Iron(II,III) sulfide

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Iron(II,III) sulfide
Other names

Ferrous-ferric sulfide, greigite

Properties
Molecular formula FeS·Fe2S3
Molar mass 295.805
Appearance Bluish-black, pinkish
Density 4.049 g/cm3
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Iron(II,III) sulfide is a blue-black (sometimes pinkish) chemical compound of iron and sulfur with formula Fe3S4 or FeS·Fe2S3, which is much similar to iron(II,III) oxide. It occurs naturally as the sulfide mineral greigite and is magnetic. It is a bio-mineral produced by and found in magnetotactic bacteria. It is a mixed valence compound, featuring both Fe2+ and Fe3+ centers, in 1:2 ratio.

Crystal structure

The crystallographic unit cell is cubic, with space group Fd3m. The S anions form a cubic close-packed lattice, and the Fe cations occupy both tetrahedral and octahedral sites.[1][2]

Crystal structure of iron(II,III) sulfide projected along the [110] direction
Emphasis on the SFe4 tetrahedra. 
Emphasis on the FeS4 tetrahedra 
Emphasis on the FeS6 octahedra 

Magnetic and electronic properties

Like the related oxide magnetite (Fe3O4), iron(II,III) sulfide is ferrimagnetic, with the spin magnetic moments of the Fe cations in the tetrahedral sites oriented in the opposite direction as those in the octahedral sites, and a net magnetization. Both metal sites have high spin quantum numbers. The electronic structure of greigite is that of a half metal.[3][4]

References

  1. ↑ Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W. and Nichols, Monte C., ed. (1990). "Greigite" (PDF). Handbook of Mineralogy. I (Elements, Sulfides, Sulfosalts). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209708. Retrieved December 5, 2011. 
  2. ↑ Vaughan, D. J.; Craig, J. R. “Mineral Chemistry of Metal Sulfides" Cambridge University Press, Cambridge: 1978. ISBN 0-521-21489-0.
  3. ↑ Devey, Anthony; R. Grau-Crespo and N.H. de Leeuw (2009). "Electronic and magnetic structure of Fe3S4: GGA+U investigation". Physical Review B 79 (19): 195126. Bibcode:2009PhRvB..79s5126D. doi:10.1103/PhysRevB.79.195126. 
  4. ↑ Wang, Jun; Cao, Shi-He; Wu, Wei; Zhao, Guo-Meng (2011). "The Curie temperature and magnetic exchange energy in half-metallic greigite Fe3S4". Physica Scripta 83 (4): 045702. Bibcode:2011PhyS...83d5702W. doi:10.1088/0031-8949/83/04/045702. 

Further reading

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