iron(III) phosphate
{{Chembox
| ImageFile1 = FePO4 structure.png
| ImageSize1 = 200px
| ImageFile2 = Iron(III)-phosphate-pentahydrate-sample.jpg
| ImageSize2 = 200px
| ImageName = Iron(III) phosphate pentahydrate
| IUPACName = Iron(III) phosphate
| OtherNames = Ferric orthophosphate, Ferric phosphate
|Section1={{Chembox Identifiers
| CASNo = 10045-86-0
| CASNo_Comment = (anhydrous)
| CASNo1 = 13463-10-0
| CASNo1_Comment = (dihydrate)
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = N6BAA189V1
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 23244
| PubChem = 24861
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 131371
| SMILES = [O-]P(=O)([O-])[O-].[Fe+3]
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/Fe.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+3;/p-3
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = WBJZTOZJJYAKHQ-UHFFFAOYSA-K
}}
|Section2={{Chembox Properties
| Formula = FePO4
| MolarMass = 150.815 g/mol (anhydrous)
| Appearance = yellow-brown solid
| Density = 3.056 g/cm3 (anhydrous)
2.87 g/cm3 (20 °C, dihydrate)
| MeltingPtC = 250
| MeltingPt_notes =
(dihydrate) decomposes
| BoilingPtC =
| Solubility = anhydrous:
insoluble
dihydrate:
0.642 g/100 mL (100 °C){{cite web|title=iron(III) phosphate dihydrate|url=http://chemister.ru/Database/properties-en.php?dbid=1&id=4418|website=chemister.ru|access-date=3 July 2014}}
| SolubilityProduct = 9.91{{e|−16}}{{cite book |author1=John Rumble |title=CRC Handbook of Chemistry and Physics |date=June 18, 2018 |publisher=CRC Press |isbn=978-1138561632 |pages=5–188|edition=99 |language=English}}
| MagSus = +11,500.0·10−6 cm3/mol
}}
|Section3={{Chembox Thermochemistry
| DeltaGf =
| DeltaHc =
| DeltaHf = −1888 kJ/mol (dihydrate)
| Entropy = 171.3 J/mol·K (dihydrate)
| HeatCapacity = 180.5 J/mol·K (dihydrate)
}}
|Section4={{Chembox Hazards
| GHSPictograms = {{GHS07}}{{Sigma-Aldrich|id=436011|name=Iron(III) phosphate dihydrate|accessdate=2014-05-03}}
| GHSSignalWord = Warning
| HPhrases = {{H-phrases|315|319|335}}
| PPhrases = {{P-phrases|261|305+351+338}}
| MainHazards =
| FlashPt =
| AutoignitionPt =
}}
}}
Iron(III) phosphate or ferric phosphate{{cite web|title=Iron(III) Phosphate|url=https://pubchem.ncbi.nlm.nih.gov/compound/ferric_phosphate|website=NIH, U.S. National Library of Medicine|access-date=22 January 2016}}{{cite web|title=FERRIC PHOSPHATE|url=http://www.endmemo.com/chem/compound/fepo4.php|website=EndMemo.com|access-date=22 January 2016}} is an inorganic compound with the formula FePO4. Four polymorphs of anhydrous FePO4 are known. Additionally, two polymorphs of the dihydrate FePO4·(H2O)2 are known. These polymorphs have attracted interest as potential cathode materials in batteries.
Structure
The most common form of FePO4 adopts the structure of α-quartz. As such the material consists of tetrahedral Fe(III) and phosphate sites.{{cite journal |doi=10.1524/zkri.218.3.193.20755|title=A neutron diffraction study of quartz-type FePO4: High-temperature behavior and α–β phase transition|year=2003|last1=Haines|first1=J.|last2=Cambon|first2=O.|last3=Hull|first3=S.|journal=Zeitschrift für Kristallographie - Crystalline Materials|volume=218|issue=3|page=193|bibcode=2003ZK....218..193H|s2cid=98195900}} As such the P and Fe have tetrahedral molecular geometry. At high pressures, a phase change occurs to a more dense structure with octahedral Fe centres. Two orthorhombic structures and a monoclinic phase are also known. In the two polymorphs of the dihydrate, the Fe centre is octahedral with two mutually cis water ligands.{{cite journal|last1=Zaghib|first1=K.|last2=Julien|first2=C. M.|title=Structure and electrochemistry of FePO4·2H2O hydrate|journal=Journal of Power Sources|date=January 2005|volume=142|issue=1–2|pages=279–284|doi=10.1016/j.jpowsour.2004.09.042|bibcode=2005JPS...142..279Z|url=https://www.researchgate.net/publication/245105788|access-date=3 July 2014}}
Uses
{{See also|Phosphate conversion coating}}
Iron(III) phosphate can be used in steel and metal manufacturing processes. When bonded to a metal surface, iron phosphate prevents further oxidation of the metal. Its presence is partially responsible for the corrosion resistance of the iron pillar of Delhi.
Iron phosphate coatings are commonly used in preparation for painting or powder coating, in order to increase adhesion to the iron or steel substrate, and prevent corrosion, which can cause premature failure of subsequent coating processes.
It can also be used for bonding fabrics, wood, and other materials to iron or steel surfaces.{{Cn|date=April 2023}}
Iron phosphate is used{{Cite web |title=Lithium iron phosphate comes to America |url=https://cen.acs.org/energy/energy-storage-/Lithium-iron-phosphate-comes-to-America/101/i4 |access-date=2023-09-12 |website=Chemical & Engineering News |language=en}} to make lithium iron phosphate, the cathode in lithium iron phosphate batteries.Roncal-Herrero, T., Rodriguez-Blanco, J.D., Benning, L.G., Oelkers, E.H. (2009) Precipitation of Iron and Aluminium Phosphates Directly from Aqueous Solution as a Function of Temperature from 50 to 200°C. Crystal Growth & Design, 9, 5197-5205. doi: 10.1021/cg900654m.{{cite journal|last1=Song|first1=Y.|last2=Zavalij|first2=P. Y.|last3=Suzuki|first3=M.|last4=Whittingham|first4=M. S.|title=New Iron(III) Phosphate Phases: Crystal Structure and Electrochemical and Magnetic Properties|journal=Inorganic Chemistry|year=2002|volume=41|pages=5778–5786|doi=10.1021/ic025688q|url=http://materials.binghamton.edu/whittingham/pdfpapers/IC_41_5778_02.pdf|access-date=3 July 2014|pmid=12401083|issue=22|archive-url=https://web.archive.org/web/20140714114934/http://materials.binghamton.edu/whittingham/pdfpapers/IC_41_5778_02.pdf|archive-date=14 July 2014|url-status=dead|df=dmy-all}}
=Pesticide=
Iron phosphate is one of the few molluscicides approved for use in the practice of organic farming.{{cite web|title=COMMISSION REGULATION (EC) No 889/2008|url=http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:2008R0889:20130101:EN:PDF|website=European Union law|access-date=3 July 2014}} Pesticide pellets contain iron phosphate plus a chelating agent, such as EDTA.{{cite web|url=http://www.regional.org.au/au/asa/2001/6/c/young.htm|title=The Regional Institute - Slugs, Snails and Iron based Baits: An Increasing Problem and a Low Toxic Specific Action Solution 1|date=11 September 2018|website=www.regional.org.au}}
Mineral
Strengite is the mineral form of hydrated ferric phosphate.
Legislation
Iron(III) phosphate is not allowed as food additive in the European Union. It was withdrawn from the list of allowed substances in the directive 2002/46/EC in 2007.
See also
- Iron(II) phosphate, commonly known as ferrous phosphate, the lower phosphate of iron
- Lithium iron phosphate battery, a battery that uses iron phosphate
- Phosphate conversion coating, an industrial process used to protect newly manufactured iron and steel from corrosion
References
{{reflist}}
External links
{{Commons category|Iron(III) phosphate}}
{{Iron compounds}}
{{Phosphates}}