Iron(III) phosphate

Iron(III) phosphate, also ferric phosphate, is the inorganic compound with the formula FePO₄. Several related materials are known, including four polymorphs of FePO₄ and two polymorphs of the dihydrate FePO₄·(H₂O)₂. These materials find several technical applications as well as occurring in the mineral kingdom.

Uses

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.

Anhydrous iron phosphate has been investigated as an intercalation electrode in a lithium-ion battery despite having low electronic conductivity.

Pesticide

Iron phosphate is one of the few molluscicides approved for use in the practice of organic farming.

Pesticide pellets containing iron phosphate plus a chelating agent, such as EDTA, leach heavy metals from soil into groundwater. The Research Institute of Organic Agriculture (FiBL) reported the EDTA content and stated products were likely to be no safer than metaldehyde baits. Ferric phosphate slug and snail baits marketed in the U.S. contain EDTA