, P501
Threshold limit value (TLV)	0.5 mg/m3 (as Cr, long term value)
	NIOSH (US health exposure limits):
PEL (Permissible)	0.5 mg/m3 (as Cr, long term value)
Related compounds
Other anions	Iron(III) chromate
Other cations	Copper chromite
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Iron(II) chromite is an inorganic compound with the chemical formula FeCr₂O₄.

Occurrence

Iron(II) chromite occurs in mineral form as chromite. It is used as a commercial source of chromium and its compounds.^[1]

Iron(II) chromite can be prepared by heating chromium(III) oxide and iron(III) oxide at 1,200 °C (2,190 °F) for 24 h in a controlled oxygen fugacity.^[6] Single crystals can be prepared by floating zone crystal growth.^[5]

Iron(II) chromite exhibits polymorphism. At standard conditions it forms a cubic spinel-type structure. A cubic-tetragonal phase transition occurs at 135 K (−138 °C; −217 °F), followed by a tetragonal-orthorhombic transition at 70 K (−203.2 °C; −333.7 °F).^[5] The space group of the tetragonal phase is I4₁/amd.^[5]

It is used as a catalyst in the synthesis of hydrogen (H₂) from the reaction between carbon monoxide and water vapor.

1 2 3 Perry, Dale L. (2016-04-19). Handbook of Inorganic Compounds. CRC Press. p. 174. ISBN 978-1-4398-1462-8.
↑ Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton, Florida: CRC Press. pp. 4–67. ISBN 9781498754293.
1 2 3 4 "SDS - Iron(II) chromite" (PDF). ltschem.com. Orangeburg, NY, USA: LTS Research Laboratories. 10 July 2015. pp. 1, 3. Retrieved 14 June 2026.
↑ Shirane, G.; Cox, D. E.; Pickart, S. J. (1964-03-01). "Magnetic Structures in FeCr2S4 and FeCr2O4". Journal of Applied Physics. 35 (3): 954–955. doi:10.1063/1.1713556. ISSN 0021-8979.
1 2 3 4 Nakamura, Shin; Fuwa, Akio (2015-01-01). Spin Order in FeCr2O4 Observed by Mössbauer Spectroscopy. 20th International Conference on Magnetism, ICM 2015. Physics Procedia. Vol. 75. pp. 747–754. doi:10.1016/j.phpro.2015.12.097. ISSN 1875-3892.
↑ Ishii, Takayuki; Kojitani, Hiroshi; Tsukamoto, Shoichi; Fujino, Kiyoshi; Mori, Daisuke; Inaguma, Yoshiyuki; Tsujino, Noriyoshi; Yoshino, Takashi; Yamazaki, Daisuke; Higo, Yuji; Funakoshi, Kenichi; Akaogi, Masaki (2014-08-01). "High-pressure Phase Transitions in FeCr₂O₄ and Structure Analysis of New Post-spinel FeCr₂O₄ and Fe₂Cr₂O₅ Phases with Meteoritical and Petrological Implications". American Mineralogist. 99 (8–9): 1788–1797. doi:10.2138/am.2014.4736. ISSN 1945-3027.