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Iron oxide - Wikipedia

From Wikipedia, the free encyclopedia

Iron oxides are chemical compounds composed of iron and oxygen. Several iron oxides are recognized. Often they are non-stoichiometric. Ferric oxyhydroxides are a related class of compounds, perhaps the best known of which is rust.^[1]

Iron oxides and oxyhydroxides are widespread in nature and play an important role in many geological and biological processes. They are used as iron ores, pigments, catalysts, and in thermite, and occur in hemoglobin. Iron oxides are inexpensive and durable pigments in paints, coatings and colored concretes. Colors commonly available are in the "earthy" end of the yellow/orange/red/brown/black range. When used as a food coloring, it has E number E172.

Stoichiometries

Iron oxide pigment. The brown color indicates that iron is at the oxidation state +3.

Iron oxides feature as ferrous (Fe(II)) or ferric (Fe(III)) or both. They adopt octahedral or tetrahedral coordination geometry. Only a few oxides are significant at the earth's surface, particularly wüstite, magnetite, and hematite.

Oxides of Fe^II
- FeO: iron(II) oxide, wüstite
Mixed oxides of Fe^II and Fe^III
- Fe₃O₄: Iron(II,III) oxide, magnetite
- Fe₄O₅^[2]
- Fe₅O₆^[3]
- Fe₅O₇^[4]
- Fe₂₅O₃₂^[4]
- Fe₁₃O₁₉^[5]
Oxides of Fe^III
- Fe₂O₃: iron(III) oxide
  - α-Fe₂O₃: alpha phase, hematite
  - β-Fe₂O₃: beta phase
  - γ-Fe₂O₃: gamma phase, maghemite
  - ε-Fe₂O₃: epsilon phase

Thermal expansion


Iron oxide	CTE (× 10⁻⁶ °C⁻¹)
Fe₂O₃	14.9^[6]
Fe₃O₄	>9.2^[6]
FeO	12.1^[6]

Oxide-hydroxides

goethite (α-FeOOH)
akaganéite (β-FeOOH)
lepidocrocite (γ-FeOOH)
feroxyhyte (δ-FeOOH)
ferrihydrite (Fe₅HO₈ · 4 H₂O approx., or 5 Fe₂O₃ · 9 H₂O, better recast as FeOOH · 0.4 H₂O)
high-pressure pyrite-structured FeOOH.^[7] Once dehydration is triggered, this phase may form FeO₂H_x (0 < x < 1).^[8]
green rust (Fe^III
_xFe^II
_yOH_{3x + y − z} (A⁻)_z where A⁻ is Cl⁻ or 0.5 SO2−4)

Reactions

In blast furnaces and related factories, iron oxides are converted to the metal. Typical reducing agents are various forms of carbon. A representative reaction starts with ferric oxide:^[9]

2 Fe₂O₃ + 3 C → 4 Fe + 3 CO₂

In nature

Iron is stored in many organisms in the form of ferritin, which is a ferrous oxide encased in a solubilizing protein sheath.^[10]

Species of bacteria, including Shewanella oneidensis, Geobacter sulfurreducens and Geobacter metallireducens, use iron oxides as terminal electron acceptors.^[11]

Uses

Almost all iron ores are oxides, so in that sense these materials are important precursors to iron metal and its many alloys.

Iron oxides are important pigments, coming in a variety of colors (black, red, yellow). Among their many advantages, they are inexpensive, strongly colored, and nontoxic.^[12]

Magnetite is a component of magnetic recording tapes.

References

^ Cornell., RM.; Schwertmann, U (2003). The iron oxides: structure, properties, reactions, occurrences and. Wiley VCH. ISBN 978-3-527-30274-1.
^ Lavina, B.; Dera, P.; Kim, E.; Meng, Y.; Downs, R. T.; Weck, P. F.; Sutton, S. R.; Zhao, Y. (Oct 2011). "Discovery of the recoverable high-pressure iron oxide Fe4O5". Proceedings of the National Academy of Sciences. 108 (42): 17281–17285. Bibcode:2011PNAS..10817281L. doi:10.1073/pnas.1107573108. PMC 3198347. PMID 21969537.
^ Lavina, Barbara; Meng, Yue (2015). "Synthesis of Fe5O6". Science Advances. 1 (5): e1400260. doi:10.1126/sciadv.1400260. PMC 4640612. PMID 26601196.
^ ^a ^b Bykova, E.; Dubrovinsky, L.; Dubrovinskaia, N.; Bykov, M.; McCammon, C.; Ovsyannikov, S. V.; Liermann, H. -P.; Kupenko, I.; Chumakov, A. I.; Rüffer, R.; Hanfland, M.; Prakapenka, V. (2016). "Structural complexity of simple Fe2O3 at high pressures and temperatures". Nature Communications. 7: 10661. Bibcode:2016NatCo...710661B. doi:10.1038/ncomms10661. PMC 4753252. PMID 26864300.
^ Merlini, Marco; Hanfland, Michael; Salamat, Ashkan; Petitgirard, Sylvain; Müller, Harald (2015). "The crystal structures of Mg2Fe2C4O13, with tetrahedrally coordinated carbon, and Fe13O19, synthesized at deep mantle conditions". American Mineralogist. 100 (8–9): 2001–2004. Bibcode:2015AmMin.100.2001M. doi:10.2138/am-2015-5369. S2CID 54496448.
^ ^a ^b ^c Fakouri Hasanabadi, M.; Kokabi, A.H.; Nemati, A.; Zinatlou Ajabshir, S. (February 2017). "Interactions near the triple-phase boundaries metal/glass/air in planar solid oxide fuel cells". International Journal of Hydrogen Energy. 42 (8): 5306–5314. doi:10.1016/j.ijhydene.2017.01.065. ISSN 0360-3199.
^ Nishi, Masayuki; Kuwayama, Yasuhiro; Tsuchiya, Jun; Tsuchiya, Taku (2017). "The pyrite-type high-pressure form of FeOOH". Nature. 547 (7662): 205–208. Bibcode:2017Natur.547..205N. doi:10.1038/nature22823. ISSN 1476-4687. PMID 28678774. S2CID 205257075.
^ Hu, Qingyang; Kim, Duckyoung; Liu, Jin; Meng, Yue; Liuxiang, Yang; Zhang, Dongzhou; Mao, Wendy L.; Mao, Ho-kwang (2017). "Dehydrogenation of goethite in Earth's deep lower mantle". Proceedings of the National Academy of Sciences. 114 (7): 1498–1501. Bibcode:2017PNAS..114.1498H. doi:10.1073/pnas.1620644114. PMC 5320987. PMID 28143928.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 1072. ISBN 978-0-08-037941-8.
^ Honarmand Ebrahimi, Kourosh; Hagedoorn, Peter-Leon; Hagen, Wilfred R. (2015). "Unity in the Biochemistry of the Iron-Storage Proteins Ferritin and Bacterioferritin". Chemical Reviews. 115 (1): 295–326. doi:10.1021/cr5004908. PMID 25418839.
^ Bretschger, O.; Obraztsova, A.; Sturm, C. A.; Chang, I. S.; Gorby, Y. A.; Reed, S. B.; Culley, D. E.; Reardon, C. L.; Barua, S.; Romine, M. F.; Zhou, J.; Beliaev, A. S.; Bouhenni, R.; Saffarini, D.; Mansfeld, F.; Kim, B.-H.; Fredrickson, J. K.; Nealson, K. H. (20 July 2007). "Current Production and Metal Oxide Reduction by Shewanella oneidensis MR-1 Wild Type and Mutants". Applied and Environmental Microbiology. 73 (21): 7003–7012. Bibcode:2007ApEnM..73.7003B. doi:10.1128/AEM.01087-07. PMC 2223255. PMID 17644630.
^ Buxbaum, Gunter; Printzen, Helmut; Mansmann, Manfred; Räde, Dieter; Trenczek, Gerhard; Wilhelm, Volker; Schwarz, Stefanie; Wienand, Henning; Adel, Jörg; Adrian, Gerhard; Brandt, Karl; Cork, William B.; Winkeler, Heinrich; Mayer, Wielfried; Schneider, Klaus (2009). "Pigments, Inorganic, 3. Colored Pigments". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.n20_n02. ISBN 978-3527306732.

External links

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Iron compounds

Fe(−II)

Fe(0)

Fe(I)

Organoiron(I) compounds	(C₅H₅FeCO)₂(CO)₂

Fe(0,II)

Fe₃C

Fe(II)

Organoiron(II) compounds	Fe(C₅H₅)₂ Fe(C₅H₅)(CO)₂I Fe(C₅H₄P(C₆H₅)₂)₂ C₄H₄Fe(CO)₃ C₄H₆Fe(CO)₃

Fe(0,III)

FeSi
FeGe

Fe(II,III)

Fe(III)

Organoiron(III) compounds	Fe(C₅H₅)₂BF₄ C₆H₈O₇·xFe³⁺·yNH₃ C ₅₄H ₁₀₅FeO ₆

Fe(IV)

FeF₄

Fe(VI)

Purported

Hemolithin (protein)

sort

v t e Oxides
Mixed oxidation states	Antimony tetroxide (Sb₂O₄) Boron suboxide (B₁₂O₂) Carbon suboxide (C₃O₂) Chlorine perchlorate (Cl₂O₄) Chloryl perchlorate (Cl₂O₆) Cobalt(II,III) oxide (Co₃O₄) Dichlorine pentoxide (Cl₂O₅) Iron(II,III) oxide (Fe₃O₄) Lead(II,IV) oxide (Pb₃O₄) Manganese(II,III) oxide (Mn₃O₄) Mellitic anhydride (C₁₂O₉) Praseodymium(III,IV) oxide (Pr₆O₁₁) Silver(I,III) oxide (Ag₂O₂) Terbium(III,IV) oxide (Tb₄O₇) Tribromine octoxide (Br₃O₈) Triuranium octoxide (U₃O₈)
+1 oxidation state	Aluminium(I) oxide (Al₂O) Copper(I) oxide (Cu₂O) Caesium monoxide (Cs₂O) Dibromine monoxide (Br₂O) Dicarbon monoxide (C₂O) Dichlorine monoxide (Cl₂O) Gallium(I) oxide (Ga₂O) Iodine(I) oxide (I₂O) Lithium oxide (Li₂O) Mercury(I) oxide (Hg₂O) Nitrous oxide (N₂O) Potassium oxide (K₂O) Rubidium oxide (Rb₂O) Silver oxide (Ag₂O) Thallium(I) oxide (Tl₂O) Sodium oxide (Na₂O) Water (hydrogen oxide) (H₂O)
+2 oxidation state	Aluminium(II) oxide (AlO) Barium oxide (BaO) Berkelium monoxide (BkO) Beryllium oxide (BeO) Boron monoxide (BO) Bromine monoxide (BrO) Cadmium oxide (CdO) Calcium oxide (CaO) Carbon monoxide (CO) Chlorine monoxide (ClO) Chromium(II) oxide (CrO) Cobalt(II) oxide (CoO) Copper(II) oxide (CuO) Dinitrogen dioxide (N₂O₂) Europium(II) oxide (EuO) Germanium monoxide (GeO) Iron(II) oxide (FeO) Iodine monoxide (IO) Lead(II) oxide (PbO) Magnesium oxide (MgO) Manganese(II) oxide (MnO) Mercury(II) oxide (HgO) Nickel(II) oxide (NiO) Nitric oxide (NO) Niobium monoxide (NbO) Palladium(II) oxide (PdO) Phosphorus monoxide (PO) Polonium monoxide (PoO) Protactinium monoxide (PaO) Radium oxide (RaO) Silicon monoxide (SiO) Strontium oxide (SrO) Sulfur monoxide (SO) Disulfur dioxide (S₂O₂) Thorium monoxide (ThO) Tin(II) oxide (SnO) Titanium(II) oxide (TiO) Vanadium(II) oxide (VO) Yttrium(II) oxide (YO) Zirconium monoxide (ZrO) Zinc oxide (ZnO)
+3 oxidation state	Actinium(III) oxide (Ac₂O₃) Aluminium oxide (Al₂O₃) Americium(III) oxide (Am₂O₃) Antimony trioxide (Sb₂O₃) Arsenic trioxide (As₂O₃) Berkelium(III) oxide (Bk₂O₃) Bismuth(III) oxide (Bi₂O₃) Boron trioxide (B₂O₃) Caesium sesquioxide (Cs₂O₃) Californium(III) oxide (Cf₂O₃) Cerium(III) oxide (Ce₂O₃) Chromium(III) oxide (Cr₂O₃) Cobalt(III) oxide (Co₂O₃) Dinitrogen trioxide (N₂O₃) Dysprosium(III) oxide (Dy₂O₃) Einsteinium(III) oxide (Es₂O₃) Erbium(III) oxide (Er₂O₃) Europium(III) oxide (Eu₂O₃) Gadolinium(III) oxide (Gd₂O₃) Gallium(III) oxide (Ga₂O₃) Gold(III) oxide (Au₂O₃) Holmium(III) oxide (Ho₂O₃) Indium(III) oxide (In₂O₃) Iron(III) oxide (Fe₂O₃) Lanthanum oxide (La₂O₃) Lutetium(III) oxide (Lu₂O₃) Manganese(III) oxide (Mn₂O₃) Neodymium(III) oxide (Nd₂O₃) Nickel(III) oxide (Ni₂O₃) Phosphorus trioxide (P₄O₆) Praseodymium(III) oxide (Pr₂O₃) Promethium(III) oxide (Pm₂O₃) Rhodium(III) oxide (Rh₂O₃) Samarium(III) oxide (Sm₂O₃) Scandium oxide (Sc₂O₃) Terbium(III) oxide (Tb₂O₃) Thallium(III) oxide (Tl₂O₃) Thulium(III) oxide (Tm₂O₃) Titanium(III) oxide (Ti₂O₃) Tungsten(III) oxide (W₂O₃) Vanadium(III) oxide (V₂O₃) Ytterbium(III) oxide (Yb₂O₃) Yttrium(III) oxide (Y₂O₃)
+4 oxidation state	Americium dioxide (AmO₂) Berkelium(IV) oxide (BkO₂) Bromine dioxide (BrO₂) Californium dioxide (CfO₂) Carbon dioxide (CO₂) Carbon trioxide (CO₃) Cerium(IV) oxide (CeO₂) Chlorine dioxide (ClO₂) Chromium(IV) oxide (CrO₂) Curium(IV) oxide (CmO₂) Dinitrogen tetroxide (N₂O₄) Germanium dioxide (GeO₂) Iodine dioxide (IO₂) Iridium dioxide (IrO₂) Hafnium(IV) oxide (HfO₂) Lead dioxide (PbO₂) Manganese dioxide (MnO₂) Molybdenum dioxide (MoO₂) Neptunium(IV) oxide (NpO₂) Nitrogen dioxide (NO₂) Niobium dioxide (NbO₂) Osmium dioxide (OsO₂) Platinum dioxide (PtO₂) Plutonium(IV) oxide (PuO₂) Polonium dioxide (PoO₂) Praseodymium(IV) oxide (PrO₂) Protactinium(IV) oxide (PaO₂) Rhenium(IV) oxide (ReO₂) Rhodium(IV) oxide (RhO₂) Ruthenium(IV) oxide (RuO₂) Selenium dioxide (SeO₂) Silicon dioxide (SiO₂) Sulfur dioxide (SO₂) Technetium(IV) oxide (TcO₂) Tellurium dioxide (TeO₂) Terbium(IV) oxide (TbO₂) Thorium dioxide (ThO₂) Tin dioxide (SnO₂) Titanium dioxide (TiO₂) Tungsten(IV) oxide (WO₂) Uranium dioxide (UO₂) Vanadium(IV) oxide (VO₂) Zirconium dioxide (ZrO₂)
+5 oxidation state	Antimony pentoxide (Sb₂O₅) Arsenic pentoxide (As₂O₅) Bismuth pentoxide (Bi₂O₅) Dinitrogen pentoxide (N₂O₅) Niobium pentoxide (Nb₂O₅) Phosphorus pentoxide (P₂O₅) Protactinium(V) oxide (Pa₂O₅) Tantalum pentoxide (Ta₂O₅) Tungsten pentoxide (W₂O₅) Vanadium(V) oxide (V₂O₅)
+6 oxidation state	Chromium trioxide (CrO₃) Molybdenum trioxide (MoO₃) Polonium trioxide (PoO₃) Rhenium trioxide (ReO₃) Selenium trioxide (SeO₃) Sulfur trioxide (SO₃) Tellurium trioxide (TeO₃) Tungsten trioxide (WO₃) Uranium trioxide (UO₃) Xenon trioxide (XeO₃)
+7 oxidation state	Dichlorine heptoxide (Cl₂O₇) Manganese heptoxide (Mn₂O₇) Rhenium(VII) oxide (Re₂O₇) Technetium(VII) oxide (Tc₂O₇)
+8 oxidation state	Iridium tetroxide (IrO₄) Osmium tetroxide (OsO₄) Ruthenium tetroxide (RuO₄) Xenon tetroxide (XeO₄) Hassium tetroxide (HsO₄)
Related	Oxocarbon Suboxide Oxyanion Ozonide Peroxide Superoxide Oxypnictide
Oxides are sorted by oxidation state. Category:Oxides

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